Performance evaluation of a rapid immunochromatographic test kit in detecting bovine mastitis-causing streptococci.

Mastitis causes significant economic losses to the dairy industry due to decreased milk production in infected cows. Identification of mastitis-causing pathogens, such as streptococci, is necessary for selecting an effective antibiotic for treating mastitis. Although bacterial cultivation is widely used for pathogen identification, it requires more than 24 hr to complete. Contrarily, Lateral flow assays are simple, rapid, and inexpensive testing procedures. In this study, the effectiveness of an immunochromatographic test kit for detecting streptococci in milk samples from cows with clinical mastitis was evaluated as an alternative to bacterial cultivation. The performance of the immunochromatographic test kit for detecting mastitis-causing pathogens was compared with that of bacterial cultivation and real-time quantitative polymerase chain reaction (qPCR). The sensitivity and specificity of the immunochromatographic test kit were 0.800 and 0.875, respectively, compared with bacterial cultivation. Additionally, the κ statistic values of the immunochromatographic test kit was 0.667, indicating substantial agreement with the results of bacterial cultivation. Statistically, sensitivity and specificity of the immunochromatographic kit and real-time qPCR did not differ significantly; thus, the immunochromatographic test kit detected mastitis-causing streptococci as effectively as real-time qPCR. Therefore, the immunochromatographic kit is a rapid, inexpensive, and simple method for detecting streptococci and contributes to the timely selection of appropriate antibiotics for treatment and promotes early recovery from mastitis.