Isolation, O-serotypic characterization and in-vitro susceptibility of Escherichia coli isolates from chickens to five common antimicrobials used in Bangladesh

Abstract

A total 1043 dead chickens were collected from different chicken farms located in Chittagong district, Bangladesh; all these dead chickens were examined postmortem. In total, 162 broiler and 183 layer chickens had lesions consisting fibrinous peri-hepatitis; of them, on bacteriological examination, 88 and 82, respectively, were positive for Escherichia coli. Serological analysis revealed that 19, 24, 26 and 48 of the isolates belonged to serotypes O1, O2, O8 and O78, respectively; 53 isolates remained “untypable.” By disc-diffusion method isolates were tested for their susceptibility to 5 antimicrobials: amoxicillin, cephalexin, co-trimoxazole (sulphamethoxazole/trimethoprim), gentamicin and oxytetracycline. Most of the E. coli isolates of broiler and layer chicken origins were resistant to co-trimoxazole (86.4 vs 91.5) and oxytetracycline (56.8 vs 78.1) followed by amoxicillin (47.7 vs 73.2); <16 % isolates from both layer and broiler chickens were resistant to gentamicin; however, 34% broiler isolates
were resistant to cephalexin.