Association Between Toxin-antitoxin Systems on Plasmids and Persister Formation in CTX-15-producing Klebsiella pneumoniae ST11 Isolates

We investigated the effect of toxin-antitoxin (TA) systems in bla(CTX-M-15)-bearing plasmids of Klebsiella pneumoniae on persister formation. The persister formation rate was notably high in transconjugants in plasmids bearing TA system than the transconjugants in plasmids bearing no TA systems. Activation of relA and spoT expression was higher in transconjugants with plasmids bearing TA systems. Thus, TA systems in plasmids may contribute to the maintenance of bla(CTX-M-15)-bearing plasmids and host survival via persister formation.

Prevalence of Fecal Carriage of CTX-M-15 Beta-Lactamase-Producing Escherichia coli in Healthy Children from a Rural Andean Village in Venezuela

OBJECTIVES: Antimicrobial resistant extended-spectrum-β-lactamase-producing Enterobacteriaceae (ESBL-PE) have been shown to be present in healthy communities. This study examined healthy children from the rural Andean village of Llano del Hato, Mérida, Venezuela, who have had little or no antibiotic exposure to determine the prevalence of fecal carriage of ESBL-producing Escherichia coli (ESBL-EC). METHODS: A total of 78 fecal samples were collected in healthy children aged from 1 to 5 years. ESBL-EC were selected in MacConkey agar plates with cefotaxime and further confirmed by the VITEK 2 system. ESBL were phenotypically detected and presence of bla genes and their variants were confirmed by molecular assays. Determination of phylogenetic groups was performed by PCR amplification. Risk factors associated with fecal carriage of ESBL-EC-positive isolates were analyzed using standard statistical methods. RESULTS: Of the 78 children studied, 27 (34.6%) carried ESBL-EC. All strains harbored the bla(CTX-M-15) allele. Of these, 8 were co-producers of bla(TEM-1), bla(TEM-5), bla(SHV-5) or bla(SHV-12). Co-resistance to aminoglycosides and/or fluoroquinolones was observed in 9 strains. 51.9% of ESBL-EC isolates were classified within phylogroup A. A significant, positive correlation was found between age (≥2.5 – ≤5 years), food consumption patterns and ESBL-EC fecal carriage. CONCLUSION: This is the first study describing the high prevalence of fecal carriage of ESBL-EC expressing CTX-M-15- among very young, healthy children from a rural Andean village in Venezuela with scarce antibiotic exposure, underlining the importance of this population as a reservoir.

Distribución de grupos filogenéticos y factores de virulencia en cepas de Escherichia coli uropatógena productora de ß-lactamasa CTX-M-15 aisladas de pacientes de la comunidad en Mérida, Venezuela / Distribution of phylogenetic groups and virulence factors in CTX-M-15 ß -lactamase-producing uropathogenic Escherichia coli strains isolated from patients in the community of Mérida, Venezuela

En este estudio se determinó el perfil de distribución de grupos filogéneticos y la detección genética de factores de virulencia en cepas de Escherichia coli uropatógena (ECUP) productoras de ß-lactamasa CTX-M-15. Veintiocho cepas fueron aisladas de pacientes con infección del tracto urinario (ITU) que asistieron al Laboratorio de Salud Pública del estado Mérida, Venezuela, durante el lapso comprendido entre enero 2009 y julio 2011. La determinación de los grupos filogenéticos y la detección de seis genes de virulencia, fimH, fyuA, kpsMTII, usp, PAI y papAH, se realizó mediante amplificación por PCR. Quince cepas de 28 se ubicaron principalmente en el filogrupo A, seguidos por el B2 (12/28) y D (1/28). No se observó una relación directa entre la recurrencia o gravedad de la ITU y la distribución de los filogrupos. Todos los factores de virulencia estudiados se encontraron con la frecuencia más alta en el grupo B2. El perfil de virulencia prevalente estuvo conformado por la asociación de tres genes principales: fimH, fyuA y kpsMTII y en menor frecuencia, por la presencia de otros determinantes como usp, PAI y/o papAH. Estos resultados indican que la mayoría de ECUP estuvieron dotadas de tres propiedades virulentas importantes: adhesión, captación de hierro y evasión de la fagocitosis, las cuales favorecieron la producción de ITU recurrentes. Este es el primer trabajo que describe la asociación de grupos filogenéticos con el potencial de virulencia de cepas de ECUP productoras de ß-lactamasa CTX-M-15 en Venezuela.

