Transcriptional analysis of D, D-carboxypeptidase genes as secondary cephalosporin resistance reporters in Escherichia coli harbouring blaCTX-M.

DacB and dacD genes are consistently upregulated in E. coli under oxyimino cephalosporin stress, indicating their potential as reporters for cephalosporin resistance detection.

• Why it matters: Detecting antimicrobial resistance is complicated by plasmid-encoded variants, so identifying endogenous resistance gene responses can improve diagnostic accuracy and understanding of resistance mechanisms.
• What they did: The study examined transcriptional responses of D,D-carboxypeptidase genes and bolA in 30 clinical E. coli isolates under antibiotic stress, using qRT-PCR, MIC testing, and network analysis.
• The result: Upregulation of dacB and dacD correlated with increased MICs, suggesting these genes may serve as reliable markers for cephalosporin resistance in future diagnostic applications.