Occurrence, pathological changes and antimicrobial susceptibility pattern of Salmonella infection in chickens in and around Hyderabad

Salmonellosis is a significant bacterial disease of poultry. It causes considerable economic losses through higher mortality, poor growth, lower productivity and reduced hatchability, and contaminated poultry products also pose a real zoonotic risk. This study examined the occurrence, age-wise distribution, pathological changes, bacteriological characteristics and antimicrobial susceptibility of Salmonella spp. in broiler chickens from farms in and around Hyderabad. The observational work ran from July to December 2025. Carcasses were examined post-mortem in detail and were also assessed by histopathology, bacterial isolation, biochemical identification and antibiotic sensitivity testing. Of 759 birds diagnosed with gastrointestinal disease, 24 cases were confirmed as salmonellosis, a case prevalence of 3.16%. Two outbreaks involving 2,500 birds gave an overall mortality rate of 0.96%. The disease was limited to chicks under two weeks of age, and the 0–7-day group had the highest number of cases. Gross examination revealed an enlarged, bronze-coloured liver with multifocal necrotic foci, intestinal congestion and haemorrhage, and haemorrhagic ovarian follicles in adult birds. Histopathology showed hepatic congestion, multifocal coagulative necrosis, fatty degeneration, inflammatory cell infiltration, degeneration and desquamation of the intestinal epithelium, villous disruption and heterophilic infiltration. Culture on selective media, followed by Gram staining and IMViC biochemical tests, confirmed the isolates as Salmonella spp. In susceptibility testing, doxycycline gave the highest sensitivity (84.61%), followed by ciprofloxacin (69.23%) and norfloxacin (61.53%), while marked resistance was seen against neomycin and penicillin. These findings show that salmonellosis remains an important bacterial disease of young broiler chicks. Continuous surveillance, better biosecurity, early diagnosis and prudent antimicrobial use are needed to reduce the disease burden and slow the emergence of antimicrobial resistance.