American Journal of Infection Control 43 (2015) 522-7
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
journal homepage: www.ajicjournal.org
Major article
Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning Síntia de Souza Evangelista MSc a, *, Simone Gonçalves dos Santos PhD b, Maria Aparecida de Resende Stoianoff PhD b, Adriana Cristina de Oliveira PhD a a b
Department of Basic Nursing, School of Nursing, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil Department of Microbiology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
Key Words: Patient safety Medical device reprocessing Infection Control Microbiology
Background: We aimed to monitor the microbial load and identify the microorganisms recovered from surgical instruments after clinical use and following manual and automated cleaning. Methods: This experimental study was carried out in the Laboratory of Oral Microbiology and Anaerobes at the Federal University of Minas Gerais in Brazil. Microbial samples were taken from 125 surgical instruments used in 25 types of gastrointestinal surgeries. Results: The average microbial load was 93.1 CFU/100 mL after clinical use and 41 CFU/100 mL and 8.24 CFU/100 mL on instruments following 2 sequential steps of manual cleaning, respectively, and 75 CFU/100 mL and 16.1 CFU/100 mL on instruments after automated cleaning. Surgical wound classification significantly affected the microbial load recovered on instruments. Coagulase-negative Staphylococcus, Escherichia coli, Pseudomonas spp, Stenotrophomonas maltophilia, and Acinetobacter baumannii complex were recovered. Conclusions: The average microbial load observed after the cleaning steps decreased, and the decrease in microbial load was more pronounced using the manual method compared with that observed using the automated method. Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Some medical devices (MDs), including most surgical instruments, are manufactured to allow reuse until the limit of their effectiveness and functionality is reached.1 This practice can lead to a reduction in both the costs and the amount of waste generated from single-use items. However, it is necessary to ensure that MDs remain safe for reuse on patients and for manipulation by medical personnel during MD reprocessing to protect them from infection hazards by avoiding microorganism transfer or other adverse events related to the use of MDs.2,3 MD reprocessing involves the use of the following set of standardized and interdependent actions: prewash, reception, cleaning, drying, assessment of integrity and functionality, preparation, disinfection or sterilization, storage, and distribution for reuse.1,4 The reduction in the microbial load on MDs during cleaning is an essential step that increases the safety and reliability of the
* Address correspondence to Síntia de Souza Evangelista, Department of Basic Nursing, School of Nursing, Universidade Federal de Minas Gerais, Rua Progresso, 1399, apt 401 e Caiçara - Belo Horizonte e Minas Gerais, Brazil. E-mail address: [email protected] (S.S. Evangelista). Conflicts of interest: None to report.
sterilization process.1-3 Although directly associated with health care quality, the inadequacy of MD reprocessing has not always been documented as being responsible for complications resulting from the care process, and it is reported only when related to episodes of outbreak.5,6 MDs can be cleaned using a manual method suitable for delicate and complex products, or using automated methods in which ultrasonic and/or decontamination washers are employed; automated cleaning methods are highly recommended because they are more likely than manual methods to be reproducible and they can be validated.1,4,7,8 Although automated cleaning typically provides superior results when compared with manual methods, Vassey et al9-11 noted an increase in residual protein on instruments that had been cleaned in an ultrasonic bath. Regardless of the cleaning method employed, improper maintenance of MDs can increase the bioburden during MD processing.8 The accumulation of proteins, salts, and dirt on MDs protects microorganisms from direct contact with sterilizing agents and favors bacterial adherence and biofilm formation. To be effective, the cleaning methods used must substantially reduce the levels of infectious agents present on MDs, such as bacteria, endotoxins,
0196-6553/$36.00 - Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2014.12.018
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
523
fungi, viruses, organic and inorganic matter that allow microbial growth and survival, and potential pyrogens.1,8 Given the concerns surrounding the appropriate procedures used for cleaning MDs, the aim of this study was to determine the microbial load and microbiologic profile of microorganisms recovered after clinical use and during manual and automated cleaning of surgical instruments used for digestive system surgeries. MATERIALS AND METHODS This experimental study was conducted in the Central Sterile Services Department (CSSD) of a large hospital in partnership with the Oral and Anaerobic Microbiology Laboratory of the Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil. We analyzed 125 instruments that were used in 25 types of gastrointestinal surgical procedures performed in a large teaching hospital; the procedures were classified as cleancontaminated procedures (involving the oral cavity, esophagus, stomach, liver, and biliary tract) and contaminated procedures (involving the large intestine).12 The inclusion criteria for the MDs selected were the following: the surgical instruments had to exhibit similar characteristics such as presence of grooves and joints, they had to be approximately 20 cm long, and they had to harbor visible dirt (eg, blood, organic matter, and inorganic matter) to ensure that a chosen MD was used during surgical procedures. The elected instruments included clamps such as crile, hemostatic, Rochester, Foerster, Kocher, and needle-holders. At the end of each surgical procedure, in the operating theatre, surgical instruments were moistened (for 30-60 minutes) using towels soaked in tap water to keep them wet before being transferred to CSSD for cleaning. We selected 5 instruments once the MDs had been transferred to CSSD, and collected study samples immediately after each of these sequential cleaning steps: (1) clinical use in digestive tract surgeries (representing the sample collected from instruments before cleaning); (2) manual cleaning involving soaking in an enzymatic detergent (Indazyme 6 plus, Indalabor Indaiá laboratório farmacêutico LTDA, Minas Gerais, Brazil, dilution: 2 mL/L water for 5 minutes [the time recommended by the manufacturer]) and brushing under tap water (5 times) by using brushes featuring with soft bristles and by applying firm strokes to detach any visible dirt attached to the instrument (Manual Method - Step 1); (3) manual cleaning and subsequent cleaning in a thermal washer-disinfector (regularly validated according to ISO 15883) (Manual Method - Step 2); (4) automated cleaning in an ultrasonic washer (Automated Method - Step 1); and (5) automated cleaning in an ultrasonic washer, followed by cleaning in an automated washer-disinfector, which was the same used in Step 2 of the manual method (Automated Method - Step 2). Figure 1 shows the steps followed for sample collection. Samples were collected according to methods described previously.2,13e16 On each day of sample collection, only 1 surgical procedure was selected. The elected instruments were transferred to a sterile plastic bag containing 500 mL sterile distilled water; this volume was used to allow complete immersion of all selected instruments. The bag was sealed and then placed in an ultrasonic bath (9 L capacity) for 3 treatments of 5 seconds each applied using an ultrasonic washer (USC-2800 model, Enge Solutions, São Paulo, Brazil), at a frequency of 40 KHz and a power of 30 W. Next, the bag containing the instrument was agitated for 5 minutes at 160 rpm in an orbital shaker (Kline 255-B model, Fanem LTDA, São Paulo, Brazil).13 During each sample collection, instruments were retrieved from the plastic bag using aseptic techniques, and the collected samples were sealed, identified, and transported to the Microbiology Laboratory of the Institute of Biological Sciences,
Fig 1. Sequential steps of manual and automated cleaning processes and respective times of sample collection.
