Serogrouping and resistance gene detection in avian pathogenic E.coli isolated from broiler chickens

E coli infection in poultry is one of the principle causes of mortality and morbidity in chickens and turkeys resulting in retardationof growth and decreased feed conversion rate . The most common form of collibacillosis is characterized as an initial respiratoryinfection (air sacculitis) followed by generalized septicemia, perihepatitis and pericarditis. The present study aimed to identify thebacteria associated with pericarditis , airsacculitis and perihapatitis in Egyptian broiler chickens. A total 300 samples of diseasedand dead broilers from 3-6 weeks age were collected. The isolated bacteria included E. coli, Klebsiella spp., Shigella spp. AndEnterobacter spp. Sero-grouping of the isolated E. coli strains revealed O125, O158, O55,O129, O20 , O6 , O8 , O27, O115,O142 and un-typed strains with prevalence of 16%, 12%, 8%, 8%, 8% , 8% , 8% , 8% ,4%,4% and 16% respectively. Themajority of E coli isolates were sensitive to colistin sulphate (38%) and Norofloxacin (38%) followed by ciprofloxacin (19%),cefotaxim (19%) and Ofloxacin (19%). On the other hand, E coli were resistant (100%)to amoxicillin, clindamycin ,Erythromycin and streptomycin. PCR analysis for antibiotic resistance genes of E coli detected that 12 serogroups isolates werepositive using the specific primers for Aada2 , BlaCTX and TetA(A) genes. The current study demonstrated the high prevalenceof E. coli indeed broilers suffered from pericarditis , perihepatitis and airsacculitis . Measures are needed to control E. colicontamination in poultry farms to reduce economic losses caused by infection of E.coli.