Investigating the efficacy of indigenous probiotic LAB strains to control MDR Avian Pathogenic Escherichia coli in broiler chicken.

Abstract

Avian Pathogenic E.coli is a subgroup of extraintestinal pathogenic E.coli which is presumed to have the potential to cause zoonotic infections. Avian pathogenic E. coli strains are lined to a range of disorders primarily outside the intestine of poultry that lead to significant economic loss. The misuse of antibiotics in poultry farms has resulted in emergence of antibiotics resistance in APEC strains. Poultry harboring antibiotic-resistant bacteria can potentially contaminate poultry products, hence heightening the likelihood of transmission of these bacteria or their antibiotic resistance genes to humans. Probiotics presents an effective substitute to antibiotics as they have reported to control various diseases in poultry and livestock animals through enhancing host immune response and natural defense mechanism against harmful pathogens. Enterococcus faecium and Lactobacillus reuteri previously isolated from poultry gut have inhibited the growth of Avian Pathogenic E.coli in in vitro experiments. In vitro techniques implemented to check the inhibitory effects of probiotics strains against APEC included co-culturing and time kill assay. One day old broilers were grown in controlled environment and challenged with MDR APEC strains; treatment groups were administered with commercial E. coli vaccine and combination of probiotics in order to evaluate the effectiveness of probiotics against MDR APEC infection in vivo. Total of sixty birds were fed with organic diet in a 28 days trail. Birds were divided into Five groups with 12 chicks in each group, PC+ was challenged with no treatment, Vacc was given commercial E. coli vaccine, PRO was administered with probiotics suspension in drinking water (108 CFU/mL), and PRO+ Vacc was administered with vaccine and probiotics in drinking water. Subcutaneous challenge of APEC (106 CFU/mL) was given to birds in all four groups. A group with no challenge and no treatment was used as a negative control. Use of probiotics in drinking water resulted in reduction of cecal E.coli population (P<0.05) and reduced the mortality of chickens. Histopathological examination of heart, liver, and spleen of challenged birds with no treatment or vaccine only showed symptoms of pericarditis, perihepatitis, and disruption of white pulp and focal necrosis in spleen. While the histopathological examination of organs of birds administered with probiotics suspension showed that probiotics have role in controlling the pathological effects of MDR APEC in broilers thus preventing the symptoms of Avian colibacillosis.