BACTERIOLOGICAL STUDIES AND MOLECULAR DETECTION OF MAJOR PATHOGENS FROM SUBCLINICAL AND CLINICAL BOVINE MASTITIS 2511
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Date
2018-03
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JAU,JUNAGADH
Abstract
The present study was carried out with an objective to screen bovine milk samples for status of subclinical mastitis (SCM) by somatic cell count (SCC), to isolate and identify major mastitis pathogens viz: S. aureus, E. coli and predominant Streptococcal species, to evaluate the antimicrobial resistance patterns and to optimize multiplex PCR for rapid and simultaneous detection of these pathogens in the milk samples. Total 390 bovine milk samples (180 from clinical cases of mastitis and 210 from apparently healthy animals) were collected from in and around Junagadh district. According to the measurement of SCC in 180 milk samples, 34.29% prevalence of SCM was observed. A primary culture isolation of 252 milk samples (72 SCM and 180 clinical mastitis milk samples) revealed 60.26% prevalence of bovine mastitis.
The prevalence of mastitis caused by S. agalactiae, S. dysgalactiae and S. uberis was found 13.59%, 2.31% and 0.77%, respectively. The overall prevalence of mastitis caused by Staphylococcus spp. was 38.72% which is highest among all other isolated bacteria, while of S. aureus and CoNS were 15.64% and 23.08% respectively. The prevalence of mastitis caused by E. coli and other bacteria were noted 10.77% and 3.59%, respectively. The prevalence of mastitis caused by mixed bacterial infection was 9.49 %.
In the present study high resistance of Staphylococcus spp. Streptococcus spp. and E. coli observed against ceftriaxone and amoxicillin-sulbactam which displays antibiotic usage pattern in this region. Likewise bacterial isolates studied were highly sensitive to levofloxacin which suggest judicious use of this antibiotic in treatment of bovine mastitis.
The molecular detection of major mastitis causing organisms was also carried out by standardizing PCR. The tuf gene and 16S rRNA was targeted to detect
Abstract…
Streptococci and Staphylococci at genus level. Further, sip, 16S rRNA and pauA gene were targeted to detect S. agalactiae, S. dysgalactiae and S. uberis respectively. The screening of 65 Streptococcal isolates revealed 53, 9 and 3 isolates as S. agalactiae, S. dysgalactiae and S. uberis respectively. S. aureus was detected by targeting nuc gene and out of 151 isolates of Staphylococci screened, 61 isolates revealed the presence of nuc gene indicating S. aureus. E. coli were detected by targeting alr gene in 42 isolates, which signifies the superiority of molecular diagnostic tools.
The two tube mPCR for simultaneous detection of five major mastitis pathogens from milk samples was optimized in this study to reduce the time and labour involved in individual detection. The efficiency of this assay was compared with conventional microbiological methods. The optimized mPCR showed promising results with 100% diagnostic sensitivity and 83.87% diagnostic specificity.
The mPCR assay optimized in the present study is very rapid and better option to choose as diagnostic tool for detection of major mastitis pathogens directly from milk samples as compare to conventional methods and can be useful for formulating the strategy for prevention and control of bovine mastitis.
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Veterinary Microbiology