Species Identification of β-hemolytic Streptococci from Diseased Companion Animals and Their Antimicrobial Resistance Data in Japan (2017).

This study determined species identification and antimicrobial resistance (AMR) properties in β-hemolytic streptococci isolated from companion animals in Japan. Strains were isolated from clinical specimens of 131 companion animals with symptoms/signs in April-May, 2017. We identified strains by 16S rRNA sequencing and antimicrobial susceptibility was determined using the broth microdilution method. AMR genes (erm(A)-erm(B)-mef(A) and tet(M)-tet(O)-tet(K)-tet(L)-tet(S)) in all isolates were amplified by PCR. The 16S rRNA sequencing identified β-hemolytic streptococcal species as Streptococcus canis (n = 117, 89.3%), S. agalactiae (n = 7), S. dysgalactiae subsp. equisimilis (n = 5), S. dysgalactiae subsp. dysgalactiae (n = 1), and S. equi subsp. zooepidemicus (n = 1). Overall AMR rates were 39.7% for minocycline, 19.8% for erythromycin, and 17.6% for clindamycin, with minimum inhibitory concentration (MIC90 ) of >4, >2, and >1 μg/mL, respectively. AMR genotyping showed single or combined types: erm(B)-mef(A) and tet(M)-tet(O)-tet(L)-tet(S). There was a significant relationship between tetracycline-resistance genotypes and open pus/skin-derived specimens. These observations suggest unique features, such as the dominant isolation of S. canis and resistance to tetracycline, macrolide, and lincosamide antibiotics, of β-hemolytic streptococcal isolates from companion animals in Japan in terms of species identification and AMR properties.