Blood Infections in Patients Treated at Transplantation Wards of a Clinical Hospital in Warsaw M. Kierzkowskaa, A. Majewskaa, K. Dobrzanieckaa, A. Sawicka-Grzelaka, A. Mlynarczykb, A. Chmurac, M. Durlikd, D. Deborska-Materkowskad, L. Paczeke, and G. Mlynarczyka,* a Department of Medical Microbiology, Medical University of Warsaw, Warsaw, Poland; bDepartment of Dental Microbiology, Medical University of Warsaw, Warsaw, Poland; cDepartment of General and Transplantation Surgery, Transplantology Institute, Medical University of Warsaw, Warsaw, Poland; dDepartment of Transplant Medicine and Nephrology, Transplantology Institute, Medical University of Warsaw, Warsaw, Poland; and eDepartment of Immunology, Transplantology and Internal Diseases, Transplantology Institute, Medical University of Warsaw, Warsaw, Poland
ABSTRACT Establishment of the etiology in blood infection is always advisable. The purpose of this study was to evaluate the proportion of different bacterial species, including aerobic and anaerobic bacteria in blood cultures of patients hospitalized in transplantation wards of a large clinical hospital between 2010 and 2012. A total of 1994 blood samples from patients who were treated at one of two transplantation wards of a large hospital in Warsaw were analyzed using an automated blood culture system, BacT/ALERT (bioMerieux, France). The 306 bacterial strains were obtained from the examined samples. The highest proportion were bacteria from the family Enterobacteriaceae (112 strains; 36.6%) with Escherichia coli (61 strains), Klebsiella pneumoniae (30 strains), and Enterobacter cloacae (10 strains) most commonly isolated. The non-fermenting bacilli constituted 21.6% (66 strains), with most common Stenotrophomonas maltophilia (31 strains), Pseudomonas aeruginosa (14 strains), Achromobacter spp. (12 strains), and Acinetobacter baumannii (3 strains). Most frequent Grampositive bacteria were staphylococci (25.2%). Of 77 staphylococcal strains, 56 were coagulase-negative staphylococci and 21 Staphylococcus aureus. Other Gram-positive bacteria included enterococci (14 strains) and Streptococcus pneumoniae (1 strain). Obligatory anaerobic bacteria were represented by 19 strains (6.2% of total isolates). Among all Enterobacteriaceae, 49 isolates (43.7%) produced extended-spectrum ß-lactamases (ESBLs). Resistance to methicillin was detected in 62% of S aureus isolates and in 46% of coagulasenegative staphylococci. Of 14 enterococci cultured from blood samples, 2 strains (14.3%) were resistant to vancomycin. Both were Enterococcus faecium. Resistant strains of Gramnegative and Gram-positive bacteria are significant problems for patients in the transplantation ward.
O
RGAN transplant recipients who constantly use immunosuppressive drugs and often receive corticosteroids are especially prone to viral, fungal, and bacterial infections. Among bacterial infections, the ones especially dangerous are those associated with bacteremia, as they may lead to sepsis, a condition characterized by a considerably high mortality. Therefore, microbiological analysis of blood always has priority in the laboratory. The following factors are of key importance in blood infections: impaired immune mechanisms and colonization with pathogens or opportunistic pathogens. Bacterial colonization is facilitated by the
use of invasive diagnostic and therapeutic methods, hospitalization, and antibiotic therapy. The most commonly colonized locations are various areas of the skin, nasopharynx, and gastrointestinal tract. If blood infection is suspected, it is always advisable to establish the etiology. If performed correctly and at the right time, a microbiological Supported by the Medical University of Warsaw, Warsaw, Poland. *Address correspondence to Grazyna Mlynarczyk, the Department of Medical Microbiology, Warsaw Medical University, T. Chalubinskiego 5 Str., 02-004. E-mail: [email protected]
ª 2014 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/14 http://dx.doi.org/10.1016/j.transproceed.2014.08.024
Transplantation Proceedings, 46, 2589e2591 (2014)
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Table 1. The Most Often Grown Bacterial Species From Blood Cultures From Patients Hospitalized in Transplantation Wards Between 2010 and 2012 Bacteria
Total Enterobacteriaceae Non-fermenting bacilli
Staphylococcus
Enterococcus Anaerobes
n (%)
The Most Common Species Within the Group (%)
306 (100%) 112 (36.6%) 1. 2. 3. 66 (21.6%) 1.