Federal University of Minas Gerais located nearby; samples were transported within 60 minutes in a cooled thermal box whose internal temperature was monitored to ensure adequate preservation of the characteristics of the samples.17 The samples were again agitated in an orbital shaker for 5 minutes at 160 rpm and then filtered (using vacuum) through an autoclavable Sterifil (47-mm Sterifil Holder; Millipore indústria e comércio LTDA, Barueri, São Paulo, Brazil) containing a previously autoclaved cellulose nitrate membrane (0.45 mm; HAWP04700); we collected 100-mL aliquots under a laminar flow hood (Microbiological Biosafe I, Vecco, Campinas, São Paulo, Brazil). The filter membranes were overlaid on selective culture media, MacConkey agar (BBL, Biomérieux, Marcy-l’Étoile, France), Mannitol agar (BBL), and Sabouraud Dextrose Agar (Difco Laboratories, Detroit, Mich), which allowed the growth of specific microorganisms. Furthermore, a nonselective medium, Brain Heart Infusion (BBL) supplemented with 5% horse blood, was used for estimating the total microbial load of the samples. The culture plates were incubated in a bacteriologic incubator (Fanem CD Model 347) at 37 C for 2448 hours, and the number of colonies formed on the plates, representing the number of microbes in the samples, was expressed in colony-forming units per 100 mL. Representative colonies of distinct morphotypes were subcultured on Brain Heart Infusion agar (BBL) to obtain pure cultures and were then stored in a freezer at 86 C in Brucella Broth (BBL) supplemented with glycerol (10%). After the collection process Gram staining was used as the first step in microorganism identification, after which specific biochemical tests were conducted for each group. Gram-positive cocci were characterized using catalase, coagulase, and DNase tests, and gram-negative rods were further characterized by performing oxidase, citrate, malonate, sulfate agar indole and motility tests, and modified Rugai tests. Isolates of epidemiologic importance and those considered to be causative agents of health care-associated infections were identified to the genus and species levels by using the Vitek II (Biomerieux) automation system together with Gram-Negative microbial identification test cards. Filamentous fungi that were recovered were identified according to their macroscopic and microscopic characteristics.18 Statistical analyses were performed using SPSS 15.0 software (IBM-SPSS Inc, Armonk, NY). The significance level for statistical difference was 5% (P ¼ .05) and the confidence interval was 95%. The microbial loads in the 5 samples were compared with other variables by using the Mann-Whitney U test, because the required assumptions for this statistical model (normality and homoscedasticity) were not met. We also used the Wilcoxon test for paired samples.
524
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
Table 1 Microbial loads recovered from surgical instruments used in digestive tract surgeries, stratified based on precleaning moistening and surgical wound classification Microbial load N (%) Moistening Yes 18 (72) No 7 (28) Surgical wound classification CC 12 (48) C 13 (52)
Mean standard deviation
Median
P value*
7878 128142
116 30
.224
4184 201126
5 266
.007
C, contaminated; CC, clean-contaminated. *Mann-Whitney U test.
The study was approved by the Federal University of Minas Gerais Ethics Committee (Procedure CAAE 11,416,512-1-00005149), considering resolution 196/96 of the National Health Council. RESULTS Among the 125 sampled instruments, 52% were used in surgical procedures classified as contaminated, and 72% were premoistened in the operating room as the first step in cleaning; Table 1 lists the microbial loads detected on these instruments. The average microbial load on the instruments obtained from surgical procedures classified as contaminated was almost 5 times higher than that recovered from instruments used in cleancontaminated procedures, and this difference was statistically significant (P ¼ .007). Following the cleaning steps, the microbial load on instruments decreased according to the sequential step used. The average microbial load on instruments that were subjected to the first cleaning step decreased from 93.1-41.0 CFU/100 mL in the case of instruments cleaned using the manual process; this is a reduction of >55% from the initial load. In instruments that were cleaned in an ultrasonic washer, the average microbial load decreased to 75.0 CFU/100 mL, a reduction of approximately 21%. During the final phase of cleaning, the average microbial load of manually cleaned instruments was 8.24 CFU/100 mL (Step 2), whereas that of the instruments subjected to the automated cleaning procedure (Step 2) was almost double this value (16.1 CFU/ 100 mL). At every stage of cleaning, some of the samples collected from surgical instruments did not exhibit bacterial contamination; however, the maximal microbial load recovered from each step measured was > 100 CFU/100 mL in all cases (300 CFU/100 mL after use; 300 and 141 CFU/100 mL and 264 and 281 CFU/100 mL after the 2 sequential steps of manual and automated cleaning, respectively). The instruments subjected to the first stage of manual cleaning exhibited a statistically significant reduction in microbial load (P ¼ .015); by contrast, no significant difference in microbial load was detected (P ¼ .094) in the case instruments that had been subjected to the first stage of automated cleaning. However, after the second cleaning step in the automated washer-disinfector, instruments that had undergone both manual and automated cleaning showed a significant reduction in microbial loads (P ¼ .001). After the instruments were used, microbes were observed growing on 92% of the evaluated culture plates. The microbial loads were in the order of 101 in approximately 32% of the samples (1099 CFU/100 mL) and > 102 CFU/100 mL in another 32% (Fig 2). In the case of instruments used in surgical procedures classified as cleancontaminated procedures, approximately 65% exhibited microbial loads of 1-9 CFU/100 mL. By contrast, 53.4% of the instruments used
in contaminated surgical procedures exhibited microbial loads > 100 CFU/100 mL, with 71% of these instruments showing microbial loads > 300 CFU/100 mL; only 1 instrument used in a cleancontaminated surgical procedure exhibited a microbial load in this range. After the first stage of manual cleaning, microbial loads were reduced in the case of instruments in the top 2 categories of microbial loads (10-99 and 100 CFU/100 mL). The reduction in microbial load was greater for instruments used in contaminated surgical procedures than for those used in clean-contaminated procedures. In the case of instruments used in clean-contaminated surgical procedures that were subjected to automated cleaning, the number of instruments exhibiting a microbial load 100 CFU/100 mL increased after the use of an ultrasonic washer (Fig 3). After the first step of automated cleaning, instruments used in contaminated surgical procedures accounted for the highest number of instruments whose microbial loads were > 100 CFU/100 mL; by contrast, instruments used in clean-contaminated surgical procedures most commonly exhibited microbial loads between 0 and 9 CFU/100 mL. The proportion of instruments used in cleancontaminated surgical procedures that exhibited microbial loads > 100 CFU/100 mL after cleaning in an ultrasonic washer increased compared with the proportions obtained after the previous cleaning step and after use in surgeries. However, no microbial loads were detected on instruments that were subjected to automated cleaning after the final cleaning step in an automated washerdisinfector (84.6%). Gram-positive cocci were isolated from 48% of the instruments after use; the most frequently isolated species were coagulasenegative Staphylococcus spp, isolated in 44% of the cases. Escherichia coli was the most commonly isolated gram-negative rod, and it was also detected on 44% of the materials analyzed. Fungi were isolated in 80% of samples, and these were mostly Cladosporium (28%) and Aspergillus (24%). Of 125 surgical instruments sampled after manual cleaning performed using an enzymatic detergent, 76% contained microbes, which were identified as gram-negative rods (52%) and grampositive cocci (20%). The microorganisms isolated at this stage belonged to the Pseudomonas spp, Staphylococcus spp, and Stenotrophomonas spp. After the second stage of manual cleaning performed using an automated washer-disinfector (Step 2), 44% of the samples contained microbes, which were identified as gram-positive cocci (16%), gram-negative rods (12%), and fungi (24%); most frequently, Staphylococcus spp and Aspergillus spp were recovered. After instruments were subjected to automated cleaning in an ultrasonic washer (Step 2), microorganisms were recovered from 76% of the samples; all of the gram-positive cocci were identified as coagulase-negative Staphylococcus (12%), and the gram-negative rods (68%) were mostly glucose nonfermenters such as Acinetobacter baumannii complex (20%), Pseudomonas putida (16%), Pseudomonas aeruginosa (16%), and Stenotrophomonas maltophilia (16%). Fungi were also recovered from 12% of the samples, and most belonged to the genus Aspergillus. After automated cleaning performed using an ultrasonic washer and then cleaning in the washer-disinfector, 16% of the samples contained gram-positive cocci, all of which were coagulasenegative Staphylococcus, and fungi such as Aspergillus (12%) and Cladosporium (8%). DISCUSSION Among the instruments examined in our study, crile clamps used for hemostasis exhibited highest microbial loads because their
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
525
Fig 2. Microbial loads recovered from surgical instruments after use and after the 2 steps of manual cleaning, categorized based on surgical wound classification. *Cleancontaminated; yContaminated.
