Molecular epidemiologic study of community-associated methicillin-resistant Staphylococcus aureus with Panton-Valentine leukocidin gene among family members in Japan

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is one of the worldwide concerns of antimicrobial chemotherapy. An accumulation of ten patients in five families (A-E) suffering from skin and soft tissue infection (SSTI) of CA-MRSA was experienced in 2012, in Fuchu-shi, Tokyo, Japan. Molecular epidemiological investigation was performed for the 10 MRSA strains obtained from 8 children and 2 of their parents to assess endemic patterns of CA-MRSA in the community. Results of molecular typing, presence of toxin genes and antimicrobial susceptibilities were analyzed combined with the patients' clinical information. Each family had its own unique MRSA strain: A, ST30-SCCmec IVd; B, ST8-SCCmec IVd; C, ST8-SCCmec IVa; D, ST8-SCCmec IVl; E, ST8-SCCmec IVl and ST858-SCCmec IVl. Seven strains from the families A-C carried Panton-Valentine leukocidin gene. Three strains from the families D and E carried toxic shock syndrome toxin gene. Strains belonged to the same family demonstrated genetically related banding patterns of pulsed-filed gel electrophoresis. The family C experienced intrafamilial transmission of USA300-0114. Our data showed the MRSA clones disseminating in this community were highly diverse. They contained USA300-0114 clone, the rapidly distributing clone in the world, as well as MRSA clones identified in Japan. Our results suggested intrafamilial transmission of MRSA could be initial phenomenon of wide transmission in a community, therefore CA-MRSA SSTI in children and their family members should be monitored closely in order to notice the spread of highly pathogenic and transmittable strains.