Detection of resistance phenotype and gene of avian Escherichia coli to β-lactam antibiotics

Abstract

Understanding and detecting ß-lactam antibiotics resistance and resistance genes and elucidating the drug-resistant mechanism is of significance to prevention and treatment of avian Escherichia coli disease. In this study, the ESBLs (Extended Spectrum β-Lactamases) producing strains were screened from 41 E. coli isolates by double paper disk test; the β-lactam antibiotics resistance was investigated by Kirby-Bauer (K-B) drug susceptibility test; and three ESBLs genes including TEM, SHV and CTX-M were tested by Polymerase Chain Reaction. The results showed that there were 31 (75.6%) ESBLs producing strains. The E. coli had highest resistance to penicillin and first generation cephalosporin followed by to second and third generation cephalosporins and monocyclic lactams. PCR revealed 73.2% (30/41) of E. coli isolates carrying ESBLs gene. The positive rate of TEM, CTX-M and SHV were 63.4% (26/41), 31.7% (13/41) and 4.9% (2/41), respectively. There were 10 strains (24.4%) carrying more than two kinds of resistance genes. In conclusion, the drug resistance is directly related to the clinical use time and range of ß-lactam antibiotics. The antibiotics resistance of E coli isolated from avian to ß-lactam in North China is mainly mediated by TEM and CTX-M genes.