Effective single and combined chemotherapeutic regimens as regards to antibiotic resistance patterns of methicillin-resistant Staphylococcus aureus (MRSA) in Japan

The incidence of gentamicin-resistant MRSA (GMr-MRSA) has been gradually increasing since early 1980's in Japan. The GMr-MRSA mainly belongs to Group-I phage type and to Group-IV coagulase type. It is rather difficult to induce methicillin-resistance in the GMr-MRSA in the presence of beta-lactam antibiotics. Since late 1980's tobramycin-resistant MRSA (TOBr-MRSA) has been increasing rapidly in place of GMr-MRSA. The TOBr-MRSA mostly belongs to Group III phage type and Group II coagulase type. It rapidly acquires resistance to methicillin and becomes highly resistant to many other related antibiotics as evidenced by statistics in 1980's in Japan. A combination chemotherapy with imipenem/cilastatin and 1st or 2nd generation cephem, or minocycline plus cephem is considered to be effective for MRSA infections. However, a combination chemotherapy with arbekacin (ABK), or vancomycin (VCM) plus beta-lactam antibiotic is recommended especially for the treatment of respiratory tract infections.