Comparative Evaluation of Leukotoxic Activities of IndigenousStaphylococcus aureus Isolates from Subclinical and Clinical Mastitic MilkSamples of Buffalo and Cattle

摘要

The present study was conducted for the comparative evaluation of leukotoxic activities of indigenousStaphylococcus aureus isolates issued from Institute of Microbiology University of Agriculture Faisalabad Pakistan. Atotal of 200 milk samples 100 each of buffalos (Nili Ravi) and cattle (Sahiwal) with subclinical and clinical mastitis werecollected. Staphylococcus aureus isolates recovered were used for extraction of leukotoxins. Leukotoxic activities weredetermined against bovine Polymorphonuclear cells (PMNs) through Toxin Limit Concentration (TLC) assay. Overallpositive percentage of mastitis was more important in cattle (32%) than for buffalos (22%). Overall and quarter basedprevalence of subclinical mastitis were higher than clinical cases in both buffalos and cattle. In TLC assay, PMNsremained normal in control wells without leukotoxins after incubation at 37°C for 30 minutes, whereas, under theinfluence of leukotoxins, PMNs flattened and spread on the gelatin coated plastic surface. TLC titers in subclinicalmastitis ranged from 4 to 16 with Geometric Mean Titer (GMT) at 6 in buffalos and 8 in cattle whereas, in clinical cases itranged from 32 to 128 with GMT of 64 in buffalo and cattle.