In this study, the distribution of streptococci has been studied by collected
twenty raw milk samples from dairy cows in Chiang Mai and Lamphun provinces.
From these samples, total of 164 isolates were isolated and can be divided into two
genus which consisted of 130 isolates (79.27%) of Enterococcus and 30 isolates
(20.73%) of Streptococcus. Based of 16S rRNA gene sequencing showed that
Enterococcus isolates belong to 10 different species (E. faecalis 59 isolates, E.
gallinarum 20 isolates, E. faecium 18 isolates, E. avium 10 isolates, E. durans 9
isolates, E. casseliflavus 6 isolates, E. gilvus 3 isolates, E. canintestini 3 isolates and E.
dispar, E. thailandicus for 1 isolate each, respectively) and Streptococcus for 30
isolates belong to 6 different species (S. lutetiensis 26 isolates, S. quinus, S.
agalactiae, S. parauberis 2 isolates each and S. uberis and S. dysgalactiae for 1
isolate each, respectively). Evaluation of antibiotic susceptibility pattern was assessed
by disc agar diffusion method with eight antibiotics. Overall, the most frequently
observed resistance was to tetracycline in 111 isolates (67.7%) followed by
erythromycin in 97 isolates (59.1%) and the antibiotic resistance genes were identified
as tetM and ermB, respectively. The D-test was used for the detection of inducible
clindamycin resistance and found that all of the isolates showed negative result.