Presence of β-lactamase encoding genes in clinical isolates of Y. enterocolitica bioserotype 1B/O8mm isolated in Poland in 2009

Abstract

Introduction: The intrinsic resistance to β-lactam antibiotics of Y. enterocolitica is mainly due to activity of two type β - lactamases, BlaA and BlaB, which are encoding by genes located on chromosome, blaA and ampC, respectively. High-pathogenicity bioserotype 1B/O8 of Y. enterocolitica has been isolated from clinical samples since 2004 year in Poland. The study shown that clinical isolates of Y. enterocolitica 1B/O8 collected from 2004 to 2009 in Poland constituted the same sensu stricto strain. The aim of present study was to determine the occurrence of genes encoding β-lactamases BlaA and BlaB with the MIC value characterization for selected antibiotics in clinical isolates of Yersinia enterocolitica bioserotype 1B/O isolated in Poland in 2009. Methods: Ampicilin and ticarcillin minimum inhibitory concentrations (MICs) for 64 clinical Y. enterocolitica bioserotype 1B/O8 isolates were determined by Etest and broth microdilution respectively. The blaA i blaB genes were detected by PCR. Results: All investigated isolates were resistant to ticarcillin (MIC 16 – 128 mg/ml), whereas 9,5% to ampicilin (MIC 12 mg/l) according to EUCAST interpretive criteria. All isolates yielded the expected amplicons of blaA and ampC genes. Conclusions: Observed differences in the resistance to ampicillin among analyzed isolates belonging to the epidemic sensu stricto strain can indicate the variable activity of genetic determinants of resistance to β-lactam antibiotics of Y. enterocolitica bioserotype 1B/O8.