Microbiology Received: December 17, 2013 Accepted after revision: March 4, 2014 Published online: May 10, 2014
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Antibiotic Resistance of Gram-Negative Bacilli Isolated from Pediatric Patients with Nosocomial Bloodstream Infections in a Mexican Tertiary Care Hospital Miguel Ángel Ares a, b Maria Dolores Alcántar-Curiel c César Jiménez-Galicia a Nora Rios-Sarabia b Sabino Pacheco d Miguel Ángel De la Cruz b
a
Laboratorio de Microbiología Clínica, Unidad Médica de Alta Especialidad, b Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, c Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, d Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
Key Words Antibiotic resistance · Gram-negative bacilli · Nosocomial bloodstream infection
Abstract Background: Gram-negative bacilli are the most common bacteria causing nosocomial bloodstream infections (NBSIs) in Latin American countries. Methods: The antibiotic resistance profiles of Gram-negative bacilli isolated from blood cultures in pediatric patients with NBSIs over a 3-year period in a tertiary care pediatric hospital in Mexico City were determined using the VITEK-2 system. Sixteen antibiotics were tested to ascertain the resistance rate and the minimum inhibitory concentration using the Clinical Laboratory Standards Institute (CLSI) broth micro-dilution method as a reference. Results: A total of 931 isolates were recovered from 847 clinically significant episodes of NBSI. Of these, 477 (51.2%) were caused by Gram-negative bacilli. The most common Gram-negative bacilli found were Klebsiella pneu-
M.Á.A. and M.D.A.-C. contributed equally to this work.
© 2014 S. Karger AG, Basel 0009–3157/14/0595–0361$39.50/0 E-Mail [email protected] www.karger.com/che
moniae (30.4%), Escherichia coli (18.9%), Enterobacter cloacae (15.1%), Pseudomonas aeruginosa (9.9%), and Acinetobacter baumannii (4.6%). More than 45 and 60% of the K. pneumoniae and E. coli isolates, respectively, were resistant to cephalosporins, and 64% of the E. coli isolates were resistant to fluoroquinolones. A. baumannii exhibited low rates of resistance to antibiotics tested. In the E. cloacae and P. aeruginosa isolates, no rates of resistance higher than 38% were observed. Conclusions: In this study, we found that the proportion of NBSIs due to antibiotic-resistant organisms is increasing in a tertiary care pediatric hospital of Mexico. © 2014 S. Karger AG, Basel
Introduction
Hospital-acquired infections, known as nosocomial infections, are a major cause of morbidity and mortality in hospitalized patients. Nosocomial infections frequently have serious consequences for the patients, such as Miguel Ángel De la Cruz Av. Cuauhtémoc 330 Colonia Doctores Mexico City 06720 (Mexico) E-Mail miguel_angel_81 @ live.com Sabino Pacheco Av. Universidad 2001 Colonia Chamilpa Cuernavaca, Morelos 62210 (Mexico) E-Mail sabinopg @ live.com
longer hospital stays which, generate substantial extra costs. Sepsis or bacteremia with a predominance of Gram-negative bacilli is the most common nosocomial infection and has critical consequences due to the increase in mortality rates [1]. Pediatric patients, mainly those who are critically ill in the intensive care unit, are particularly vulnerable to acquiring nosocomial bloodstream infections (NBSIs) [2, 3]. Moreover, immunocompromised patients often develop multiorgan dysfunction and require mechanical ventilation or renal replacement therapy [4]. Antibiotic resistance among NBSI-causing bacteria has increased over the past decades and this has led to limited therapy alternatives and the delayed administration of effective antibiotics [5–7]. Hence, this phenomenon suggests a need for surveillance programs to define species, distributions and resistance rates in order to choose the most appropriate antibiotic treatment for hospitalized patients, and the implementation of more effective control programs to prevent or decrease the rate of nosocomial infections [8, 9]. The epidemiology, location, and risk factors of nosocomial infections in adults, as well as the measures to prevent adults from acquiring nosocomial infections, have been the subject of many studies. However, studies focusing on the pediatric population, particularly in developing countries, are quite limited [10]. The aim of this study was to determine the bacterial species, distribution, and antibiotic resistance of Gramnegative bacilli among clinical isolates of pediatric patients with NBSIs in a tertiary care hospital in Mexico during a 3-year period.
tryptic soy broth supplemented with brain hearth infusion solids and activated charcoal) and incubated in a BacT/ALERT 3D machine (bioMérieux, France) according to the specifications of manufacturer for a maximum of 7 days. Positive blood cultures were selected to isolate and identify the microbial species. An aliquot of 50 μl was inoculated onto MacConkey agar plates and incubated in aerobic conditions for 24–48 h at 37 ° C.
Bacterial Identification and Antimicrobial Susceptibility Testing After incubation, colonies grown on agar plates were suspended in 3 ml of sterile saline solution (0.45% NaCl, pH 7.0) to reach a McFarland turbidity of 0.5–0.63. Afterwards, bacterial identification and an antibiotic susceptibility test were carried out using the VITEK-2 system (bioMérieux). Briefly, Gram-negative bacilli identification cards (VITEK-2, ID-GNB) and antimicrobial susceptibility testing for Gram-negative bacilli cards (VITEK-2, ASTGN04) were inoculated with the bacterial suspensions using an integrated vacuum apparatus and incubated at 37 ° C in the incubation chamber of the system. For all assays, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 strains were used for quality control. Finally, the results reported by the VITEK 2 system were obtained after 24 h. Analyses were processed according CLSI recommendations (document M100-S20) [11]. The susceptibilities of the strains to tigecycline were determined using the E-test method (AB Biodisk, Solna, Sweden). The breakpoints for tigecycline were those set by the US Food and Drug Administration (FDA) [12].
Statistical Analysis Descriptive statistics were used to present the results of this study. Data were analyzed using SPSS v.19 software. In order to carry out comparisons, Pearson’s χ2 and Fisher’s exact tests were used with a 95% confidence interval. p < 0.05 was considered statistically significant.
Results Materials and Methods Study Design and Clinical Data This study was carried out prospectively over a period of 3 years, i.e. from September 2010 to August 2013, at the Laboratory of Clinical Microbiology, Pediatric Hospital, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico. All pediatric patients included in this study were hospitalized for more than 48 h. A clinical examination was conducted by the medical staff in order to rule out sepsis acquired outside of the hospital. Patients were classified according to age into 4 groups, and their name, sex, hospital department, diagnosis, and date of admission were registered. Only one blood culture per patient with an NBSI positive for Gram-negative bacilli was included. Sample Collection and Bacterial Cultures A blood sample volume of 4 ml was collected from patients aseptically. The samples were immediately inoculated with BacT/ ALERT PF pediatric FAN liquid media (20 ml of peptone-enriched
362
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Study and Patient Characteristics In this study, a total of 10,817 samples of pediatric patients with a potential risk of bloodstream infection in the Centro Médico Nacional Siglo XXI of the IMSS in Mexico City were analyzed. Among these, a total of 963 isolates were recovered from 847 clinically significant episodes of NBSI. Gram-negative bacilli caused 51.2% of these NBSIs; Gram-positive organisms caused 43.7% of the cases, and fungi caused 5.1% of the cases. In this study, we evaluated only the 477 isolates recovered from 434 episodes of NBSI caused by Gram-negative bacilli, of which 230 (53%) were from males and 204 (47%) were from female patients. There was no statistically significant difference with regard to gender (p = 0.211). At the time of the diagnosis of NBSI, nearly one third of the patients were hospitalized in a pediatric or neonatal intensive care unit (133; 30.6%). Ares/Alcántar-Curiel/Jiménez-Galicia/ Rios-Sarabia/Pacheco/De la Cruz
Table 1. Epidemiologic and demographic data of pediatric patients
with NBSIs due to Gram-negative bacilli Total patients, n Gender Male Female Clinical care units NICU (age 0–28 days) PITU (age 0–17 years) Pediatric hospitalization units Infants (age 1–24 months) Preschool children (age 2–5 years) Children/adolescents (age 6–17 years) Patients, n/year Patients, n/month Monobacterial infections Multibacterial infections Reinfection eventsa Isolated bacilli, n
434 230 (52.9) 204 (47.0) 77 (17.7) 56 (12.9) 122 (28.1) 68 (15.6) 111 (25.5) 144.66±3.5 12.42±4.4 408 (94.0) 26 (6.0) 9 (2.0) 477
Values are presented as numbers (%) unless otherwise stated. NICU = Neonatal intensive care unit; PITU = pediatric intensive therapy unit. a Reinfection events were considered if different Gram-negative bacilli were isolated after 7 days of the first bloodstream culture.
