Abstract / Summary
This study aimed to isolate and identify Escherichia coli from chickens with suspected colibacillosis and characterize their antibiotic susceptibility and carriage of β-lactam and aminoglycoside resistance genes. A total of two hundred and fifty (n = 250) samples (blood, spleen, liver and faeces) were collected from chickens with suspected colibacillosis across different poultry farms. Isolates were identified by biochemical and molecular (USP-gene PCR) testing, followed by disk-diffusion susceptibility testing and PCR-based detection of resistance genes. E. coli was recovered and confirmed in 61.2% (153/250) of samples, with the highest proportion, 41.83% (64/153), found in 25–30-day-old chicks, followed by 31–35-day-old chicks at 37.25% (57/153) and 11–15-day-old chicks at 20.91% (32/153). Culture susceptibility testing showed that ciprofloxacin (80.39%, 123/153) had the highest in vitro susceptibility, followed by colistin sulphate (60.13%, 92/153). The highest resistance was observed against cefalexin (87.5%, 134/153), followed by streptomycin (86.27%, 132/153). The aminoglycoside resistance gene aac(6′)-Ib was detected in 13.73% (21/153) of isolates, while among β-lactam resistance genes, bla′TEM was identified in 62.75% (96/153) of isolates, followed by blaCTX-M in 73.86% (113/153) and blaSHV in 31.37% (48/153). E. coli-associated morbidity and mortality have been increasing in young chicks, leading to substantial financial and agricultural losses.