Aims: Isolates obtained from various regions in Korea in 2002 were identified and their susceptibility to extended-spectrum cephalosporins, monobactams and/or cephamycins was studied along with any production of extended-spectrum β-lactamases (ESBLs). Methods and Results: Bacteria identified by the conventional techniques and Vitek GNI card were Klebsiella pneumoniae and Escherichia coli. Using disk diffusion and double-disk synergy tests, we found that 39.2% of strains produced ESBLs. About 52% of isolates transferred resistance to ceftazidime by conjugation. Banding patterns of PCR amplification with the designed primers showed that 837- and 259-bp fragments specific to blaTEM genes were amplified in 63.3% of strains. 929- and 231-bp fragments (blaSHV), 847- and 520-bp fragments (bla CMY), 597- and 858-bp fragments (blaCTX-M) were amplified in 61.5, 17.3 and 7.7% of strains respectively. About 51.9% of strains contained more than two types of β-lactamase genes. Especially, one strain contained blaTEM, blaCMY and blaCTX-M genes. Significance: Resistance mechanisms to β-lactams, comprising mostly 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 make therapeutic failure and lack of eradiation of these strains by extended-spectrum cephalosporins or cephamycins.
All Science Journal Classification (ASJC) codes
- Applied Microbiology and Biotechnology