A possible immunomodulating activity of arbekacin (ABK), a newly synthesized antibiotic against methicillin-resistant Staphylococcus aureus (MRSA).

Arbekacin (ABK) is a newly developed aminoglycoside in Japan which can cause bactericidal effects on methicillin-resistant Staphylococcus aureus (MRSA). However, details of the mechanism on effective antibacterial activity of this drug in host patients has not been completely elucidated. We studied the modulating effects on some functional activities of immunocompetent cells in in vitro and in vivo mouse experimental systems. (i) ABK stimulated the phagocytic activity against S. aureus into mouse phagocytic cells in a dose-dependent manner. (ii) ABK enhanced oxygen radical generation with chemiluminescence in mouse phagocytic cells. (iii) ABK exhibited a stimulatory effect on interleukin 1 alpha release from mouse adherent cells. (iv) Injection with ABK into mice showed an adjuvant activity which stimulated antibody production against sheep red blood cells and S. aureus. These experimental results indicate the possibility that ABK has not only a direct antibacterial activity but also a modulating activity for immunocompetent cells to enhance host defense against S. aureus infection.