Table 2. Gram-negative bacilli isolated from pediatric patients with NBSIs Klebsiella pneumoniae 145 (30.4) Kluyvera ascorbata Escherichia coli 90 (18.9) Kluyvera intermedia Enterobacter Enterobacter cloacae 72 (15.1) agglomerans Pseudomonas aeruginosa 47 (9.9) Kluyvera cryocrescens Acinetobacter baumannii 22 (4.6) Moraxella lacunata Serratia marcescens 14 (2.9) Proteus mirabilis Salmonella enterica 11 (2.3) Raoultella planticola Pseudomonas Achromobacter putida 9 (1.9) xylosoxidans Aeromonas hydrophila 7 (1.5) Aeromonas caviae Acinetobacter Bordetella haemolyticus 5 (1.0) bronchiseptica Citrobacter freundii 5 (1.0) Pantoea agglomerans Klebsiella oxytoca 5 (1.0) Pseudomonas alcaligenes Pseudomonas fluorescens 5 (1.0) Ralstonia mannitolilytica Burkholderia cepacia 4 (0.8) Ralstonia pickettii Enterobacter aerogenes 4 (0.8) Raoultella ornithinolytica Acinetobacter iwoffii 3 (0.8) Serratia liquefaciens Enterobacter asburiae 3 (0.8) Yersinia intermedia
3 (0.6) 3 (0.6) 2 (0.4) 2 (0.4) 2 (0.4) 2 (0.4) 2 (0.4) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2)
Values are presented as numbers (%).
Table 3. Rank order of the nosocomial bloodstream Gram-negative bacilli most frequently isolated in pediatric patients
Organisms
K. pneumoniae E. coli E. cloacae P. aeruginosa A. baumannii
Total isolates
Isolates, %
n
%
neonates (age 0–28 days)
infants (age 1–24 months)
preschool children (age 2–5 years)
children/adolescents (age 6–17 years)
145 90 72 47 22
30.4 18.9 15.1 9.9 4.6
31.8 15.0 15.9 5.6 3.7
31.7 22.2 16.2 8.7 4.1
31.8 15.9 12.5 11.4 5.7
28.4 19.4 14.9 13.4 5.2
Six percent of the episodes due to Gram-negative bacilli (n = 26) were multibacterial. In these cases, the most frequently isolated pathogens were K. pneumoniae (46.2%), E. coli (26.9%), E. cloacae (19.2%), and P. aeruginosa (7.7%). Most of the multibacterial infections presented 2 pathogens (24 patients), and only 2 patients were infected with 3 and 4 pathogens, respectively. Nine reinfection events with Gram-negative bacilli were detected in the total patients and most of them presented an immunocompromised condition, such as HIV, cystic fibrosis, or cancer, including leukemia and lymphoma. A summary of this information is presented in table 1.
Bacterial Isolates A total of 34 different species were isolated (table 2) and the 5 most frequent Gram-negative bacilli were: K. pneumoniae (30.4%), E. coli (18.9%), E. cloacae (15.1%), P. aeruginosa (9.9%), and A. baumannii (4.6%). When different age groups were compared (table 3), the proportion of K. pneumoniae decreased from 32% in neonate and infant patients to 28% in child/adolescent patients. For E. coli, E. cloacae and A. baumannii, the proportions remained relatively stable. On the other hand, the proportions of P. aeruginosa increased in the same patient populations from 6 to 13%.
Antibiotic Resistance of Gram-Negative Bacilli
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
363
Table 4. MIC data and resistance of the most frequent clinical isolates of Enterobacteriaceaea
Antibiotic
Amp/Sul Pip/Taz Cefazolin Ceftriaxone Cefepime Aztreonam Ertapenem Imipenem Meropenem Amikacin Gentamicin Tobramycin Ciprofloxacin Moxifloxacin Tigecyclineb Trim/Sulf
K. pneumoniae (n = 145)
E. coli (n = 90)
E. cloacae (n = 72)
MIC50 MIC90
MIC range
R, %
MIC50 MIC90 MIC range
R, %
MIC50
MIC90
MIC range
R, %
16 2 ≤4 >8 16 >16 ≤0.12 ≤0.12 ≤0.12 1 ≤1 1 ≤0.5 ≤0.5 0.25 ≤0.5
1–>32 ≤0.5–>64 ≤4–>16 ≤0.06–>8 ≤0.5–>16 ≤0.12–>16 ≤0.12–>8 ≤0.12–>8 ≤0.12–>8 0.5–>32 ≤1–>8 ≤0.12–>16 ≤0.5–>4 ≤0.5–>4 ≤0.03–>4 ≤0.5–>4
55.1 6.8 55.8 48.9 45.5 46.8 0.6 0.6 2.0 5.5 24.1 32.4 2.0 2.0 2.7 37.2
32 8 4 8 16 16 ≤0.12 ≤0.12 ≤0.12 ≤4 ≤1 1 >4 >4 0.12 >4
64.4 31.1 64.4 63.3 63.3 63.3 1.1 1.1 1.1 8.8 42.2 52.2 64.4 64.4 0 52.2
ND 4 ND ND ≤0.5 0.5 ≤0.12 ≤0.12 ≤0.12 2 ≤1 0.5 ≤0.5 ≤0.5 0.25 ≤0.5
ND >64 ND ND >16 8 0.25 0.25 0.25 16 4 8 2 2 1 >4
ND ≤0.5–>64 ND ND ≤0.5–>16 ≤0.12–>16 ≤0.12–>8 ≤0.12–>8 ≤0.12–>8 0.5–>32 ≤1–>8 ≤0.12–>16 ≤0.5–>4 ≤0.5–>4 0.06–4 ≤0.5–>4
ND 16.6 ND ND 8.3 22.2 2.7 2.7 2.7 6.9 4.1 18.0 5.5 6.9 1.3 23.6
>32 32 >16 >8 >16 >16 0.25 0.25 0.25 >32 >8 >16 2 2 1 >4
>32 32 >16 >8 >16 >16 0.25 0.25 0.25 8 >8 >16 >4 >4 0.25 >4
≤0.25–>32 ≤0.5–>64 ≤4–>16 ≤0.06–>8 ≤0.5–>16 ≤0.12–>16 ≤0.12–>8 ≤0.12–>8 ≤0.12–>8 0.5–>32 ≤1–>8 ≤0.25–>16 ≤0.5–>4 ≤0.5–>4 ≤0.03–1 ≤0.5–>4
Values are presented as micrograms per milliliter unless otherwise stated. MIC = Minimum inhibitory concentration; R = resistance; Amp/Sul = ampicillin/sulbactam; Pip/Taz = piperazillin/tazobactam; Trim/Sulf = trimethoprim/sulfamethoxazole; ND = not determined. a Criteria as published by the CLSI [11]. b US FDA breakpoints were applied [12].
