Incidence, Serotyping and Antimicrobial Susceptibility Profile of Avibacterium Paragallinarum Isolated From Local Commercial Poultry of Balochistan

Abstract Background Infectious coryza (IC) caused by Avibacterium paragallinarum, a Gram negative, non-motile coccobacilli, is a severe upper respiratory tract disease of poultry. This study aimed to report on the isolation rate and serotyping of Avibacterium paragallinarum causing Infectious Coryza (IC) in commercial layer poultry in Balochistan. Results Total 500 samples were collected from IC-suspected or recently dead birds Results revealed that 80.62% of sample were found positive for A. paragallinarum. Of these, serotype B was 59.60% and serotype C was 21.02%. The isolates of A. paragallinarum were growing well at 35–37 oC, however, growth rate was declined at 24 oC, and 42 oC. Similarly, A. paragallinarum showed optimal growth between pH 5 and 9, but the superlative pH growth values were from 6 to 8 pH. Antimicrobial susceptibility test showed that all tested isolates displayed resistance against metronidazole, colistin sulphate, bacitracin, streptomycin, chloramphenicol and lincomycine, while were found susceptible to tetracycline, erythromycin, vancomycin, amoxicillin, and ciprofloxacin. Pathogenicity test performed indicated that experimental birds showed signs of dullness, fever, serous nasal discharge and facial swelling with pus inside infra-orbital sinus, severe congestion in the trachea and partial cloudiness of air sacs. conclusions Overall, we report, for the first time, on high incidence rate of pathogenic A. paragallinarum among layer birds.