Determination of Antimicrobial Activity of Selected Commercial Antibiotics, Bromelain and Chitosan against Gut Bacteria Isolated from Chicken Kept in Juja Sub-County, Kenya

Abstract

Antimicrobial resistance (AMR) is a threat to poultry industry and thus requires surveillance and search for alternative drugs. A cross-sectional study was conducted in Juja Sub-County, Kenya, to determine the prevalence and risk factors of gut bacteria isolated from 200 chicken. A structured questionnaire was administered to 40 chicken farmers to evaluate risk factors. A total of 200 cloacal swab samples were collected from chicken for bacteriological analysis. In vitro activity of selected antibiotics against the bacteria was conducted using the disc diffusion method. The activity of bromelain and chitosan against six randomly selected antibiotic resistant bacteria was also conducted. The prevalence of gut bacteria in the chicken was 92.5% (185/200) and was higher on chicken from farms where chickens were mixed with other species, starters and those with history of gut conditions (p<0.05). The isolated bacteria were Salmonella spp. (46.5%), Escherichia coli (34%) and Staphylococcus aureus (12%). Salmonella spp. and E. coli isolates had the highest resistance against nalidixic acid (90.4%; 92.9%), and penicillin (76.2%; 85.7%), respectively. Notably, S. aureus isolates were more resistant to penicillin (90%) and nalidixic acid (90%). The minimum inhibitory concentration of bromelain and chitosan were: Salmonella spp., (125 µg/ml, 250 µg/ml) and E. coli (125 µg/ml, 500 µg/ml). These findings show that the burden of gut bacteria and AMR in the chicken in the study area was high. However, bromelain and chitosan exhibited some antimicrobial activity against antibiotic-resistant bacteria. This study highlights the potential development of bromelain and chitosan as alternative antimicrobial agents.