Bacterial Detection and Antimicrobial Susceptibility Profiling in a Broiler Breeder Flock

Abstract

Background: The health of breeders is essential for the next generation of chicks. Bacterial agents,such as Escherichia coli, Salmonella enterica and Mycoplasma gallisepticum or Mycoplasmasynoviae, are the leading causes of disease and mortality in breeder poultry. The widespread usage ofantimicrobials in poultry, has raised concerns about the potential for spread of antimicrobialresistance. The present study aimed to identify bacterial infections and antibiotic resistance patternsin the case of breeder’s mortality.

Methods: Samples were collected from tissues and bone marrow of sixteen broiler breeders. Thespecimens were cultured onto blood agar, MacConkey agar and confirmatory biochemical media forthe bacteriological examination. Sabouraud dextrose agar was used for fungal isolation. Thespecimens were cultured on Mueller-Hinton agar to assess their antibiotic resistance to gentamicin,ceftriaxone, tetracycline, penicillin, erythromycin, streptomycin, lincomycin, and amoxicillin

Results: The bacteria including Escherichia coli (93.8%), Staphylococcus (31.3%), Streptococcus(12.5%), Bacillus (12.5%) and Clostridium (6.3%) were isolated. Co-infection was observed in 50%of carcasses, most frequently involving E. coli and Staphylococcus. Isolates from 62.5% were resistantto all the antibiotics tested. Gentamicin was the most effective antibiotic.

Conclusion: Escherichia coli was the dominant isolate, and its detection in the bone marrow of31.3% of cases confirms systemic dissemination. Consequently, enhanced biosecurity protocols areessential to prevent the spread of pathogens such as E. coli. Antimicrobial susceptibility testingrevealed a multidrug-resistant pattern. Therefore, poultry farms should base antibiotic selection onspecific laboratory results rather than relying on empirical broad-spectrum therapy