Antimicrobial Susceptibility For K. pneumoniae, a relatively high proportion of the isolates displayed a resistance to ampicillin/sulbactam, cefazolin, ceftriaxone, and cefepime (55.1, 55.8, 48.9 and 45.5%, respectively). A resistance to aztreonam was seen in 46.8% of the isolates. Piperazillin/tazobactam and amikacin displayed good activity. All carbapenems, fluoroquinolones and tigecycline were highly active (64 ND ND 16 8 ND >8 4 >32 4 8 2 2 ND ND
ND ≤0.5–>64 ND ND ≤0.5–16 0.5–>16 ND ≤0.12–>8 ≤0.06–>8 ≤0.25–>32 ≤1–>8 ≤0.12–16 ≤0.5–>4 ≤0.12–>4 ND ND
ND 38.2 ND ND 8.5 19.1 ND 21.2 2.1 14.8 10.6 23.4 4.2 10.6 ND ND
1 2 ND ND ≤0.5 ND ND ≤0.12 ≤0.12 0.5 ≤1 0.25 ≤0.5 ≤0.5 ≤0.03 ≤0.5
1 32 ND ND 2 ND ND 0.12 0.25 4 1 0.25 2 2 0.03 >4
1–>32 ≤0.5–>64 ND ND ≤0.5–16 ND ND ≤0.12–>8 ≤0.06–>8 0.5–>32 ≤1–>8 0.25–16 ≤0.5–>4 ≤0.12–>4 ≤0.03–>4 ≤0.5–>4
0 9.0 ND ND 4.5 ND ND 0 4.5 4.5 0 0 4.5 4.5 0 9.0
Values are presented as micrograms per milliliter unless otherwise stated. MIC = Minimum inhibitory concentration; R = resistance; Amp/Sul = ampicillin/sulbactam; Pip/Taz = piperazillin/tazobactam; Trim/Sulf = trimethoprim/sulfamethoxazole; ND = not determined. a Criteria as published by the CLSI [11]. b US FDA breakpoints were applied [12].
ly, to 70.6 and 12.5%, respectively, from 2010 to 2013. For A. baumannii, relatively stable and low rates of resistance to all antimicrobials were observed. For P. aeruginosa a decline in the resistance to aztreonam was observed, i.e. from 45.5% in 2010 to 18.2% in 2013. The resistance rates for carbapenems remained low for the 5 most frequently bacteria isolated over this time period.
Antimicrobial resistance is a public health problem which requires monitoring programs that provide regional and global data. NBSIs are the most serious and potentially life-threatening infectious disease in pediatric patients [13, 14]. Both the study of the distribution of the bacterial species most frequently involved in nosocomial infections and the prevalence of resistance among pathogenic bacteria are important as they provide the basis for appropriate empiric therapy [2, 15]. For these reasons, knowledge of the pathogens causing NBSIs and the resistance profile is essential for successful therapy and infection control.
Many different Gram-negative bacteria may cause nosocomial infections. In this study, we described that K. pneumoniae, E. coli, E. cloacae, P. aeruginosa, and A. baumannii were the Gram-negative bacilli most frequently isolated in pediatric patients with NBSIs in a Mexican tertiary care hospital (tables 2, 3). In accordance with other studies of NBSIs in pediatric patients conducted in Latin America [16], we report a higher prevalence of Gramnegative bacilli over Gram-positive organisms (51.2 vs. 43.7%, respectively). A recent study of regional resistance surveillance in 11 countries of Latin America including Mexico reported similar prevalent pathogens isolated from various types of clinical infections in patients in tertiary care hospitals [17]. In another study performed in Brazil, K. pneumoniae, A. baumannii, Enterobacter spp., and P. aeruginosa, were most frequently isolated from children with NBSIs [16]. These observations showed that the microorganisms causing NBSIs in Latin American countries are very similar, with 4 of them, i.e. K. pneumoniae, Enterobacter spp., A. baumannii, and P. aeruginosa, belonging to the ESKAPE group [18]. It is worth mentioning the prevalence of NBSIs in different wards within the hospital: the great majority (69%)
Antibiotic Resistance of Gram-Negative Bacilli
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Discussion
365
Table 6. Percentage of antibiotic resistance by year among the most frequently isolated Gram-negative bacillia
Antibiotic
Enterobacteriaceae K. pneumoniae
Amp/Sul Pip/Taz Cefazolin Ceftriaxone Cefepime Aztreonam Ertapenem Imipenem Meropenem Amikacin Gentamicin Tobramycin Ciprofloxacin Moxifloxacin Tigecyclineb Trim/Sulf Antibiotic
E. coli
E. cloacae
2010–2011 2011–2012 2012–2013 2010–2011 2011–2012 2012–2013 (n = 39) (n = 58) (n = 48) (n = 29) (n = 27) (n = 34)
2010–2011 2011–2012 2012–2013 (n = 27) (n = 29) (n = 16)
35.9 7.7 41.0 28.2 28.2 28.2 0 0 2.6 7.7 17.9 23.1 2.6 2.6 0 25.6
ND 18.5 ND ND 14.8 25.9 3.7 3.7 3.7 14.8 11.1 22.2 7.4 7.4 0 29.6
63.7 13.8 58.6 53.4 51.7 53.4 1.7 1.7 3.4 1.7 32.8 44.8 1.7 1.7 6.9 46.6
60.4 0 64.6 60.4 52.1 54.2 0 0 0 8.3 18.8 25.0 2.1 2.1 0 35.4
58.6 44.8 65.5 62.1 62.1 62.1 0 0 0 6.9 51.7 55.2 51.7 51.7 0 37.9
51.9 37.0 44.4 44.4 44.4 44.4 0 0 0 3.7 29.6 44.4 70.4 70.4 0 48.1
ND 20.7 ND ND 0 20.7 3.4 3.4 3.4 0 0 13.8 0 3.4 0 20.7
ND 6.3 ND ND 12.5 18.8 0 0 0 6.3 0 18.8 12.5 12.5 6.3 18.8
Non-fermenters P. aeruginosa
Amp/Sul Pip/Taz Cefazolin Ceftriaxone Cefepime Aztreonam Ertapenem Imipenem Meropenem Amikacin Gentamicin Tobramycin Ciprofloxacin Moxifloxacin Tigecyclineb Trim/Sulf
79.4 14.7 79.4 79.4 79.4 79.4 2.94 2.94 2.94 14.7 44.1 55.9 70.6 70.6 0 70.6
A. baumannii
2010–2011 (n = 11)
2011–2012 (n = 14)
2012–2013 (n = 22)
2010–2011 (n = 6)
2011–2012 (n = 10)
2012–2013 (n = 6)
ND 72.7 ND ND 18.2 45.5 ND 18.2 9.1 18.2 18.2 36.4 18.2 27.3 ND ND
ND 57.1 ND ND 0 0 ND 28.6 0 14.3 0 14.3 0 0 ND ND
ND 4.6 ND ND 9.1 18.2 ND 18.2 0 13.6 13.6 22.7 0 9.1 ND ND
0 0 ND ND 0 33.3 ND 0 0 0 0 0 0 0 0 16.7
0 20 ND ND 10 40 ND 0 10 10 0 0 10 10 0 10
0 0 ND ND 0 50 ND 0 0 0 0 0 0 0 0 0
Amp/Sul = Ampicillin/sulbactam; Pip/Taz = piperazillin/tazobactam; Trim/Sulf = trimethoprim/sulfamethoxazole; ND = not determined. a Criteria as published by the CLSI [11]. b US FDA breakpoints were applied [12].
was detected in patients in pediatric hospitalization units and the remainder (31%) was in intensive care units (table 1). This prevalence was lower than that previously reported in the critical care setting in hospitals in the USA (50%) and Brazil (45%) [15, 16]. 366
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Milliken et al. [19] found that the age-specific infection ratio was highest for the age group younger than 1 month of age. In contrast, we did not observe a correlation between NBSI rates and pediatric population age (table 3). Ares/Alcántar-Curiel/Jiménez-Galicia/ Rios-Sarabia/Pacheco/De la Cruz
In another study, an antimicrobial susceptibility test was performed and none of the isolates was resistant to imipenem [20]. We also found low rates of resistance to imipenem for isolated Enterobacteriaceae family members. In contrast, for P. aeruginosa it was observed that almost one quarter of the isolates were resistant to this antimicrobial. In general, the resistance pattern of E. coli evaluated in this study presented higher levels (ceftriaxone, 63%; cefepime, 63%; gentamicin, 42%; tobramycin, 52%, and piperazillin/tazobactam, 31%) than those previously reported in Latin America (ceftriaxone, 37%; cefepime, 23%; gentamicin, 27%; tobramycin, 32%, and piperazillin/ tazobactam, 5%) [17]. Interestingly, we found that P. aeruginosa and A. baumannii presented lower rates of antimicrobial resistance [mainly to imipenem (21 and 0%), meropenem (2 and 4%), and amikacin (14 and 4%), respectively] when compared to the results of a Latin American study [imipenem (44 and 75%), meropenem (38 and 75%), and amikacin (20 and 67%), respectively] [17]. It must be noted that antibiotic administration programs differ with respect to patient age (adult vs. pediatric), and this could have had an effect on the observed antimicrobial susceptibility. In Mexico, the A. baumannii resistance rates to meropenem in two different regions were 59 and 88% for adults in Monterrey and Guadalajara, respectively [21, 22]. This study, performed in Mexico City, showed a resistance of 4.5% for meropenem in pediatric patients (table 5). These data are particularly important because they suggest an adequate management of patients, an accurate antimi-
crobial stewardship, and appropriate surveillance programs in this Mexico City hospital. Ceftriaxone, a thirdgeneration cephalosporin, has a broad spectrum of activity against Gram-positive and Gram-negative organisms and is commonly recommended in empirical treatment guidelines as it provides successful treatment [23]. However, in K. pneumoniae and E. coli isolates, the antibiotic resistance rates increased for ceftriaxone in the last year of this study. The study of antimicrobial resistance during the 3-year period showed an increase in rates of resistance, indicating a low antimicrobial activity and demonstrating the importance of ongoing monitoring of the activity of these compounds against the most important nosocomial pathogens in hospitals in our region and country. This is the first study in pediatric patients in Mexico, and its importance lies in the fact that resistance data from adult patients are frequently extrapolated to pediatric patients. This study establishes data of regional resistance and is important for the surveillance of antibiotic resistance in regional and national pediatric populations with nosocomial infections.
