Investigation of extended-spectrum &bgr;-lactamases produced by clinical isolates of Klebsiella pneumoniae and Escherichia coli in Korea

다국어 초록 (Multilingual Abstract)

<P>Abstract</P><P>Aims: </P><p>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 <i>&bgr;</i>-lactamases (ESBLs).</p><P>Methods and Results: </P><p>Bacteria identified by the conventional techniques and Vitek GNI card were <i>Klebsiella pneumoniae</i> and <i>Escherichia coli</i>. 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 <i>bla</i><SUB>TEM</SUB> genes were amplified in 63·3% of strains. 929- and 231-bp fragments (<i>bla</i><SUB>SHV</SUB>), 847- and 520-bp fragments (<i>bla</i><SUB>CMY</SUB>), 597- and 858-bp fragments (<i>bla</i><SUB>CTX-M</SUB>) were amplified in 61·5, 17·3 and 7·7% of strains respectively. About 51·9% of strains contained more than two types of <i>&bgr;</i>-lactamase genes. Especially, one strain contained <i>bla</i><SUB>TEM</SUB>, <i>bla</i><SUB>CMY</SUB> and <i>bla</i><SUB>CTX-M</SUB> genes.</p><P>Significance: </P><p>Resistance mechanisms to <i>&bgr;</i>-lactams, comprising mostly ESBL production, lead to the resistance against even recently developed <i>&bgr;</i>-lactams in enterobacteria, which is now a serious threat to antibiotic therapy. The high prevalence of <i>bla</i><SUB>CMY</SUB> genes and multidrug-resistant genes may also make therapeutic failure and lack of eradiation of these strains by extended-spectrum cephalosporins or cephamycins.</p>