Dissemination of the CTX-M-25 family -lactamases among Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae and identification of the novel enzyme CTX-M-41 in Proteus mirabilis in Israel (original) (raw)
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Occurrence of CTX-M-I Type β-lactamases Gene in Certain Gram Negative Bacteria
ABSTRACT: BACKGROUND: The CTX-M-type β-lactamases represent a group with a typical extended-spectrum β-lactamase (ESBL)-resistance phenotype. These enzymes, encoded by transferable plasmids. They have a preferential hydrolysis of Cefotaxime over Ceftazidime. The CTX-M-type β-lactamases have been described in species of Enterobacteriaceae and Pseudomonas aeruginosa. OBJECTIVE : This study was designed to investigate of the occurrence of CTX-M-I type in some Gram negative bacteria species isolated from clinical cases of in Iraq. METHODS: A group of Gram negative bacteria were isolated from different sources.Plasmid DNA extraction, and electrophoresis were performed. Using specific primers, CTX-M-I enzyme genes were amplified by PCR. RESULTS: Plasmid profile of the tested isolates reveals the presence of relatively large plasmids, their Wight was more than 10 kb some isolates posses’ 3-4 kb plasmids. The results of PCR amplification showed the presence of CTX-I genes. All isolates of Salmonella enterica serovar Typhimurium (100%) are negative for CTX-M-I gene as well as most of P. aeruginosa isolates (86.7%). In contrast, all of E. coli (100%) and most of Proteus Spp isolates were positive for CTX-M-I gene. CONCLUSION: CTX-M genes are predominant in E.coli followed by Proteus Spp. while Salmonella enterica serovar Typhimurium and P. aeruginosa isolates showed low incidence of blaCTX-M genes occurrence. The alarming situation with dissemination of CTX-M producing isolates highlights the need for their epidemiological monitoring and prudent use of antimicrobial agents.
Antimicrobial Agents and Chemotherapy, 2005
The rate of occurrence of the extended-spectrum beta-lactamase (ESBL)-producing phenotype among Escherichia coli isolates in Tel Aviv is 12% (22). The aim of this study was to understand the molecular epidemiology of E. coli ESBL producers and to identify the ESBL genes carried by them. We studied 20 single-patient ESBL-producing E. coli clinical isolates. They comprised 11 distinct nonrelated pulsed-field gel electrophoresis (PFGE) genotypes: six isolates belonged to the same PFGE clone, four other clones included two isolates each, and six unrelated clones included only one isolate. All isolates produced various beta-lactamases with pIs ranging from 5.2 to 8.2, varying within similar PFGE clones. The most prevalent ESBL gene was bla CTX-M ; 16 isolates carried bla CTX-M-2 and three carried a new ESBL gene designated bla CTX-M-39 . Three strains carried bla SHV (two bla SHV-12 and one bla SHV-5 ), and two strains carried inhibitor-resistant ESBL genes, bla TEM-33 and bla TEM-30 ; 18 strains carried bla TEM-1 and eight strains carried bla OXA-2 . Plasmid mapping and Southern blot analysis with a CTX-M-2 probe demonstrated that bla CTX-M-2 is plasmid borne. The wide dissemination of ESBLs among E. coli isolates in our institution is partly related to clonal spread, but more notably to various plasmid-associated ESBL genes, occurring in multiple clones, wherein the CTX-M gene family appears almost uniformly. We report here a new CTX-M gene, designated bla CTX-M-39 , which revealed 99% homology with bla CTX-M-26 , with a substitution of arginine for glutamine at position 225.
International Journal of Antimicrobial Agents, 2007
CTX-M-3 is the most common extended-spectrum -lactamase produced by Enterobacteriaceae in Taiwan. The present study was conducted to characterise the genetic environment surrounding bla CTX-M-3 . A total of 11 ceftriaxone-resistant isolates were studied: Escherichia coli (n = 4), Klebsiella pneumoniae (n = 5) and Salmonella enterica serotypes Anatum (SA831R) and Potsdam (SC72). Molecular methods used included polymerase chain reaction, sequencing, DNA-DNA hybridisation, conjugation, physical mapping and restriction fragment length polymorphism (RFLP) analysis. All isolates examined carried bla CTX-M-3 on large plasmids (>70 kb). The resistance plasmids of the two Salmonella and two K. pneumoniae strains (KP104 and KP116) were confirmed to be conjugative in vitro. RFLP analysis indicated that the plasmids were different. Physical mapping also revealed the difference between the two Salmonella plasmids, pSA831R (82 kb) and pSC72 (74 kb). An insertion sequence, ISEcp1, was found upstream of each bla CTX-M-3 gene. However, sequencing of downstream regions of the bla genes showed two different patterns: the presence of orf477 in pSA831R and of orf1-mucA in pSC72, pKP104 and pKP116. IncI1-type oriT and nikA sequences were present in the plasmids of all the clinical isolates tested, except S. Anatum. Different bla CTX-M-3 -carrying plasmids were identified among the enterobacteria studied. The presence of ISEcp1 in all isolates may be associated with the widespread resistance among Enterobacteriaceae. Although the plasmids were not identical, they appeared to belong to the same incompatibility group (IncI1-like plasmids), suggesting that they are genetically related but may have evolved divergently over time.
