engleski

ASSESSMENT OF ZAGREB MASTITIS TEST AND SOMATIC CELLS IN DIAGNOSIS SUBCLINICAL MASTITIS CAUSED BY BACTERIA STAPHYLOCOCCUS AUREUS

The aim of this study was to estimate the prevalence of subclinical mastitis caused by Staphylococcus aureus in Croatia. Reliability of Zagreb Mastitis Test as a screening test in the diagnosis of subclinical mastitis caused by Staphylococcus aureus was estimated based on the prevalence and bacteriological findings from dairy cow quarters. The study was carried out within the framework of subclinical mastitis monitoring in Varaždin region. Comparison and assessment of somatic cells and mastitis test compatibility was performed using the Kappa test. Staphylococcus aureus is a cause of subclinical mastitis in 52.66% cows and 32.97% of quarters. According to the number of infected quarters, Staphylococcus aureus was isolated in 36.90% of cows in one quarter, 29, 17% in two quarters, 16, 67% in three quarters and in 17, 26% of cows in four quarters. Mean of somatic cell count in bacteriological negative samples was 115.637 cells /ml, while infection was confirmed in 25% of milk samples. In the positive samples the mean of somatic cells was 1, 460, 965 cells / ml. Zagreb mastitis screening test showed high sensitivity (95%, 95% confidence interval), low specificity (69%, 95% confidence interval), and high negative predictive value (98%, 95% confidence interval). To determine the number of somatic cells as a diagnostic procedure was compared limiting value of 400, 000 cells / ml. The sensitivity of this test was 86% (95% confidence interval), and specificity was 83% (95% confidence interval). The values of true prevalence (31%, 95% confidence interval) and prevalence of acquired test (39%, 95% confidence interval) were equal.

subclinical mastitis; Staphylococcus aureus; prevalence; somatic cell count; Zagreb mastitis test

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