A case of refractory disseminated subcutaneous abscess with intrahousehold transmission by a USA300-LV-like strain of PVL-positive community-acquired MRSA clone

A 44-year-old man with hypertension and dyslipidemia presented with pain in the buttocks. The patient was diagnosed with perianal ischiorectal fossa abscesses and cellulitis. He was subsequently diagnosed with a perineal subcutaneous abscess after a week, a right lower leg impetigo after a month, right periorchitis, a scrotal abscess, and Fournier's gangrene after two months. The patient was treated with various antimicrobials and underwent incisional drainage. Methicillin-resistant Staphylococcus aureus (MRSA) was detected in all draining specimens. Her daughter and son, who lived with the patient, presented with subcutaneous abscesses caused by MRSA. Suspecting repeated infections and household infections by virulent types of MRSA, such as PVL-positive strains, we performed genetic analyses of his and his son's strains. The results showed that the genotype and toxin gene profiles [ST8/t008/SCCmec type IVc/Panton-Valentine leucocidin (PVL) (+)/arginine catabolic mobile element (ACME) (−)] of both strains matched. single nucleotide polymorphism (SNP) analysis confirmed genetic homology between the two, concluding that home transmission by the same clone had occurred. In addition, the strain in this case differed from USA300 [ST8/t008/SCCmec type IVa/PVL (+) ACME (+)], which is a PVL-positive MRSA worldwide, including Japan, and its genetic profile matches that of USA300-LV, which is detected mainly in South America. Furthermore, SNP analysis showed that this strain is similar to USA300-LV/J (derived from USA300-LV) detected on Ishigaki Island, Okinawa Prefecture, Japan. This is the first report of refractory infections and household transmission of USA300-LV/J. Therefore, it is necessary to closely monitor both the USA300 and the USA300-LV.