Phenotypic characterization of Escherichia coli isolated from broiler chickens

Colibacillosis is one of the most important diseases of chickens, resulting in significant losses. The current study aimed to investigate the prevalence of E. coli infections in broiler chickens detecting their phenotypic characters such as Congo red binding activity, serum resistance and proteolytic activities. Samples were collected from 297 broiler chickens of different ages from different farms in El-Fayoum Governorate during the period from April 2017 up to March 2018. Bacteriological examination showed that 98 E. coli isolates were recovered with a prevalence rate of 33%. Results of Congo red binding activity and serum resistance revealed that all E. coli isolates (100%) showed Congo red binding activity and survive for 1 and 6 hrs and grown for 18 hrs in the presence of serum. Results of proteolytic activity revealed that 43 E. coli isolates (43.9%) were able to digest casein of skimmed milk while 16 isolates (16.3%) were positive for gelatin liquefaction test.