Isolation, identification, molecular detection and sensitivity to antibiotics of Salmonella from cattle faeces

The present study was designed with the aim of isolation and identification of Salmonella by con-ventional culture method and their confirmation by polymerase chain reaction (PCR). Antibacte-rial sensitivity study of isolated Salmonella from cattle faeces was also performed. During the study period of July 2017 to June 2018, a total of 200 faecal samples were collected from different government and private farms in Sylhet district of Bangladesh. Out of 200 samples, 24 (12%) were found to be positive for Salmonella by conventional culture methods. Among the twenty four suspected colonies of Salmonella, seventeen were confirmed by biochemical test and same number was detected by PCR estimating a prevalence of 8.5% (17/200). The prevalence was high-er in calves under 1 year of age (16%) compared with older animals (11.25% of 1–2 years; 10% of above 2 years of age) but without statistically significant differences (χ2=4.835, P=0.089). Moreo-ver, in diarrhoeic animals the prevalence was significantly higher (32.14%, χ2=49.414, P<0.01) than in apparently healthy animals (8.72%). The antibiotic sensitivity test showed that highest number of Salmonella isolates were sensitive to ciprofloxacin (100%), gentamicin (100%) and neomycin (100%). On the other hand, significantly high resistance of Salmonella isolates was detected to erythromycin (100%), amoxicillin (100%), cotrimoxazole (81.48%), streptomycin (62.96%) followed by tetracycline (55.56%).