Acknowledgments We would like to thank all members of the Laboratory of Clinical Microbiology, Pediatric Hospital, Centro Médico Nacional Siglo XXI, IMSS. We also thank Edmundo Calva and Jorge A. Girón for their critical reading of this paper. Dr. María Dolores AlcántarCuriel gratefully acknowledges the support of UNAM-DGAPAPAPIIT IN220613.
References 1 Raymond J, Aujard Y: Nosocomial infections in pediatric patients: a European, multicenter prospective study. European Study Group. Infect Control Hosp Epidemiol 2000;21:260– 263. 2 Wisplinghoff H, Seifert H, Tallent SM, Bischoff T, Wenzel RP, Edmond MB: Nosocomial bloodstream infections in pediatric patients in United States hospitals: epidemiology, clinical features and susceptibilites. Pediatr Infect Dis J 2003;22:686–691. 3 Esteban E, Ferrer R, Urrea M, Suarez D, Rozas L, Balaguer M, Palomeque A, Jordan I: The impact of a quality improvement intervention to reduce nosocomial infections in a PICU. Pediatr Crit Care Med 2013;14:525–532. 4 Laupland KB, Gregson DB, Zygun DA, Doig CJ, Mortis G, Church DL: Severe bloodstream infections: a population-based assessment. Crit Care Med 2004;32:992–997. 5 Gales AC, Castanheira M, Jones RN, Sader HS: Antimicrobial resistance among Gramnegative bacilli isolated from Latin America:
Antibiotic Resistance of Gram-Negative Bacilli
6
7 8
9
results from SENTRY Antimicrobial Surveillance Program (Latin America, 2008–2010). Diagn Microbiol Infect Dis 2012;73:354–360. Ariffin N, Hasan H, Ramli N, Ibrahim NR, Taib F, Rahman AA, Mohamed Z, Wahab S, Isaacs D, Van Rostenberghe H: Comparison of antimicrobial resistance in neonatal and adult intensive care units in a tertiary teaching hospital. Am J Infect Control 2012;40:572–575. Alanis AJ: Resistance to antibiotics: are we in the post-antibiotic era? Arch Med Res 2005; 36:697–705. Piéboji JG, Koulla-Shiro S, Ngassam P, Adiogo D, Njine T, Ndumbe P: Antimicrobial resistance of Gram-negative bacilli isolates from inpatients and outpatients at Yaounde Central Hospital, Cameroon. Int J Infect Dis 2004;8:147–154. Becerra MR, Tantaleán JA, Suárez VJ, Alvarado MC, Candela JL, Urcia FC: Epidemiologic surveillance of nosocomial infections in a Pediatric Intensive Care Unit of a developing country. BMC Pediatr 2010;10:66.
10 Abramczyck ML, Carvalho WB, Carvalho ES, Medeiros EA: Nosocomial infection in a pediatric intensive care unit in a developing country. Braz J Infect Dis 2003;6:375–380. 11 Clinical Laboratory Standards Institute: Performance standards for antimicrobial susceptibility testing: twentieth informational supplement (CLSI document M100-S20). Wayne, CLSI, 2010. 12 Pillar CM, Draghi DC, Dowzicky MJ, Sahm DF: In vitro activity of tigecycline against Gram-positive and Gram-negative pathogens as evaluated by broth microdilution and Etest. J Clin Microbiol 2008;46:2862–2867. 13 Gray J, Gossain S, Morris K: Three-year survey of bacteremia and fungemia in a pediatric intensive care unit. Pediatr Infect Dis J 2001; 4:416–421. 14 Joram N, de Saint Blanquat L, Stamm D, Launay E, Gras-Le Guen C: Healthcare-associated infection prevention in pediatric intensive care units: a review. Eur J Clin Microbiol Infect Dis 2012;31:2481–2490.
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
367
15 Wisplinghoff H, Bischoff T, Tallent SM, Seifert H, Wenzel RP, Edmond MB: Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study. Clin Infect Dis 2004; 39:309–317. 16 Pereira CA, Marra AR, Camargo LF, Pignatari AC, Sukiennik T, Behar PR, Medeiros EA, Ribeiro J, Girão E, Correa L, Guerra C, Carneiro I, Brites C, Reis M, de Souza MA, Tranchesi R, Barata CU, Edmond MB; Brazilian SCOPE Study Group: Nosocomial bloodstream infections in Brazilian pediatric patients: microbiology, epidemiology, and clinical features. PLoS One 2013; 8: e68144.
368
17 Jones RN, Guzman-Blanco M, Gales AC, Gallegos B, Castro AL, Martino MD, Vega S, Zurita J, Cepparulo M, Castanheira M: Susceptibility rates in Latin American nations: report from a regional resistance surveillance program (2011). Braz J Infect Dis 2013; 17: 672–681. 18 Rice LB: Progress and challenges in implementing the research on ESKAPE pathogens. Infect Control Hosp Epidemiol 2010; 31(suppl 1): S7–S10. 19 Milliken J, Tait GA, Ford-Jones EL, Mindorff CM, Gold R, Mullins G: Nosocomial infections in a pediatric intensive care unit. Crit Care Med 1988;16:233–237. 20 Muro S, Garza-González E, Camacho-Ortiz A, González GM, Llaca-Díaz JM, Bosques F, Rositas F: Risk factors associated with extendedspectrum β-lactamase-producing enterobacteriaceae nosocomial bloodstream infections in a tertiary care hospital: a Clinical and molecular analysis. Chemotherapy 2012;58:217–224.
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
21 Garza-González E, Mendoza Ibarra SI, LlacaDíaz JM, González GM: Molecular characterization and antimicrobial susceptibility of extended-spectrum {β}-lactamase-producing Enterobacteriaceae isolates at a tertiary-care centre in Monterrey, Mexico. J Med Microbiol 2011;60:84–90. 22 Morfín-Otero R, Alcántar-Curiel MD, Rocha MJ, Alpuche-Aranda CM, Santos-Preciado JI, Gayosso-Vázquez C, Araiza-Navarro JR, Flores-Vaca M, Esparza-Ahumada S, GonzálezDíaz E, Pérez-Gómez HR, Rodríguez-Noriega E: Acinetobacter baumannii infections in a tertiary care hospital in Mexico over the past 13 years. Chemotherapy 2013;59:57–65. 23 Dailly E, Verdier MC, Deslandes G, Bouquié R, Tribut O, Bentué-Ferrer D: Level of evidence for therapeutic drug monitoring of ceftriaxone. Therapie 2012;67:145–149.
Ares/Alcántar-Curiel/Jiménez-Galicia/ Rios-Sarabia/Pacheco/De la Cruz
Copyright: S. Karger AG, Basel 2014. Reproduced with the permission of S. Karger AG, Basel. Further reproduction or distribution (electronic or otherwise) is prohibited without permission from the copyright holder.
