Alterations in gene expression of recA and umuDC in antibiotic-resistant Acinetobacter baumannii

Acinetobacter baumannii is a critical pathogen with an efficient SOS (Save Our Ship) system that plays a significant role in antibiotic resistance. This prospective descriptive study aimed to investigate the association between expression levels of recA and umuDC genes, which are critical in SOS pathways, and antibiotic resistance in A. baumannii. We analyzed 78 clinical isolates and 31 ecological isolates using the Vitek-2 system for bacterial identification and antibiotic susceptibility testing and confirmed molecular identification of A. baumannii by conventional PCR of bla_OXA-51 and bla_OXA-23. Quantitative real-time polymerase chain reaction was used to determine gene expression levels of recA and umuDC. The results showed that in 25 clinical strains, 14/25 strains showed upregulation of recA, 7/25 strains exhibited upregulation of both umuDC and recA, and 1/25 strains showed upregulation of umuDC. Of these, 16/25 clinical strains were extensively resistant to antibiotics, except for colistin, and showed upregulation of recA and/or umuDC gene expression levels. In 6 ecological strains, recA showed upregulation in 3/6 strains, while both recA and umuDC were upregulated in 1/6 strain. In conclusion, high expression levels of recA and/or umuDC genes in A. baumannii complex and A. baumannii strains may contribute to increasing resistance to a wide range of antibiotics and may result in the initiation of an extensively drug-resistant (XDR) phenotype.