Isolation, serotyping and antibiotic resistance of Salmonella isolated from chicken carcasses in Guilan province

The aim of this study was determining the prevalence rate, serotyping and sensitivity to antibiotics of Salmonella isolated from slaughtered broiler chickens of Guilan province. Two hundred carcasses were randomly selected out of 20 slaughtered broiler flocks and then 1000 samples were collected from different parts of carcasses (skin, meat, gallbladder, liver and intestine). All samples were cultured in different media, and the isolated Salmonella serotypes were identified. Sensitivity and resistance of isolated Salmonella were determined to 15 antibiotics. Three flocks (15%) and in 8 cases (0.8%) were positive to the Salmonella. Two serotypes were identified, including 6 samples (75%) of Salmonella enteritidis and 2 samples (25%) of Salmonella thompson. Salmonella was isolated from 4 samples of liver (50%), 2 samples of skin (25%) and 2 samples of caecum (25%). In this study, no salmonella was isolated from poultry meat. The results of sensitivity and resistance of Salmonella to antibiotics indicated that, 100% of isolates were resistant to cefazolin, streptomycin, kanamycin, tetracycline, nalidixic acid and sulfonamide + trimetoprim. There were three resistance patterns among the isolates, 100% of isolates were resistant at least to seven antibiotics and 25% were resistant to eight antibiotics from fifteen antibiotics. It is concluded that, the prevalence rate of Salmonella infection was lower than to the other studies, the dominant serotype was Salmonella entritidis and 100% of isolates were sensitive to ceftriaxone, gentamicin and chloramphenicol.