[Antimicrobial susceptibility of Yersinia enterocolitica and Yersinia pseudotuberculosis strains isolated from humans in Poland during 2004-2009].

The number of yersiniosis has increased in the last few years in Poland, especially an increase of Yersinia enterocolitica bioserotype 1B/O:8 infections was observed. From 2004 to 2009 265 of Y. enterocolitica 4/O:3, 108 of Y. enterocolitica 1B/O:8, 8 of Y. enterocolitica 2/O:9 and 4 of Y. pseudotuberculosis clinical isolates were collected. To obtain basic data for resistance monitoring purpose 385 Yersinia strains were tested by standard disc diffusion method for their susceptibilities to 12 antimicrobial agents. In addition beta-lactamase (enzyme A) inhibition assays were undertaken with ticarcillin and clavulanic acid and beta-lactamase (enzyme B) induction tests were perfonned with imipenem as the inducer for 135 strains. The present study demonstrated a high susceptibility of clinical strains to most of the tested antibiotics with the exception of ampicillin, ticarcillin and streptomycin. No strains were resistant to third-generation cephalosporins, fluoroquinolones, gentamicin and tetracyclin. Less than 10% isolates were resistant to amoxicillin with clavulanic acid (except--all Y. enterocolitica 2/O:9 strains were resistant), sulfonamide, trimetoprim/sulfamethoxazole and chloramphenicol. Four isolates of Y. enterocolitica 4/O:3 and one Y. enterocolitica 2/O:9 was multidrug resistant (MDR). Detection of enzyme A by disc diffusion in all tested strains, with the exception of the three Y. pseudotubeculosis I isolates, was highly reliable but results of enzyme B detection by the disc diffusion test were, especially for Y. enterocolitica 1B/O:8, faced with the difficulties.