Antibiotic resistance in Salmonella enterica subsp. enterica strains isolated in Poland from 1998 to 1999.

A total of 326 Salmonella enterica subsp. enterica strains representing 29 serotypes, isolated from human stool specimens during 1998-1999 in sanitary-epidemiological units in Poland were tested for antibiotic susceptibility by a standard disk diffusion method. The antibiotics used were ampicillin, cefotaxime, chloramphenicol, tetracycline, streptomycin, gentamicin, kanamycin, nalidixic acid, ciprofloxacin, furazolidone, cotrimoxazole, sulphonamides and trimethoprim. In addition, 201 strains belonging to the five most commonly isolated serotypes (S. Enteritidis, S. Typhimurium, S. Hadar, S. Infantis and S. Virchow) also had minimal inhibitory concentrations (MICs) determined for amoxycillin/clavulanic acid. Selected strains were screened for production of extended spectrum beta-lactamases (ESBLs). There were 49.4% of Salmonella enterica subsp. enterica strains resistant to two or more antibiotics, with the highest prevalence of multiple resistant strains among serotypes Typhimurium, Hadar and Virchow. Resistance to ampicillin, streptomycin, tetracycline, nalidixic acid, furazolidone and sulphonamides occurred most frequently. Over 93% of S. Virchow strains were resistant to furazolidone. No strains resistant to ciprofloxacin by disk-diffusion method were detected but 31.3% of isolates of the 201 strains representing the five most common serotypes had reduced ciprofloxacin susceptibility (MICs ranging 0.125-0.5 mg/l). One strain (S. Mbandaka) was resistant to cefotaxime and produced ESBL.