Colibacillosis in a 5- week-old broiler flock – case report

Avian colibacillosis caused by avian pathogenic Escherichia coli (APEC), is a localized or systemic infection manifesting in several ways including acute fatal septicemia, hemorrhagic septicemia, swollen head syndrome, coli granuloma, salpingitis, peritonitis, omphalitis and enteritis. A farmer with one hundred, five-week old broilers complained of reduced feed and water intake and dullness of some of the broilers. He also reported that the broilers had earlier been administered both LaSota and Infectious bursal disease vaccinations. On a visit to the farm some of the birds were examined and post mortem examination carried out on one dead bird and one sick bird. Cloacal swabs were collected from 10 broilers selected randomly in the pen for microbiological examination. The samples were cultured, incubated aerobically, then were sub-cultured on Eosin-methylene blue (EMB) agar and incubated again at 37°C for 24 hours. The colonies were gram - stained following standard procedures. Preliminary identification of the isolate was done using morphological (colonial and microscopic) characteristics, while further identification was done by conducting biochemical tests such as Triple sugar iron fermentation, Indole and Simons citrate test following standard methods. Antimicrobial sensitivity test (AST) was conducted to help in the choice of drug for treatment. Results revealed that some of the broilers were anorexic, dull and depressed. Post mortem examination revealed hemorrhagic septicemia, air sacculitis and enteritis while the culture and biochemical results identified the isolates as Escherichia coli (E. coli). The AST results showed that the isolates were susceptible to cefotaxime, Amoxicillin-clavulanic acid and resistant to ceftazidime, aztreonam and meropenem. Based on these results, amoxicillin-clavulanate was recommended to be administered at the dose of 0.5 g/L in drinking water for 5 - 7days. The farmer was advised to maintain strict biosecurity measures in and around the farm and to get a better source of drinking water for the birds.