Aims: Isolates from various samples obtained during 1998 and 1999 were identified and their susceptibility to third-generation cephalosporins, monobactams and/or cephamycins studied along with any production of ESBLs. Methods and Results: Of these samples, bacteria most frequently isolated by the conventional techniques and Vitek GNI card were Escherichia coli (37%), Klebsiella pneumoniae (27%) and Enterobacter cloacae (16%). Using disk diffusion and double-disk synergy tests, we found that 71% strains produced ESBLs and 18% strains produced ESBLs and cephamycinases. Banding patterns of PCR amplification with the designed primers showed that 57% strains were capable of harbouring blaSHV genes. The blaTEM, blaCMY and blaAmpC genes were harboured by 55%, 31% and 12% strains, respectively. Forty-five percent of strains contained more than two types of β-lactamase genes. In particular, one strain contained blaTEM, blaSHV, blaCMY and blaAmpC genes. Conclusions: The percentage of ESBL-producing strains was high. The most prevalent β-lactamase gene was blaSHV gene. The blaCMY genes have been prevalent in cephamycin-resistant strains. The multidrug-resistant strains resistant to third-generation cephalosporins and cephamycins were detected in high percentage. Significance and Impact of the Study: Resistance mechanisms to β-lactams, comprising mostly extended-spectrum β-lactamase (ESBL) production, lead to the resistance against even recently developed β-lactams in enterobacteria, which is now a serious threat to antibiotic therapy. The high prevalence of blaCMY genes and multidrug-resistant genes may also cause therapeutic failure and lack of eradiation of these strains by third-generation cephalosporins or cephamycins.
All Science Journal Classification (ASJC) codes
- Applied Microbiology and Biotechnology