Transcriptomic responses of XDR Klebsiella pneumoniae to N-acetyl cysteine reveals suppression of major biogenesis pathways leading to bacterial killing and biofilm eradication

Carbapenemase-producing K. pneumoniae is categorized as a "critical global priority-one" pathogen by WHO and new and efficient treatment options are warranted. This study aims to assess the antibacterial and antibiofilm potential of N-acetyl cysteine (NAC), against clinical isolates of extensively drug resistant (XDR) K. pneumoniae and elucidate the mechanism of killing. XDR-K. pneumoniae were isolated from patients admitted to Madras Medical Mission Hospital, India. Antibiofilm activity of NAC was checked using in vitro continuous flow model and RNA sequencing was done using Illumina Novoseq. Data quality was checked using FastQC and MultiQC software. Our findings revealed that NAC at a concentration of 100 mg/mL was safe, and could inhibit the growth and completely eradicate mature biofilms of all XDR- K. pneumoniae isolates. Transcriptomic responses in XDR- K. pneumoniae to NAC showed significant downregulation of the genes associated with crucial biogenesis pathways including electron transport chain and oxidoreductase activity besides a specific cluster of genes linked to ribosomal proteins. Our results indicate that NAC kills the XDR- K. pneumoniae clinical isolates by shutting the overall metabolism and hence, successfully eradicate in vitro biofilms formed on catheters.