The impact of DNA adenine methyltransferase knockout on the development of triclosan resistance and antibiotic cross-resistance in .

BACKGROUND

DNA adenine methyltransferase () has been well documented for its role in regulation of replication, mismatch repair and transposition. Recent studies have also suggested a role for in protection against antibiotic stress, although this is not yet fully defined. We therefore evaluated the role of in the development of antibiotic resistance and triclosan-associated cross-resistance.

RESULTS

A significant impact on growth rate was seen in the knockout compared to the parental strain. Known triclosan resistance-associated mutations in were seen regardless of status, with an additional mutation in seen in the knockout. The expression of multiple antibiotic resistance-associated genes was significantly different between the parent and knockout post-resistance induction. Reversion rate assays showed that resistance mechanisms were stable.

CONCLUSIONS

knockout had a significant effect on growth, but its role in the development of antibiotic resistance is likely confined to those antibiotics using -containing efflux pumps.