Fig 3. Microbial loads recovered from surgical instruments after use and after the 2 steps of automated cleaning, categorized based on surgical wound classification. *Cleancontaminated; yContaminated.
shape and design allows the accumulation of visible dirt, which made them meet the inclusion criteria. Moistening the instruments did not show a statistically significant effect on microbial loads decrease; this might be because of the small sample size: only 25 surgical instruments were analyzed after moistening. Moreover, the samples were collected within 30 minutes after the end of the surgical procedure. In our study, we did not aim to evaluate whether moistening increases the detachment and removal of organic materials and lowers the personnel exposure time during the cleaning process. However, Secker et al19 reported that moistening reduces the absorption of proteins on surfaces of surgical instruments and thus increases their removal, which lowers cleaning times and costs. The mean microbial load on instruments was observed to decrease during the cleaning steps; this trend was more pronounced when manual cleaning was used than when automated cleaning was performed. The microbial load was significantly reduced on instruments that were manually cleaned using procedures that included the use of a brush and soaking in an enzymatic detergent (P ¼ .015); however, this difference was not observed in the case of instruments that were submitted to automated cleaning in an ultrasonic washer (P ¼ .094). Studies that have compared distinct manual and automated cleaning protocols used for MDs have reported that automated
cleaning methods are superior to manual methods.6,7 However, Vassey et al11 noted that the recovery of residual protein was substantially higher from dental instruments subjected to manual plus ultrasonic cleaning processes than that from instruments submitted to only manual cleaning or automated washer-disinfector cleaning. In our study, the ultrasonic exchange solution in the cleaning process was monitored for turbidity of the medium as a subjective step or for each 6 hours, both according to the manufacturer’s recommendation. The finding that the use of ultrasonic washers did not outperform manual cleaning might be related to automated cleaning being the most-used method in this institution and also to the subjective assessment of turbidity; therefore, the use of this method might be more prone to failure than manual cleaning possibly due to the saturation of the enzymatic detergent solution, which would result in a loss of the ability to remove debris such as proteins, carbohydrates, and fats. The resolution of the executive board (RDC 55/2012), which regulates the use and commercialization of enzymatic detergents in Brazil, recommends the use of these cleaning products immediately after dilution in water and warns of the loss of efficiency in an event of reuse.1 However, explicit guidelines are not provided for each use, which leaves gaps in the protocol that allow for subjective interpretations, and the use of the proposed protocols might be
526
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
detrimental to the cleaning process.20 Therefore, strict guidelines must be provided for the use of enzymatic detergent solutions prepared for ultrasonic washers; these guidelines must consider the probability of saturation and loss of effectiveness. Ultrasonic cleaning solutions can harbor microbial contamination21 and can act as a culture medium for microorganisms, which will allow contamination and increase the microbial load on instruments. The detergent solution might also act as a source of microorganism transmission, which could affect the final outcome of the process and increase the microbial load on instruments that are subjected to this form of automated cleaning, compared with the load on instruments cleaned manually.7 Ultrasonic washers are devices featuring large cleaning capacities in which high-frequency sound waves are employed. The use of these devices was made compulsory by national legislation that aimed to improve the effectiveness of cleaning MDs that display complex conformations and whose lumens are < 5 mm in size. However, the results of our study showed that the inclusion of automated cleaning equipment is not adequate for ensuring improvements in the cleaning process; the protocols adopted must also be appropriate for the types of solutions used and the machines must be operated properly. The major challenge involved is related to the skills of the professionals who operate the equipment and their education, training, and supervision. Therefore, the result showing that the effectiveness of cleaning MDs was decreased after automated cleaning cannot be generalized. However, the finding provides this crucial warning: The use of cleaning equipment and solutions must be appropriate, and their inadequate manipulation by users might affect the quality of cleaning, the possibility of relapse, and adverse events related to the use of processed products. Although microbial loads were lowered to distinct extents following the first steps of manual and automated cleaning, after cleaning in the washer-disinfector, microbial loads were significantly decreased on instruments subjected to both manual cleaning (P ¼ .001) and automated cleaning (P ¼ .001); this highlights the importance of using washer-disinfectors for reducing the final microbial load on MDs. The use of washer-disinfectors has been identified as a safe method for processing MDs; however, users must follow manufacturer and legislative standards for installation, maintenance, validation, repair, and monitoring of the equipment.22 Surgical wound classification significantly affected the microbial load recovered on instruments (P ¼ .007). As expected, microbial loads were higher on instruments used for contaminated surgical procedures than on instruments used for clean-contaminated surgical procedures. However, Nystrom,2 who used a similar method and also expected to detect an elevated level of contamination during contaminated surgical procedures, did not observe a relationship between the microbial load on instruments and the distinct surgical wound classifications used (ie, clean/potentially contaminated vs contaminated/infected). This could be because Nystrom2 evaluated only a small number of instruments used during contaminated/infected surgical procedures (n ¼ 4), compared with the number of instruments used in clean/potentially contaminated surgical procedures (n ¼ 27). On the other hand, Pinto et al13 analyzed the microbial load recovered from surgical instruments used in clean, contaminated, and infected orthopedic procedures and observed a statistically significant difference in the numbers of microbes recovered from instruments used in clean versus contaminated surgical procedures (P ¼ .08) and in clean versus infected procedures (P < .001). Surgical instruments can be contaminated during surgery by contact with the resident flora on the skin of the patient or surgical team members; this can occur because of inappropriate
preparation of the skin of patients or medical personnel or because of contact with microorganisms in the digestive tract, duodenum, or colon.23 Clean surgical procedures are performed in sterilized tissues without a breakdown in the use of sterile techniques, whereas clean-contaminated, contaminated, and infected surgical procedures are performed in areas colonized by microorganisms belonging to the patient’s microflora or involved in infectious processes; these microorganisms can emerge as a source of instrument contamination during surgical procedures. Other factors that were not assessed in our study but might be involved in the risk of contamination of both surgical fields and surgical instruments are external sources of infection, including the air, the surgical team, preoperative skin preparation, surgical technique used, cleanliness of the operating room and surfaces, proper use of surgical scrubs, and change of gloves during procedures that last > 3 hours.4 After clinical use, microbes were isolated from 92% of the collected samples; in 32% of these samples, microbial loads were 10-99 CFU/100 mL, and in another 32%, the loads were 100 CFU/ 100 mL. In previous studies, the main microorganisms isolated from surgical instruments after use in a surgical procedure were Staphylococcus, Micrococcus spp, and Diphtheroids; however, after cleaning, in addition to these nonfermenting gram-negative rods, Pseudomonas and Stenotrophomonas were isolated.13e16,23 During the evaluation of surgical instruments after clinical use, Chu et al15 recovered gram-positive cocci (Staphylococcus and Micrococcus spp) and gram-positive rods (Diphtheroids and Bacillus) and, after cleaning, recovered gram-positive and nonfermenting gram-negative rods (Staphylococcus, Micrococcus spp, Stenotrophomonas, and Pseudomonas). Rutala et al3 also determined that the main microorganisms contaminating surgical instruments after cleaning were coagulase-negative Staphylococcus, Bacillus spp, Diphtheroids, Alcaligenes xylosoxidans, Stenotrophomonas maltophilia, Micrococcus spp, and Propionibacterium spp. The recovery of numerous fungi in our study might be