In this study, the distribution of phylogenetic groups and the genetic detection of virulence factors in CTX-M-15 ß-lactamase-producing uropathogenic Escherichia coli (UPEC) strains were analyzed. Twenty eight strains were isolated between January 2009 and July 2011 from patients with urinary tract infection (UTI) who attended the Public Health Laboratory at Mérida, Venezuela. Determination of phylogenetic groups and detection of six virulence genes, fimH, fyuA, kpsMTII, usp, PAI and papAH, were performed by PCR amplification. Fifteen of the 28 isolates were mainly located in the phylogenetic group A, followed by B2 (12/28) and D (1/28). No direct relationship between the severity or recurrence of UTI and the distribution of phylogroups was observed. All studied virulence factors were found in group B2 strains with the highest frequency. The prevalent virulence profile included the combination of three main genes: fimH, kpsMTII and fyuA and, to a lesser extent, the presence of other determinants such as usp, PAI and/or papAH. These results indicate that virulent UPEC incorporated three important properties: adhesion, iron uptake and evasion of phagocytosis, which favored the production of recurrent UTI. This is the first report describing the association of phylogenetic groups with the potential virulence of CTX-M-15 ß-lactamase producing UPEC strains in Venezuela.

Prevalencia de β-lactamasa CTX-M-15 en grupos filogenéticos de Escherichia coli uropatógena aisladas en pacientes de la comunidad en Mérida, Venezuela / Prevalence of β-lactamase CTX-M-15 in phylogenetic groups of uropathogenic Escherichia coli isolated from patients in the community of Merida, Venezuela

En este estudio se determinó la prevalencia de b-lactamasas de espectro extenso (BLEEs) en grupos filogenéticos de E. coli uropatógena (ECUP) aislados en pacientes de la comunidad. Durante Enero 2009 a Julio 2010, se coleccionaron 21 cepas de ECUP, con susceptibilidad disminuida a las cefalosporinas de amplio espectro, provenientes de pacientes que asistieron al Laboratorio de Salud Pública del estado Mérida, Venezuela con diagnóstico de infección del tracto urinario (ITU). La caracterización genotípica determinó que todas las cepas ECUP albergaban genes blaBLEEs. En el 76,2% de las cepas se observó la presencia de un único gen productor de BLEE, representado por blaCTX-M-15, mientras que el 23,8% estuvo conformado por ECUP con diversas combinaciones de genes bla (blaCTX-M-15 + blaTEM-1, blaCTX-M-15 + blaSHV y blaSHV + blaTEM-1). El 61,9% de los aislados se ubicó en el filogrupo A y el resto de las cepas en el grupo B2 (38,1%). No se evidenció la diseminación de una clona de ECUP particular, solo 7 cepas demostraron pertenecer a un grupo clonal con un índice de similitud de más de 85%. De acuerdo a nuestro conocimiento, esta es la primera descripción de blaCTX-M-15 en ECUP causantes de ITU en pacientes de la comunidad, lo que evidencia que Venezuela también forma parte de la llamada pandemia CTX-M-15. Los hallazgos obtenidos en este estudio y las implicaciones clínicas y epidemiológicas que de ello derivan, conllevan a la necesidad de controlar y vigilar la diseminación de ECUP productora de CTX-M-15 no sólo en el ámbito regional sino también nacional.

