Occurrence, prevalence and genetic environment of CTX-M beta-lactamases in Enterobacteriaceae from Indian hospitals.
OBJECTIVE
To determine occurrence, prevalence and CTX-M genotypes produced by Enterobacteriaceae from clinical samples from three geographically distant Indian hospitals and to detect linkage of IS26 with bla(CTX-M) and map its precise insertion position.


METHODS
A total of 130, non-duplicate Escherichia coli and Klebsiella pneumoniae resistant to a third-generation cephalosporin (3GC) from three Indian centres were screened for extended-spectrum beta-lactamase (ESBL) production using phenotypic detection methods. All isolates were screened for bla(CTX-M) using multiplex PCR. Precise CTX-M genotype was identified using reverse-line hybridization. All CTX-M-producing isolates were screened for linkage of IS26 with bla(CTX-M). DNA sequencing was used to map the exact insertion position of this mobile element.


RESULTS
Ninety-five of 130 3GC-resistant (73%) (73% of total E. coli, 72% of total K. pneumoniae) isolates were found to carry bla(CTX-M-15). No other CTX-M genotype was detected. IS26 linkage with bla(CTX-M-15) was detected in 31% of isolates carrying bla(CTX-M-15). DNA sequencing revealed variable insertion of this mobile element within tnpA of ISEcp1. RAPD-PCR typing demonstrated great diversity in isolates carrying bla(CTX-M-15); no predominant clone was identified.


CONCLUSIONS
In contrast with other studies where greater diversity exists, CTX-M-15 was the only CTX-M ESBL produced in this Indian collection of unrelated E. coli and K. pneumoniae. This is the first systematic survey report from India detecting CTX-M-type beta-lactamases This is also the first report indicating such high mobility/diversity of insertion of IS26 in close association with bla(CTX-M) in a single bacterial collection.
Ensor
V M
VM
Antimicrobial Agents Research Group, Institute of Biomedical Research, University of Birmingham, Vincent Drive, Edgbaston, Birmingham B15 2TT, UK.
Shahid
M
M
Evans
J T
JT
Hawkey
P M
PM
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D015373:Bacterial Typing Techniques; D002511:Cephalosporins / Q000494:pharmacology; D016172:DNA Fingerprinting; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D005838:Genotype; D006761:Hospitals; D006801:Humans; D007194:India; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D019105:Random Amplified Polymorphic DNA Technique; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D001618:beta-Lactamases