Informatics Publishing Limited

Susmita Pal ¹, Samir Dey ¹, Kunal Batabyal ¹, Abhiroop Banerjee ¹, Siddhartha Narayan Joardar ¹, Indranil Samanta ¹, Devi Prasad Isore ¹

Affiliations
1 Department of Veterinary Microbiology, West Bengal University of Animal and Fishery Sciences, Belgachia, Kolkata - 700 037, West Bengal, IN

Abstract

Aim: The aim was to characterize Salmonella enterica serovar Gallinarum isolated from backyard poultry by polymerase chain reaction (PCR) detection of virulence genes invasion (invA) and Salmonella plasmid virulence C (spvC).

Materials and Methods: Two strains of Salmonella serovar Gallinarum isolates used in this study were obtained from an outbreak of fowl typhoid in backyard Vanaraja fowl. PCR technique was used for detection of invA and spvC genes using standard methodology. The invA PCR product from one representative isolate was sequenced and compared with other related Salmonella serovars in GenBank data.

Results: Salmonella Gallinarum produced expected amplicons of invA and spvC gene products. Nucleotide sequence of 285 bp invA gene was deposited in GenBank with accession no. KX788214. Sequence analysis of invA gene was found conserved in Salmonella serovars and demonstrated 100% homology with closely related serovars of Salmonella.

Conclusion: Invasion gene (invA) was found to be highly conserved in Salmonella Gallinarum and highly similar with closely related serovars. The isolates also contained plasmid-mediated spvC gene indicating possession of virulence plasmid.

Keywords

invA, Polymerase Chain Reaction, Salmonella gallinarum, Salmonella Plasmid Virulence C, Virulence Genes.

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Arnab Das ¹, Chanchal Guha ², Ujjwal Biswas ², Partha Sarathi Jana ², Amaresh Chatterjee ², Indranil Samanta ³

Affiliations
1 Animal Resources Development Department, Institute of Animal Health and Veterinary Biologicals, Government of West Bengal, Kolkata, West Bengal, IN
2 Department of Veterinary Epidemiology and Preventive Medicine, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, IN
3 Department of Veterinary Microbiology, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, IN

Abstract

Aim: The aim of this work was to detect antibiotic resistance in Gram-negative bacteria isolated from subclinical mastitis in cattle in West Bengal.
Materials and Methods: The milk samples were collected from the cattle suffering with subclinical mastitis in West Bengal. The milk samples were inoculated into the nutrient broth and incubated at 37°C. On the next day, the growth was transferred into nutrient agar and MacConkey agar. All the pure cultures obtained from nutrient agar slant were subjected to Gram-staining and standard biochemical tests. All the bacterial isolates were tested in vitro for their sensitivity to different antibiotics commonly used in veterinary practices. All Gram-negative isolates including positive control were subjected to polymerase chain reaction (PCR) for detection of bla_CTX-M, bla_TEM, bla_SHV, bla_VIM, tetA, tetB, tetC, and tetM genes considered for extended-spectrum β-lactamase (ESBL), metallo-β-lactamase, and tetracycline resistance.
Results: In total, 50 Gram-negative organisms (Escherichia coli, Proteus, Pseudomonas, Klebsiella, and Enterobacter) were isolated from milk samples of subclinical mastitis infected cattle. Among these Gram-negative isolates, 48% (24/50) were found either ESBL producing or tetracycline resistant. Out of total 50 Gram-negative isolates, bla_CTX-M was detected in 18 (36%) isolates, and 6 (12%) harbored bla_TEM genes in PCR. None of the isolates carried bla_SHV genes. Further, in this study, 5 (10%) isolates harbored tet(A) gene, and 8 (16%) isolates carried tet(B) gene. No tet(C) gene was detected from the isolates.
Conclusion: This study showed emerging trend of antibiotic-resistant Gram-negative bacteria associated with subclinical mastitis in cattle in West Bengal, India.

Keywords

Antibiotic Resistance, Cattle, Escherichia coli, India, Sub-Clinical Mastitis.

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