In this study we determined the prevalence of extended-spectrum b-lactamases (ESBLs) in phylogenetic groups of uropathogenic E. coli (UPEC) isolated from patients in the community. Twenty one UPEC strains with reduced susceptibility to broad-spectrum cephalosporins were collected between January 2009 and July 2010, from patients with urinary tract infection who attended the Public Health Laboratory in Mérida, Venezuela. Genotypic characterization determined that all UPEC strains harbored blaBLEEs genes: 76.2% of the strains showed the presence of a single ESBL-producer gene, represented by blaCTX-M-15, whereas 23.8% of UPEC showed various combinations of bla genes (blaCTX-M-15 + blaTEM-1, blaCTX-M-15 + blaSHV and blaSHV + blaTEM-1). In this study, 61.9% of the isolates were placed in phylogroup A and the remaining strains were assigned to group B2 (38.1%). There was no evidence of spread of a particular UPEC clone; only seven strains belonged to a clonal group with an index of similarity greater than 85%. To our knowledge, this is the first description of blaCTX-M-15 in UPEC from patients with community-acquired urinary tract infections, which shows that Venezuela is also part of the so-called CTX-M-15 pandemic. The findings in this study, as well as its clinical and epidemiological implications, lead to the need for monitoring and controlling the spread of CTX-M-15 producing UPECs, not only regionally, but also nationwide.

Characterization of cephalosporin-resistant clinical Enterobacteriaceae for CTX-M ESBLs in Bahrain

OBJECTIVE@#To detect the presence of specific CTX-M class of extended spectyum β-lactamases (ESBLs) in a collection of cephalosporin-resistant Enterobacteriaceae isolates from Bahrain.@*METHODS@#A subset of 80 cephalosporin-resistant Enterobacteriaceae collected from Salmaniya Medical Complex, Bahrain, were characterized further for the presence of specific genogroups of CTX-M β-lactamases by multiplex- and monoplex- PCRs. The primers used for the multiplex and monoplex PCRs were of genogroups- 1, 2, 8, 9 and 25. Sequencing of the representative isolates was performed to find the circulating CTX-M-types.@*RESULTS@#A total of 93.8% (75/80) isolates showed the amplicons corresponding to any of the genogroups (1, 2, 8, 9, 25) and the remaining 6.2% isolates turned out negative in multiplex PCR. Some of the isolates demonstrated multiple bands corresponding to the sizes of different genogroups. Further confirmation with respective monoplex PCR on these 75 isolates demonstrated that 93.3% (70/75) harbored CTX-M genogroup-1 and 6.7% (5/75) harbored genogroup-9. We did not find the presence of genogroups 2, 8, and 25 in these isolates by monoplex PCR. Sequencing results of genogroup-1 isolates demonstrated the presence of CTX-M-15-like ESBL, however, discrepant results were noticed in genogroup-9 isolates, sequencing showed them as CTX-M-55-like ESBL.@*CONCLUSIONS@#This is the first report from Bahrain characterizing the CTX-M genogroups of ESBLs and reporting the emergence of blaCTX-M-55-like gene in this region.

Characterization of cephalosporin-resistant clinical Enterobacteriaceae for CTX-M ESBLs in Bahrain

Objective: To detect the presence of specific CTX-M class of extended spectyum β-lactamases (ESBLs) in a collection of cephalosporin-resistant Enterobacteriaceae isolates from Bahrain. Methods: A subset of 80 cephalosporin-resistant Enterobacteriaceae collected from Salmaniya Medical Complex, Bahrain, were characterized further for the presence of specific genogroups of CTX-M β-lactamases by multiplex- and monoplex- PCRs. The primers used for the multiplex and monoplex PCRs were of genogroups- 1, 2, 8, 9 and 25. Sequencing of the representative isolates was performed to find the circulating CTX-M-types. Results: A total of 93.8% (75/80) isolates showed the amplicons corresponding to any of the genogroups (1, 2, 8, 9, 25) and the remaining 6.2% isolates turned out negative in multiplex PCR. Some of the isolates demonstrated multiple bands corresponding to the sizes of different genogroups. Further confirmation with respective monoplex PCR on these 75 isolates demonstrated that 93.3% (70/75) harbored CTX-M genogroup-1 and 6.7% (5/75) harbored genogroup-9. We did not find the presence of genogroups 2, 8, and 25 in these isolates by monoplex PCR. Sequencing results of genogroup-1 isolates demonstrated the presence of CTX-M-15-like ESBL, however, discrepant results were noticed in genogroup-9 isolates, sequencing showed them as CTX-M-55-like ESBL. Conclusions: This is the first report from Bahrain characterizing the CTX-M genogroups of ESBLs and reporting the emergence of bla

