Table 3.
Proportion of qPCR positive herds to bacteria in bulk tank milk samples
| Parameter | Proportion [CI (95 %)] of herds | ||||
|---|---|---|---|---|---|
| S. aureus | CNSa | E. coli | Coliform bacteriab | ||
| Negative | 41.0 % (31.9–50.8 %) | – | 25.0 % (17.5–34.3 %) | 65.0 % (55.3–73.6 %) | |
| Positive | >35 ≤ 37 Ct (+) | 12.0 % (7.0–19.8 %) | – | 21.0 % (14.2–30.0 %) | 6.0 % (2.8–12.5 %) |
| >30 ≤ 35 Ct (++) | 42.0 % (32.8–51.8 %) | 89.0 % (81.4–93.7 %) | 40.0 % (30.1–49.8 %) | 15.0 % (9.3–23.3 %) | |
| ≤30 Ct (+++) | 5.0 % (2.2–11.2 %) | 11.0 % (6.3–18.6 %) | 14.0 % (8.5–22.1 %) | 14.0 % (8.5–22.1 %) | |
CI (95 %) 95 % confidence interval, Ct threshold cycle, (+) low amount of DNA detected, (++) moderate amount of DNA detected, (+++) high amount of DNA detected
aCNS (coagulase-negative staphylococci): S. chromogenes, S. epidermidis, S. hemolyticus, S. saprohyticus, S. simulans, S. warneri and S. xylosus
bColiform bacteria: Klebsiella oxytoca, Klebsiella pneumoniae and Serratia marcescens