Characterization of Cephalosporinases Produced by Clinical Isolates of Enterobacteriacae in North Lebanon

Background: The problem of Enterobacteriacae resistance to β-Lactamase drugsis of growing concern in hospitals. Enterobacteria have developed multiple mechanismsof resistance to antibiotics, the main one is the enzymatic resistance mediatedby the beta-lactamases. This study aims to characterize the occurrence ofcephalosporinases in clinical isolates of Enterobacteriacae isolates in North Lebanon.Methods. Twenty two strains of Enterobacteriacae producing high level of cephalosporinaseshave been studied. The antibiotic susceptibility of each strain wastested on Mueller Hinton agar contains cloxacilline (250 mg/L) and by using E-testaccording the guidelines of the Antibiogram Committee of the French Society forMicrobiology. The search for plasmid-mediated cephalosporinases was performedusing PCR and primers for plasmid-mediated cephalosporinases genes (CMY-2,DHA-1, ACT-1, ACC-1, FOX-1 and MOX-1).Results: Thirteen positive strains were detected, of these 9 strains produced theplasmid-mediated cephalosporinase (CMY-2) and one strain produced the plasmidmediatedcephalosporinase (DHA-1). The remaining 9 strains were high-level chromosomalcephalosporinase producers since they belong to group-three Enterobacteria.They did neither produce plasmid-mediated cephalosporinase, nor did theyhave resistance to third generation cephalosporins except for cefepim. Two strains(CMUL E. coli 021) and CMUL E. coli 255) which were not susceptible for cefepim byE-test produced plasmid-mediated cephalosporinase The sequencing result of these2 E.coli strains did not show any mutation in the promoter that is responsible forhigh expression level of the chromosomal cephalosporinase. All examined strainsproducing plasmid-mediated cephalosporinase CMY-2 were analyzed by ERIC-PCRtechnique. The results showed that two of these strains had the same pattern (C4and C5) and three others had another pattern (C10, C12 and C13).Conclusion: This study shows the variations of cephalosporinases produced byclinical isolates of Enterobacteriacae in North Lebanon.



via The International Arabic Journal of Antimicrobial Agents http://imedpub.com/ojs/index.php/IAJAA/article/view/639

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