[Synergistic action of cefodizime and other antimicrobial agents on clinically isolated microorganisms. I. Synergistic action with minocycline].

Since cefodizime (CDZM) shows a broad antimicrobial spectrum and relatively long half life in blood, we examined its synergistic action with minocycline (MINO) in vitro against Staphylococcus aureus. 1. CDZM in the presence of MINO, most of cases 1 MIC showed FIC index greater than 0.5-less than or equal to 2 against methicillin-susceptible S. aureus (MSSA), thus the results suggested a synergistic action against S. aureus. 2. CDZM in combination with MINO at 1 MIC or sub MIC where therapeutically a favorable efficacy is expected on MINO-susceptible strains exhibited FIC index less than or equal to 0.5-less than or equal to 1, Methicillin-resistant S. aureus (MRSA), thus suggesting a synergistic action against MINO-susceptible MRSA strains. Synergism was hardly recognized against MINO-resistant MRSA strains, however. 3. Synergism by both drugs was produced in MINO-susceptible strains of S. aureus including MRSA where MIC by CDZM was high or moderate, but no synergism was demonstrated against MINO-resistant strains. That is, synergistic action by both drugs was thought to depend on antimicrobial activity of MINO.