Multiplex PCR: A Tool for Identification of Streptococci of Importance in Udder Health and Milk Quality in Chilean Dairies

摘要

Streptococci and Streptococci-like organisms (SSLO) are a heterogeneous group of gram-positive cocci bacteria involving genus such as Enterococcus, Lactococcus, Aerococcus, and Streptococcus, among others. Furthermore, SSLO bacteria are commonly foundin the cow's environment and in the mammary gland, udder skin, and teats. Within the SSLO group, bacteria of the genus Streptococcus are particularly relevant as cause of disease in both animals and humans (Persson-Waller, 2016). Three species of this genus are frequently involved as cause of intramammary infections in dairy herds; i.e. S. agalactiae, S. uberis, and S. dysgalactiae. Whether from environmental contamination of milk or from the shedding of infected cows, these three pathogens can be identified by culture of bulk tank milk (BTM) samples. Conventional cultures results, however, may show discrepancies in the species identification of Streptococci among laboratories. The use of molecular techniques such as PCR for species identification ofstreptococci results in more specific and consistent results. The objective of this study was to identify S. uberis, S. dysgalactiae, and S. agalactiae among SSLO microorganisms isolated from bulk tank milk samples collected from Chilean dairy operations, using standard culture methods combined with multiplex PCR.