Molecular epidemiology of CTX-M producing Enterobacteriaceae isolated from bloodstream infections in Rio de Janeiro, Brazil: emergence of CTX-M-15

OBJECTIVE: The present studywas designed to evaluate the molecular epidemiology of CTX-M producing Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli isolated from bloodstream infections at tertiary care hospitals in the State of Rio de Janeiro, Brazil. MATERIAL AND METHODS: A total of 231 nonduplicate Enterobacteriaceae were isolated from five Brazilian hospitals between September 2007 and September 2008. The antimicrobial susceptibility testing was performed by disk diffusion method according to the Clinical Laboratory Standard Institute. Isolates showing resistance to third-generation cephalosporins were screened for ESBL activity by the double-disk synergy test. The presence of blaCTX-M , blaCTX-M-15 and blaKPC genes was determined by Polymerase Chain Reaction (PCR) amplification andDNA sequencing. The molecular typing of CTX-M producing isolateswas performed by pulsed-field gel electrophoresis (PFGE). RESULTS AND DISCUSSION: Ninety-three isolates were screened as ESBL positive and 85 (91%) were found to carry CTX-M-type, as follows: K. pneumoniae 59 (49%), E. cloacae 15 (42%), and E. coli 11 (15%). Ten isolates resistant for carbapenems in K. pneumoniae were blaKPC-2 gene positive. Among CTX-M type isolates, CTX-M-15 was predominant in more than 50% of isolates for K. pneumoniae, E. coli, and E. cloacae. PFGE analysis of CTX-M producing isolates showed the predominance of CTX-M-15 in 10 of 24 pulsotypes in K. pneumoniae, 6 of 13 in E. cloacae and 3 of 6 in E. coli. CTX-M-15 was also predominant among KPC producing isolates. In conclusion, this study showed that CTX-M-15 was circulating in Rio de Janeiro state in 2007-2008. This data reinforce the need for continuing surveillance because this scenario may have changed over the years.

Neonatal septicaemia caused by diverse clones of Klebsiella pneumoniae & Escherichia coli harbouring blaCTX-M-15.

Background & objectives: Information about the genetic diversity of the extended-spectrum β-lactamases (ESBLs) and the clonal relationship of the organisms causing neonatal infections is limited, particularly from India where neonatal mortality is high. This study was undertaken to investigate the molecular epidemiology and risk factors associated with neonatal septicaemia caused by ESBL-producing Klebsiella pneumoniae and Escherichia coli. Methods: Bloodstream isolates (n=26) of K. pneumoniae (n=10) and E. coli (n=16) from the neonates admitted in a tertiary care hospital in New Delhi during January to May 2008 were characterized. Antimicrobial susceptibility tests were carried out and ESBL production was assessed phenotypically. PCR was carried out for ESBL and ampC genes. Genotyping was performed by pulsed-field gel electrophoresis (PFGE). Conjugation experiments were done to determine the mobility of ESBL genes. Risk factors associated with ESBL-producing K. pneumoniae and E. coli infections were analysed. Results: Resistance rates to most of the antibiotics tested were high, except for imipenem. Among the isolates tested, 60 per cent of K. pneumoniae and 75 per cent of E. coli were ESBL producers. PFGE of the isolates demonstrated a vast diversity of genotypes with no epidemic clones. Despite the clonal diversity, blaCTX-M-15 was detected in 100 per cent of ESBL-positive isolates. The other genes present in ESBL-positive isolates were blaTEM-1, blaSHV-1, blaSHV-28, blaSHV-11, and blaSHV-12. Class 1 integrons were detected in 7 of 18 ESBL-positive isolates. Moreover, the plasmid carrying blaCTX-M-15, in E. coli and K. pneumoniae were self transferable. Feeding through an enteral tube was identified as the only risk factor for sepsis by ESBL-producing organisms. Interpretation & conclusions: The study emphasises the presence of blaCTX-M-15 in clonally diverse isolates indicating probable horizontal transfer of this gene. The widespread dissemination of CTX-M-15 is of great concern as it further confines the limited therapeutic interventions available for neonates.

