Fig. 4

Antibiotic testing to confirm erythromycin resistance in S. salivarius, MGAS10394, and S. agalactiae. Ampicillin (always the second panel) serves as negative control (all strains susceptible). a + b, Media only. c + d, MGAS10394 (mef(A) positive). e + f, MGAS6180 (mef(A) negative). g + h, S. agalactiae (ermB positive and mef(A) negative). i + j, S. salivarius (mef(A) positive)