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Antibiotic Resistance of Gram-Negative Bacilli Isolated from Pediatric Patients with Nosocomial Bloodstream Infections in a Mexican Tertiary Care Hospital Miguel Ángel Ares a, b Maria Dolores Alcántar-Curiel c César Jiménez-Galicia a Nora Rios-Sarabia b Sabino Pacheco d Miguel Ángel De la Cruz b
a
Laboratorio de Microbiología Clínica, Unidad Médica de Alta Especialidad, b Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, c Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, d Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
Key Words Antibiotic resistance · Gram-negative bacilli · Nosocomial bloodstream infection
Abstract Background: Gram-negative bacilli are the most common bacteria causing nosocomial bloodstream infections (NBSIs) in Latin American countries. Methods: The antibiotic resistance profiles of Gram-negative bacilli isolated from blood cultures in pediatric patients with NBSIs over a 3-year period in a tertiary care pediatric hospital in Mexico City were determined using the VITEK-2 system. Sixteen antibiotics were tested to ascertain the resistance rate and the minimum inhibitory concentration using the Clinical Laboratory Standards Institute (CLSI) broth micro-dilution method as a reference. Results: A total of 931 isolates were recovered from 847 clinically significant episodes of NBSI. Of these, 477 (51.2%) were caused by Gram-negative bacilli. The most common Gram-negative bacilli found were Klebsiella pneu-
M.Á.A. and M.D.A.-C. contributed equally to this work.
© 2014 S. Karger AG, Basel 0009–3157/14/0595–0361$39.50/0 E-Mail [email protected] www.karger.com/che
moniae (30.4%), Escherichia coli (18.9%), Enterobacter cloacae (15.1%), Pseudomonas aeruginosa (9.9%), and Acinetobacter baumannii (4.6%). More than 45 and 60% of the K. pneumoniae and E. coli isolates, respectively, were resistant to cephalosporins, and 64% of the E. coli isolates were resistant to fluoroquinolones. A. baumannii exhibited low rates of resistance to antibiotics tested. In the E. cloacae and P. aeruginosa isolates, no rates of resistance higher than 38% were observed. Conclusions: In this study, we found that the proportion of NBSIs due to antibiotic-resistant organisms is increasing in a tertiary care pediatric hospital of Mexico. © 2014 S. Karger AG, Basel
Introduction
Hospital-acquired infections, known as nosocomial infections, are a major cause of morbidity and mortality in hospitalized patients. Nosocomial infections frequently have serious consequences for the patients, such as Miguel Ángel De la Cruz Av. Cuauhtémoc 330 Colonia Doctores Mexico City 06720 (Mexico) E-Mail miguel_angel_81 @ live.com Sabino Pacheco Av. Universidad 2001 Colonia Chamilpa Cuernavaca, Morelos 62210 (Mexico) E-Mail sabinopg @ live.com
longer hospital stays which, generate substantial extra costs. Sepsis or bacteremia with a predominance of Gram-negative bacilli is the most common nosocomial infection and has critical consequences due to the increase in mortality rates [1]. Pediatric patients, mainly those who are critically ill in the intensive care unit, are particularly vulnerable to acquiring nosocomial bloodstream infections (NBSIs) [2, 3]. Moreover, immunocompromised patients often develop multiorgan dysfunction and require mechanical ventilation or renal replacement therapy [4]. Antibiotic resistance among NBSI-causing bacteria has increased over the past decades and this has led to limited therapy alternatives and the delayed administration of effective antibiotics [5–7]. Hence, this phenomenon suggests a need for surveillance programs to define species, distributions and resistance rates in order to choose the most appropriate antibiotic treatment for hospitalized patients, and the implementation of more effective control programs to prevent or decrease the rate of nosocomial infections [8, 9]. The epidemiology, location, and risk factors of nosocomial infections in adults, as well as the measures to prevent adults from acquiring nosocomial infections, have been the subject of many studies. However, studies focusing on the pediatric population, particularly in developing countries, are quite limited [10]. The aim of this study was to determine the bacterial species, distribution, and antibiotic resistance of Gramnegative bacilli among clinical isolates of pediatric patients with NBSIs in a tertiary care hospital in Mexico during a 3-year period.
tryptic soy broth supplemented with brain hearth infusion solids and activated charcoal) and incubated in a BacT/ALERT 3D machine (bioMérieux, France) according to the specifications of manufacturer for a maximum of 7 days. Positive blood cultures were selected to isolate and identify the microbial species. An aliquot of 50 μl was inoculated onto MacConkey agar plates and incubated in aerobic conditions for 24–48 h at 37 ° C.
Bacterial Identification and Antimicrobial Susceptibility Testing After incubation, colonies grown on agar plates were suspended in 3 ml of sterile saline solution (0.45% NaCl, pH 7.0) to reach a McFarland turbidity of 0.5–0.63. Afterwards, bacterial identification and an antibiotic susceptibility test were carried out using the VITEK-2 system (bioMérieux). Briefly, Gram-negative bacilli identification cards (VITEK-2, ID-GNB) and antimicrobial susceptibility testing for Gram-negative bacilli cards (VITEK-2, ASTGN04) were inoculated with the bacterial suspensions using an integrated vacuum apparatus and incubated at 37 ° C in the incubation chamber of the system. For all assays, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 strains were used for quality control. Finally, the results reported by the VITEK 2 system were obtained after 24 h. Analyses were processed according CLSI recommendations (document M100-S20) [11]. The susceptibilities of the strains to tigecycline were determined using the E-test method (AB Biodisk, Solna, Sweden). The breakpoints for tigecycline were those set by the US Food and Drug Administration (FDA) [12].
Statistical Analysis Descriptive statistics were used to present the results of this study. Data were analyzed using SPSS v.19 software. In order to carry out comparisons, Pearson’s χ2 and Fisher’s exact tests were used with a 95% confidence interval. p < 0.05 was considered statistically significant.
Results Materials and Methods Study Design and Clinical Data This study was carried out prospectively over a period of 3 years, i.e. from September 2010 to August 2013, at the Laboratory of Clinical Microbiology, Pediatric Hospital, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico. All pediatric patients included in this study were hospitalized for more than 48 h. A clinical examination was conducted by the medical staff in order to rule out sepsis acquired outside of the hospital. Patients were classified according to age into 4 groups, and their name, sex, hospital department, diagnosis, and date of admission were registered. Only one blood culture per patient with an NBSI positive for Gram-negative bacilli was included. Sample Collection and Bacterial Cultures A blood sample volume of 4 ml was collected from patients aseptically. The samples were immediately inoculated with BacT/ ALERT PF pediatric FAN liquid media (20 ml of peptone-enriched
362
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Study and Patient Characteristics In this study, a total of 10,817 samples of pediatric patients with a potential risk of bloodstream infection in the Centro Médico Nacional Siglo XXI of the IMSS in Mexico City were analyzed. Among these, a total of 963 isolates were recovered from 847 clinically significant episodes of NBSI. Gram-negative bacilli caused 51.2% of these NBSIs; Gram-positive organisms caused 43.7% of the cases, and fungi caused 5.1% of the cases. In this study, we evaluated only the 477 isolates recovered from 434 episodes of NBSI caused by Gram-negative bacilli, of which 230 (53%) were from males and 204 (47%) were from female patients. There was no statistically significant difference with regard to gender (p = 0.211). At the time of the diagnosis of NBSI, nearly one third of the patients were hospitalized in a pediatric or neonatal intensive care unit (133; 30.6%). Ares/Alcántar-Curiel/Jiménez-Galicia/ Rios-Sarabia/Pacheco/De la Cruz
Table 1. Epidemiologic and demographic data of pediatric patients
with NBSIs due to Gram-negative bacilli Total patients, n Gender Male Female Clinical care units NICU (age 0–28 days) PITU (age 0–17 years) Pediatric hospitalization units Infants (age 1–24 months) Preschool children (age 2–5 years) Children/adolescents (age 6–17 years) Patients, n/year Patients, n/month Monobacterial infections Multibacterial infections Reinfection eventsa Isolated bacilli, n
434 230 (52.9) 204 (47.0) 77 (17.7) 56 (12.9) 122 (28.1) 68 (15.6) 111 (25.5) 144.66±3.5 12.42±4.4 408 (94.0) 26 (6.0) 9 (2.0) 477
Values are presented as numbers (%) unless otherwise stated. NICU = Neonatal intensive care unit; PITU = pediatric intensive therapy unit. a Reinfection events were considered if different Gram-negative bacilli were isolated after 7 days of the first bloodstream culture.
