ABSTRACT
Escherichia coli isolates resistant to ceftazidime isolated in the University Malaya Medical Center (UMMC) Kuala Lumpur, Malaysia, between the years 1998 and 2000 were studied for extended-spectrum beta-lactamase (ESBL) production. All strains were analysed phenotypically and genotypically and found to be ESBL-producing organisms harbouring SHV-5 beta-lactamase. This was confirmed by PCR-SSCP and nucleotide sequencing of the blaSHV amplified gene. As there was no evidence of ESBL activity in E. coli prior to this, coupled with the fact that there was a predominance of SHV-5 beta-lactamases in Klebsiella pneumoniae isolates in UMMC, we postulate that the E. coli obtained the SHV-5 beta-lactamase genes by plasmid transfer from the ESBL-producing K. pneumoniae.
Subject(s)
Escherichia coli Infections/microbiology , Escherichia coli/enzymology , Escherichia coli/isolation & purification , Klebsiella pneumoniae/genetics , beta-Lactam Resistance , beta-Lactamases/genetics , Anti-Bacterial Agents/pharmacology , Ceftazidime/pharmacology , DNA, Bacterial , Drug Resistance, Bacterial , Escherichia coli/drug effects , Escherichia coli/genetics , Gene Transfer, Horizontal , Genotype , Humans , Malaysia , Microbial Sensitivity Tests , Phenotype , Polymerase Chain Reaction , Polymorphism, Single-Stranded Conformational , beta-Lactamases/isolation & purificationABSTRACT
Twenty-eight (28) strains of ceftazidime-resistant Klebsiella pneumoniae were isolated from blood cultures of in-patients from University Hospital, Kuala Lumpur between March 1995 and August 1996. Three methods were used to detect the production of ESBL enzymes by these strains. These three methods include the double-disc synergy test (DDST), inhibitor-potentiated disc-diffusion test (IPDD) and the E-test ESBL method. All strains could be identified as ESBL producers using the DDST method by a minimum of two beta-lactams and these included either a combination of ceftazidime and ceftriaxone with clavulanate respectively or cefotaxime and aztreonam with clavulanate respectively. Similarly using a combination of either cefotaxime and ceftriaxone with clavulanate or ceftriaxone and aztreonam with clavulanate respectively would have detected all strains as ESBL producers. The IPDD method could also detect for ESBL activity based on combinations of beta-lactam antibiotics with clavulanate respectively. All combinations of beta-lactam antibiotics could detect for ESBL activity in all the strains except a combination of either ceftazidime and aztreonam or cefotaxime and ceftriaxone with clavulanate respectively. The E-Test method using ceftazidime alone and in combination with clavulanate was found to be the most effective method in the presumptive identification of ESBL activity in all the strains.
Subject(s)
Ceftazidime/pharmacology , Cephalosporins/pharmacology , Drug Resistance, Bacterial , Klebsiella pneumoniae/physiology , Microbiological Techniques/standards , beta-Lactamases/biosynthesis , HumansABSTRACT
OBJECTIVES: To describe the epidemiology, antimicrobial susceptibility, genomic profiles, and control of a nosocomial outbreak of multidrug-resistant Klebsiella pneumoniae (MRKP) that occurred in the pediatric oncology unit of the University of Malaya Medical Centre in Kuala Lumpur. MATERIALS AND METHODS: A prospective epidemiologic and microbiologic study was conducted of MRKP isolated from the blood and wound of a boy with necrotizing fasciitis after a 7-day course of ceftazidime and amikacin. In the following 2 weeks, phenotypically similar MRKP were isolated from the blood cultures of four other patients and rectal swabs of another three patients and two liquid soap samples located in the same ward. RESULTS: Antimicrobial profiles demonstrated that all the isolates were resistant to ceftazidime, sensitive to imipenem and ciprofloxacin, and confirmed to be extended-spectrum beta-lactamase producers. Plasmids of varying molecular weights were present in all isolates. In eight of these isolates, which included four from blood, there were common large molecular weight plasmids ranging from 80 kb to 100 kb. Pulsed-field gel electrophoresis analysis using XbaI demonstrated six different DNA profiles, A to F. Profile A was shared by two blood culture isolates and were related by 91%. Profile B was found in one rectal swab isolate and one isolate from liquid soap and were related by 94%. Profile C was shared by one blood isolate and one liquid soap isolate and showed 100% relatedness. Profiles D, E, and F each were demonstrated by one blood isolate and two rectal swab isolates, respectively. These showed only 65% relatedness. CONCLUSIONS: The MRKP strains in this outbreak were not clonal in origin. The decline of the outbreak after 4 weeks was attributed to the reemphasis of standard infection control procedures and the implementation of a program that addressed sites of environmental contamination.