Escherichia coli (54%) Klebsiella pneumoniae (27%) Other (19%) Stenotrophomonas maltophilia (47%) 2. Pseudomonas aeruginosa (21%) 3. Achromobacter spp. (18%) 4. Acinetobacter baumanii (4.5%) 5. Other (9,5%) 77 (25.2%) 1. Coagulase-negative staphylococci (CNS) (73%) 2. S.aureus (27%) 14 (4.6%) 1. Enterococcus faecium (57%) 2. Enterococcus faecalis (43%) 19 (6.2%) 1. Propionibacterium acnes (78.9%) 2. Bacteroides spp. (10.5%)
examination can support the clinical diagnosis and help in the treatment. The purpose of this study was to evaluate the proportion of aerobic and anaerobic bacteria in blood cultures of patients hospitalized in transplantation wards of a large clinical hospital. MATERIALS AND METHODS Between 2010 and 2012, a total of 1994 blood samples from patients treated at two transplantation wards at a large hospital in Warsaw were analyzed. Each sample was cultured in a set of two bottles (for aerobic and anaerobic bacteria). According to this hospital’s practice, blood samples for a microbiological examination were collected by trained ward personnel who followed aseptic techniques. An automated blood culture system, BacT/ALERT (bioMerieux, France) was used at the laboratory. Standard incubation, though no longer than 7 days, was conducted to achieve growth. Identification and drug sensitivity of strains was established via the Vitek2 system and the automated ATB Expression (bioMerieux, France) system according to the local laboratory practice.
RESULTS
During a 3-year period of observation, positive culture results were obtained in 306 (15.3%) of 1994 analyzed blood samples. The 306 strains of bacteria that were isolated were classified into 37 different species. The highest proportion of strains cultured from blood were bacteria from the family Enterobacteriaceae (36.6%), with the most commonly isolated species being Escherichia coli (61 strains), Klebsiella pneumoniae (30 strains), and Enterobacter cloacae (10 strains). The most often isolated non-fermenting bacilli were Stenotrophomonas maltophilia (31 strains), with Pseudomonas aeruginosa (14 strains) less commonly isolated. A total of 77 staphylococcal
strains were cultured, with Staphylococcus aureus constituting 27% (Table 1). A sample from one patient yielded Streptococcus pneumoniae. There were 19 strains of obligatory anaerobic bacteria isolated. This kind of bacteria was most numerously represented by Gram-positive bacilli: Propionibacterium acnes (15), Lactobacillus spp (1), and Eubacterium lentum (1). Among the isolated Gram-negative bacilli were Bacteroides fragilis (1) and Bacteroides vulgatus (1). Eighty percent of K pneumoniae strains and 37.7% of Escherichia coli strains produced extended-spectrum ß-lactamases. Resistance to methicillin was detected in 62% of S aureus isolates (MRSA) and in 46% of coagulase-negative staphylococci (MRCNS). Of 14 enterococci cultured from blood samples, 2 strains of Enterococcus faecium were resistant to vancomycin (VRE). DISCUSSION
This study showed that the main causes of bacteremia were Gram-negative bacilli from the Enterobacteriaceae family and staphylococci. The E coli and K pneumoniae species dominated in our findings, which was consistent with the literature. One micro-organism commonly isolated from blood cultures from patients with suspected bacteremia from various hospitals in Poland and all over the world is S aureus [1,2]. MRSA infections require the use of glycopeptides, which results in the selection of VRE and vancomycin-resistant staphylococci. The study also yielded a number of isolates of non-fermenting Gram-negative bacilli Stenotrophomonas maltophilia that is just naturally resistant to aminoglycoside and virtually all b-lactam antibiotics, which makes therapy more difficult [3]. Anaerobic bacteria are rarely isolated from blood samples due to the broad-spectrum empirical antibiotic therapy. This study, similar to studies by other authors, revealed Gram-positive anaerobic bacteria sensitivity to ß-lactam antibiotics. Natural resistance to metronidazole was detected in the genus Propionibacterium. Gram-negative bacteria of the genus Bacteroides were found to be resistant to