Background and objective: It is well recognized that life infections due to variety of β-lactamases producing isolates of Klebsiella spp. are the major problematic in the treatment of these types of infections due to their expression high level of resistance to the most effective antimicrobial agents. This study has been undertaken for detecting the ability of Klebsiella species to produce extended-spectrum β-lactamases (ESBLs) and Ambler class C (AmpC). Further, for determining the genetic elements encoding for such enzymes whether chromosomally or conjugated plasmid mediated. The study was performed on 110 wound patients admitted to Department of Surgery, Ramadi Teaching Hospital.Rapid iodometric β-lactamase production test, double disk synergy test, and phenotypic and confirmatory tests for production of extended spectrum and AmpCβ- lactamases were performed. Plasmid DNA extraction, conjugation and curing experiments were performed. Fifty isolates were bacteriologically identified as Klebsiellae spp. including 36 (72%) Klebsiellae pneumoniae and 14 (28%) Klebsiellae oxytoca. In double disk synergy test, out of the 25 β-lactamase producer isolates, 12 (48%) and 7 (70%) isolates of K. pneumonia and K. oxytoca respectively demonstrated a clavulanic acid effect with cefotaxime or ceftazidime.In the plasmid profile analysis, the results revealed that 7 (87.5%) of Eight ESBLproducer isolates of Klebsiella spp. respectively were conjugative plasmid mediated. The result of curing experiments showed successful curing for all the study isolates by both methods. The study suggested that the production of β-lactamases of type ESBLs and Amp C, appeared to be the major mechanisms ofresistance of Klebsiellae spp. to β-lactams. In addition, conjugative plasmids were found to be the main genetic elements encoding for ESBLs produced by Klebsiellae spp. Finally, the study suggested that sodium dodecyl sulphate was of higher potency than elevated growth temperature in the curing of plasmid DNA.
Key words: β-lactamases, Klebsiella, Plasmids, Conjugation, Curing
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