Susceptibility of various serogroups of streptococci to clindamycin and lincomycin.

The minimal inhibitory concentration of lincomycin and clindamycin for a large number of strains from multiple serogroups of streptococci was determined. The median minimal inhibitory concentration for streptococci from groups A, B, C, F, G, H, L, and M and nongroupable organisms ranged from 0.02 to 0.39 mug of lincomycin per ml and from </=0.01 to 0.09 mug of clindamycin per ml. Among the group D strains, Streptococcus faecium and Streptococcus faecalis were resistant to lincomycin and clindamycin, whereas Streptococcus bovis and four American strains of Streptococcus durans resembled nongroup D isolates in their susceptibility to these agents. Occasional strains of nongroup D streptococci were highly resistant to lincomycin and clindamycin.