Antimicrobial resistance of ESBLand AmpC-producing Escherichia coli isolated from meat

Abstract In the present study, 25 Escherichia coli strains isolated from beef, pork, and poultry meat, and producing extended-spectrum β-lactamases (ESBL) (18 strains) or AmpC- cephalosporinases (7 strains) were tested for antimicrobial resistance using the minimum inhibitory concentration method with 16 antimicrobial agents. All examined strains were resistant to ampicillin and the first-generation cephalosporins. Variable resistance to the third-generation cephalosporins (40%-100% among ESBL-producing strains and 0-72% among AmpC-producing strains) was noted. Less than 30% of examined strains were resistant to ciprofloxacin. All isolates were susceptible to the fourth-generation cephalosporins, cephalosporins connected with inhibitors of β-lactamases, carbapenems, and gentamycin. Keywords: meat, Escherichia coli, ESBL, AmpC, antimicrobial resistance. Introduction β-lactamases are the leading cause of resistance to β-lactam antibiotics among Gram-negative bacteria (1). Genes encoding β-lactamases, found either in Gram-negative or Gram-positive microorganisms, are located on bacterial chromosome and on plasmids. β-lactamases can be distinguished on the basis of their nucleotide sequence homologies and differences in their ability to hydrolyse the various β-lactam antibiotics (1). Extended spectrum β-lactamases (ESBL) and AmpC cephalosporinases, recently classified as ESBL group, are particular groups of these enzymes, discovered in the last decades of the 20