An outbreak of CTX-M-15-producing Klebsiella pneumoniae isolates in an intensive care unit of a teaching hospital in Kuwait.

Objective: This study reports an outbreak of Klebsiella pneumoniae infections in 14 patients during a 2-month period (August-September, 2008) in the intensive care unit (ICU) of a teaching hospital in Kuwait. Materials and Methods: The clinical sources were blood (9), urine (3) and respiratory secretions (2) identified by the automated VITEK-2 ID System. Susceptibility testing was performed by the E-test method. Extended-spectrum β-lactamase (ESBL) production was assessed using the ESBL E-test and confirmed by PCR. Carriage of bla genes was determined by PCR and sequence analysis. The transferability of resistance phenotypes was demonstrated by conjugation experiments and clonal relatedness was determined by PFGE. Results: The isolates were susceptible to imipenem, meropenem, and tigecycline and produced ESBL. All isolates yielded an amplicon of 499 bp with universal consensus primers (MA primers). DNA sequence analysis showed that they all harboured blaCTX-M-15 and blaTEM-1 genes. The environmental isolate obtained from a suction machine was also CTX-M-15/TEM-1 producer. The resistance phenotypes were transferrable to the Escherichia coli J53 r strain. PFGE, revealed two clones, A and B, related with a Dice coefficient of >94.1%. A mortality rate of 21.4% was recorded. Conclusion: The outbreak was contained by robust and aggressive infection control measures. This study highlights the first outbreak of CTX-M-15-producing K. pneumoniae associated with high mortality in an adult medical ICU in Kuwait.

Study on the epidemic plasmid carrying blaCTX-M-15 in Guangzhou / 中华微生物学和免疫学杂志

Objective To study the molecular characteristic of the epidemic plasmids carrying blaCTX-M-15 in Guangzhou. Methods A total of 38 strains of E. coli and 47 strains of K. pneumoniae both producing CTX-M-15 ESBLs were collected from nine hospitals in Guangzhou from 2007 to 2008. The clonal relationship of isolates carrying blaCTX-M-15 was determined by PFGE and MLST. Antimicrobial susceptibility was determined by microdilution test for all isolates. Conjugative plasmids carrying blaCTX-M-15 were obtained by mating and were subject to restriction analysis. PCR was used to determine phylogenetic groups of E. coli,and to study replicon type and the genetic contexts of the plasmids harboring blaCTX-M-15. Serum agglutination test was used to detect the serotype of E. coli. Results The 37 strains of E. coli were classified into 28 genotypes, while the 47 strains of K. pneumoniae were divided into 30 genotypes. ST131 was found in E. coli but not O25 serotype. Two novel-alleles of tonB and new ST were determined in K. pneumoniae. Forty out of 58 isolates represented independent genotypes have been succeeded to transfer the plasmid carrying blaCTX-M-15 to the E. coli C600(Rif) by conjugation. The sizes of plasmids carrying blaCTX-M-15 are 65 kb in 57.9% isolates of E. coli and 92 kb in 87.5% isolates of K. pneumoniae. Two epidemic plasmids were detected in E.coli and K. pneumoniae by restriction enzyme, designated p15-e and p15-k respectively. The blaCTX-M-15 and ISEcpI were identified on p15-e, and the blaCTX-M-15 ,ISEcpI,aac(6')- Ⅰ b,aac(3')-Ⅲ ,blaOXA-1 ,qnrB,qnrS,blaDHA-1 , blaTEM-1 were determined on p15-k. The p15-k also was identified to belong to the incompatible group FⅡ. Conclusion The local dissemination of blaCTX-M-15 appears to be due to the spread of epidemic plasmids harboring blaCTX-M-15. No evidence supports the dissemination of clone strains which carried blaCTX-M-15.

