MOLECULAR STUDY OF SOME VIRULENCE GENES OF ENVIRONMENTAL STREPTOCOCCI ISOLATED FROM BOVINE SUBCLINICAL MASTITIS IN KAFR ELSHEIKH GOVERNORATE | ||
| Journal of the Egyptian Veterinary Medical Association | ||
| Volume 76, Issue 3, August 2016, Pages 309-323 PDF (1010.24 K) | ||
| Document Type: Original Research Articles | ||
| Abstract | ||
| The aim of this study was to investigate the genotypic characteristics of environmental Streptococci (Streptococcus uberis and Streptococcus dysgalactiae) isolated from subclinical mastitis (SCM) cases, and to examine the possible association of some virulence genes between both species. Samples collected from 4 dairy farms, (653) quarter milk samples / 169 animals from 2 dairy cow's farms and (531) quarter milk samples / 135 animals from 2 dairy buffalo's farms were examined by California mastitis test (CMT). The results of CMT scores 1, 2 and 3 positives were 373 quarters (57.1%) divided into 75 (20.1%), 122 (32.7%) & 176 (47.2%) in cow's dairy farms. On the other hand, the results of CMT scores 1, 2 and 3 positives were 219 quarters (41.2%) divided into 94 (42.9%), 81 (37.0%) & 44 (20.1%) respectively in buffalo's dairy farms. A total of 79 (21.2 %) & 33 (15.1 %) environmental Streptococcus spp. were isolated from 373 & 219 positive (CMT) cow's quarters milk samples and buffalo's quarters milk samples, respectively. The isolates were identified biochemically as 34 (43.0%) S. uberis, 25 (31.6%) S. dysgalactiae and 20 (25.3%) other streptococci in cows' milk samples and 16 (48.5%) S. uberis, 10 (30.3%) S. dysgalactiae and 7 (21.2%) other streptococci in buffalos' milk samples. Meanwhile, PCR method revealed a total of 68 (18.2%) & 27 (12.3%) environmental Streptococci isolated from cow's quarters milk samples and buffalo quarters milk samples, respectively. 29 (42.6%) S. uberis, 17 (25.0%) S. dysgalactiae and 22 (32.4%) other streptococcus in cow's samples and 11 (40.7%) S. ubris, 8 (29.6%), S. dysgalactiae and 8 (29.6%) other streptococcus in buffalo samples. The S.uberis and dysgalactiae strains were characterized genotypically by the presence of virulence genes: plasminogen (mig) and streptokinase (sk) in S. uberis strains and haemolysin (hl) and surface protein (sp) in S. dysgalactiae strains. S. uberis strains expressed these genes were (3.4 % and 6.9%) in cows' isolates and it was (12.5% and 0%) in buffalos' isolates, respectively. S. dysgalactiae strains which have these genes were (11.8 % and 0%) in cows' isolates meanwhile it was (18.2% and 0%) in buffalos' isolates, respectively.Virulence profiles were identified on the basis of the combination of virulence factors. Bovine S. uberis and S. dysgalactiae isolates causing SCM included in the present study showed pathogenicity in regard to their genotypic characteristics. | ||
| Keywords | ||
| Bovine subclinical mastitis; Environmental streptococci; PCR and virulence genes | ||
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