penicillin G, and sensitive to imipenem and metronidazole [4e6]. Detection of coagulase-negative staphylococci, some nonfermenting bacilli, Streptococcus viridans, or anaerobic bacteria of the genus Propionibacterium spp. in blood samples requires a comprehensive assessment of the patient’s condition and laboratory test results to distinguish an infection from sample contamination with bacterial skin flora. Opportunistic pathogens often colonize vascular catheters, and may cause catheter-related infections. Physiological microflora can be shown to be the etiological factors if bacterial isolates are obtained from at least two blood samples and there are risk factors facilitating the development of opportunistic infections [7,8]. REFERENCES [1] Bourbeau PP, Foltzer M. Routine incubation of BacT/ ALERT FA and FN blood culture bottles for more than 3 days may not be necessary. J Clin Microbiol 2005;43:2506e9. [2] Kawecki D, Kwiatkowski A, Michalak G, et al. Etiologic agents of bacteremia in the early period after simultaneous
BLOOD INFECTIONS pancreas-kidney transplantation. Transplant Proc 2009;41: 3151e3. [3] Rattanaumpawan P, Ussavasodhi P, Kiratisin P, et al. Epidemiology of bacteremia caused by uncommon non-fermentative gram-negative bacteria. BMC Infect Dis 2013;13:167e74. [4] Maciejewska K, Kedzia A, Zienkiewicz J, et al. Study on susceptibility of anaerobes isolated from blood of patients surgically treated within oral cavity to certain antibiotics and chemotherapeutic agents. Ann Acad Med Gedam 2006;36:133e8. [5] Hartmeyer GN, Sóki J, Nagy E, et al. Multidrug-resistant Bacteroides fragilis group on the rise in Europe? J Med Microbiol 2012;61:1784e8.
2591 [6] Kierzkowska M, Majewska A, Sawicka-Grzelak A, et al. Participation of strictly anaerobic bacteria in infections among hospitalized transplant patients in a clinical hospital in Warsaw. Transplant Proc 2011;43:3130e1. [7] Dubiel G, Dziublewska B, Zaloudik E. Blood culture results in specialistic unit for pulmonary illness and tuberculosis in Bystra in 2008-2010. Przegl Epidemiol 2011;65: 447e50. [8] Saito T, Senda K, Takakura S, et al. Anaerobic bacteremia: the yield of positive anaerobic blood cultures: patient characteristics and potential risk factors. Clin Chem Lab Med 2003;4: 293e7.
ABSTRACT Establishment of the etiology in blood infection is always advisable. The purpose of this study was to evaluate the proportion of different bacterial species, including aerobic and anaerobic bacteria in blood cultures of patients hospitalized in transplantation wards of a large clinical hospital between 2010 and 2012. A total of 1994 blood samples from patients who were treated at one of two transplantation wards of a large hospital in Warsaw were analyzed using an automated blood culture system, BacT/ALERT (bioMerieux, France). The 306 bacterial strains were obtained from the examined samples. The highest proportion were bacteria from the family Enterobacteriaceae (112 strains; 36.6%) with Escherichia coli (61 strains), Klebsiella pneumoniae (30 strains), and Enterobacter cloacae (10 strains) most commonly isolated. The non-fermenting bacilli constituted 21.6% (66 strains), with most common Stenotrophomonas maltophilia (31 strains), Pseudomonas aeruginosa (14 strains), Achromobacter spp. (12 strains), and Acinetobacter baumannii (3 strains). Most frequent Grampositive bacteria were staphylococci (25.2%). Of 77 staphylococcal strains, 56 were coagulase-negative staphylococci and 21 Staphylococcus aureus. Other Gram-positive bacteria included enterococci (14 strains) and Streptococcus pneumoniae (1 strain). Obligatory anaerobic bacteria were represented by 19 strains (6.2% of total isolates). Among all Enterobacteriaceae, 49 isolates (43.7%) produced extended-spectrum ß-lactamases (ESBLs). Resistance to methicillin was detected in 62% of S aureus isolates and in 46% of coagulasenegative staphylococci. Of 14 enterococci cultured from blood samples, 2 strains (14.3%) were resistant to vancomycin. Both were Enterococcus faecium. Resistant strains of Gramnegative and Gram-positive bacteria are significant problems for patients in the transplantation ward.
