摘要：The plasmid-borne qacA and qacB genes encode a multidrug efflux protein. The proteins encoded by qacA and qacB mediate efflux of cationic antiseptic agents such as quaternary ammonium compounds. In methicillin-resistant Staphylococcus aureus (MRSA), qacA and qacB are widely prevalent and decrease antiseptic susceptibility. However, it is difficult to find the plasmids encoding qacA or qacB in community-associated MRSA (C-MRSA) isolated from patients with impetigo. Most MRSA, the strains causative of impetigo, carry the plasmid-borne exfoliative toxin-producing gene etb . To find the reason for the paucity of qacA or qacB in MRSA isolated from patients with impetigo, we performed transfer experiments of the plasmid pTZ2162 qacB encoding qacB . The pTZ2162 qacB was transferred to S. aureus strain RN4220 by transduction, although no pTZ2162 qacB was transferred by conjugation. Additionally, pTZ2162 qacB was transduced to MRSA carrying etb , and was coexistence with the plasmid encoding etb . Our results showed that pTZ2162 qacB was horizontally transferred by transduction and was compatible with the plasmid encoding etb . Consequently, there will be risk of the emergence of C-MRSA with decreased antiseptic susceptibility among patients with impetigo.
