The Occurrence ofblaCTX-M,blaSHV, andblaTEMGenes in Extended-Spectrumβ-Lactamase-Positive Strains ofKlebsiella pneumoniae,Escherichia coli, andProteus mirabilisin Poland

Bacteria belonging to the Enterobacteriaceae family that produce extended-spectrum β-lactamase (ESBL) enzymes are important pathogens of infections. Increasing numbers of ESBL-producing bacterial strains exhibiting multidrug resistance have been observed. The aim of the study was to evaluate the prevalence of , , and genes among ESBL-producing Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis strains and to examine susceptibility to antibiotics of tested strains. In our study, thirty-six of the tested strains exhibited genes , , , and . Moreover, twelve ESBL-positive strains harbored genes , , , and , and the presence of a gene in twenty-five ESBL-positive strains was revealed. Among K. pneumoniae the multiple ESBL genotype composed of , and genes encoding particular ESBL variants was observed. Analysis of bacterial susceptibility to antibiotics revealed that, among β-lactam antibiotics, the most effective against E. coli strains was meropenem (100%), whereas K. pneumoniae were completely susceptible to ertapenem and meropenem (100%), and P. mirabilis strains were susceptible to ertapenem (91.7%). Moreover, among non-β-lactam antibiotics, gentamicin showed the highest activity to E. coli (91.7%) and ciprofloxacin the highest to K. pneumoniae (83.3%). P. mirabilis revealed the highest susceptibility to amikacin (66.7%).