O
RGAN transplant recipients who constantly use immunosuppressive drugs and often receive corticosteroids are especially prone to viral, fungal, and bacterial infections. Among bacterial infections, the ones especially dangerous are those associated with bacteremia, as they may lead to sepsis, a condition characterized by a considerably high mortality. Therefore, microbiological analysis of blood always has priority in the laboratory. The following factors are of key importance in blood infections: impaired immune mechanisms and colonization with pathogens or opportunistic pathogens. Bacterial colonization is facilitated by the
use of invasive diagnostic and therapeutic methods, hospitalization, and antibiotic therapy. The most commonly colonized locations are various areas of the skin, nasopharynx, and gastrointestinal tract. If blood infection is suspected, it is always advisable to establish the etiology. If performed correctly and at the right time, a microbiological Supported by the Medical University of Warsaw, Warsaw, Poland. *Address correspondence to Grazyna Mlynarczyk, the Department of Medical Microbiology, Warsaw Medical University, T. Chalubinskiego 5 Str., 02-004. E-mail: [email protected]
ª 2014 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/14 http://dx.doi.org/10.1016/j.transproceed.2014.08.024
Transplantation Proceedings, 46, 2589e2591 (2014)
2589
2590
KIERZKOWSKA, MAJEWSKA, DOBRZANIECKA ET AL
Table 1. The Most Often Grown Bacterial Species From Blood Cultures From Patients Hospitalized in Transplantation Wards Between 2010 and 2012 Bacteria
Total Enterobacteriaceae Non-fermenting bacilli
Staphylococcus
Enterococcus Anaerobes
n (%)
The Most Common Species Within the Group (%)
306 (100%) 112 (36.6%) 1. 2. 3. 66 (21.6%) 1.
Escherichia coli (54%) Klebsiella pneumoniae (27%) Other (19%) Stenotrophomonas maltophilia (47%) 2. Pseudomonas aeruginosa (21%) 3. Achromobacter spp. (18%) 4. Acinetobacter baumanii (4.5%) 5. Other (9,5%) 77 (25.2%) 1. Coagulase-negative staphylococci (CNS) (73%) 2. S.aureus (27%) 14 (4.6%) 1. Enterococcus faecium (57%) 2. Enterococcus faecalis (43%) 19 (6.2%) 1. Propionibacterium acnes (78.9%) 2. Bacteroides spp. (10.5%)
examination can support the clinical diagnosis and help in the treatment. The purpose of this study was to evaluate the proportion of aerobic and anaerobic bacteria in blood cultures of patients hospitalized in transplantation wards of a large clinical hospital. MATERIALS AND METHODS Between 2010 and 2012, a total of 1994 blood samples from patients treated at two transplantation wards at a large hospital in Warsaw were analyzed. Each sample was cultured in a set of two bottles (for aerobic and anaerobic bacteria). According to this hospital’s practice, blood samples for a microbiological examination were collected by trained ward personnel who followed aseptic techniques. An automated blood culture system, BacT/ALERT (bioMerieux, France) was used at the laboratory. Standard incubation, though no longer than 7 days, was conducted to achieve growth. Identification and drug sensitivity of strains was established via the Vitek2 system and the automated ATB Expression (bioMerieux, France) system according to the local laboratory practice.
