Extended-spectrum beta-lactamase-producing Enterobacteriaceae, Central African Republic

Molecular epidemiology of antimicrobial resistance in central africa: A systematic review

Background

In Central Africa, it is difficult to tackle antibiotic resistance, because of a lack of data and information on bacterial resistance, due to the low number of studies carried out in the field. To fill this gap, we carried out a systematic review of the various studies, and devised a molecular epidemiology of antimicrobial resistance from humans, animals and the environmental samples.

Method

A systematic search of all publications from 2005 to 2020 on bacterial resistance in Central Africa (Gabon, Cameroon, Democratic Republic of Congo, Central African Republic, Chad, Republic of Congo, Equatorial Guinea, São Tomé and Príncipe, Angola) was performed on Pubmed, Google scholar and African Journals Online (AJOL). All circulating resistance genes, prevalence and genetic carriers of these resistances were collected. The study area was limited to the nine countries of Central Africa.

Results

A total of 517 studies were identified through a literature search, and 60 studies carried out in eight countries were included. Among all articles included, 43 articles were from humans. Our study revealed not only the circulation of beta-lactamase and carbapenemase genes, but also several other types of resistance genes. To finish, we noticed that some studies reported mobile genetic elements such as integrons, transposons, and plasmids.

Conclusion

The scarcity of data poses difficulties in the implementation of effective strategies against antibiotic resistance, which requires a health policy in a 'One Health' approach.

Emergence and Spread of Cephalosporinases in Wildlife: A Review

Simple Summary

Antimicrobial resistance (AMR) is one of the global public health challenges nowadays. AMR threatens the effective prevention and treatment of an ever-increasing range of infections, being present in healthcare settings but also detected across the whole ecosystem, including wildlife. This work compiles the available information about an important resistance mechanism that gives bacteria the ability to inactivate cephalosporin antibiotics, the cephalosporinases (extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase), in wildlife. Through a rigorous systematic literature review in the Web of Science database, the available publications on this topic in the wildlife sphere were analysed. The emergence and spread of cephalosporinases in wildlife has been reported in 46 countries from all continents (52% in Europe), with descriptions mainly in birds and mammals. The most widely disseminated cephalosporinases in human-related settings (e.g. CTX-M-1, CTX-M-14, CTX-M-15 and CMY-2) are also the most reported in wildlife, suggesting that anthropogenic pressure upon natural environments have a strong impact on antimicrobial resistance spread, including the dissemination of genes encoding these enzymes. Our work highlights the urgence and importance of public and ecosystem health policies, including improved surveillance and control strategies that breakdown AMR transmission chains across wildlife, as part of an integrated strategy of the One Health approach.

Abstract

In the last decade, detection of antibiotic resistant bacteria from wildlife has received increasing interest, due to the potential risk posed by those bacteria to wild animals, livestock or humans at the interface with wildlife, and due to the ensuing contamination of the environment. According to World Health Organization, cephalosporins are critically important antibiotics to human health. However, acquired resistance to β-lactams is widely distributed and is mainly mediated by extended-spectrum beta-lactamase and AmpC beta-lactamases, such as cephalosporinases. This work thus aimed to compile and analyse the information available on the emergence and dissemination of cephalosporinases in wildlife worldwide. Results suggest a serious scenario, with reporting of cephalosporinases in 46 countries from all continents (52% in Europe), across 188 host species, mainly birds and mammals, especially gulls and ungulates. The most widely reported cephalosporinases, CTX-M-1, CTX-M-14, CTX-M-15 and CMY-2, were also the most common in wild animals, in agreement with their ubiquity in human settings, including their association to high-risk clones of Escherichia coli (E. coli), such as the worldwide distributed CTX-M-15/ST131 E. coli. Altogether, our findings show that anthropogenic activities affect the whole ecosystem and that public policies promoting animal and environmental surveillance, as well as mitigation measures to avoid antimicrobial misuse and AMR spread, are urgently needed to be out in practise.

Genetic Determinants of Resistance among ESBL-Producing Enterobacteriaceae in Community and Hospital Settings in East, Central, and Southern Africa: A Systematic Review and Meta-Analysis of Prevalence

Background

The world prevalence of community and hospital-acquired extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae is increasing tremendously. Bacteria harboring ESBLs are currently the number one critical pathogens posing a major threat to human health.

