First Description of CTX-M-15-Producing Klebsiella pneumoniae

The first CTX-M-15 -lactamase was found in several en-terobacterial isolates from India in 1999 (4). Worldwide spread of CTX-M-15 -lactamases is now well documented (1–5, 7, 8, 12). CTX-M -lactamases confer high-level resistance to cefo-taxime, ceftriaxone, and aztreonam and are well inhibited by clavulanate and tazobactam (10, 11). Klebsiella pneumoniae 193KFFUL was isolated from a blood culture in September 2003 at the Hospital de Santa Maria. The clinical isolate was resistant to cefotaxime and cefepime (MIC, 256 g/ml) and ceftazidime and aztreonam (MIC, 96 g/ml) and susceptible to imipenem (MIC, 0.125 g/ml). Tazobactam and clavulanate restored the activities of piperacillin, cefo-taxime, ceftazidime, and cefepime as determined by E-test strips (Table 1). Genomic DNA was prepared as described elsewhere (6), and PCR experiments were performed usin