CEFTAZIDIME-RESISTANT ENTEROBACTERIACEAE ISOLATES FROM 3 POLISH HOSPITALS - IDENTIFICATION OF 3 NOVEL TEM-TYPE AND SHV-5-TYPE EXTENDED-SPECTRUM BETA-LACTAMASES

Twelve ceftazidime-resistant isolates of the family Enterobacteriaceae (11 Klebsiella Pneumoniae isolates and 1 Escherichia coli isolate) we re collected in 1995 from three Polish hospitals located in different cities. All were identified as producers of extended-spectrum beta-lac tamases (ESBLs). Detailed analysis of their beta-lactamase contents re vealed that six of them expressed SHV-5-like ESBLs. The remaining six were found to produce three different TEM enzymes, each characterized by a pI value of 6.0 and specified by new combinations of amino acid s ubstitutions. The amino acid substitutions compared to the TEM-1 beta- lactamase sequence were Gly238Ser, Glu240Lys, and Thr265Met for TEM-47 ; Leu21Phe, Gly238Ser, Glu240Lys, and Thr265Met for TEM-48; and Leu21P he, Gly238Ser, Glu240Lys, Thr265Met, and Ser268Gly for TEM-49. The new TEM beta-lactamases, TEM-47, TEM-48, and TEM-49, belong to a subfamil y of TEM-2-related enzymes. Genes coding for TEM-47 and TEM-49 could h ave originated from the TEM-48-encoding sequence by various single gen etic events. The new TEM derivatives probably document the already adv anced microevolution of ESBLs ongoing in Polish hospitals, in a majori ty of which no monitoring of ESBL producers was performed before 1996.