Objective

To provide a summary of molecular evidence on the prevalence of ESBL-producing Enterobacteriaceae (ESBL-E) and associated genes at community and hospital settings in East, Central, and Southern African countries.

Methods

We conducted a systematic literature search on PubMed and Google Scholar databases for the available molecular studies on ESBL-E in hospitals and community settings in East, Central, and Sothern Africa (ECSA). Published studies in English language involving gene characterization of ESBLs from human samples in hospital and community settings were included in the review, inception to November 2019. A random effect meta-analysis was performed to estimate the prevalence of ESBL-E.

Results

A total of 27 studies involving molecular characterization of resistance genes from 20,225 ESBL-E isolates were included in the analysis. Seventy-four percent of all studies were hospital based, 15% were based in community settings, and others were done in both hospital and community settings. Of all the studies, 63% reported E. coli as the dominant isolate among ESBL-E recovered from clinical samples and Klebsiella pneumoniae was reported dominant isolates in 33% of all studies. A random pooled prevalence of ESBL-E was 38% (95% CI = 24–53%), highest in Congo, 92% (95% CI = 90–94%), and lowest in Zimbabwe, 14% (95% CI = 9–20%). Prevalence was higher in hospital settings 41% (95% CI = 23–58%) compared to community settings 34% (95% CI = 8–60%). ESBL genes detected from clinical isolates with ESBL-E phenotypes in ECSA were those of Ambler molecular class A [1] that belongs to both functional groups 2be and 2d of Bush and Jacob classification of 2010 [2]. Majority of studies (n = 22, 81.5%) reported predominance of blaCTX-M gene among isolates, particularly CTX-M-15. Predictors of ESBL-E included increased age, hospital admissions, previous use of antibiotics, and paramedical use of herbs.

Conclusion

Few studies have been conducted at a molecular level to understand the genetic basis of increased resistance among members of ESBL-E in ECSA. Limited molecular studies in the ECSA region leave a gap in estimating the burden and risk posed by the carriage of ESBL genes in these countries. We found a high prevalence of ESBL-E most carrying CTX-M enzyme in ECSA with a greater variation between countries. This could be an important call for combined (regional or global) efforts to combat the problem of antimicrobial resistance (AMR) in the region. Antibiotic use and hospital admission increased the carriage of ESBL-E, while poor people contributed little to the increase of AMR due to lack of access and failure to meet the cost of healthcare compared to high income individuals.

2003-2019: explosive spread of enterobacteria producing extended-spectrum beta-lactamases in Bangui Central African Republic

Introduction

the spread of enterobacteria producing extended-broad-spectrum beta-lactamases (ESBL) is a global public health-problem. In a study carried in 2003-2005 at the Pasteur Institute in Bangui, 450 enterobacteria were identified in clinical isolates, of which 17 were ESBL (prevalence: 3.78%). The aim of this study was to update this data.

Methods

from May 2018 to April 2019, a total of 941 enterobacteria were isolated and identified under identical conditions of recruitment and with the same techniques used in the previous study: phenotypic identification using Api 20E strips (bioMérieux SA, Marcy-l'Etoile, France) and antimicrobial drug susceptibility using the disk diffusion method (Bio-Rad antibiotic discs, Marnes la Coquette, France). Resistance genes were identified by polymerase chain reaction (PCR) and sequencing.

Results

from May 2018 to April 2019, a total of 941 enterobacteria were isolated of which 478 were ESBL, thus amounting to a prevalence of 50.80%. The genetic profiles of the bla CTX-M resistance genes exhibited the emergence of the CTX-M28 variant (CTX-M1 group) and variants of the M2 and M9 groups. There was also a notable increase, from 35 to 64%, in the ESBL with a bla SHV gene.

Conclusion

this study documents a 13 fold increase in the prevalence of ESBL derived from clinical isolates of the bacteriology laboratory of the Institute Pasteur in Bangui, by comparing its data with that of the publication by Frank et al. 2006. Together with this increase a significant diversification of the circulating CTX-M resistance genes was noticed.