related to the surrounding environment: The high heat and humidity of the place are conditions that allow the growth and development of fungi. In the institution where the study was conducted, no cooling system is available and, therefore, the recommended temperature range of 18 C to 22 C cannot be assured; this is particularly the case because windows that are open to the outside environment are used for air circulation in the cleaning areas. Moreover, at the time of the sampling, construction work was underway in an adjacent area; this occurs frequently in health care facilities and allows the occurrence of outbreaks of Aspergillus spp.18 Among the main microorganisms recovered in this study, coagulase-negative Staphylococcus was isolated during all phases of sampling. These findings are similar with results from other studies that evaluated the microbial load on surgical instruments; in those studies, Staphylococcus was described in all cases as the most frequently isolated microorganism.13e16,23 This reaffirmed the conclusion that these microorganisms, when recovered from surgical instruments, could originate from contact with a patient’s skin or from perforated or contaminated gloves of medical professionals during surgery, and even from the handling of instruments without gloves during processing.23 Therefore, the presence of Staphylococcus on surgical equipment and surfaces suggests that crosscontamination from personnel hands and/or surgical-site manipulation occurred during the surgical procedure, considering that this is the main microorganism that colonizes the skin. Another point that warrants attention is that contaminated instruments could provide an opportunity for microorganisms introduced into the operative site during a surgery. Contamination of the body cavity is a key factor that might lead to infection at the surgical site, and this reinforces the importance of adhering to good
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
practices during surgeries, especially in the use and cleaning of instruments, with the aim being to reduce the microbial load present to reduce or prevent contamination of the surgical site.4 CONCLUSIONS The average microbial load recovered from surgical instruments decreased at each cleaning stage evaluated for both manual and automated methods. The comparison of these methods showed that microbial loads were decreased in a statistically significant manner on instruments cleaned manually, but this was not observed in instruments cleaned using the automated method, possibly because of the saturation of an enzymatic detergent solution. However, when thermal disinfection was used as the final step of the cleaning process, the number of contaminating microorganisms was decreased on instruments cleaned using both methods. Microbial loads were significantly higher on instruments used in contaminated surgical procedures than on those used in clean-contaminated surgical procedures. The main microorganisms isolated from the surgical instruments were coagulase-negative Staphylococcus (gram-positive cocci), Pseudomonas spp, E coli, Stenotrophomonas maltophilia, and Acinetobacter baumannii complex (gram-negative rods), and Cladosporium spp, Aspergillus spp, and Candida spp. These microorganisms were probably derived from the surgical site and the skin flora of patients and health care professionals, as well as from airborne contaminants and cleaning solutions. References 1. Brazil Ministry of Health Brazilian National Health Surveillance Agency (ANVISA). College Board of Directors’ Resolution (RDC) N 15, dated march 15, 2012. Provides for the best practice standards for the processing of health products and other provisions. Brasilia. 2012. 2. Nyström B. Disinfection of surgical instruments. J Hosp Infect 1981;2: 363-8. Available from: http://www.sciencedirect.com/science/article/pii/ 0195670181900694. 3. Rutala WA, Gergen MF, Jones JF, Weber DJ. Levels of microbial contamination on surgical instruments. Am J Infect Control 1998;26:143-5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/9584809. 4. WHO. Guidelines for safe surgery 2009. Safe Surgery Saves Lives. Geneva: World Health Organization. p. 133. Available from: http://ncbi.nlm.nih.gov/ books/NBK143243; 2009. Accessed March 12, 2013. 5. Tosh PK, Disbot M, Duffy JM, Boom ML, Heseltine G, Srinivasan A, et al. Outbreak of Pseudomonas aeruginosa surgical site infections after arthroscopic procedures: Texas, 2009. Infect Control Hosp Epidemiol 2011;32:1179-86. 6. Dancer SJ, Stewart M, Coulombe C, Gregori A, Virdi M. Surgical site infections linked to contaminated surgical instruments. J Hosp Infect 2012;81: 231-8. Available from: http://www.sciencedirect.com/science/article/pii/ S0195670112001442. 7. BC HEALTH AUTHORITIES. Best Practice Guidelines For Cleaning, Disinfection and Sterilization of Critical and Semi-critical Medical Devices. British Columbia Health Authorities. p. 136. Available from: http://www.health.gov. bc.ca/library/publications/year/2007/BPGuidelines_Cleaning_Disinfection_ Sterilization_MedicalDevices.pdf; 2011. Accessed April 17, 2013.
527
8. Rutala WA, Weber DJ, HICPAC. CDC Guideline for disinfection and sterilization in healthcare facilities, 2008. Centers for Disease Control and Prevention. p. 158. Available from: http://www.cdc.gov.br/hicpac/pdf/guidelines/ disinfection_nov_2008.pdf; 2008. Accessed April 12, 2013. 9. Alfa MJ, Nemes R. Manual versus automated methods for cleaning reusable accessory devices used for minimally invasive surgical procedures. J Hosp Infect 2004;58:50-8. Avaiable from: http://www.sciencedirect.com/science/ article/pii/S0195670104002105. 10. Alfa MJ, Nemes R, Olson N, Mulaire A. Manual methods are suboptimal compared with automated methods for cleaning of single-use biopsy forceps. Infect Control Hosp Epidemiol 2006;27:841-6. Available from: http://jstor.org/ stable/10.106/506397. 11. Vassey M, Budge C, Poolman T, Jones P, Perrett D, Nayuni N, et al. A quantitative assessment of residual protein levels on dental instruments reprocessed by manual, ultrasonic and automated cleaning methods. Br Dent J 2011;210:E14. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21372833. 12. Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for Prevention of Surgical Site Infection, 1999. Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee. Am J Infect Control 1999;27:247-78. Available from: http://www.cdc.gov/hicpac/ pdf/guidelines/SSI_1999.pdf. 13. Pinto FMG, de Souza RQ, da Silva CB, Jenné Mimica LM, Graziano KU. Analysis of the microbial load in instruments used in orthopedic surgeries. Am J Infect Control 2010;38:229-33. Available from: http://www.sciencedirect.com/ science/article/pii/S0196655309008207. 14. Vilas-Boas VA, Levy CE, Freitas MIPD. Carga microbiana de trocartes reprocessáveis após laparoscopias ginecológicas. Rev Bras Ginecol Obstet 2009;31:586-91. Available from: http://www.scielo.br/scielo.php?script¼sci_ arttext&pid¼S010072032009001200002&nrm¼iso. 15. Chu NS, Chan-Myers H, Ghazanfari N, Antonoplos P. Levels of naturally occurring microorganisms on surgical instruments after clinical use and after washing. Am J Infect Control 1999;27:315-9. Available from: http://www. sciencedirect.com/science/article/pii/S0196655399700507. 16. Chan-Myers H, Mcalister D, Antonoplos P. Natural bioburden levels detected on rigid lumened medical devices before and after cleaning. Am J Infect Control 1997;25:471-6. Available from: http://www.sciencedirect.com/science/article/ pii/S0196655397900705. 17. Kumari S, Ichhpujani RL. Guidelines on Standard Operating Procedures for Microbiology. Regional Office for South-East Asia, New Delhi, India: World Health Organization; 2000. 18. Brazil Ministry of Health Brazilian National Health Surveillance Agency (ANVISA). Clinical microbiology for Healthcare Acquired infection control. Module 8: Detection and identification of medically important fungi. Brasília. 2013. p.46. 19. Secker TJ, Hervé R, Keevil CW. Absorption of prion and tissue proteins to surgical stainless steel surfaces and the efficacy of decontamination following dry and wet storage conditions. J Hosp Infect 2011;78:251-5. Available from: http://www.sciencedirect.com/science/article/pii/S019567011100168X. 20. Brazil Ministry of Health Brazilian National Health Surveillance Agency (ANVISA). College Board of Directors’ Resolution (RDC) N 55, dated November 14, 2012. Provides for enzymatic detergents of restricted use in healthcare establishments indicated for cleansing medical devices, and other provisions. Brasilia. 2012. 21. Miller CH, Riggen SD, Sheldrake MA, Neeb JM. Presence of microorganisms in used ultrasonic cleaning solutions. Am J Dent 1993;6:27-31. Available from:, http://www.scopus.com/inward/record.url?eid¼2s2.00027549602&partner ID¼40&md5¼71e0ea3e59a8099791c640be7bb42144. 22. NHS. Welsh Health Technical Memorandum 01-01-Decontamination of medical device, part D: washer-disinfector. Department of Health. England: NHS Wales Services partnership; 2013. p. 70. 23. Saito Y, Kobayashi H, Uetera Y, Yasuhara H, Kajiura T, Okubo T. Microbial contamination of surgical instruments used for laparotomy. Am J Infect Control 2014;42:43-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/ 24189327.
