1994 Volume 47 Issue 6 Pages 693-700
Efficacies of combined uses of arbekacin(ABK)with other antibiotics against between 57 and 76 clinically isolated methicillin-resistant Staphylococcus aureus(MRSA) were examined. Other antibiotics tested were fosfomycin(FOM),5 cephems(CEPs), 2 penicillins(PCs) and imipenem. Percentages of strains that grew at various combination of serially diluted drugs in a microdilution method were scored, and for each pair of drugs ≥MIC50 or ≥MIC90 was determined. FIC-indices were calculated at ≥MIC50.Bacterial growth was inhibited by low concentrations of ABK dose-dependently,while most of the strains tested were resistant to 9 other drugs. FIC-indices with ABK were lowest when used together with ampicillin (ABPC)(0.516) followed by combinations with cefotiam(CTM) and cefuzonam(CZON)(each, 0.53), and FOM(0.625). When combined with 0.5μg/ml of ABK,0.5μg/ml of ABPC inhibited more than 50% of MRSA strains. CTM or CZON in combination with the same amount of ABK to 2μg/ml inhibited more than 50% of MRSA. Thus ABPC was found to be the most efficient in combined use with ABK to inhibit clinical MRSA strains.
