[In vitro antibacterial activity of a new macrolide: miokamycin. Comparison with erythromycin and josamycin]

Minimal inhibitory concentrations (MIC) of miokamycin (M) were evaluated by agar dilution, comparatively with erythromycin (E) and josamycin (J) for 81 bacterial strains chosen as a function of susceptibility and resistance to Macrolides-Lincosamides-Streptogramins group (MLS). On Gram positive cocci, mode MIC of E, J, and M for strains sensitive to MLS were respectively (micrograms/ml): Staphylococci: 0.25; 1; 2-Streptococci and Pneumococci: 0.016; 0.03-0.12; 0.06-0.25-Enterococci: 0.5; 0.5-1; 1-2. Activity of the three antibiotics was similar against Staphylococci resistant to lincomycin and streptogramin A, those resistant to streptogramins A and B, on Staphylococci and Streptococci only resistant to lincosamides by inactivation. M, as J, was active on coagulase negative (Staphylococci resistant to E by inactivation and on MLBB inducible Staphylococci; on these strains, M is a resistance non-inducible macrolide. Activity of E, J and M was reduced on MLSB inducible Streptococci. The three antibiotics were inactive on Staphylococci Streptococci and Enterococci MLSB resistant constitutive. On Haemophilus, E (2-8 micrograms/ml) was more active than J (2-16) and M (8-32). Thus, M, as J, was shown to be among macrolide antibiotics of resistance non-inducing type on MLSB inducible resistant Staphylococci; its activity was slightly inferior to that of J, but very similar to that of spiramycin, other macrolide of this group.