Molecular characterization & multidrug resistance of Salmonella gallinarum isolates from commercial layer farms in Bangladesh

Abstract

Background: Worlwide, salmonella is one of the most important pathogens responsible for decreased egg production and chicken products are widely acknowledged to be significant reservoir for salmonella But approximately 48–57% drop in egg production & around 200 grams body weight decreases in commercial layer because of salmonellosis. Moreover, maximum farmers are ignorant about the fact that production varies from month to month in farms due to salmonella in Bangladesh. Henceforth, we need to find out specific salmonella species, and how it reduces eggs production. Afterwards, developing a scientific technique and guideline from feed production to feed medication in farm, to control salmonella and maintaining good production all over the year. The study was conducted aiming at the isolation, identification & characterization of Salmonella gallinarum from layers during egg production drop in different districts of Bangladesh. Methods and materials: Total 760 random samples have been collected from 12 commercial layer farms (70.78% cloacal swab and 5.52% visceral organ) and Salmonella was isolated followed by sero-grouping. From positive Group-D samples, Salmonella gallinarum was confirmed by PCR and used for molecular characterization by PCR technique for detection of invA and spvC genes. The invA & spvC PCR products from four representative samples were sequenced and obtained accession no from GenBank. Then multidrug resistance pattern of the positive isolates has also been analyzed to find out an effective prophylaxis to minimize salmonella infection and production loss. Results: Among 760 samples, total isolate identified positive were 83. Nucleotide sequence of 284 bp for invA gene & 571 bp for spvC gene were deposited in GenBank (NCBI) with accession no. MK801112, MK801113, MK801114 & MK801115 respectively. In respect to antimicrobial susceptibility testing, most of the Salmonella gallinarum isolates were resistant to seven antibiotics. A few isolates were intermediate resistant to three antibiotics while some were susceptible to three antibiotics. Moreover,out of 83 Salmonella gallinarum positive isolates71 (85.56%) isolates were detected as multidrug resistant. Conclusion: This study indicates the presence of multidrug resistant Salmonella gallinarum isolates from different farms in Bangladesh. Continuous studies and monitoring are required to effectively minimize the Salmonella contamination in layer farms and subsequent egg production drop.