Detection and characterization of pathogenic from bovine subclinical mastitis in West Bengal, India.

AIM

Subclinical mastitis in bovines is mainly responsible for the huge economic loss of the dairy farmers, of which is one of the causative agents. The study was aimed at a screening of suspected milk samples from different cattle farms of West Bengal for detection and confirmation of strains followed by their characterization.

MATERIALS AND METHODS

Around 422 milk samples were screened from different dairy farms primarily by on-spot bromothymol blue (BTB) test and then in the lab by somatic cell counts (SCC) to finally consider 352 samples for detection of . Selective isolation and confirmation of the isolates were done using selective media, ., cetrimide and Pseudomonas agar followed by confirmation by fluorescent technique. Molecular characterization of the strains was done by polymerase chain reaction for the presence of A (enterotoxin A, 352 bp) and S (exoenzyme S, 504 bp) genes.

RESULTS

Approximately, 371 (87.9%) samples were positive in on-spot BTB test among which 352 (94.8%) samples revealed high SCC values (more than 3 lakh cells/ml) showing infection when screened. Among these, 23 (6.5%) samples yielded typical sp. isolates out of which only 19 (5.4%) isolates were confirmed to be which showed characteristic blue-green fluorescence due to the presence of pigment pyoverdin under ultraviolet light. Out of these 19 isolates, 11 isolates were positive for A, 6 isolates for S, and 2 for both these pathogenic genes.

CONCLUSION

Approximately, 5.4% cases of bovine subclinical mastitis infections in South Bengal were associated with which possess pathogenic genes such as A (63.2%) and S (36.8%).