Phenotypic and genotypic characterization of Pseudomonas aeruginosa associated with airsacculitis in broiler chickens

Abstract

Airsacculitis is one of the respiratory manifestations caused by many bacterial and viral agents. The current work focused on airsacculitis syndrome and phenotypic as well as genotypic characterization of P. aeruginosa associated with airsacculitis in broiler chickens. A total of 105 airsacculitis samples were collected aseptically from slaughtered diseased and freshly dead broiler chickens from different farms in El-Fayoum, Beni-Suef and El-Menia Governorates. The prevalence of airsacculitis in the examined broiler chickens was 43.9%. A total of 56 P. aeruginosa isolates were recovered from the examined samples with a prevalence of 53.3%. The results of in-vitro antimicrobial susceptibility tests revealed that P. aeruginosa isolates showed high resistances against β-lactams, gentamicin and sulfa antimicrobials meanwhile showed high sensitivities against fluoroquinolones and phenicols. All isolates have been subjected to both combined disc diffusion and cefinase tests for phenotypic detection of ESβLs production which was confirmed in 39.3% and 42.9% of isolates, respectively. Haemolytic activity, biofilm formation and pyocyanin production were phenotypically detected in all isolates. PCR was conducted on 6 MDR isolates for determination of 5 resistance genes, ampC, bla_CTX, bla_TEM, aadB and sul1. The results revealed that all the tested P. aeruginosa isolates had ampC, bla_CTX and bla_TEM, while 66.7% had both sul1 and aadB genes. Also, PCR was conducted to detect 6 virulence genes; toxA, exoS, lasI, lasB, phzM and hlyA. The results revealed that all isolates had exoS, lasI, lasB and phzM genes while 83.3% and 66.7% of tested isolates had toxA and hlyA genes, respectively.