Multidrug-Resistant Escherichia Coli and Staphylococcus Aureus Co- Infection Complicating Respiratory Infection in Brahma Chickens in a Zoological Garden: A Case Report

Abstract

Respiratory diseases are major causes of morbidity and mortality in captive birds. This report
describes the clinical, pathological, and microbiological features of a case caused by a multidrug-
resistant Escherichia coli (E. coli) and Staphylococcus aureus in a small flock of exotic Brahma
chickens at the University of Ibadan Zoological Garden. It highlights its zoonotic and
antimicrobial-resistance implications. This paper reports a case of small Brahma birds that
experienced an initial respiratory infection compounded by moderate intestinal coccidiosis. Two
carcasses were necropsied. Samples from the liver, trachea and intestine were collected for aerobic
bacterial culture and identification using API kits while antimicrobial susceptibility testing was
performed using Kirby Bauer disk diffusion method. Intestinal scrapings were examined for
coccidia species by light microscopy, and representative tissues were processed for histopathology.
Three (75%) out of the four affected chickens died. Post-mortem examination revealed severe air
sacculitis, pulmonary congestion, hepatomegaly with steatosis, and: catarrhal enteritis with
petechiae haemorages. Aerobic cultures isolated E. coli and S. aureus from multiple organs.
Antimicrobial testing confirmed the isolates as multidrug resistant, including resistance to
gentamicin, amoxicillin, and cephalosporins (cefotaxime, ceftriaxone). Histopathology
corroborated air sacculitis, tracheitis, hepatic steatosis, and enteritis. Empirical oxytetracycline
therapy failed to control the infection. The case shows that small captive bird flocks can serve as reservoirs of multidrug-resistant, potentially zoonotic pathogens and highlights the limitations of
empirical treatment without laboratory confirmation.