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
journal homepage: www.ajicjournal.org
Major article
Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning Síntia de Souza Evangelista MSc a, *, Simone Gonçalves dos Santos PhD b, Maria Aparecida de Resende Stoianoff PhD b, Adriana Cristina de Oliveira PhD a a b
Department of Basic Nursing, School of Nursing, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil Department of Microbiology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
Key Words: Patient safety Medical device reprocessing Infection Control Microbiology
Background: We aimed to monitor the microbial load and identify the microorganisms recovered from surgical instruments after clinical use and following manual and automated cleaning. Methods: This experimental study was carried out in the Laboratory of Oral Microbiology and Anaerobes at the Federal University of Minas Gerais in Brazil. Microbial samples were taken from 125 surgical instruments used in 25 types of gastrointestinal surgeries. Results: The average microbial load was 93.1 CFU/100 mL after clinical use and 41 CFU/100 mL and 8.24 CFU/100 mL on instruments following 2 sequential steps of manual cleaning, respectively, and 75 CFU/100 mL and 16.1 CFU/100 mL on instruments after automated cleaning. Surgical wound classification significantly affected the microbial load recovered on instruments. Coagulase-negative Staphylococcus, Escherichia coli, Pseudomonas spp, Stenotrophomonas maltophilia, and Acinetobacter baumannii complex were recovered. Conclusions: The average microbial load observed after the cleaning steps decreased, and the decrease in microbial load was more pronounced using the manual method compared with that observed using the automated method. Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Some medical devices (MDs), including most surgical instruments, are manufactured to allow reuse until the limit of their effectiveness and functionality is reached.1 This practice can lead to a reduction in both the costs and the amount of waste generated from single-use items. However, it is necessary to ensure that MDs remain safe for reuse on patients and for manipulation by medical personnel during MD reprocessing to protect them from infection hazards by avoiding microorganism transfer or other adverse events related to the use of MDs.2,3 MD reprocessing involves the use of the following set of standardized and interdependent actions: prewash, reception, cleaning, drying, assessment of integrity and functionality, preparation, disinfection or sterilization, storage, and distribution for reuse.1,4 The reduction in the microbial load on MDs during cleaning is an essential step that increases the safety and reliability of the
* Address correspondence to Síntia de Souza Evangelista, Department of Basic Nursing, School of Nursing, Universidade Federal de Minas Gerais, Rua Progresso, 1399, apt 401 e Caiçara - Belo Horizonte e Minas Gerais, Brazil. E-mail address: [email protected] (S.S. Evangelista). Conflicts of interest: None to report.
sterilization process.1-3 Although directly associated with health care quality, the inadequacy of MD reprocessing has not always been documented as being responsible for complications resulting from the care process, and it is reported only when related to episodes of outbreak.5,6 MDs can be cleaned using a manual method suitable for delicate and complex products, or using automated methods in which ultrasonic and/or decontamination washers are employed; automated cleaning methods are highly recommended because they are more likely than manual methods to be reproducible and they can be validated.1,4,7,8 Although automated cleaning typically provides superior results when compared with manual methods, Vassey et al9-11 noted an increase in residual protein on instruments that had been cleaned in an ultrasonic bath. Regardless of the cleaning method employed, improper maintenance of MDs can increase the bioburden during MD processing.8 The accumulation of proteins, salts, and dirt on MDs protects microorganisms from direct contact with sterilizing agents and favors bacterial adherence and biofilm formation. To be effective, the cleaning methods used must substantially reduce the levels of infectious agents present on MDs, such as bacteria, endotoxins,
0196-6553/$36.00 - Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2014.12.018
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
523
fungi, viruses, organic and inorganic matter that allow microbial growth and survival, and potential pyrogens.1,8 Given the concerns surrounding the appropriate procedures used for cleaning MDs, the aim of this study was to determine the microbial load and microbiologic profile of microorganisms recovered after clinical use and during manual and automated cleaning of surgical instruments used for digestive system surgeries. MATERIALS AND METHODS This experimental study was conducted in the Central Sterile Services Department (CSSD) of a large hospital in partnership with the Oral and Anaerobic Microbiology Laboratory of the Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil. We analyzed 125 instruments that were used in 25 types of gastrointestinal surgical procedures performed in a large teaching hospital; the procedures were classified as cleancontaminated procedures (involving the oral cavity, esophagus, stomach, liver, and biliary tract) and contaminated procedures (involving the large intestine).12 The inclusion criteria for the MDs selected were the following: the surgical instruments had to exhibit similar characteristics such as presence of grooves and joints, they had to be approximately 20 cm long, and they had to harbor visible dirt (eg, blood, organic matter, and inorganic matter) to ensure that a chosen MD was used during surgical procedures. The elected instruments included clamps such as crile, hemostatic, Rochester, Foerster, Kocher, and needle-holders. At the end of each surgical procedure, in the operating theatre, surgical instruments were moistened (for 30-60 minutes) using towels soaked in tap water to keep them wet before being transferred to CSSD for cleaning. We selected 5 instruments once the MDs had been transferred to CSSD, and collected study samples immediately after each of these sequential cleaning steps: (1) clinical use in digestive tract surgeries (representing the sample collected from instruments before cleaning); (2) manual cleaning involving soaking in an enzymatic detergent (Indazyme 6 plus, Indalabor Indaiá laboratório farmacêutico LTDA, Minas Gerais, Brazil, dilution: 2 mL/L water for 5 minutes [the time recommended by the manufacturer]) and brushing under tap water (5 times) by using brushes featuring with soft bristles and by applying firm strokes to detach any visible dirt attached to the instrument (Manual Method - Step 1); (3) manual cleaning and subsequent cleaning in a thermal washer-disinfector (regularly validated according to ISO 15883) (Manual Method - Step 2); (4) automated cleaning in an ultrasonic washer (Automated Method - Step 1); and (5) automated cleaning in an ultrasonic washer, followed by cleaning in an automated washer-disinfector, which was the same used in Step 2 of the manual method (Automated Method - Step 2). Figure 1 shows the steps followed for sample collection. Samples were collected according to methods described previously.2,13e16 On each day of sample collection, only 1 surgical procedure was selected. The elected instruments were transferred to a sterile plastic bag containing 500 mL sterile distilled water; this volume was used to allow complete immersion of all selected instruments. The bag was sealed and then placed in an ultrasonic bath (9 L capacity) for 3 treatments of 5 seconds each applied using an ultrasonic washer (USC-2800 model, Enge Solutions, São Paulo, Brazil), at a frequency of 40 KHz and a power of 30 W. Next, the bag containing the instrument was agitated for 5 minutes at 160 rpm in an orbital shaker (Kline 255-B model, Fanem LTDA, São Paulo, Brazil).13 During each sample collection, instruments were retrieved from the plastic bag using aseptic techniques, and the collected samples were sealed, identified, and transported to the Microbiology Laboratory of the Institute of Biological Sciences,
Fig 1. Sequential steps of manual and automated cleaning processes and respective times of sample collection.
