Abstract
Aim:Subclinical mastitis in bovines is mainly responsible for the huge economic loss of the dairy farmers, of which Pseudomonas aeruginosa 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 P. aeruginosa 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 P. aeruginosa. Selective isolation and confirmation of the isolates were done using selective media, viz., 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 toxA (enterotoxin A, 352 bp) and exoS (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 Pseudomonas sp. isolates out of which only 19 (5.4%) isolates were confirmed to be P. aeruginosa 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 toxA, 6 isolates for exoS, and 2 for both these pathogenic genes.Conclusion:Approximately, 5.4% cases of bovine subclinical mastitis infections in South Bengal were associated with P. aeruginosa which possess pathogenic genes such as toxA (63.2%) and exoS (36.8%).
Highlights
India is one among the largest milk producing countries in the world
Approximately, 5.4% cases of bovine subclinical mastitis infections in South Bengal were associated with P. aeruginosa which possess pathogenic genes such as toxA (63.2%) and exoenzyme S (exoS) (36.8%)
All milk samples (422 in no.) were screened by on-spot positive bromothymol blue (BTB) test according to the standard method [7] with BTB paper, and 371 samples were collected from different organized government farms (8 farms were covered) and small rural farmers (46 farmers were considered for collection) of different districts of South Bengal for this study during October 2013-April 2014
Summary
India is one among the largest milk producing countries in the world . Dairy industry plays a significant role in livestock economy by generating self-employment. Dairy industry by cooperative society brought socioeconomic transformation in innumerable small, marginal dairy farmers and downtrodden people of mainly western part of India along with other parts the country. These livestock farmers in India mainly contribute the major total national milk production which rose up to approximately 132.4 million tons in 2012-13 from 17 million tons in 1950-51 [1]. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated
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