Antibiotic resistance acquired through a DNA damage‐inducible response in Acinetobacter baumannii

Abstract

Acinetobacter baumannii is an emerging nosocomial, opportunistic pathogen. It can survive desiccation and acquire resistance to multiple antibiotics. Escherichia coli can gain antibiotic resistances as a result of the expression of genes involved in a global response to DNA damage. Therefore, we asked whether A. baumannii does the same through a yet undetermined DNA damage response akin to the E. coli paradigm. Here we present evidence consistent with this hypothesis. We find that recA, which is essential to mount a response in E. coli, and multiple, error‐prone DNA Polymerase V genes are induced upon DNA damage. The regulation of these genes was found to be governed by RecA. Consequently, we find that the frequency of rifampicin resistant mutants is dramatically increased upon DNA damage and desiccation in a RecA‐dependent manner. It appears that the number of error‐prone DNA polymerase genes A. baumannii strains have acquired may directly contribute to mutagenesis. These studies provide evidence for an A. baumannii global and inducible DNA damage response that directly contributes to genomic evolution and acquisition of antibiotic resistance, especially in hospitals where A. baumannii desiccates and survives on equipment.