Federal University of Minas Gerais located nearby; samples were transported within 60 minutes in a cooled thermal box whose internal temperature was monitored to ensure adequate preservation of the characteristics of the samples.17 The samples were again agitated in an orbital shaker for 5 minutes at 160 rpm and then filtered (using vacuum) through an autoclavable Sterifil (47-mm Sterifil Holder; Millipore indústria e comércio LTDA, Barueri, São Paulo, Brazil) containing a previously autoclaved cellulose nitrate membrane (0.45 mm; HAWP04700); we collected 100-mL aliquots under a laminar flow hood (Microbiological Biosafe I, Vecco, Campinas, São Paulo, Brazil). The filter membranes were overlaid on selective culture media, MacConkey agar (BBL, Biomérieux, Marcy-l’Étoile, France), Mannitol agar (BBL), and Sabouraud Dextrose Agar (Difco Laboratories, Detroit, Mich), which allowed the growth of specific microorganisms. Furthermore, a nonselective medium, Brain Heart Infusion (BBL) supplemented with 5% horse blood, was used for estimating the total microbial load of the samples. The culture plates were incubated in a bacteriologic incubator (Fanem CD Model 347) at 37 C for 2448 hours, and the number of colonies formed on the plates, representing the number of microbes in the samples, was expressed in colony-forming units per 100 mL. Representative colonies of distinct morphotypes were subcultured on Brain Heart Infusion agar (BBL) to obtain pure cultures and were then stored in a freezer at 86 C in Brucella Broth (BBL) supplemented with glycerol (10%). After the collection process Gram staining was used as the first step in microorganism identification, after which specific biochemical tests were conducted for each group. Gram-positive cocci were characterized using catalase, coagulase, and DNase tests, and gram-negative rods were further characterized by performing oxidase, citrate, malonate, sulfate agar indole and motility tests, and modified Rugai tests. Isolates of epidemiologic importance and those considered to be causative agents of health care-associated infections were identified to the genus and species levels by using the Vitek II (Biomerieux) automation system together with Gram-Negative microbial identification test cards. Filamentous fungi that were recovered were identified according to their macroscopic and microscopic characteristics.18 Statistical analyses were performed using SPSS 15.0 software (IBM-SPSS Inc, Armonk, NY). The significance level for statistical difference was 5% (P ¼ .05) and the confidence interval was 95%. The microbial loads in the 5 samples were compared with other variables by using the Mann-Whitney U test, because the required assumptions for this statistical model (normality and homoscedasticity) were not met. We also used the Wilcoxon test for paired samples.
524
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
Table 1 Microbial loads recovered from surgical instruments used in digestive tract surgeries, stratified based on precleaning moistening and surgical wound classification Microbial load N (%) Moistening Yes 18 (72) No 7 (28) Surgical wound classification CC 12 (48) C 13 (52)
Mean standard deviation
Median
P value*
7878 128142
116 30
.224
4184 201126
5 266
.007
C, contaminated; CC, clean-contaminated. *Mann-Whitney U test.
The study was approved by the Federal University of Minas Gerais Ethics Committee (Procedure CAAE 11,416,512-1-00005149), considering resolution 196/96 of the National Health Council. RESULTS Among the 125 sampled instruments, 52% were used in surgical procedures classified as contaminated, and 72% were premoistened in the operating room as the first step in cleaning; Table 1 lists the microbial loads detected on these instruments. The average microbial load on the instruments obtained from surgical procedures classified as contaminated was almost 5 times higher than that recovered from instruments used in cleancontaminated procedures, and this difference was statistically significant (P ¼ .007). Following the cleaning steps, the microbial load on instruments decreased according to the sequential step used. The average microbial load on instruments that were subjected to the first cleaning step decreased from 93.1-41.0 CFU/100 mL in the case of instruments cleaned using the manual process; this is a reduction of >55% from the initial load. In instruments that were cleaned in an ultrasonic washer, the average microbial load decreased to 75.0 CFU/100 mL, a reduction of approximately 21%. During the final phase of cleaning, the average microbial load of manually cleaned instruments was 8.24 CFU/100 mL (Step 2), whereas that of the instruments subjected to the automated cleaning procedure (Step 2) was almost double this value (16.1 CFU/ 100 mL). At every stage of cleaning, some of the samples collected from surgical instruments did not exhibit bacterial contamination; however, the maximal microbial load recovered from each step measured was > 100 CFU/100 mL in all cases (300 CFU/100 mL after use; 300 and 141 CFU/100 mL and 264 and 281 CFU/100 mL after the 2 sequential steps of manual and automated cleaning, respectively). The instruments subjected to the first stage of manual cleaning exhibited a statistically significant reduction in microbial load (P ¼ .015); by contrast, no significant difference in microbial load was detected (P ¼ .094) in the case instruments that had been subjected to the first stage of automated cleaning. However, after the second cleaning step in the automated washer-disinfector, instruments that had undergone both manual and automated cleaning showed a significant reduction in microbial loads (P ¼ .001). After the instruments were used, microbes were observed growing on 92% of the evaluated culture plates. The microbial loads were in the order of 101 in approximately 32% of the samples (1099 CFU/100 mL) and > 102 CFU/100 mL in another 32% (Fig 2). In the case of instruments used in surgical procedures classified as cleancontaminated procedures, approximately 65% exhibited microbial loads of 1-9 CFU/100 mL. By contrast, 53.4% of the instruments used
in contaminated surgical procedures exhibited microbial loads > 100 CFU/100 mL, with 71% of these instruments showing microbial loads > 300 CFU/100 mL; only 1 instrument used in a cleancontaminated surgical procedure exhibited a microbial load in this range. After the first stage of manual cleaning, microbial loads were reduced in the case of instruments in the top 2 categories of microbial loads (10-99 and 100 CFU/100 mL). The reduction in microbial load was greater for instruments used in contaminated surgical procedures than for those used in clean-contaminated procedures. In the case of instruments used in clean-contaminated surgical procedures that were subjected to automated cleaning, the number of instruments exhibiting a microbial load 100 CFU/100 mL increased after the use of an ultrasonic washer (Fig 3). After the first step of automated cleaning, instruments used in contaminated surgical procedures accounted for the highest number of instruments whose microbial loads were > 100 CFU/100 mL; by contrast, instruments used in clean-contaminated surgical procedures most commonly exhibited microbial loads between 0 and 9 CFU/100 mL. The proportion of instruments used in cleancontaminated surgical procedures that exhibited microbial loads > 100 CFU/100 mL after cleaning in an ultrasonic washer increased compared with the proportions obtained after the previous cleaning step and after use in surgeries. However, no microbial loads were detected on instruments that were subjected to automated cleaning after the final cleaning step in an automated washerdisinfector (84.6%). Gram-positive cocci were isolated from 48% of the instruments after use; the most frequently isolated species were coagulasenegative Staphylococcus spp, isolated in 44% of the cases. Escherichia coli was the most commonly isolated gram-negative rod, and it was also detected on 44% of the materials analyzed. Fungi were isolated in 80% of samples, and these were mostly Cladosporium (28%) and Aspergillus (24%). Of 125 surgical instruments sampled after manual cleaning performed using an enzymatic detergent, 76% contained microbes, which were identified as gram-negative rods (52%) and grampositive cocci (20%). The microorganisms isolated at this stage belonged to the Pseudomonas spp, Staphylococcus spp, and Stenotrophomonas spp. After the second stage of manual cleaning performed using an automated washer-disinfector (Step 2), 44% of the samples contained microbes, which were identified as gram-positive cocci (16%), gram-negative rods (12%), and fungi (24%); most frequently, Staphylococcus spp and Aspergillus spp were recovered. After instruments were subjected to automated cleaning in an ultrasonic washer (Step 2), microorganisms were recovered from 76% of the samples; all of the gram-positive cocci were identified as coagulase-negative Staphylococcus (12%), and the gram-negative rods (68%) were mostly glucose nonfermenters such as Acinetobacter baumannii complex (20%), Pseudomonas putida (16%), Pseudomonas aeruginosa (16%), and Stenotrophomonas maltophilia (16%). Fungi were also recovered from 12% of the samples, and most belonged to the genus Aspergillus. After automated cleaning performed using an ultrasonic washer and then cleaning in the washer-disinfector, 16% of the samples contained gram-positive cocci, all of which were coagulasenegative Staphylococcus, and fungi such as Aspergillus (12%) and Cladosporium (8%). DISCUSSION Among the instruments examined in our study, crile clamps used for hemostasis exhibited highest microbial loads because their
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
525
Fig 2. Microbial loads recovered from surgical instruments after use and after the 2 steps of manual cleaning, categorized based on surgical wound classification. *Cleancontaminated; yContaminated.