Epidemiology and prevalence of extended-spectrum β-lactamase- and carbapenemase-producing Enterobacteriaceae in humans, animals and the environment in West and Central Africa

Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) and carbapenemase-producing Enterobacteriaceae (CPE) are widespread. Here we used the 'One Health' approach to determine knowledge gaps on ESBL-E and CPE in West and Central Africa. We searched all articles on ESBL-E and CPE in these African regions published in PubMed, African Journals Online and Google Scholar from 2000 onwards. Among the 1201 articles retrieved, we selected 165 studies (West Africa, 118; Central Africa, 47) with data from 22 of the 26 West and Central Africa countries. Regarding the settings, 136 articles focused only on humans (carriage and/or infection), 6 articles on humans and animals, 13 on animals, 1 on humans and the environment, 8 on the environment and 1 on humans, animals and environments. ESBL-E prevalence ranged from 11-72% in humans and 7-79% in aquatic environments (wastewater). In animals, ESBL-E prevalence hugely varied: 0% in cattle, 11-36% in chickens, 20% in rats, 21-71% in pigs and 32-75% in dogs. The bla_CTX-M-15 gene was the predominant ESBL-encoding gene and was associated with plasmids of incompatibility groups F, H, K, Y, N, I1 and R. CPE were studied only in humans. Class B metallo-β-lactamases (NDM) and class D oxacillinases (OXA-48 and OXA-181) were the most common carbapenemases. Our results show major knowledge gaps, particularly on ESBL and CPE in animals and the environment, that might limit antimicrobial resistance management in these regions. The results also emphasise the urgent need to improve active surveillance programmes in each country and to support antimicrobial stewardship.

High prevalence of ESBL-Producing E. coli in private and shared latrines in an informal urban settlement in Dar es Salaam, Tanzania

Background

Data about the burden of extended-spectrum beta-lactamase (ESBL)-producing microorganisms in Africa are limited. Our study aimed to estimate the prevalence of human faecal ESBL carriage in the community of an informal urban settlement in Dar es Salaam (Tanzania, East Africa) by using environmental contamination of household latrines with ESBL as a surrogate marker.

Methods

Within the context of a large survey in February 2014 assessing 636 randomly selected household latrines for faecal contamination by the detection of growth of E. coli and total faecal coliform bacteria, a randomly selected subset of the samples were screened for ESBL.

Results

Seventy latrines were screened for ESBL. An average of 11.4 persons (SD ±6.5) were sharing one latrine. Only three (4.3%) latrines had hand-washing facilities and 50 showed faeces on the floor. ESBL-producing Enterobacteriaceae were confirmed in 17 (24.3%) of the 70 latrine samples: 16 E. coli and 1 Klebsiella pneumoniae. Five ESBL E. coli strains were detected on door handles. The most prevalent ESBL type was CTX-M-1 group (76.5%). Pulsed-field gel electrophoresis typing of a subset of ESBL-producing E. coli isolates revealed both diverse singular types and a cluster of 3 identical isolates. There was no significant difference of the latrine and household characteristics between the group with ESBL (n = 17) and the group with non-ESBL E. coli (n = 53) (p > 0.05).

Conclusions

Almost a quarter of private and shared latrines in an informal urban settlement in Tanzania are contaminated with ESBL-producing microorganisms, suggesting a high prevalence of human ESBL faecal carriage in the community. Shared latrines may serve as a reservoir for transmission in urban community settings in Tanzania.

Meta-analysis of proportion estimates of Extended-Spectrum-Beta-Lactamase-producing Enterobacteriaceae in East Africa hospitals

Background

A high proportion of Extended-Spectrum-Beta-Lactamase (ESBL) producing Enterobacteriaceae is causing common infections in all regions of the world. The burden of antibiotic resistance due to ESBL in East Africa is large but information is scarce and thus it is unclear how big the problem really is. To gain insight into the magnitude and molecular epidemiology of ESBL-producing Enterobacteriaceae in East Africa a literature search was performed in PubMed on 31 July 2015 to retrieve articles with relevant information on ESBL.

Methods and results

Meta-analysis was performed to determine overall proportion estimate of ESBL-producing Enterobacteriaceae. A total of 4076 bacterial isolates were included in the analysis. The overall pooled proportion of ESBL-producing Enterobacteriaceae among included surveys done in East African hospitals was found to be 0.42 (95 % CI: 0.34–0.50). Heterogeneity (I²) between countries’ proportions in ESBL was significantly high (96.95 % and p < 0.001). The frequently detected genes encoding ESBL were CTX-M, TEM, SHV and OXA while the most infrequent reported genes were KPC and NDM.

