STUDIES ON BOVINE SUBCLINICAL MASTITIS WITH SPECIAL EMPHASIS TO BACTERIAL PATHOGENS AND ANTIBIOGRAM AT DINAJPIUR DISTRICT

Abstract

The study was undertaken to determine the distribution of bacteria in bovine subclinical mastitis (SCM), sensitivity pattern of isolated organisms to commonly used antibiotics. The study was performed by using different indirect tests like California Mastitis Test (CMT), Surf Field Mastitis Test (SFMT) and White Side Test (WST), morphological, cultural, biochemical tests and antibiogram study during the period of March to August, 2011 at dinajpur district of Bangladesh. A total of 106 milk samples were tested randomly from healthy milch cows by using and among which 76 (71.69%) were found to be positive SCM. The positive milk samples were collected and brought to the Department of Medicine, Surgery and Obstetrics, Faculty of Veterinary and Animal Science, Hajee Mohammad Danesh Science and Technology University, Dinajpur. The major pathogens isolated from positive milk samples were Stapylococcus spp. (23.69%), Escherichia coli (31.58%), Bacillus spp. (13.16%), Staphalococcus spp. + Escherichia coli (10.53%), Staphalococcus spp.+ Bacillus spp. (05.26%), Bacillus spp.+ Escherichia coli (07.89%). During cultural examination, all isolates produce turbidity on nutrient broth. Staphylococcus spp. showed golden yellowish colonies on nutrient agar; hemolysis on blood agar media; In Gram's staining technique Staphylococcus spp. revealed Gram positive, violet color, cocci arranged in grape-like clusters. All isolates produce acid but no gas by fermenting various sugars and Gram positive reaction to Catalase and Methyl red test but negative reaction to Indole and Voges Proskeur test. Bacillus spp. revealed grayish colored colonies on nutrient agar; hemolysis on blood agar; In Gram's staining technique Bacillus spp. revealed Gram positive, violet color, short cocco-bacilli or rod and arranged in chain. All isolates produce acid but no gas by fermenting various sugars and negative reaction to Indol, Methyl red and Voges Proskeur test. Escherichia coli showed circular smooth colored colony on nutrient agar; hemolysis on blood agar; bright pink or red colony on MacConkey agar and characteristic metallic sheen on EMB agar. All isolates produce acid and gas by fermenting various sugars and Gram positive reaction to Indol, Motility Indole Urease, Methyl red and Catalase test but negative reaction to Voges Proskeur test. Over all antibiotic sensitivity revealed that gentamicin, ciprofloxacin and oxytetracycline are most efficacious followed by chloramphenicol and amoxicillin. It is concluded that Escherichia coli, Staphalococcus spp. and Bacillas spp is major pathogens to produce subclinical mastitis in dairy cows at dinajpur district of Bangladesh as well as it may be recommended that ciprofloxacin, gentamycin and oxytetracycline in optimum doses would resolve most cases of subclinical mastitis in dairy cows.