Fig 3. Microbial loads recovered from surgical instruments after use and after the 2 steps of automated cleaning, categorized based on surgical wound classification. *Cleancontaminated; yContaminated.
shape and design allows the accumulation of visible dirt, which made them meet the inclusion criteria. Moistening the instruments did not show a statistically significant effect on microbial loads decrease; this might be because of the small sample size: only 25 surgical instruments were analyzed after moistening. Moreover, the samples were collected within 30 minutes after the end of the surgical procedure. In our study, we did not aim to evaluate whether moistening increases the detachment and removal of organic materials and lowers the personnel exposure time during the cleaning process. However, Secker et al19 reported that moistening reduces the absorption of proteins on surfaces of surgical instruments and thus increases their removal, which lowers cleaning times and costs. The mean microbial load on instruments was observed to decrease during the cleaning steps; this trend was more pronounced when manual cleaning was used than when automated cleaning was performed. The microbial load was significantly reduced on instruments that were manually cleaned using procedures that included the use of a brush and soaking in an enzymatic detergent (P ¼ .015); however, this difference was not observed in the case of instruments that were submitted to automated cleaning in an ultrasonic washer (P ¼ .094). Studies that have compared distinct manual and automated cleaning protocols used for MDs have reported that automated
cleaning methods are superior to manual methods.6,7 However, Vassey et al11 noted that the recovery of residual protein was substantially higher from dental instruments subjected to manual plus ultrasonic cleaning processes than that from instruments submitted to only manual cleaning or automated washer-disinfector cleaning. In our study, the ultrasonic exchange solution in the cleaning process was monitored for turbidity of the medium as a subjective step or for each 6 hours, both according to the manufacturer’s recommendation. The finding that the use of ultrasonic washers did not outperform manual cleaning might be related to automated cleaning being the most-used method in this institution and also to the subjective assessment of turbidity; therefore, the use of this method might be more prone to failure than manual cleaning possibly due to the saturation of the enzymatic detergent solution, which would result in a loss of the ability to remove debris such as proteins, carbohydrates, and fats. The resolution of the executive board (RDC 55/2012), which regulates the use and commercialization of enzymatic detergents in Brazil, recommends the use of these cleaning products immediately after dilution in water and warns of the loss of efficiency in an event of reuse.1 However, explicit guidelines are not provided for each use, which leaves gaps in the protocol that allow for subjective interpretations, and the use of the proposed protocols might be
526
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
detrimental to the cleaning process.20 Therefore, strict guidelines must be provided for the use of enzymatic detergent solutions prepared for ultrasonic washers; these guidelines must consider the probability of saturation and loss of effectiveness. Ultrasonic cleaning solutions can harbor microbial contamination21 and can act as a culture medium for microorganisms, which will allow contamination and increase the microbial load on instruments. The detergent solution might also act as a source of microorganism transmission, which could affect the final outcome of the process and increase the microbial load on instruments that are subjected to this form of automated cleaning, compared with the load on instruments cleaned manually.7 Ultrasonic washers are devices featuring large cleaning capacities in which high-frequency sound waves are employed. The use of these devices was made compulsory by national legislation that aimed to improve the effectiveness of cleaning MDs that display complex conformations and whose lumens are < 5 mm in size. However, the results of our study showed that the inclusion of automated cleaning equipment is not adequate for ensuring improvements in the cleaning process; the protocols adopted must also be appropriate for the types of solutions used and the machines must be operated properly. The major challenge involved is related to the skills of the professionals who operate the equipment and their education, training, and supervision. Therefore, the result showing that the effectiveness of cleaning MDs was decreased after automated cleaning cannot be generalized. However, the finding provides this crucial warning: The use of cleaning equipment and solutions must be appropriate, and their inadequate manipulation by users might affect the quality of cleaning, the possibility of relapse, and adverse events related to the use of processed products. Although microbial loads were lowered to distinct extents following the first steps of manual and automated cleaning, after cleaning in the washer-disinfector, microbial loads were significantly decreased on instruments subjected to both manual cleaning (P ¼ .001) and automated cleaning (P ¼ .001); this highlights the importance of using washer-disinfectors for reducing the final microbial load on MDs. The use of washer-disinfectors has been identified as a safe method for processing MDs; however, users must follow manufacturer and legislative standards for installation, maintenance, validation, repair, and monitoring of the equipment.22 Surgical wound classification significantly affected the microbial load recovered on instruments (P ¼ .007). As expected, microbial loads were higher on instruments used for contaminated surgical procedures than on instruments used for clean-contaminated surgical procedures. However, Nystrom,2 who used a similar method and also expected to detect an elevated level of contamination during contaminated surgical procedures, did not observe a relationship between the microbial load on instruments and the distinct surgical wound classifications used (ie, clean/potentially contaminated vs contaminated/infected). This could be because Nystrom2 evaluated only a small number of instruments used during contaminated/infected surgical procedures (n ¼ 4), compared with the number of instruments used in clean/potentially contaminated surgical procedures (n ¼ 27). On the other hand, Pinto et al13 analyzed the microbial load recovered from surgical instruments used in clean, contaminated, and infected orthopedic procedures and observed a statistically significant difference in the numbers of microbes recovered from instruments used in clean versus contaminated surgical procedures (P ¼ .08) and in clean versus infected procedures (P < .001). Surgical instruments can be contaminated during surgery by contact with the resident flora on the skin of the patient or surgical team members; this can occur because of inappropriate
preparation of the skin of patients or medical personnel or because of contact with microorganisms in the digestive tract, duodenum, or colon.23 Clean surgical procedures are performed in sterilized tissues without a breakdown in the use of sterile techniques, whereas clean-contaminated, contaminated, and infected surgical procedures are performed in areas colonized by microorganisms belonging to the patient’s microflora or involved in infectious processes; these microorganisms can emerge as a source of instrument contamination during surgical procedures. Other factors that were not assessed in our study but might be involved in the risk of contamination of both surgical fields and surgical instruments are external sources of infection, including the air, the surgical team, preoperative skin preparation, surgical technique used, cleanliness of the operating room and surfaces, proper use of surgical scrubs, and change of gloves during procedures that last > 3 hours.4 After clinical use, microbes were isolated from 92% of the collected samples; in 32% of these samples, microbial loads were 10-99 CFU/100 mL, and in another 32%, the loads were 100 CFU/ 100 mL. In previous studies, the main microorganisms isolated from surgical instruments after use in a surgical procedure were Staphylococcus, Micrococcus spp, and Diphtheroids; however, after cleaning, in addition to these nonfermenting gram-negative rods, Pseudomonas and Stenotrophomonas were isolated.13e16,23 During the evaluation of surgical instruments after clinical use, Chu et al15 recovered gram-positive cocci (Staphylococcus and Micrococcus spp) and gram-positive rods (Diphtheroids and Bacillus) and, after cleaning, recovered gram-positive and nonfermenting gram-negative rods (Staphylococcus, Micrococcus spp, Stenotrophomonas, and Pseudomonas). Rutala et al3 also determined that the main microorganisms contaminating surgical instruments after cleaning were coagulase-negative Staphylococcus, Bacillus spp, Diphtheroids, Alcaligenes xylosoxidans, Stenotrophomonas maltophilia, Micrococcus spp, and Propionibacterium spp. The recovery of numerous fungi in our study might be related to the