Variety of TEM-, SHV-, and CTX-M-type β-lactamases present in recent clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae from Taiwan

A total of 171 hospitals' isolates of E. coli, K. pneumoniae, and E. cloacae with a minimum inhibitory concentration (MIC) of >= 2 mu g/ml for ceftazidime or cefotaxime were evaluated for the production of beta-lactamases. PCR amplification with specific primers for the bla(SHV), bla(TEM), and bla(CTX) genes revealed that a total of 53, 81, and 43 of these genes were amplified, respectively. Sequencing results confirmed that TEM-1, CTX-M-3 and -14, SHV-1, -5, -11, -12, and -33, OXY-1a, and LEN-1 were presented among these isolates. No specific large cluster of isolates carried the same beta-lactamases, indicating the wide diversity of the collected strains. Plasmid spread between E. coli and K. neumoniae was identified in few isolates. Combinations of TEM, SHV, and CTX beta-lactamase genes, including extended-spectrum beta-lactamase genes, were observed in all three species.