Conclusion

The available studies show a very wide variation in resistance due to ESBL between countries. This highlights a need for active surveillance systems which can help understand the actual epidemiology of ESBL, aid in formulating national or regional guidelines for proper screening of ESBL, and support developing standardized approaches for managing patients colonized with ESBL.

Electronic supplementary material

The online version of this article (doi:10.1186/s13756-016-0117-4) contains supplementary material, which is available to authorized users.

Antimicrobial Resistance of Enteric Salmonella in Bangui, Central African Republic

Introduction. The number of Salmonella isolated from clinical samples that are resistant to multiple antibiotics has increased worldwide. The aim of this study was to determine the prevalence of resistant Salmonella enterica isolated in Bangui. Methods. All enteric Salmonella strains isolated from patients in 2008 were identified and serotyped, and the phenotypes of resistance were determined by using the disk diffusion method. Nine resistance-associated genes, bla TEM , bla OXA , bla SHV , tetA, aadA1, catA1, dhfrA1, sul I, and sul II, were sought by genic amplification in seven S.e. Typhimurium strains. Results. The 94 strains isolated consisted of 47 S.e. Typhimurium (50%), 21 S.e. Stanleyville (22%), 18 S.e. Enteritidis (19%), 4 S.e. Dublin (4%), 4 S.e. Hadar (4%), and 1 S.e. Papuana (1%). Twenty-five (28%) were multiresistant, including 20 of the Typhimurium serovar (80%). Two main phenotypes of resistance were found: four antibiotics (56%) and to five antibiotics (40%). One S.e. Typhimurium isolate produced an extended-spectrum β-lactamase (ESBL). Only seven strains of S.e. Typhimurium could be amplified genically. Only phenotypic resistance to tetracycline and aminosides was found. Conclusion. S. Typhimurium is the predominant serovar of enteric S. enterica and is the most widely resistant. The search for resistance genes showed heterogeneity of the circulating strains.

Extended-spectrum β-lactamase-producing Enterobacteriaceae in Cameroonian hospitals

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae have been described worldwide, but there are few reports on the carriage of these bacteria in Cameroon. In order to investigate the types of ESBLs and to analyse some risk factors associated with ESBL carriage, faecal samples were collected between 3 January and 3 April 2009 from hospitalised patients at Yaounde Central Hospital and at two hospitals in Ngaoundere, Cameroon. Enterobacterial isolates resistant to third-generation cephalosporins were screened for ESBL production using the double-disk synergy test. Polymerase chain reaction (PCR) and DNA sequencing were performed in order to find out the different types of ESBL genes in presumptive ESBL-positive isolates. During the study period, a total of 121 different patients were screened for ESBL carriage. The prevalence among these patients whose faecal samples were found to contain ESBL-producers was 55.3 % (67/121). According to a univariate analysis, hospitalisation during the previous year was found to be associated with ESBL carriage. Of the 71 bacteria isolated, Escherichia coli was predominant and represented 48 % of all isolates. ESBL characterisation revealed two types of ESBLs, CTX-M-15 (96 %) and SHV-12 (4 %). The present study emphasises the importance of screening for ESBLs in laboratories in African countries. The monitoring and detection of ESBL-producing bacteria are important in the setting up of appropriate treatment of patients and to ensure effective infection control efforts.

Emergence of quinolone resistance among extended-spectrum beta-lactamase-producing Enterobacteriaceae in the Central African Republic: genetic characterization

BACKGROUND

Cross-resistance to quinolones and beta-lactams is frequent in Enterobacteriaceae, due to the wide use of these antibiotics clinically and in the food industry. Prescription of one of these categories of antibiotic may consequently select for bacteria resistant to both categories. Genetic mechanisms of resistance may be secondary to a chromosomal mutation located in quinolone resistance determining region of DNA gyrase or topoisomerase IV or to a plasmid acquisition. The insertion sequence ISCR1 is often associated with qnr and may favour its dissemination in Gram-negative bacteria. The aim of this study was to determine the genetic mechanism of quinolone resistance among extended-spectrum beta-lactamase-producing Enterobacteriaceae strains in the Central African Republic.