Table 2. Gram-negative bacilli isolated from pediatric patients with NBSIs Klebsiella pneumoniae 145 (30.4) Kluyvera ascorbata Escherichia coli 90 (18.9) Kluyvera intermedia Enterobacter Enterobacter cloacae 72 (15.1) agglomerans Pseudomonas aeruginosa 47 (9.9) Kluyvera cryocrescens Acinetobacter baumannii 22 (4.6) Moraxella lacunata Serratia marcescens 14 (2.9) Proteus mirabilis Salmonella enterica 11 (2.3) Raoultella planticola Pseudomonas Achromobacter putida 9 (1.9) xylosoxidans Aeromonas hydrophila 7 (1.5) Aeromonas caviae Acinetobacter Bordetella haemolyticus 5 (1.0) bronchiseptica Citrobacter freundii 5 (1.0) Pantoea agglomerans Klebsiella oxytoca 5 (1.0) Pseudomonas alcaligenes Pseudomonas fluorescens 5 (1.0) Ralstonia mannitolilytica Burkholderia cepacia 4 (0.8) Ralstonia pickettii Enterobacter aerogenes 4 (0.8) Raoultella ornithinolytica Acinetobacter iwoffii 3 (0.8) Serratia liquefaciens Enterobacter asburiae 3 (0.8) Yersinia intermedia
3 (0.6) 3 (0.6) 2 (0.4) 2 (0.4) 2 (0.4) 2 (0.4) 2 (0.4) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2) 1 (0.2)
Values are presented as numbers (%).
Table 3. Rank order of the nosocomial bloodstream Gram-negative bacilli most frequently isolated in pediatric patients
Organisms
K. pneumoniae E. coli E. cloacae P. aeruginosa A. baumannii
Total isolates
Isolates, %
n
%
neonates (age 0–28 days)
infants (age 1–24 months)
preschool children (age 2–5 years)
children/adolescents (age 6–17 years)
145 90 72 47 22
30.4 18.9 15.1 9.9 4.6
31.8 15.0 15.9 5.6 3.7
31.7 22.2 16.2 8.7 4.1
31.8 15.9 12.5 11.4 5.7
28.4 19.4 14.9 13.4 5.2
Six percent of the episodes due to Gram-negative bacilli (n = 26) were multibacterial. In these cases, the most frequently isolated pathogens were K. pneumoniae (46.2%), E. coli (26.9%), E. cloacae (19.2%), and P. aeruginosa (7.7%). Most of the multibacterial infections presented 2 pathogens (24 patients), and only 2 patients were infected with 3 and 4 pathogens, respectively. Nine reinfection events with Gram-negative bacilli were detected in the total patients and most of them presented an immunocompromised condition, such as HIV, cystic fibrosis, or cancer, including leukemia and lymphoma. A summary of this information is presented in table 1.
Bacterial Isolates A total of 34 different species were isolated (table 2) and the 5 most frequent Gram-negative bacilli were: K. pneumoniae (30.4%), E. coli (18.9%), E. cloacae (15.1%), P. aeruginosa (9.9%), and A. baumannii (4.6%). When different age groups were compared (table 3), the proportion of K. pneumoniae decreased from 32% in neonate and infant patients to 28% in child/adolescent patients. For E. coli, E. cloacae and A. baumannii, the proportions remained relatively stable. On the other hand, the proportions of P. aeruginosa increased in the same patient populations from 6 to 13%.
Antibiotic Resistance of Gram-Negative Bacilli
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
363
Table 4. MIC data and resistance of the most frequent clinical isolates of Enterobacteriaceaea
Antibiotic
Amp/Sul Pip/Taz Cefazolin Ceftriaxone Cefepime Aztreonam Ertapenem Imipenem Meropenem Amikacin Gentamicin Tobramycin Ciprofloxacin Moxifloxacin Tigecyclineb Trim/Sulf
K. pneumoniae (n = 145)
E. coli (n = 90)
E. cloacae (n = 72)
MIC50 MIC90
MIC range
R, %
MIC50 MIC90 MIC range
R, %
MIC50
MIC90
MIC range
R, %
16 2 ≤4 >8 16 >16 ≤0.12 ≤0.12 ≤0.12 1 ≤1 1 ≤0.5 ≤0.5 0.25 ≤0.5
1–>32 ≤0.5–>64 ≤4–>16 ≤0.06–>8 ≤0.5–>16 ≤0.12–>16 ≤0.12–>8 ≤0.12–>8 ≤0.12–>8 0.5–>32 ≤1–>8 ≤0.12–>16 ≤0.5–>4 ≤0.5–>4 ≤0.03–>4 ≤0.5–>4
55.1 6.8 55.8 48.9 45.5 46.8 0.6 0.6 2.0 5.5 24.1 32.4 2.0 2.0 2.7 37.2
32 8 4 8 16 16 ≤0.12 ≤0.12 ≤0.12 ≤4 ≤1 1 >4 >4 0.12 >4
64.4 31.1 64.4 63.3 63.3 63.3 1.1 1.1 1.1 8.8 42.2 52.2 64.4 64.4 0 52.2
ND 4 ND ND ≤0.5 0.5 ≤0.12 ≤0.12 ≤0.12 2 ≤1 0.5 ≤0.5 ≤0.5 0.25 ≤0.5
ND >64 ND ND >16 8 0.25 0.25 0.25 16 4 8 2 2 1 >4
ND ≤0.5–>64 ND ND ≤0.5–>16 ≤0.12–>16 ≤0.12–>8 ≤0.12–>8 ≤0.12–>8 0.5–>32 ≤1–>8 ≤0.12–>16 ≤0.5–>4 ≤0.5–>4 0.06–4 ≤0.5–>4
ND 16.6 ND ND 8.3 22.2 2.7 2.7 2.7 6.9 4.1 18.0 5.5 6.9 1.3 23.6
>32 32 >16 >8 >16 >16 0.25 0.25 0.25 >32 >8 >16 2 2 1 >4
>32 32 >16 >8 >16 >16 0.25 0.25 0.25 8 >8 >16 >4 >4 0.25 >4
≤0.25–>32 ≤0.5–>64 ≤4–>16 ≤0.06–>8 ≤0.5–>16 ≤0.12–>16 ≤0.12–>8 ≤0.12–>8 ≤0.12–>8 0.5–>32 ≤1–>8 ≤0.25–>16 ≤0.5–>4 ≤0.5–>4 ≤0.03–1 ≤0.5–>4
Values are presented as micrograms per milliliter unless otherwise stated. MIC = Minimum inhibitory concentration; R = resistance; Amp/Sul = ampicillin/sulbactam; Pip/Taz = piperazillin/tazobactam; Trim/Sulf = trimethoprim/sulfamethoxazole; ND = not determined. a Criteria as published by the CLSI [11]. b US FDA breakpoints were applied [12].
