Investigations On The Resistance Of Porcine Commensal E. Coli Isolates To Beta Lactams

The aim of this study was to describe the prevalence of antibiotic resistance to beta-lactams and to evaluate two resistance genes bla_TEM and bla_OXA-1 in Escherichia coli isolates from faeces on six swine farms in the Republic of Bulgaria. A total of 186 E. coli isolates from 192 faecal swabs were tested by the disk diffusion method to determine resistance patterns to 11 antimicrobial agents. Resistance to beta-lactams was determined by disk diffusion method, E-test, micro-broth dilution method and PCR. About 40.3% of the E. coli isolates from swine were resistant to ampicillin. The highest resistance was observed in E.coli isolates from weaned pigs to ampicillin – 60.0% and to cephalotin – 45.5 %. The E. coli isolates resistant to beta-lactams were examined for the presence of bla_TEM and bla_OXA-1 genes. The most common bla gene identified was bla_TEM, which was found in 92.0% of swine isolates.