[Antibacterial activity of minocycline alone and associated with other antibiotics (author's transl)].

The authors study in vitro effects of minocycline and compare its activity with tetracycline. 909 strains of cocci and bacilli selected among strains isolated from Clermont-Ferrand Hospital Center during the third trimester 1974 were used. Study involves 3 parts : comparison between bacteriostatic activity of both antibiotics ; evaluation of R-factor resistance ; evaluation of bactericidal activity of antibiotic associations including minocycline. M.I.C. study included all strains. A better bacteriostatic activity was noted with minocycline against multi-resistant strains of staphylococcus, streptococcus, E. coli, Serratia and Moraxella. R-factor resistance has been studied upon 27 strains of Gram-negative bacilli selected for their high M.I.C. to tetracycline (M.I.C. greater than or equal to 64 mcg/ml) and to minocycline (M.I.C. greater than or equal to 32 mcg/ml). Both types of transferable tetracycline resistance characters Ta and Tb have been found. More than 250 bactericidal associations were studied upon 38 strains.