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.