EPIDEMIOLOGY OF FARM ESCHERICHIA COLI INFECTION AND ANTIBIOGRAM OF ESCHERICHIA COLI IN COMMERCIAL CHICKENS IN CHATTOGRAM, BANGLADESH

Abstract

Escherichia coli (E. coli), a Gram-negative bacterium of the family Enterobacteriaceae, is a commensal to the digestive tract of human and animals, can cause extra intestinal infections and serious food poisoning in human. Avian pathogenic E. coli, strains can also cause systemic disease in poultry, which is called colibacillosis. Sign of colibacillosis include omphalitis, acute fatal septicemia or subacute pericarditis, airsacculitis, salpingitis, cellulitis and peritonitis. Poultry farm level E. coli prevalence and risk factors associated with biosecurity measures have not been reported yet in Bangladesh. In addition, indiscriminate use of antimicrobials in commercial chicken industry associated with poor biosecurity might play a role in the emergence and dissemination of multi-drug resistant E. coli. Hence, a cross-sectional study was conducted on 140 commercial broiler and layer farms in Chattogram in 2019. This study aimed to assess the farm level E. coli prevalence and describe antimicrobial susceptibility pattern of E. coli (farm and individual level) and determine associated potential risk factors related to biosecurity. Pool of cloacal (from 5 birds) and environmental swabs (5 sites) were collected from each per farm. Data on demographics, husbandry practices and antimicrobial application were collected with questionnaire, while a physical inspection of the farms was also conducted. E. coli was isolated by using selective culture media and antimicrobial susceptibility testing was performed by standard disc diffusion for 12 common antimicrobials of veterinary and/or human health importance. The total of 74.7% broiler and 84.2% of layer farm tested E. coli positive (at least one sample per farm tested positive). For environmental samples, 50.6% of broiler and 73.7% of layer, and for cloacal swabs, 54.2% of broiler and 63.2% of layer farms tested positive. Broiler farms having an isolation shed for sick birds had lower odds of farm level occurrence of E. coli (OR=0.4; 95% CI: 0.1- 1.0). In case of layer farms that only partly conducted cleaning and disinfecting of farm surfaces and equipment had greater odds of E. coli (OR=3.4; 95% CI: 1.0-11.3) occurrence. Regardless of farm types, in average, E. coli isolates were resistant to 10 of the 12 antibiotics tested per farm. On broiler farms, 100% of isolates were resistant to amoxicillin, ampicillin, erythromycin and cephalexin followed by pefloxacin (98.8%), sulfamethoxazole and trimethoprim (96.5%), enrofloxacin (95.4%), doxycycline (94.2%); on layer farms, 100% of isolates were resistant to amoxicillin, ampicillin, erythromycin and cephalexin followed by pefloxacin (98.8%), sulfamethoxazole and xiv trimethoprim (96.3%), doxycycline (92.5%). On the other hand, Colistin sensitivity was high (~97%) for both production types. Interestingly, the antibiotic resistance to E. coli on broiler farms significantly increased with the level of education (p<0.05), but this was not the case for farms. This research highlighted a high prevalence of E. coli as well as high level of antimicrobial resistance on commercial poultry farms. Use of antimicrobial guidelines along with routine monitoring of antimicrobial susceptibility should be implemented to further reduce the antimicrobial resistance in Bangladesh.