Faecal carriage of CTX-M-15-producing Klebsiella pneumoniae in patients with acute gastroenteritis.

Background & objectives: Data on extended-spectrum β-lactamases (ESBLs) produced by Gram-negative bacteria including Klebsiella pneumoniae especially molecular types of ESBL genes from India are limited. The present study was conducted to investigate the carriage and ESBL contents of multidrug-resistant K. pneumoniae recovered from patients with gastroenteritis in a rural village in southern India. Methods: Nine K. pneumoniae isolates obtained from 45 stool samples from patients with gastroenteritis from one rural and two urban sites, in southern India were included in the study. Antibiotic susceptibility testing, PCR analysis and sequencing were conducted to characterize the ESBL genes. Clonal relatedness was assessed by pulsed-fi eld gel electrophoresis (PFGE). Results: All the isolates were found to be resistant to at least one of the third generation cephalosporins tested. All the study isolates were confi rmed to produce ESBLs. PCR and sequencing revealed the responsible gene to be blaCTX-M-15. blaTEM and blaSHV were absent. PFGE indicated that fi ve of seven isolates were absent. PFGE indicated that fi ve of seven isolates from villagers were genetically closely related, and in turn were related to isolates from patients in two urban areas in this region. Interpretation & conclusions: Our fi ndings showed that genetically-related isolates of K. pneumoniae producing CTX-M-15 were present in multiple areas in southern India. Larger studies need to be done in various geographical regions of the country to better defi ne the molecular epidemiology of ESBLproducing K. pneumoniae and its clinical implications.

Case Report of Pediatric Gastroenteritis Due to CTX-M-15 Extended-Spectrum beta-Lactamase-Producing Salmonella enterica Serotype Enteritidis / 대한진단검사의학회지

A clinical isolate of Salmonella enterica serotype Enteritidis in Korea was found to produce the extended-spectrum beta-lactamase CTX-M-15. The isolate was recovered in 2008 from the stool of a 3-yr-old boy with gastroenteritis. This isolate was found to be resistant to multiple drugs, including ampicillin, piperacillin, cefotaxime, ceftazidime, cefepime, and aztreonam. The resistance to cefotaxime was transferred by conjugation to recipient Escherichia coli J53. The patient was eventually successfully treated with trimethoprim-sulfamethoxazole. This is the first report of the bla (CTX-M-15) gene in S. enterica serotype Enteritidis in Korea.

Detection of Extended-spectrum ?-Lactamases in 5 Shigella sonnei Isolates / 中华医院感染学杂志

OBJECTIVE To detect ESBLs genes in 5 Shigella sonnei isolates.METHODS Susceptibility test to common antibiotics was performed through disk diffusion test,and ESBLs were confirmed according to CLSI.Conjugation experiment was performed to determine whether the resistance was transferable.The ESBLs gene was detected by PCR using universal primers for TEM,SHV,CTX-M,and the PCR products were also directly sequenced and analyzed.At the same time,the five isolates were analyzed by PFGE. RESULTS The five S.sonnei isolates were ESBLs producers and produced CTX-M-15 ESBLs,which were resistant to the most of the ?-lactams such as aztreonam,the first and second generation cephalosporins,cefotaxime,and non ?-lactam such as gentamicin,SF,but susceptible to ceftazidime,the 4th generation cephalosporins,Amikacin and meropenem.These strains were also intermediate to quinolones.CTX-M-15 gene could be transferred through conjugation.PFGE patterns of one isolate were different from the others.CONCLUSIONS Five S.sonnei isolates producing CTX-M-15 ESBLs are resistant to the most antibiotics.Clone spread is evident in these isolates.We should pay more attention to monitor these strains.