Antimicrobial Susceptibility For K. pneumoniae, a relatively high proportion of the isolates displayed a resistance to ampicillin/sulbactam, cefazolin, ceftriaxone, and cefepime (55.1, 55.8, 48.9 and 45.5%, respectively). A resistance to aztreonam was seen in 46.8% of the isolates. Piperazillin/tazobactam and amikacin displayed good activity. All carbapenems, fluoroquinolones and tigecycline were highly active (64 ND ND 16 8 ND >8 4 >32 4 8 2 2 ND ND
ND ≤0.5–>64 ND ND ≤0.5–16 0.5–>16 ND ≤0.12–>8 ≤0.06–>8 ≤0.25–>32 ≤1–>8 ≤0.12–16 ≤0.5–>4 ≤0.12–>4 ND ND
ND 38.2 ND ND 8.5 19.1 ND 21.2 2.1 14.8 10.6 23.4 4.2 10.6 ND ND
1 2 ND ND ≤0.5 ND ND ≤0.12 ≤0.12 0.5 ≤1 0.25 ≤0.5 ≤0.5 ≤0.03 ≤0.5
1 32 ND ND 2 ND ND 0.12 0.25 4 1 0.25 2 2 0.03 >4
1–>32 ≤0.5–>64 ND ND ≤0.5–16 ND ND ≤0.12–>8 ≤0.06–>8 0.5–>32 ≤1–>8 0.25–16 ≤0.5–>4 ≤0.12–>4 ≤0.03–>4 ≤0.5–>4
0 9.0 ND ND 4.5 ND ND 0 4.5 4.5 0 0 4.5 4.5 0 9.0
Values are presented as micrograms per milliliter unless otherwise stated. MIC = Minimum inhibitory concentration; R = resistance; Amp/Sul = ampicillin/sulbactam; Pip/Taz = piperazillin/tazobactam; Trim/Sulf = trimethoprim/sulfamethoxazole; ND = not determined. a Criteria as published by the CLSI [11]. b US FDA breakpoints were applied [12].
ly, to 70.6 and 12.5%, respectively, from 2010 to 2013. For A. baumannii, relatively stable and low rates of resistance to all antimicrobials were observed. For P. aeruginosa a decline in the resistance to aztreonam was observed, i.e. from 45.5% in 2010 to 18.2% in 2013. The resistance rates for carbapenems remained low for the 5 most frequently bacteria isolated over this time period.
Antimicrobial resistance is a public health problem which requires monitoring programs that provide regional and global data. NBSIs are the most serious and potentially life-threatening infectious disease in pediatric patients [13, 14]. Both the study of the distribution of the bacterial species most frequently involved in nosocomial infections and the prevalence of resistance among pathogenic bacteria are important as they provide the basis for appropriate empiric therapy [2, 15]. For these reasons, knowledge of the pathogens causing NBSIs and the resistance profile is essential for successful therapy and infection control.
Many different Gram-negative bacteria may cause nosocomial infections. In this study, we described that K. pneumoniae, E. coli, E. cloacae, P. aeruginosa, and A. baumannii were the Gram-negative bacilli most frequently isolated in pediatric patients with NBSIs in a Mexican tertiary care hospital (tables 2, 3). In accordance with other studies of NBSIs in pediatric patients conducted in Latin America [16], we report a higher prevalence of Gramnegative bacilli over Gram-positive organisms (51.2 vs. 43.7%, respectively). A recent study of regional resistance surveillance in 11 countries of Latin America including Mexico reported similar prevalent pathogens isolated from various types of clinical infections in patients in tertiary care hospitals [17]. In another study performed in Brazil, K. pneumoniae, A. baumannii, Enterobacter spp., and P. aeruginosa, were most frequently isolated from children with NBSIs [16]. These observations showed that the microorganisms causing NBSIs in Latin American countries are very similar, with 4 of them, i.e. K. pneumoniae, Enterobacter spp., A. baumannii, and P. aeruginosa, belonging to the ESKAPE group [18]. It is worth mentioning the prevalence of NBSIs in different wards within the hospital: the great majority (69%)
Antibiotic Resistance of Gram-Negative Bacilli
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Discussion
365
Table 6. Percentage of antibiotic resistance by year among the most frequently isolated Gram-negative bacillia
Antibiotic
Enterobacteriaceae K. pneumoniae
Amp/Sul Pip/Taz Cefazolin Ceftriaxone Cefepime Aztreonam Ertapenem Imipenem Meropenem Amikacin Gentamicin Tobramycin Ciprofloxacin Moxifloxacin Tigecyclineb Trim/Sulf Antibiotic
E. coli
E. cloacae
2010–2011 2011–2012 2012–2013 2010–2011 2011–2012 2012–2013 (n = 39) (n = 58) (n = 48) (n = 29) (n = 27) (n = 34)
2010–2011 2011–2012 2012–2013 (n = 27) (n = 29) (n = 16)
35.9 7.7 41.0 28.2 28.2 28.2 0 0 2.6 7.7 17.9 23.1 2.6 2.6 0 25.6
ND 18.5 ND ND 14.8 25.9 3.7 3.7 3.7 14.8 11.1 22.2 7.4 7.4 0 29.6
63.7 13.8 58.6 53.4 51.7 53.4 1.7 1.7 3.4 1.7 32.8 44.8 1.7 1.7 6.9 46.6
60.4 0 64.6 60.4 52.1 54.2 0 0 0 8.3 18.8 25.0 2.1 2.1 0 35.4
58.6 44.8 65.5 62.1 62.1 62.1 0 0 0 6.9 51.7 55.2 51.7 51.7 0 37.9
51.9 37.0 44.4 44.4 44.4 44.4 0 0 0 3.7 29.6 44.4 70.4 70.4 0 48.1
ND 20.7 ND ND 0 20.7 3.4 3.4 3.4 0 0 13.8 0 3.4 0 20.7
ND 6.3 ND ND 12.5 18.8 0 0 0 6.3 0 18.8 12.5 12.5 6.3 18.8
Non-fermenters P. aeruginosa
Amp/Sul Pip/Taz Cefazolin Ceftriaxone Cefepime Aztreonam Ertapenem Imipenem Meropenem Amikacin Gentamicin Tobramycin Ciprofloxacin Moxifloxacin Tigecyclineb Trim/Sulf
79.4 14.7 79.4 79.4 79.4 79.4 2.94 2.94 2.94 14.7 44.1 55.9 70.6 70.6 0 70.6
A. baumannii
2010–2011 (n = 11)
2011–2012 (n = 14)
2012–2013 (n = 22)
2010–2011 (n = 6)
2011–2012 (n = 10)
2012–2013 (n = 6)
ND 72.7 ND ND 18.2 45.5 ND 18.2 9.1 18.2 18.2 36.4 18.2 27.3 ND ND
ND 57.1 ND ND 0 0 ND 28.6 0 14.3 0 14.3 0 0 ND ND
ND 4.6 ND ND 9.1 18.2 ND 18.2 0 13.6 13.6 22.7 0 9.1 ND ND
0 0 ND ND 0 33.3 ND 0 0 0 0 0 0 0 0 16.7
0 20 ND ND 10 40 ND 0 10 10 0 0 10 10 0 10
0 0 ND ND 0 50 ND 0 0 0 0 0 0 0 0 0
Amp/Sul = Ampicillin/sulbactam; Pip/Taz = piperazillin/tazobactam; Trim/Sulf = trimethoprim/sulfamethoxazole; ND = not determined. a Criteria as published by the CLSI [11]. b US FDA breakpoints were applied [12].
was detected in patients in pediatric hospitalization units and the remainder (31%) was in intensive care units (table 1). This prevalence was lower than that previously reported in the critical care setting in hospitals in the USA (50%) and Brazil (45%) [15, 16]. 366
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
Milliken et al. [19] found that the age-specific infection ratio was highest for the age group younger than 1 month of age. In contrast, we did not observe a correlation between NBSI rates and pediatric population age (table 3). Ares/Alcántar-Curiel/Jiménez-Galicia/ Rios-Sarabia/Pacheco/De la Cruz
In another study, an antimicrobial susceptibility test was performed and none of the isolates was resistant to imipenem [20]. We also found low rates of resistance to imipenem for isolated Enterobacteriaceae family members. In contrast, for P. aeruginosa it was observed that almost one quarter of the isolates were resistant to this antimicrobial. In general, the resistance pattern of E. coli evaluated in this study presented higher levels (ceftriaxone, 63%; cefepime, 63%; gentamicin, 42%; tobramycin, 52%, and piperazillin/tazobactam, 31%) than those previously reported in Latin America (ceftriaxone, 37%; cefepime, 23%; gentamicin, 27%; tobramycin, 32%, and piperazillin/ tazobactam, 5%) [17]. Interestingly, we found that P. aeruginosa and A. baumannii presented lower rates of antimicrobial resistance [mainly to imipenem (21 and 0%), meropenem (2 and 4%), and amikacin (14 and 4%), respectively] when compared to the results of a Latin American study [imipenem (44 and 75%), meropenem (38 and 75%), and amikacin (20 and 67%), respectively] [17]. It must be noted that antibiotic administration programs differ with respect to patient age (adult vs. pediatric), and this could have had an effect on the observed antimicrobial susceptibility. In Mexico, the A. baumannii resistance rates to meropenem in two different regions were 59 and 88% for adults in Monterrey and Guadalajara, respectively [21, 22]. This study, performed in Mexico City, showed a resistance of 4.5% for meropenem in pediatric patients (table 5). These data are particularly important because they suggest an adequate management of patients, an accurate antimi-
crobial stewardship, and appropriate surveillance programs in this Mexico City hospital. Ceftriaxone, a thirdgeneration cephalosporin, has a broad spectrum of activity against Gram-positive and Gram-negative organisms and is commonly recommended in empirical treatment guidelines as it provides successful treatment [23]. However, in K. pneumoniae and E. coli isolates, the antibiotic resistance rates increased for ceftriaxone in the last year of this study. The study of antimicrobial resistance during the 3-year period showed an increase in rates of resistance, indicating a low antimicrobial activity and demonstrating the importance of ongoing monitoring of the activity of these compounds against the most important nosocomial pathogens in hospitals in our region and country. This is the first study in pediatric patients in Mexico, and its importance lies in the fact that resistance data from adult patients are frequently extrapolated to pediatric patients. This study establishes data of regional resistance and is important for the surveillance of antibiotic resistance in regional and national pediatric populations with nosocomial infections.
