Virulence of Some Pathogenic Bacteria Isolated from Broiler Chicks up to Two Weeks of Age

Abstract

Pathogenic bacteria causing diseases in broiler chicks are widely distributed. One hundred and fifty cases of broiler chick samples were obtained from 15 farms with complain of early mortalities. Out of them,  100 diseased and 50 freshly dead chicks aged 1 - 14 days were examined. Liver, heart blood, lung, yolk sac and thigh bones were collected . Bacteriological investigation in both diseased and freshly dead chicks revealed that the prevalence rate of E. coli was 70% with higher incidence in liver followed by yolk sac, S. aureus isolates represented as 18.5% mainly from thigh bone followed by liver, incidence of Pseudomonas aeruginosa was 20% mainly from yolk sac proceeded by liver,  Klebsiella pneumonia incidences was 13.3% with high rate from liver. Prevalence of all previous isolated bacteria was higher in freshly dead than in diseased chicks. Serological identification of 68 isolates of E. coli (64.8%) were typed with 5 different serotypes as 15 (O119:H6), 8 (O1:H7), 10 (O146:H21), 20 (O78), 8 (O29) and 7 (O144) while 37 (35.2%) were untyped.  E. coli antimicrobial resistance was performed with marked sensitivity reported with amoxicillin. PCR performed for detection of some  virulence genes mainly eaeA and iss from  E. coli isolates, and enterotoxin B (SEB) and enterotoxin D (SED) from S. aureus isolates  with positivity 100% for each genes. This study indicated presence of  some pathogenic bacteria in broiler chicks up to two weeks as  E. coli, S. aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae which cause diseases with a consequence of economic losses.