VIRULENCE GENE PROFILING OF Escherichia coli FROM BOVINE MASTITIS AND THERAPEUTIC MANAGEMENT OF COLIFORM MASTITIS
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Date
2019-09-30
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Kerala Veterinary and Animal Sciences Mannuthy, Thrissur
Abstract
Coliforms are the major etiological agents of bovine mastitis which is an
economically devastating disease causing substantial loss to the dairy farmers through
reduction in the milk production. The present study was conducted to detect the
virulence genes of E. coli by Polymerase Chain Reaction (PCR), to study the
therapeutic efficacy of various antibiotics in E. coli mastitis and to identify the risk
factors associated with coliform mastitis. Epidemiological investigations revealed
that affected cows were in younger age and early stage of lactation having average
milk yield. Absence of hygienic practices for clean milk production such as teat
dipping resulted in poor udder hygiene which led to the occurrence of coliform
mastitis. The affected animals had elevated temperature with varying degree of udder
oedema and pale yellow coloured milk. In the present study, out of 168 animals
affected with clinical mastitis, 123 bacterial isolates could be isolated of which 26
constituted coliforms such as Escherichia coli (14), Klebsiella spp. (10),
Enterobacter spp. (1) and Citrobacter spp. (1) with the prevalence of 21.13 per cent
and the remaining were Gram positive isolates. In vitro antibacterial sensitivity test of
coliform isolates revealed that ceftizoxime was the most sensitive drug. Treatment of
affected cases was done with sensitive antibiotics according to the antibiogram, fluid
therapy, flunixin meglumine and trisodium citrate were administered based on the
resolution of clinical signs. After treatment, clinical recovery with increase in milk
yield was noticed in all the cases but for the resolution of udder oedema.
Haematological analysis prior and after treatment revealed significant increase in
total blood count and reduction in leukocyte counts. Polymerase chain reaction was
performed to identify the virulence genes of E.coli viz., traT, stx 1, stx 2, eaeA and
aerobactin (iucD) which revealed that among 14 isolates, two were positive for traT
gene, two were positive for aerobactin gene and one was positive for stx 2 gene.
Thus, the present study revealed the presence of virulence genes among E.coli
isolates causing bovine mastitis.
Description
Submitted in partial fulfillment of the requirement for the degree of
Master of Veterinary Science in Veterinary Epidemiology and Preventive Medicine