[Effect of arbekacin on the production of toxic shock syndrome toxin 1 by methicillin-resistant Staphylococcus aureus].

The effect of arbekacin (ABK), vancokmycin (VCM) and teicoplanin (TEIC) on the production of toxic shock syndrome toxin-1 (TSST-1) by methicillin-resistant Staphylococcus aureus was examined. In logarithmic-phase cultures, ABK, VCM and TEIC inhibited TSST-1 production by 85, 10 and 25%, respectively, at the concentration of one-fourth the each MIC. In stationary-phase cultures, ABK inhibited TSST-1 production by 50% or 90% compared with the control at the concentration of 4.0 micrograms/ml or 5.0 micrograms/ml respectively. VCM and TEIC did not inhibit TSST-1 production at the concentration of 8.0 micrograms/ml or lower. In human blood cultures, TSST-1 production was inhibited by ABK by 50% at 0.04 microgram/ml (1/256 of Cmax), but not inhibited by VCM and TEIC at the concentration of 1/16 of Cmax or lower. It has been already known that ABK has higher bactericidal activity than VCM and TEIC. ABK combined the inhibition of TSST-1 production with high bactericidal activity in both bacterial growth phases, and therefore ABK should be considered for the treatment of TSST-1-mediated MRSA-infection.