RESULTS
During a 3-year period of observation, positive culture results were obtained in 306 (15.3%) of 1994 analyzed blood samples. The 306 strains of bacteria that were isolated were classified into 37 different species. The highest proportion of strains cultured from blood were bacteria from the family Enterobacteriaceae (36.6%), with the most commonly isolated species being Escherichia coli (61 strains), Klebsiella pneumoniae (30 strains), and Enterobacter cloacae (10 strains). The most often isolated non-fermenting bacilli were Stenotrophomonas maltophilia (31 strains), with Pseudomonas aeruginosa (14 strains) less commonly isolated. A total of 77 staphylococcal
strains were cultured, with Staphylococcus aureus constituting 27% (Table 1). A sample from one patient yielded Streptococcus pneumoniae. There were 19 strains of obligatory anaerobic bacteria isolated. This kind of bacteria was most numerously represented by Gram-positive bacilli: Propionibacterium acnes (15), Lactobacillus spp (1), and Eubacterium lentum (1). Among the isolated Gram-negative bacilli were Bacteroides fragilis (1) and Bacteroides vulgatus (1). Eighty percent of K pneumoniae strains and 37.7% of Escherichia coli strains produced extended-spectrum ß-lactamases. Resistance to methicillin was detected in 62% of S aureus isolates (MRSA) and in 46% of coagulase-negative staphylococci (MRCNS). Of 14 enterococci cultured from blood samples, 2 strains of Enterococcus faecium were resistant to vancomycin (VRE). DISCUSSION
This study showed that the main causes of bacteremia were Gram-negative bacilli from the Enterobacteriaceae family and staphylococci. The E coli and K pneumoniae species dominated in our findings, which was consistent with the literature. One micro-organism commonly isolated from blood cultures from patients with suspected bacteremia from various hospitals in Poland and all over the world is S aureus [1,2]. MRSA infections require the use of glycopeptides, which results in the selection of VRE and vancomycin-resistant staphylococci. The study also yielded a number of isolates of non-fermenting Gram-negative bacilli Stenotrophomonas maltophilia that is just naturally resistant to aminoglycoside and virtually all b-lactam antibiotics, which makes therapy more difficult [3]. Anaerobic bacteria are rarely isolated from blood samples due to the broad-spectrum empirical antibiotic therapy. This study, similar to studies by other authors, revealed Gram-positive anaerobic bacteria sensitivity to ß-lactam antibiotics. Natural resistance to metronidazole was detected in the genus Propionibacterium. Gram-negative bacteria of the genus Bacteroides were found to be resistant to penicillin G, and sensitive to imipenem and metronidazole [4e6]. Detection of coagulase-negative staphylococci, some nonfermenting bacilli, Streptococcus viridans, or anaerobic bacteria of the genus Propionibacterium spp. in blood samples requires a comprehensive assessment of the patient’s condition and laboratory test results to distinguish an infection from sample contamination with bacterial skin flora. Opportunistic pathogens often colonize vascular catheters, and may cause catheter-related infections. Physiological microflora can be shown to be the etiological factors if bacterial isolates are obtained from at least two blood samples and there are risk factors facilitating the development of opportunistic infections [7,8]. REFERENCES [1] Bourbeau PP, Foltzer M. Routine incubation of BacT/ ALERT FA and FN blood culture bottles for more than 3 days may not be necessary. J Clin Microbiol 2005;43:2506e9. [2] Kawecki D, Kwiatkowski A, Michalak G, et al. Etiologic agents of bacteremia in the early period after simultaneous
BLOOD INFECTIONS pancreas-kidney transplantation. Transplant Proc 2009;41: 3151e3. [3] Rattanaumpawan P, Ussavasodhi P, Kiratisin P, et al. Epidemiology of bacteremia caused by uncommon non-fermentative gram-negative bacteria. BMC Infect Dis 2013;13:167e74. [4] Maciejewska K, Kedzia A, Zienkiewicz J, et al. Study on susceptibility of anaerobes isolated from blood of patients surgically treated within oral cavity to certain antibiotics and chemotherapeutic agents. Ann Acad Med Gedam 2006;36:133e8. [5] Hartmeyer GN, Sóki J, Nagy E, et al. Multidrug-resistant Bacteroides fragilis group on the rise in Europe? J Med Microbiol 2012;61:1784e8.
2591 [6] Kierzkowska M, Majewska A, Sawicka-Grzelak A, et al. Participation of strictly anaerobic bacteria in infections among hospitalized transplant patients in a clinical hospital in Warsaw. Transplant Proc 2011;43:3130e1. [7] Dubiel G, Dziublewska B, Zaloudik E. Blood culture results in specialistic unit for pulmonary illness and tuberculosis in Bystra in 2008-2010. Przegl Epidemiol 2011;65: 447e50. [8] Saito T, Senda K, Takakura S, et al. Anaerobic bacteremia: the yield of positive anaerobic blood cultures: patient characteristics and potential risk factors. Clin Chem Lab Med 2003;4: 293e7.
