[The occurrence and characterisation of oxy-imino-beta-lactams resistant strains among Salmonella enterica subsp. enterica isolated in Poland].

Extended-spectrum beta-lactamases (ESBLs) are enzymes manifesting considerable hydrolyzing activity on a wide variety of beta-lactam antibiotics including oxyiminocephalosporins and aztreonam. In the study reported here we investigated the types of ESBL produced by Salmonella enterica subsp. enterica strains isolated from clinical samples in the microbiological laboratories of sanitary-epidemiological units in Poland from 1999 to 2004. Among 239 ampicillin-resistant Salmonella enterica subsp. enterica strains isolated from clinical samples in the microbiological laboratories of sanitary-epidemiological units in Poland, 68 isolates of oximino-beta-lactams resistant of 6 serovars were found. There were 16 epidemiological unrelated strains (6 isolates of S. Enteritidis, 5 isolates of S. Thompson, 3 isolates of S. Typhimurium, one-fold isolate of S. Muenster and S. enterica 1,9,12:-:-) coming from different areas of country and 52 epidemiologically related isolates of S. Oranienburg, coming from a prolonged outbreak in an orphanage in Lódź. All the strains were identified as the ESBLs producers. The molecular analysis revealed that most of them expressed CTX-M-3 ESBL which is widely observed in Poland and additional enzyme TEM-1. All tested isolates of S. Thompson and one of three S. Typhimurium isolates were found to produce SHV-5 ESBL. This is the first report regarding the presence of SHV-5 in the genus Salmonella in Poland.