Quarter milk samples were taken from 150 cows from three dairy farms in south-east Queensland at drying off, two, four and six weeks after drying off, at calving, and one, two and three weeks after calving. In each of the herds, the cows were randomly allocated to three groups of approximately equal size. One group had all the quarters of all the cows treated at drying off with a dry cow antibiotic infusion containing cloxacillin; the second group was given no treatment, and the third group had selected quarters treated on the basis of their high activity of N-acetyl-beta-D-glucosaminidase at drying off. Dry cow treatment resulted in a marked reduction in the number of infected quarters at two and four weeks after drying off, so that the comprehensively treated group had significantly less infected quarters at these times (P<0.02). Twelve dinical cases of mastitis were detected two weeks after drying off in the untreated groups, 10 in the untreated quarters of the selectively treated groups, and no cases in the comprehensively treated groups. These cases were due mainly to Streptococcus uberis and Streptococcus dysgalactiae. The number of infected untreated quarters increased markedly between drying off and two weeks later, but in all three groups there was a marked decrease in the number of infected quarters between six weeks after drying off and calving, suggesting that the mammary glands were more able to overcome infections at this time.
This study compared the enzymatic activity of clinical isolates of Cryptococcus neoformans, Cryptococcus gattii, environmental isolates of C. neoformans and non-neoformans Cryptococcus. Most of the cryptococcal isolates investigated in this study exhibited proteinase and phospholipase activities. Laccase activity was detected from all the C. neoformans and C. gattii isolates, but not from the non-neoformans Cryptococcus isolates. There was no significant difference in the proteinase, phospholipase and laccase activities of C. neoformans and C. gattii. However, significant difference in the enzymatic activities of beta-glucuronidase, alpha-glucosidase, beta-glucosidase and N-acetyl-beta-glucosaminidase between C. neoformans and C. gattii isolates was observed in this study. Environmental isolates of C. neoformans exhibited similar enzymatic profiles as the clinical isolates of C. neoformans, except for lower proteinase and laccase activities.