Journal of Clinical Microbiology, 2002
During the course of a molecular epidemiology study of mechanisms of antibiotic resistance in the area served by our hospital (516,000 inhabitants), we isolated the gene encoding CTX-M-14 -lactamase. Thirty clinical strains (27 Escherichia coli and 3 Klebsiella pneumoniae isolates) with a phenotype of extended-spectrum -lactamase were collected from January to October 2001 and studied for the presence of the CTX-M-14 lactamase gene. By isoelectric point determination, PCR, and nucleotide sequencing, we detected the presence of this gene in 17 E. coli strains belonging to 15 different genotypes (REP-PCR) causing infections in 17 different patients. Epidemiological studies based on medical records did not suggest any relationship between the patients infected with these E. coli strains and, interestingly, 7 of 30 patients harboring strains with extended-spectrum -lactamases never had contact with the hospital environment before the clinical E. coli isolation. Conjugation experiments revealed that this gene was plasmid mediated in the 17 E. coli strains, and plasmid restriction fragment length polymorphisms showed 9 different patterns in the 17 E. coli strains. By PCR, the sequence of the tnpA transposase gene of the insert sequence ISEcp-1 was detected in all the plasmids harboring the CTX-M-14 gene. These results strongly suggest that plasmid dissemination between different E. coli strains in addition to a mobile element (transposon) around the -lactamase gene may be involved in the spreading of the CTX-M-14 gene. This study reinforces the hypothesis that the epidemiology of the prevalence of the -lactamase genes is changing and should alert the medical community to the increase in the emergence of the CTX-M -lactamases worldwide.
Journal of Clinical Microbiology, 2002
During the course of a molecular epidemiology study of mechanisms of antibiotic resistance in the area served by our hospital (516,000 inhabitants), we isolated the gene encoding CTX-M-14 β-lactamase. Thirty clinical strains (27 Escherichia coli and 3 Klebsiella pneumoniae isolates) with a phenotype of extended-spectrum β-lactamase were collected from January to October 2001 and studied for the presence of the CTX-M-14 β- lactamase gene. By isoelectric point determination, PCR, and nucleotide sequencing, we detected the presence of this gene in 17 E. coli strains belonging to 15 different genotypes (REP-PCR) causing infections in 17 different patients. Epidemiological studies based on medical records did not suggest any relationship between the patients infected with these E. coli strains and, interestingly, 7 of 30 patients harboring strains with extended-spectrum β-lactamases never had contact with the hospital environment before the clinical E. coli isolation. Conjugation experim...
Journal of Clinical Microbiology, 2012
Escherichia coli is the species most frequently associated with clinical infections by extended-spectrum--lactamase (ESBL)producing isolates, with the CTX-M ESBL enzymes being predominant and found in genetically diverse E. coli isolates. The main objective of this study was to compare, on the basis of a case-control design, the phylogenetic diversity of 152 CTX-M-producing and 152 non-ESBL-producing clinical E. coli isolates. Multilocus sequence typing revealed that even though CTX-M enzymes were largely disseminated across the diversity of E. coli isolates, phylogenetic group B2 showed a particularly heterogeneous situation. First, clone ST131 of group B2 was strongly associated with CTX-M production (55 [79%] of 70 isolates), with CTX-M-15 being predominant. Second, the remaining members of group B2 were significantly less frequently associated with CTX-M production (9 [12%] of 75) than E. coli phylogenetic groups A, B1, and D (88 [55%] of 159). CTX-M-producing ST131 E. coli isolates were significantly more frequent in patients hospitalized in geriatric wards or long-term care facilities. Besides, the non-ESBL ST131 isolates significantly more frequently showed resistance to penicillins than the non-ESBL, non-ST131 isolates did. In conclusion, the present study emphasizes the particular antimicrobial resistance and epidemiologic characteristics of clone ST131 within group B2, which could result from the higher antibiotic exposure of this clone, as it is the predominant clone of group B2 carried in the human gut.
Dissemination of CTX-M-Type Extended-Spectrum -Lactamase Genes to Unusual Hosts
Journal of Clinical Microbiology, 2005
A Citrobacter amalonaticus and a Morganella morganii producing the CTX-M-1 extended-spectrum -lactamase (ESBL) were isolated from an area where this enzyme is now widespread in Escherichia coli. This is the first report of CTX-M-1 in the former species. In both cases the ESBL determinant was possibly acquired by these unusual hosts in vivo, after coinfection with E. coli strains carrying conjugative plasmids encoding CTX-M-1.