Molecular Epidemiological Survey of Prophages in MRSA Isolates in Taiwan.

INTRODUCTION

The prevalence of methicillin-resistant (MRSA) type SCC IV or V is increasing in Taiwan. It has been suggested that the surface protein SasX is responsible for their transmission. However, the gene was not detected in our SCC IV or V isolates. Since was originally found in and believed to be transferred to by a prophage, studies were conducted to detect and type this prophage in our clinical isolates.

MATERIALS AND METHODS

A total of 1192 MRSA isolates collected from 2006 to 2014 were examined. Multiplex PCRs were performed to determine SCC, and prophage types.

RESULTS

The prevalence of SCC IV and V isolates was increased in recent years (from 2006 to 2014). The gene was present in most SCC III isolates but was absent in SCC IV or V isolates. The Sa5 prophage was found only in SCC IV and SCC V (or V) isolates, and the Sa6 prophage was mainly present in SCC III isolates. MRSA isolates harboring prophage combinations Sa1, Sa2, and Sa3; Sa2 and Sa3; Sa2, Sa3, and Sa7; or Sa2 and Sa7 were mainly of SCC II, and those that harbored prophage combinations Sa3 and Sa6; Sa3, Sa6, and Sa7; or Sa3 and Sa7 were mostly of SCC III. The numbers of SCC II isolates containing prophages Sa2, Sa3, and Sa7 and those of SCC III isolates containing prophages Sa3 and Sa6 or Sa3, Sa6, and Sa7 were decreased from 2010 to 2014. The number of SCC IV isolates with prophage Sa3 or prophages Sa3 and Sa5 was decreased, but that of those with prophage Sa6 or prophages Sa2 and Sa3 was increased from 2010 to 2014.

CONCLUSION

The gene was found to play no role in clonal selection of MRSA. The finding that different SCC types of MRSA harbored different types of prophages suggests that these prophages may affect the survival and clonal expansion of certain types of MRSA.