[Clinical efficacy of arbekacin in patients with methicillin-resistant Staphylococcus aureus infections. Research Group of MRSA Forum].

We investigated the clinical efficacy of arbekacin (ABK) in patients with methicillin-resistant Staphylococcus aureus (MRSA) infections, and also studied coagulase types, beta-lactamase producing activity and drug sensitivity of MRSA isolated from various clinical specimens. A total of 23 patients with MRSA infections (13 cases of pneumonia, 1 case of sepsis, 1 case of pneumonia and sepsis and 8 cases of the others) who were hospitalized from April 1992 to September 1993 were enrolled in this study. They were 14 males and 9 females, and the mean age was 66.9 years (range, 18-91 years). All patients had underlying diseases (mainly malignant tumors and cerebrovascular diseases). ABK was given intravenously at doses ranging from 75 to 100 mg twice daily. The clinical efficacy rate was 90%; 8 cases showed excellent responses, 10 cases good, 1 case fair, 1 case poor and 3 cases were unevaluable. The eradication rate of MRSA was 81.8%; 16 cases were judged as eradicated, 3 cases decreased, 2 cases replaced, 1 case unchanged and in 1 case the bacteriological response was unknown. Side effects were not observed, but S-GPT was elevated in 1 case. Coagulase types of MRSA (123 strains) isolated at the institutes involved in the study were type II (56 strains), type IV (12 strains), type VII (13 strains) and other types (2 strains), but coagulase types of 40 strains could not be determined. Eighty-four strains (68.3%) produced beta-lactamases. MICs of ABK were 0.5 microgram/ml against 43 strains and 1 microgram/ml against 37 strains, and all of the MICs were under 4 micrograms/ml. In summary, ABK showed high antimicrobial activity against MRSA and clinical usefulness in the infections investigated.