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Characterization of CTX-M ESBLs in Enterobacter cloacae, Escherichia coli and Klebsiella pneumoniae clinical isolates from Cairo, Egypt.

ABSTRACT: BACKGROUND: A high rate of resistance to 3rd generation cephalosporins among Enterobacteriaceae isolates from Egypt has been previously reported. This study aims to characterize the resistance mechanism (s) to extended spectrum cephalosporins among resistant clinical isolates at a medical institute in Cairo, Egypt. METHODS: Nonconsecutive Klebsiella pneumoniae (Kp), Enterobacter cloacae (ENT) and Escherichia coli (EC) isolates were obtained from the clinical laboratory at the medical institute. Antibiotic susceptibility was tested by CLSI disk diffusion and ESBL confirmatory tests. MICs were determined using broth microdilution. Isoelectric focusing (IEF) was used to determine the pI values, inhibitor profiles, and cefotaxime (CTX) hydrolysis by the beta-lactamases. PCR and sequencing were performed using blaCTX-M and ISEcp1-specific primers, with DNA obtained from the clinical isolates. Conjugation experiments were done to determine the mobility of blaCTX-M. RESULTS: All five clinical isolates were resistant to CTX, and were positive for ESBL screening. IEF revealed multiple beta-lactamases produced by each isolate, including a beta-lactamase with a pI of 8.0 in Kp and ENT and a beta-lactamase with a pI of 9.0 in EC. Both beta-lactamases were inhibited by clavulanic acid and hydrolyzed CTX. PCR and sequence analysis identified blaCTX-M-14 in Kp and ENT and a blaCTX-M-15 in EC. Both blaCTX-M-14 and blaCTX-M-15 were preceded by ISEcp1 elements as revealed by partial sequence analysis of the upstream region of the blaCTX-M genes. blaCTX-M-15 was transferable but not blaCTX-M-14. CONCLUSION: This is the first report of CTX-M-14 in Kp and ENT isolates from Egypt, the Middle East and North Africa.

SUBMITTER: Khalaf NG

PROVIDER: S-EPMC2701952 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

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Characterization of CTX-M ESBLs in Enterobacter cloacae, Escherichia coli and Klebsiella pneumoniae clinical isolates from Cairo, Egypt.

Khalaf Noha G NG Eletreby Mona M MM Hanson Nancy D ND

BMC infectious diseases 20090604

<h4>Background</h4>A high rate of resistance to 3rd generation cephalosporins among Enterobacteriaceae isolates from Egypt has been previously reported. This study aims to characterize the resistance mechanism (s) to extended spectrum cephalosporins among resistant clinical isolates at a medical institute in Cairo, Egypt.<h4>Methods</h4>Nonconsecutive Klebsiella pneumoniae (Kp), Enterobacter cloacae (ENT) and Escherichia coli (EC) isolates were obtained from the clinical laboratory at the medica ...[more]

PMID: 19497111

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Project description:BackgroundThe epidemiology of extended-spectrum β-lactamases (ESBLs) has undergone dramatic changes, with CTX-M-type enzymes prevailing over other types. blaCTX-M genes, encoding CTX-M-type ESBLs, are usually found on plasmids, but chromosomal location is becoming common. Given that blaCTX-M-harboring strains often exhibit multidrug resistance (MDR), it is important to investigate the association between chromosomally integrated blaCTX-M and the presence of additional antimicrobial resistance (AMR) genes, and to identify other relevant genetic elements.MethodsA total of 46 clinical isolates of cefotaxime-resistant Enterobacteriaceae (1 Enterobacter cloacae, 9 Klebsiella pneumoniae, and 36 Escherichia coli) from Zambia were subjected to whole-genome sequencing (WGS) using MiSeq and MinION. By reconstructing nearly complete genomes, blaCTX-M genes were categorized as either chromosomal or plasmid-borne.ResultsWGS-based genotyping identified 58 AMR genes, including four blaCTX-M alleles (i.e., blaCTX-M-14, blaCTX-M-15, blaCTX-M-27, and blaCTX-M-55). Hierarchical clustering using selected phenotypic and genotypic characteristics suggested clonal dissemination of blaCTX-M genes. Out of 45 blaCTX-M gene-carrying strains, 7 harbored the gene in their chromosome. In one E. cloacae and three E. coli strains, chromosomal blaCTX-M-15 was located on insertions longer than 10 kb. These insertions were bounded by ISEcp1 at one end, exhibited a high degree of nucleotide sequence homology with previously reported plasmids, and carried multiple AMR genes that corresponded with phenotypic AMR profiles.ConclusionOur study revealed the co-occurrence of ISEcp1-blaCTX-M-15 and multiple AMR genes on chromosomal insertions in E. cloacae and E. coli, suggesting that ISEcp1 may be responsible for the transposition of diverse AMR genes from plasmids to chromosomes. Stable retention of such insertions in chromosomes may facilitate the successful propagation of MDR clones among these Enterobacteriaceae species.

Dataset Information

Characterization of CTX-M ESBLs in Enterobacter cloacae, Escherichia coli and Klebsiella pneumoniae clinical isolates from Cairo, Egypt.

Publications

Characterization of CTX-M ESBLs in Enterobacter cloacae, Escherichia coli and Klebsiella pneumoniae clinical isolates from Cairo, Egypt.

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