Dissemination of CTX-M Type Extended-Spectrum beta-Lactamases and Emergence of CTX-M-12 in Escherichia coli / 대한진단검사의학회지

BACKGROUND: Clinical isolates of Escherichia coli were evaluated to determine the prevalence and genotypes of Ambler class A extended-spectrum beta -lactamases (ESBLs). METHODS: Clinical isolates of E. coli were collected from 12 hospitals from February through July, 2004. Antimicrobial susceptibility was tested by disk diffusion and agar dilution methods, and ESBLproduction was determined by double-disk synergy test. TEM, SHV, CTX-M, PER-1, VEB, IBC, GES, and TLA type ESBL genes were detected by PCR amplifications, and the PCR products were subjected to direct sequencing. RESULTS: The double-disk synergy test was positive in 90.9% (149 in 164) of the ceftazidime- or cefotaxime-resistant E. coli isolates. The most prevalent types of Ambler class A ESBLs in E. coliisolates were CTX-M-15 (n=53). CTX-M-14 (n=24), CTX-M-3 (n=9), CTX-M-9 (n=3), CTX-M-12 (n=3), SHV-2a (n=1), SHV-12 (n=5) and TEM-52 (n=3) were also found. CTX-M-12 ESBL had never been reported before in Korea. CONCLUSIONS: CTX-M type ESBL-producing E. coli isolates are spreading and CTX-M-12 is emerging in Korea.

Prevalence of CTX-M-type Extended-Spectrum beta-Lactamase-Producing Esherichia coli and Klebsiella pneumoniae Isolates in Korea / 대한임상미생물학회지

BACKGROUND: The aim of this study was to survey the nation wide susceptibilities of Esherichia coli and Klebsiella pneumoniae against cefotaxime and to determine the prevalence of CTX-M-type extended-spectrum beta- lactamases(ESBLs). METHODS: During the period of April to June, 2002, E. coli and K. pneumoniae isolates were collected from 13 hospitals. Antimicrobial susceptibilities to cefotaxime were tested by the disk diffusion method. ESBL production was determined by double disk synergy test. Cefotaxime-resistance of the ESBL-producers was transferred to azide-resistant E. coli J53 by conjugation. MICs of beta- lactam antibiotics were determined by agar dilution method. Searches for blaCTX-M genes were performed by PCR amplication. pIs of beta-lactamases were determined by isoelectric focusing. RESULTS: Ten percents of E. coli and 35 percents of K. pneumoniae isolates among 260 strains of each were intermediate or resistant to cefotaxime. Twenty-three isolates of E. coli and 78 K. pneumoniae isolates showed positive results in the double disk synergy test. One isolate of E. coli and 2 K. pneumoniae isolates harbored blaCTX-M-3 gene, 2 E. coli isolates harbored blaCTX-M-15 gene, and 2 E. coli and 2 K. pneumoniae isolates harbored blaCTX-M-14 gene. CONCLUSION: E. coli and K. pneumoniae isolates producing CTX-M-type ESBLs are not uncommon in Korean hospitals. The spread of CTX-M-type ESBL genes could compromise the future usefulness of 3rd generation cephalosporins and aztreonam for the treatment of E. coli and K. pneumoniae infections.

Prevalence of CTX-M-type Extended-Spectrum beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolates in Korea, 2003 / 대한임상미생물학회지

BACKGROUND: The aims of this study were to survey nationwide susceptibilities of Escherichia coli and Klebsiella pneumoniae isolates against cefotaxime and to determine the prevalences of CTX-Mtype extended-spectrum beta-lactamases(ESBLs). METHODS: During the period of February to July, 2003, E. coli and K. pneumoniae isolates were collected from 12 hospitals. Antimicrobial susceptibilities to cefotaxime were tested by the disk diffusion method. ESBL production was determined by the double disk synergy test. Cefotaxime-resistance of the ESBL-producers was transfered to E. coli DH5alphaand E. coli Top10-F by transformation. MICs of beta-lactam antibiotics were determined by the agar dilution method. Searches for blaCTX-M genes was performed by PCR amplication; pIs of beta-lactamases were determined by isoelectric focusing. RESULTS: Among 230 isolates of E. coli and 232 isolates of K. pneumoniae, 27 (11.7%) and 79 (34.1%) were intermediate or resistant to cefotaxime, respectively. Twenty-four (10.4%) isolates of E. coli and 58 (25.0%) K. pneumoniae isolates showed positive results in the double disk synergy test. Three isolates of E. coli and 13 K. pneumoniae isolates harbored blaCTX-M-3 gene, 4 E. coli isolates harbored blaCTX-M-15 gene, and 1 E. coli and 5 K. pneumoniae isolates harbored blaCTX-M-14 gene. CONCLUSION: E. coli and K. pneumoniae isolates producing CTX-M-type ESBLs were not uncommon in Korean hospitals. It is thought that periodical surveys are necessary for inspecting the spread of CTX-M-type ESBL genes are necessary.