FINDINGS

Among seventeen ESBL-producing Enterobacteriaceae isolated from urine, pus or stool between January 2003 and October 2005 in the Central African Republic, nine were resistant to ciprofloxacin (seven from community patients and two from hospitalized patients). The ESBL were previously characterized as CTX-M-15 and SHV-12. Susceptibility to nalidixic acid, norfloxacin and ciprofloxacin, and the minimal inhibitory concentrations of these drugs were determined by disc diffusion and agar dilution methods, respectively. The presence of plasmid-borne ISCR1-qnrA region was determined by PCR and amplicons, if any, were sent for sequencing. Quinolone resistance determining region of DNA gyrase gyrA gene was amplified by PCR and then sequenced for mutation characterization. We found that all CTX-M-producing strains were resistant to the tested quinolones. All the isolates had the same nucleotide mutation at codon 83 of gyrA. Two Escherichia coli strains with the highest MICs were shown to harbour an ISCR1-qnrA1 sequence. This genetic association might favour dissemination of resistance to quinolone and perhaps other antibiotics among Enterobacteriaceae.

CONCLUSIONS

This study shows that at least two mechanisms might explain the emerging resistance of Enterobacteriaceae to quinolones in the CAR. Beside the classical topoisomerase mutation, the cause may be acquisition of a plasmid-borne qnrA1. Clinicians and bacteriologists should be made aware of possible dissemination of ISCR1-qnrA1 among Enterobacteriacae.

Extended-spectrum beta-lactamase-producing bacteria isolated from hematologic patients in Manaus, State of Amazonas, Brazil

Antibiotic therapy in hematologic patients, often weak and susceptible to a wide range of infections, particularly nosocomial infections derived from long hospitalization periods, is a challenging issue. This paper presents ESBL-producing strains isolated from such hematologic patients treated at the Amazon Hematology and Hemotherapy Foundation (HEMOAM) in the Brazilian Amazon Region to identify the ESBL genes carried by them as well as the susceptibility to 11 antimicrobial agents using the E-test method. A total of 146 clinical samples were obtained from July 2007 to August 2008, when 17 gram-negative strains were isolated in our institution. The most frequent isolates confirmed by biochemical tests and 16S rRNA sequencing were E. coli (8/17), Serratia spp. (3/17) and B.cepacia (2/17). All gram-negative strains were tested for extended-spectrum-beta-lactamases (ESBLs), where: (12/17) strains carried ESBL; among these, (8/12) isolates carried bla TEM, bla CTX-M, bla OXA , bla SHV genes, (1/12) bla TEM gene and (3/12) bla TEM, bla CTX-M, bla OXA genes. Antibiotic resistance was found in (15/17) of the isolates for tetracycline, (12/17) for ciprofloxacin, (1/17) resistance for cefoxitin and chloramphenicol, (1/17) for amikacin and (3/17) cefepime. This research showed the presence of gram-negative ESBL-producing bacteria infecting hematologic patients in HEMOAM. These strains carried the bla TEM, bla SHV, bla CTX-M and bla OXA genes and were resistant to different antibiotics used in the treatment. This finding was based on a period of 13 months, during which clinical samples from specific populations were obtained. Therefore, caution is required when generalizing the results that must be based on posological orientations and new breakpoints for disk diffusion and microdilution published by CLSI 2010.

Polymicrobial necrotizing fasciitis involving enterobacteria producing CTX-M-15 extended-spectrum β-lactamases

Necrotizing fasciitis due to multiple Gram-negative organisms in a Nigerian patient is described. Morganella morganii and Citrobacter freundii carrying the CTX-M-15 extended-spectrum β-lactamase gene were isolated, highlighting the emergence of this β-lactamase in Western Africa and its successful spread amongst a wider range of members of the Enterobacteriaceae.

Extended-spectrum beta-lactamase-producing pathogens in a children's hospital: a 5-year experience

BACKGROUND

Pediatric infection with bacteria producing extended-spectrum beta-lactamases (ESBLs) has not been well described. We sought to determine the proportion of isolates producing ESBLs and the incidence of infection or colonization with these organisms in our tertiary care pediatric facility over 5 years. In addition, we sought to evaluate the characteristics of children affected.

METHODS

We identified all Escherichia coli or Klebsiella spp cultured from children younger than 18 years of age at our facility between January 2003 and December 2007. Medical records were reviewed for affected children.

