Ma L, Ishii Yoshikazu, Chang Feng-Yee, Yamaguchi Keizo, Ho Monto, Siu L K
Division of Clinical Research, National Health Research Institutes, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Antimicrob Agents Chemother. 2002 Jun;46(6):1985-8. doi: 10.1128/AAC.46.6.1985-1988.2002.
Four Escherichia coli isolates harboring CTX-M-14, with a single Ala231-->Val substitution compared to CTX-M-9, had three different ribotypes. Cefotaxime resistance was plasmid encoded and conjugatively transferable. Three isolates had the same plasmid restriction enzyme digestion profile, suggesting clonal spread of a resistant plasmid. A high k(cat)/K(m) value for cefotaxime (20.3 microM(-1) s(-1)) but low values for ceftazidime and aztreonam (< 0.02 microM(-1) s(-1)) were observed in hydrolysis assays, indicating resistance to cefotaxime (MIC > or = 64 microg/ml) but susceptibility to ceftazidime (MIC < or = 2 microg/ml).
四株携带CTX-M-14的大肠杆菌分离株，与CTX-M-9相比有单个Ala231→Val替换，具有三种不同的核糖体分型。头孢噻肟耐药性由质粒编码且可接合转移。三株分离株具有相同的质粒限制性内切酶消化图谱，提示耐药性质粒的克隆传播。在水解试验中观察到头孢噻肟的高k(cat)/K(m)值（20.3μM-1 s-1），但头孢他啶和氨曲南的值较低（<0.02μM-1 s-1），表明对头孢噻肟耐药（MIC≥64μg/ml）但对头孢他啶敏感（MIC≤2μg/ml）。