Prevalence of CTX-M Extended-spectrum Beta-lactamases in Clinical Isolates of Enterobacteriaceae in Korea

The evolution and dissemination of extended-spectrum beta-lactamases (ESBL) have compromised the clinical use of third-generation cephalosporins worldwide. Although most ESBLs belong to the TEM and SHV beta-lactamase families, the members of CTX-M, a novel ESBL family, are increasing worldwide in Gram-negative bacteria. We examined the prevalence of CTX-M ESBL in clinical isolates of the family Enterobacteriaceae collected from three university hospitals located in three different cities in Korea. Among a total of 603 isolates collected, 163 isolates (27.0%) revealed > or =2 microgram/ ml of MIC against cefotaxime, and 93 isolates (15.4%) produced ESBL confirmed by the double disk synergy test. Among 93 ESBL-producing isolates, blaCTX-M genes were detected in 41 isolates by PCR method and they included 1 isolate of C. freundii, 3 of E. aerogenes, 2 of E. cloacae, 17 of E. coli, 9 of K. pneumoniae, and 9 of S. marcescens. Thus, the overall prevalence of CTX-M ESBL-producing isolates among the family Enterobacteriaceae was 6.8% (41 of 603 isolates) and the proportion of CTX-M-producers among the ESBL-producing isolates was 44.1% (41 of 93 isolates). Further determination of the blaCTX-M subtype by nucleotide sequencing revealed blaCTX-M-3 in 17, blaCTX-M-15 in 11, blaCTX-M-14 in 9, and blaCTX-M-9 in 4 isolates. To our knowledge, this is the first report on the dissemination of CTX-M ESBL among clinical isolates of the family Enterobacteriaceae in Korea.

Prevalence of CTX-M Extended-spectrum Beta-lactamases in Clinical Isolates of Enterobacteriaceae in Korea

The evolution and dissemination of extended-spectrum beta-lactamases (ESBL) have compromised the clinical use of third-generation cephalosporins worldwide. Although most ESBLs belong to the TEM and SHV beta-lactamase families, the members of CTX-M, a novel ESBL family, are increasing worldwide in Gram-negative bacteria. We examined the prevalence of CTX-M ESBL in clinical isolates of the family Enterobacteriaceae collected from three university hospitals located in three different cities in Korea. Among a total of 603 isolates collected, 163 isolates (27.0%) revealed > or =2 microgram/ ml of MIC against cefotaxime, and 93 isolates (15.4%) produced ESBL confirmed by the double disk synergy test. Among 93 ESBL-producing isolates, blaCTX-M genes were detected in 41 isolates by PCR method and they included 1 isolate of C. freundii, 3 of E. aerogenes, 2 of E. cloacae, 17 of E. coli, 9 of K. pneumoniae, and 9 of S. marcescens. Thus, the overall prevalence of CTX-M ESBL-producing isolates among the family Enterobacteriaceae was 6.8% (41 of 603 isolates) and the proportion of CTX-M-producers among the ESBL-producing isolates was 44.1% (41 of 93 isolates). Further determination of the blaCTX-M subtype by nucleotide sequencing revealed blaCTX-M-3 in 17, blaCTX-M-15 in 11, blaCTX-M-14 in 9, and blaCTX-M-9 in 4 isolates. To our knowledge, this is the first report on the dissemination of CTX-M ESBL among clinical isolates of the family Enterobacteriaceae in Korea.