RESULTS

Of 2697 E coli, K pneumoniae, and K oxytoca cultured, 26 ESBL producers were isolated from 16 children. Rates of ESBL production among cultured isolates significantly increased, from 0.53% in the first half of the study period to 1.4% in the second. Incidence of a primary ESBL infection also increased significantly, from 0.14/10,000 patient encounters to 0.31/10,000. The majority of children infected or colonized with ESBL-producing organisms were those with chronic medical conditions, frequent hospitalizations, or a history of recurrent infection. However, 4 affected children were less than 5 months old and evaluated in an outpatient setting.

CONCLUSION

Rates and incidence of ESBL infection increased over the study period. Whereas most patients belonged to traditional risk groups for antibiotic-resistant infection, infants in the ambulatory setting were also affected, an at-risk population not previously described.

Antibiotic resistance among bacterial pathogens in Central Africa: a review of the published literature between 1955 and 2008

A systematic review of the published literature on bacterial resistance in Central Africa between 1955 and 2008 was performed. Eighty-three publications from seven countries were retrieved, the majority presenting data on enteric and other gram-negative pathogens. Despite methodological limitations in many studies, alarming resistance rates are noted in nearly all pathogens. Of special concern are multidrug resistance in Shigella and Salmonella spp. and the emergence of meticillin-resistant Staphylococcus aureus, high-level penicillin-resistant Streptococcus pneumoniae and extended-spectrum beta-lactamases among gram-negative pathogens. These findings make clear that the Central African region shares the worldwide trend of increasing antimicrobial resistance and is in urgent need of sound surveillance based on competent and affordable microbiology to provide clear data on antimicrobial resistance. These data could enable redaction of local treatment guidelines and fuel national and regional policies to contain antimicrobial resistance.

Characterization of sulphonamide resistance genes and class 1 integron gene cassettes in Enterobacteriaceae, Central African Republic (CAR)

OBJECTIVES

The aim of this study was to characterize genes encoding sulphonamide resistance and gene cassettes associated with class 1 integrons in trimethoprim-sulphamethoxazole resistant Enterobacteriaceae recovered from Bangui, Central African Republic (CAR).

METHODS

We studied 78 clinical Enterobacteriaceae isolates, including 16 extended-spectrum beta-lactamases producers, 10 Salmonella and 9 Shigella, resistant to trimethoprim-sulphamethoxazole as assessed by the disc diffusion method. PCR was used to test for sul1 and sul2 genes. Class 1 integron resistance gene cassettes were characterized by directly sequencing PCR products obtained with primers recognising 5' and 3' conserved regions.

RESULTS

The sul1 gene was found in 67 isolates, the sul2 gene in 72 isolates and both genes in 62 isolates, while the int1 gene was found in 74 isolates. The most prevalent dfr genes were dfrA7 (49%), dfrA1 (17%) and dfrA2d (13%).

CONCLUSION

These results illustrate the wide distribution of sulphonamide and trimethoprim resistance genes among Enterobacteriaceae in Bangui (CAR).

Emergence and outbreaks of CTX-M beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae strains in a Tunisian hospital

Sixty-two isolates of Enterobacteriaceae (35 Escherichia coli and 27 Klebsiella pneumoniae isolates) producing CTX-M-type beta-lactamases were collected between March 2000 and June 2003 in different wards of Charles Nicolle Hospital in Tunis (Tunisia). Sequencing identified the bla(CTX-M-15) determinant in 55 isolates and bla(CTX-M-16) in 7 isolates. The CTX-M-15-producing strains were isolated in several wards and consisted mainly of two successive clonal groups of E. coli and a major clonal group of K. pneumoniae. The second clonal group of E. coli belonged to phylogenetic group B2 and harbored more virulence factors than the first clonal group. Among the 22 transconjugants or electroporants obtained with selected E. coli and K. pneumoniae CTX-M-15-producing strains, a predominant plasmid restriction pattern was obtained with 17 isolates. The four CTX-M-16-producing strains of E. coli yielded the same pulsed-field gel electrophoresis (PFGE) pattern, while the three CTX-M-16-producing strains of K. pneumoniae yielded two different PFGE patterns. All of the CTX-M-16-producing isolates were recovered in the pediatric ward and had the same plasmid restriction pattern.