Acknowledgments We would like to thank all members of the Laboratory of Clinical Microbiology, Pediatric Hospital, Centro Médico Nacional Siglo XXI, IMSS. We also thank Edmundo Calva and Jorge A. Girón for their critical reading of this paper. Dr. María Dolores AlcántarCuriel gratefully acknowledges the support of UNAM-DGAPAPAPIIT IN220613.
References 1 Raymond J, Aujard Y: Nosocomial infections in pediatric patients: a European, multicenter prospective study. European Study Group. Infect Control Hosp Epidemiol 2000;21:260– 263. 2 Wisplinghoff H, Seifert H, Tallent SM, Bischoff T, Wenzel RP, Edmond MB: Nosocomial bloodstream infections in pediatric patients in United States hospitals: epidemiology, clinical features and susceptibilites. Pediatr Infect Dis J 2003;22:686–691. 3 Esteban E, Ferrer R, Urrea M, Suarez D, Rozas L, Balaguer M, Palomeque A, Jordan I: The impact of a quality improvement intervention to reduce nosocomial infections in a PICU. Pediatr Crit Care Med 2013;14:525–532. 4 Laupland KB, Gregson DB, Zygun DA, Doig CJ, Mortis G, Church DL: Severe bloodstream infections: a population-based assessment. Crit Care Med 2004;32:992–997. 5 Gales AC, Castanheira M, Jones RN, Sader HS: Antimicrobial resistance among Gramnegative bacilli isolated from Latin America:
Antibiotic Resistance of Gram-Negative Bacilli
6
7 8
9
results from SENTRY Antimicrobial Surveillance Program (Latin America, 2008–2010). Diagn Microbiol Infect Dis 2012;73:354–360. Ariffin N, Hasan H, Ramli N, Ibrahim NR, Taib F, Rahman AA, Mohamed Z, Wahab S, Isaacs D, Van Rostenberghe H: Comparison of antimicrobial resistance in neonatal and adult intensive care units in a tertiary teaching hospital. Am J Infect Control 2012;40:572–575. Alanis AJ: Resistance to antibiotics: are we in the post-antibiotic era? Arch Med Res 2005; 36:697–705. Piéboji JG, Koulla-Shiro S, Ngassam P, Adiogo D, Njine T, Ndumbe P: Antimicrobial resistance of Gram-negative bacilli isolates from inpatients and outpatients at Yaounde Central Hospital, Cameroon. Int J Infect Dis 2004;8:147–154. Becerra MR, Tantaleán JA, Suárez VJ, Alvarado MC, Candela JL, Urcia FC: Epidemiologic surveillance of nosocomial infections in a Pediatric Intensive Care Unit of a developing country. BMC Pediatr 2010;10:66.
10 Abramczyck ML, Carvalho WB, Carvalho ES, Medeiros EA: Nosocomial infection in a pediatric intensive care unit in a developing country. Braz J Infect Dis 2003;6:375–380. 11 Clinical Laboratory Standards Institute: Performance standards for antimicrobial susceptibility testing: twentieth informational supplement (CLSI document M100-S20). Wayne, CLSI, 2010. 12 Pillar CM, Draghi DC, Dowzicky MJ, Sahm DF: In vitro activity of tigecycline against Gram-positive and Gram-negative pathogens as evaluated by broth microdilution and Etest. J Clin Microbiol 2008;46:2862–2867. 13 Gray J, Gossain S, Morris K: Three-year survey of bacteremia and fungemia in a pediatric intensive care unit. Pediatr Infect Dis J 2001; 4:416–421. 14 Joram N, de Saint Blanquat L, Stamm D, Launay E, Gras-Le Guen C: Healthcare-associated infection prevention in pediatric intensive care units: a review. Eur J Clin Microbiol Infect Dis 2012;31:2481–2490.
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
367
15 Wisplinghoff H, Bischoff T, Tallent SM, Seifert H, Wenzel RP, Edmond MB: Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study. Clin Infect Dis 2004; 39:309–317. 16 Pereira CA, Marra AR, Camargo LF, Pignatari AC, Sukiennik T, Behar PR, Medeiros EA, Ribeiro J, Girão E, Correa L, Guerra C, Carneiro I, Brites C, Reis M, de Souza MA, Tranchesi R, Barata CU, Edmond MB; Brazilian SCOPE Study Group: Nosocomial bloodstream infections in Brazilian pediatric patients: microbiology, epidemiology, and clinical features. PLoS One 2013; 8: e68144.
368
17 Jones RN, Guzman-Blanco M, Gales AC, Gallegos B, Castro AL, Martino MD, Vega S, Zurita J, Cepparulo M, Castanheira M: Susceptibility rates in Latin American nations: report from a regional resistance surveillance program (2011). Braz J Infect Dis 2013; 17: 672–681. 18 Rice LB: Progress and challenges in implementing the research on ESKAPE pathogens. Infect Control Hosp Epidemiol 2010; 31(suppl 1): S7–S10. 19 Milliken J, Tait GA, Ford-Jones EL, Mindorff CM, Gold R, Mullins G: Nosocomial infections in a pediatric intensive care unit. Crit Care Med 1988;16:233–237. 20 Muro S, Garza-González E, Camacho-Ortiz A, González GM, Llaca-Díaz JM, Bosques F, Rositas F: Risk factors associated with extendedspectrum β-lactamase-producing enterobacteriaceae nosocomial bloodstream infections in a tertiary care hospital: a Clinical and molecular analysis. Chemotherapy 2012;58:217–224.
Chemotherapy 2013;59:361–368 DOI: 10.1159/000362085
21 Garza-González E, Mendoza Ibarra SI, LlacaDíaz JM, González GM: Molecular characterization and antimicrobial susceptibility of extended-spectrum {β}-lactamase-producing Enterobacteriaceae isolates at a tertiary-care centre in Monterrey, Mexico. J Med Microbiol 2011;60:84–90. 22 Morfín-Otero R, Alcántar-Curiel MD, Rocha MJ, Alpuche-Aranda CM, Santos-Preciado JI, Gayosso-Vázquez C, Araiza-Navarro JR, Flores-Vaca M, Esparza-Ahumada S, GonzálezDíaz E, Pérez-Gómez HR, Rodríguez-Noriega E: Acinetobacter baumannii infections in a tertiary care hospital in Mexico over the past 13 years. Chemotherapy 2013;59:57–65. 23 Dailly E, Verdier MC, Deslandes G, Bouquié R, Tribut O, Bentué-Ferrer D: Level of evidence for therapeutic drug monitoring of ceftriaxone. Therapie 2012;67:145–149.
Ares/Alcántar-Curiel/Jiménez-Galicia/ Rios-Sarabia/Pacheco/De la Cruz
Copyright: S. Karger AG, Basel 2014. Reproduced with the permission of S. Karger AG, Basel. Further reproduction or distribution (electronic or otherwise) is prohibited without permission from the copyright holder.
