Successful Conservative Treatment of Mycotic Pulmonary Artery Aneurysms Caused by MRSA Bacteremia.

Mycotic pulmonary artery aneurysms (MPAAs) are rare and life-threatening with currently no recommended treatment strategies. In this report, we describe a successfully treated case of ventricular septal defect in an 11-month-old girl who developed bacteremia, infective endocarditis, and MPAA caused by methicillin-resistant Staphylococcus aureus (MRSA). We first started vancomycin, gentamycin, and panipenem-betamipron for infective endocarditis but switched to teicoplanin and arbekacin on day 3 after initiating treatment because bacteremia persisted, and vancomycin minimum inhibitory concentration was relatively high at 2 mg/L. Although we added clindamycin on day 5 and fosfomycin on day 7, MRSA bacteremia persisted, and we finally added daptomycin at 10 mg/kg per day on day 8, whereupon the bacteremia subsided within a day. Although the bacteremia subsided, the patient developed septic pulmonary embolisms and septic arthritis on her left knee. We continued daptomycin but switched the concomitant drug to linezolid, trimethoprim-sulfamethoxazole, and rifampicin on day 11. After several repeats of puncture and lavage of her knee joint, she became afebrile on day 16. Computed tomography scans taken on day 32 revealed right pulmonary artery MPAAs. She was treated with long-term multidrug therapy, and MPAAs were absent on subsequent computed tomography scans on day 184. Multidrug therapy mainly based on daptomycin could be a possible salvage therapy for refractory MRSA bacteremia with high vancomycin minimum inhibitory concentration. Conservative treatment should be selectively considered as a treatment option for clinically stable MPAA instead of surgical and endovascular treatment.