Occurrence of Multi-drug Resistant Avian Salmonellae in Commercial Poultry

Background: Salmonellosis is of great concern among the infectious diseases of poultry and has been responsible for serious economic losses to the poultry producers and a shift in Salmonella serotypes has been evident in recent years. Study was carried out to know the occurrence and pathology of Salmonellae infection in poultry along with their multi-drug resistance. Methods: Samples for study were collected from 26 organized poultry farms. To determine the presence of Salmonella in the farms, microbial culture from fecal swabs and pooled fecal samples was carried out for isolation of bacteria. Molecular detection of Salmonella isolates was also performed using direct PCR. Biofilm producing ability of the bacteria was also assessed and antibiotic sensitivity test was done to detect the resistance of bacterial isolates. Result: Salmonellosis in broiler and layer farms was recorded as 20% and 45.4% respectively and in 1.58% of the necropsy cases through microbial culture. Molecular detection of Salmonella isolates by PCR targeting invA gene was confirmed in 13.33% broiler farms and 36.3%-layer farms. Further detection of Salmonella Enteritidis was performed by PCR targeting ent gene and 11.11% positivity was determined. Biofilm producing ability of the bacteria was found 40% using biofilm assay. Serological examination using polyvalent antisera diagnosed 27.27% isolates as motile salmonellae. During necropsy of positive cases gross lesions comparable to salmonellosis were noted in liver, intestine, spleen and ovary. Multi-drug resistant (MDR) pattern was observed with highest resistance towards oxytetracycline, streptomycin followed by amikacin, amoxicillin and enrofloxacin. The presence of multiple drug resistant Salmonella in chicken has rendered the food chain unsafe from farm to table and hence continuous surveillance of the disease should be encouraged.