Coagulase-Negative Staphylococcus (CNS)

CNS species are the organisms most frequently isolated from bovine milk samples.  CNS species usually are designated as "skin flora opportunists", rather than as environmental or contagious bacteria since CNS are a part of the normal teat skin flora. CNS can colonize the teat canal.  Some species also are found free-living in the environments.  A culture may be positive for CNS, but this does not mean the quarter is infected.  Because CNS are commonly found on teat skin and in the streak canal, they are a common cause of contaminated milk cultures.