SCC mec transformation requires living donor cells in mixed biofilms

Mais Maree; Yuri Ushijima; Pedro B Fernandes; Masato Higashide; Kazuya Morikawa

doi:10.1016/j.bioflm.2024.100184

SCC mec transformation requires living donor cells in mixed biofilms

Biofilm. 2024 Feb 16:7:100184. doi: 10.1016/j.bioflm.2024.100184. eCollection 2024 Jun.

Authors

Mais Maree¹, Yuri Ushijima¹, Pedro B Fernandes¹, Masato Higashide², Kazuya Morikawa¹

Affiliations

¹ Institute of Medicine, University of Tsukuba, Japan.
² Kotobiken Medical Laboratories, Inc., Kamiyokoba, Tsukuba, Japan.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen that has emerged through the horizontal acquisition of the staphylococcal cassette chromosome mec (SCCmec). Previously, we showed that SCCmec from heat-killed donors can be transferred via natural transformation in biofilms at frequencies of 10^-8-10^-7. Here, we show an improved transformation assay of SCCmec with frequencies up to 10^-2 using co-cultured biofilms with living donor cells. The Ccr-attB system played an important role in SCCmec transfer, and the deletion of ccrAB recombinase genes reduced the frequency ∼30-fold. SCCmec could be transferred from either MRSA or methicillin-resistant coagulase-negative staphylococci to some methicillin-sensitive S. aureus recipients. In addition, the transformation of other plasmid or chromosomal genes is enhanced by using living donor cells. This study emphasizes the role of natural transformation as an evolutionary ability of S. aureus and in MRSA emergence.

Keywords: Antimicrobial resistance; Biofilm; Natural transformation; SCC; Staphylococcus aureus.