Bacteriological Assessment Of Clindamycin, A New Lincomycin Derivative

The activity of clindamycin, a new lincomycin derivative, was measured against over 500 strains of bacteria. The assessment was quantitative in terms of drug concentration and bacterial population size, and comparative in that the major groups of bacteria were tested simultaneously for their sensitivity to lincomycin, erythromycin, benzylpenicillin and oxacillin. Clindamycin at a low concentration was highly active against most Gram-positive cocci excepting Strep. faecalis, and showed appreciable activity against H. influenzae, but was inactive against enterobacteria. Two strains of coagulase-positive staphylococci out of 300 tested were highly resistant to clindamycin; a further seven showed a low degree of resistance. Resistance to lincomycin and erythromycin was considerably commoner. Variation in inoculum size produced a small change in MIC comparable with that found for lincomycin and erythromycin, but much less than that found for benzylpenicillin. On a weight-for-weight basis clindamycin was from 4 to 16 times more active than lincomycin against staphylococci.