surrounding environment: The high heat and humidity of the place are conditions that allow the growth and development of fungi. In the institution where the study was conducted, no cooling system is available and, therefore, the recommended temperature range of 18 C to 22 C cannot be assured; this is particularly the case because windows that are open to the outside environment are used for air circulation in the cleaning areas. Moreover, at the time of the sampling, construction work was underway in an adjacent area; this occurs frequently in health care facilities and allows the occurrence of outbreaks of Aspergillus spp.18 Among the main microorganisms recovered in this study, coagulase-negative Staphylococcus was isolated during all phases of sampling. These findings are similar with results from other studies that evaluated the microbial load on surgical instruments; in those studies, Staphylococcus was described in all cases as the most frequently isolated microorganism.13e16,23 This reaffirmed the conclusion that these microorganisms, when recovered from surgical instruments, could originate from contact with a patient’s skin or from perforated or contaminated gloves of medical professionals during surgery, and even from the handling of instruments without gloves during processing.23 Therefore, the presence of Staphylococcus on surgical equipment and surfaces suggests that crosscontamination from personnel hands and/or surgical-site manipulation occurred during the surgical procedure, considering that this is the main microorganism that colonizes the skin. Another point that warrants attention is that contaminated instruments could provide an opportunity for microorganisms introduced into the operative site during a surgery. Contamination of the body cavity is a key factor that might lead to infection at the surgical site, and this reinforces the importance of adhering to good
S.S. Evangelista et al. / American Journal of Infection Control 43 (2015) 522-7
practices during surgeries, especially in the use and cleaning of instruments, with the aim being to reduce the microbial load present to reduce or prevent contamination of the surgical site.4 CONCLUSIONS The average microbial load recovered from surgical instruments decreased at each cleaning stage evaluated for both manual and automated methods. The comparison of these methods showed that microbial loads were decreased in a statistically significant manner on instruments cleaned manually, but this was not observed in instruments cleaned using the automated method, possibly because of the saturation of an enzymatic detergent solution. However, when thermal disinfection was used as the final step of the cleaning process, the number of contaminating microorganisms was decreased on instruments cleaned using both methods. Microbial loads were significantly higher on instruments used in contaminated surgical procedures than on those used in clean-contaminated surgical procedures. The main microorganisms isolated from the surgical instruments were coagulase-negative Staphylococcus (gram-positive cocci), Pseudomonas spp, E coli, Stenotrophomonas maltophilia, and Acinetobacter baumannii complex (gram-negative rods), and Cladosporium spp, Aspergillus spp, and Candida spp. These microorganisms were probably derived from the surgical site and the skin flora of patients and health care professionals, as well as from airborne contaminants and cleaning solutions. References 1. Brazil Ministry of Health Brazilian National Health Surveillance Agency (ANVISA). College Board of Directors’ Resolution (RDC) N 15, dated march 15, 2012. Provides for the best practice standards for the processing of health products and other provisions. Brasilia. 2012. 2. Nyström B. Disinfection of surgical instruments. J Hosp Infect 1981;2: 363-8. Available from: http://www.sciencedirect.com/science/article/pii/ 0195670181900694. 3. Rutala WA, Gergen MF, Jones JF, Weber DJ. Levels of microbial contamination on surgical instruments. Am J Infect Control 1998;26:143-5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/9584809. 4. WHO. Guidelines for safe surgery 2009. Safe Surgery Saves Lives. Geneva: World Health Organization. p. 133. Available from: http://ncbi.nlm.nih.gov/ books/NBK143243; 2009. Accessed March 12, 2013. 5. Tosh PK, Disbot M, Duffy JM, Boom ML, Heseltine G, Srinivasan A, et al. Outbreak of Pseudomonas aeruginosa surgical site infections after arthroscopic procedures: Texas, 2009. Infect Control Hosp Epidemiol 2011;32:1179-86. 6. Dancer SJ, Stewart M, Coulombe C, Gregori A, Virdi M. Surgical site infections linked to contaminated surgical instruments. J Hosp Infect 2012;81: 231-8. Available from: http://www.sciencedirect.com/science/article/pii/ S0195670112001442. 7. BC HEALTH AUTHORITIES. Best Practice Guidelines For Cleaning, Disinfection and Sterilization of Critical and Semi-critical Medical Devices. British Columbia Health Authorities. p. 136. Available from: http://www.health.gov. bc.ca/library/publications/year/2007/BPGuidelines_Cleaning_Disinfection_ Sterilization_MedicalDevices.pdf; 2011. Accessed April 17, 2013.
527
8. Rutala WA, Weber DJ, HICPAC. CDC Guideline for disinfection and sterilization in healthcare facilities, 2008. Centers for Disease Control and Prevention. p. 158. Available from: http://www.cdc.gov.br/hicpac/pdf/guidelines/ disinfection_nov_2008.pdf; 2008. Accessed April 12, 2013. 9. Alfa MJ, Nemes R. Manual versus automated methods for cleaning reusable accessory devices used for minimally invasive surgical procedures. J Hosp Infect 2004;58:50-8. Avaiable from: http://www.sciencedirect.com/science/ article/pii/S0195670104002105. 10. Alfa MJ, Nemes R, Olson N, Mulaire A. Manual methods are suboptimal compared with automated methods for cleaning of single-use biopsy forceps. Infect Control Hosp Epidemiol 2006;27:841-6. Available from: http://jstor.org/ stable/10.106/506397. 11. Vassey M, Budge C, Poolman T, Jones P, Perrett D, Nayuni N, et al. A quantitative assessment of residual protein levels on dental instruments reprocessed by manual, ultrasonic and automated cleaning methods. Br Dent J 2011;210:E14. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21372833. 12. Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for Prevention of Surgical Site Infection, 1999. Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee. Am J Infect Control 1999;27:247-78. Available from: http://www.cdc.gov/hicpac/ pdf/guidelines/SSI_1999.pdf. 13. Pinto FMG, de Souza RQ, da Silva CB, Jenné Mimica LM, Graziano KU. Analysis of the microbial load in instruments used in orthopedic surgeries. Am J Infect Control 2010;38:229-33. Available from: http://www.sciencedirect.com/ science/article/pii/S0196655309008207. 14. Vilas-Boas VA, Levy CE, Freitas MIPD. Carga microbiana de trocartes reprocessáveis após laparoscopias ginecológicas. Rev Bras Ginecol Obstet 2009;31:586-91. Available from: http://www.scielo.br/scielo.php?script¼sci_ arttext&pid¼S010072032009001200002&nrm¼iso. 15. Chu NS, Chan-Myers H, Ghazanfari N, Antonoplos P. Levels of naturally occurring microorganisms on surgical instruments after clinical use and after washing. Am J Infect Control 1999;27:315-9. Available from: http://www. sciencedirect.com/science/article/pii/S0196655399700507. 16. Chan-Myers H, Mcalister D, Antonoplos P. Natural bioburden levels detected on rigid lumened medical devices before and after cleaning. Am J Infect Control 1997;25:471-6. Available from: http://www.sciencedirect.com/science/article/ pii/S0196655397900705. 17. Kumari S, Ichhpujani RL. Guidelines on Standard Operating Procedures for Microbiology. Regional Office for South-East Asia, New Delhi, India: World Health Organization; 2000. 18. Brazil Ministry of Health Brazilian National Health Surveillance Agency (ANVISA). Clinical microbiology for Healthcare Acquired infection control. Module 8: Detection and identification of medically important fungi. Brasília. 2013. p.46. 19. Secker TJ, Hervé R, Keevil CW. Absorption of prion and tissue proteins to surgical stainless steel surfaces and the efficacy of decontamination following dry and wet storage conditions. J Hosp Infect 2011;78:251-5. Available from: http://www.sciencedirect.com/science/article/pii/S019567011100168X. 20. Brazil Ministry of Health Brazilian National Health Surveillance Agency (ANVISA). College Board of Directors’ Resolution (RDC) N 55, dated November 14, 2012. Provides for enzymatic detergents of restricted use in healthcare establishments indicated for cleansing medical devices, and other provisions. Brasilia. 2012. 21. Miller CH, Riggen SD, Sheldrake MA, Neeb JM. Presence of microorganisms in used ultrasonic cleaning solutions. Am J Dent 1993;6:27-31. Available from:, http://www.scopus.com/inward/record.url?eid¼2s2.00027549602&partner ID¼40&md5¼71e0ea3e59a8099791c640be7bb42144. 22. NHS. Welsh Health Technical Memorandum 01-01-Decontamination of medical device, part D: washer-disinfector. Department of Health. England: NHS Wales Services partnership; 2013. p. 70. 23. Saito Y, Kobayashi H, Uetera Y, Yasuhara H, Kajiura T, Okubo T. Microbial contamination of surgical instruments used for laparotomy. Am J Infect Control 2014;42:43-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/ 24189327.
