Occurrence and detection of extended-spectrum ß-lactamases in Klebsiella isolates in Hilla, Iraq
total of 88 K. pneumoniae strains were isolated from different environmental and clinical samples in Hilla/Iraq during the period from January to July 2003. Primary screening of ß-Lactam resistant isolates showed that 73.8% (65 strains) were resistant to ß-Lactam antibiotics. 58.4% of these strains were ß-lactamase-producers. All the ß- lactamase-producing Klebsiella strains showed multiple-drug resistance to least 8 antibiotics. Klebsiella strains were also tested for their ability to produce extended-spectrum beta-lactamases (ESBLs) using three methods. Determination of minimum inhibitory concentration (MIC) with and without clavulanate was the most accurate method for detection of ESBL-producing isolates, by which 8 (21%) ESBL-producing isolates were detected. Plasmid profile of Klebsiella strains (including ESBL-producers) was detected. The genes encoding for the production of ESBLs and resistance to penicillin, ampicillin, amoxicillin, tetracycline, refampin, and erythromycin were located on conjugative plasmids whereas genes encoding for resistance to cephalothin, cefazolin, cephalexin and gentamycin were located on the chromosome.
Key words: Antimicrobial resistance, ß-lactamases, ESBLs, plasmid profile, Klebsiella pneumoniae.