Studies on multiple-resistant staphylococcus aureus. (II): Fundamental and Clinical Investigation on Synergism of Minocycline and Amikacin on Multiple-Resistant Staphylococcal Infection

Fundamental and clinical investigation of the synergism of minocycline and amikacin on multipleresistant staphylococcal infection was carried out. In vitro antimicrobial activity of a total of 18 chemotherapeutic agents were determined against the strain of multiple-resistant Staphylococcus aureus isolated from the aspirated sputum of the patient with lower respiratory infection. As a result, it was revealed that antimicrobial activity of minocycline, amikacin and vancomycin were more active against the strain than any other chemotherapeutic agents. Then, in vitro combined effect of minocycline and amikacin against the strain was examined. The combination was shown to be synergistic with 0.375 of the FIC index. To the patient, 100 mg of minocycline was administered intravenously once a day and 100 mg of amikacin intramuscularly twice a day. Clinical response to the above combination therapy was good in the case, and the strain isolated was eradicated immediately after the beginning of the therapy. It is concluded from the above results that the combination of minocycline and amikacin is of value in the treatment of multiple-resistant staphylococcal infection.