Ceftazidime-Resistant Enterobacteriaceae Isolates from Three Polish Hospitals: Identification of Three Novel TEM- and SHV-5-Type Extended-Spectrum β-Lactamases

摘要: Extended-spectrum β-lactamases (ESBLs) are enzymes manifesting considerable hydrolyzing activity on a wide variety of β-lactam antibiotics including oxyiminocephalosporins and aztreonam. The genes coding for ESBLs usually carried by plasmids, which strongly facilitates their spread among strains many species gram-negative bacteria. Nevertheless, Klebsiella pneumoniae Escherichia coli remain the most frequently reported producers (12, 22). Since first ESBL-expressing isolate was discovered in Germany 15 years ago (24, 25) kinds have been characterized described. They exhibit high degrees diversity structures activities, several families reflecting evolutionary and/or functional similarities can be distinguished (13, 22). Among prevalent types members TEM SHV related to widespread, plasmid-borne, broad-spectrum TEM-1 or TEM-2 SHV-1, respectively. variety, mostly with respect ranges substrate preferences levels hydrolytic 22). is determined differences structures. To date about amino acid positions ESBL protein sequences heterogeneous (26). Mutations some these critical expanding profiles raising activities. Such substitutions efficiently selected under pressure use. Other described mutations no influence β-lactamase activity, as neutral they do not undergo any selective constraints. Together silent observed β-lactamases, provide information degree relatedness lines within Isolation sequencing natural encoding important data from an epidemiological point view contribute our understanding functions β-lactamases. Little known prevalence expressed bacterial present clinical environments Central Eastern Europe. In study here we investigated produced group 12 isolates family Enterobacteriaceae (11 K. 1 E. isolate) collected three Polish hospitals at beginning 1995. Six were identified being SHV-5-like remaining six found express new sequence variants derivatives; likely form subfamily highly β-lactamases.