Pathogenicity and drug susceptibility of the Pasteurella anatis isolated in chickens in Taiwan

A strain of Pasteurella anatis (PA) was isolated from the sinus of an adult leghorn laying chicken with sinusitis, nasal discharge, drop in egg produc tion, and low mortality, symptoms initially thought to indicate infectious coryza. The tiny, smooth, whitish colonies were identified as PA. To compar e its pathogenicity with that of commercial broilers, nine groups, 10 birds per group, of 10-day-old broilers were individually inoculated with the st rain of PA, Pasteurella multocida (PM), or Escherichia coli (EC) by intrave nous, intraperitoneal, intramuscular, or subcutaneous inoculation. The PA w as determined to cause the signs, lesions, and septicemic death, which arc similar to the symptoms of PM or EC infection. At 1 wk postinfection (PI), the mortality rate was between that of PM and EC infection at 1 wk PI. Twen ty antimicrobial-containing discs were evaluated, and the isolate was highl y sensitive to cetiofer, amoxicillin, lincopectin, and furazolidone. Furthe rmore, it was moderately sensitive to tetracycline and enrofloxacin and onl y slightly sensitive to cephalothin, chloramphenicol, flumequine, nalidixic acid, neomycin, oxolinic acid, streptomycin, and trimethoprim. The PA infe ction was treated successfully with amoxicillin.