MRSA tricuspid valve infective endocarditis with multiple embolic lung abscesses treated by combination therapy of vancomycin, rifampicin, and sulfamethoxazole/trimethoprim

A 26-year-old pregnant woman who was an intravenous drug user (IDU) was admitted to our hospital for the treatment of tricuspid valve infective endocarditis (IE) and lung abscesses due to methicillin-resistant Staphylococcus aureus (MRSA). We started to treat her with vancomycin (VCM) alone and then in combination with rifampicin (RFP), but her condition did not improve. Then we added sulfamethoxazole/trimethoprim (SMZ/TMP) to VCM and RFP. After that, she improved rapidly. In Japan, there are very few reports about tricuspid valve IE caused by MRSA in IDUs. This case suggests that the combination of VCM, RFP, and SMZ/TMP may be effective for the treatment of severe MRSA infections.