Collateral Sensitivity to β-Lactam Drugs in Drug-Resistant Tuberculosis Is Driven by the Transcriptional Wiring of BlaI Operon Genes

The evolution of resistance to one antimicrobial can result in enhanced sensitivity to another, known as collateral sensitivity. This underexplored phenomenon opens new therapeutic possibilities for patients infected with pathogens unresponsive to classical treatments. Intrinsic resistance to beta-lactams in Mycobacterium tuberculosis (the causative agent of tuberculosis) has traditionally curtailed the use of these low-cost and easy-to-administer drugs for tuberculosis treatment. Recently, beta-lactam sensitivity has been reported in strains resistant to classical tuberculosis therapy, resurging the interest in beta-lactams for tuberculosis. However, a lack of understanding of the molecular underpinnings of this sensitivity has delayed exploration in the clinic. We performed gene expression and network analyses and in silico knockout simulations of genes associated with beta-lactam sensitivity and genes associated with resistance to classical tuberculosis drugs to investigate regulatory interactions and identify key gene mediators. We found activation of the key inhibitor of beta- lactam resistance, blaI, following classical drug treatment as well as transcriptional links between genes associated with beta-lactam sensitivity and those associated with resistance to classical treatment, suggesting that regulatory links might explain collateral sensitivity to beta- lactams. Our results support M. tuberculosis beta-lactam sensitivity as a collateral consequence of the evolution of resistance to classical tuberculosis drugs, mediated through changes to transcriptional regulation. These findings support continued exploration of beta-lactams for the treatment of patients infected with tuberculosis strains resistant to classical therapies. IMPORTANCE Tuberculosis remains a significant cause of global mortality, with strains resistant to classical drug treatment considered a major health concern by the World Health Organization. Challenging treatment regimens and difficulty accessing drugs in low-income communities have led to a high prevalence of strains resistant to multiple drugs, making the development of alternative therapies a priority. Although Mycobacterium tuberculosis is naturally resistant to beta-lactam drugs, previous studies have shown sensitivity in strains resistant to classical drug treatment, but we currently lack understanding of the molecular underpinnings behind this phenomenon. We found that genes involved in beta-lactam susceptibility are activated after classical drug treatment resulting from tight regulatory links with genes involved in drug resistance. Our study supports the hypothesis that beta-lactam susceptibility observed in drug-resistant strains results from the underlying regulatory network of M. tuberculosis, supporting further exploration of the use of beta-lactams for tuberculosis treatment.

Automated summary

The evolution of resistance to one antimicrobial can result in enhanced sensitivity to another, known as collateral sensitivity, which opens new therapeutic possibilities for patients infected with pathogens unresponsive to classical treatments. Recent studies have found beta-lactam sensitivity in strains resistant to classical drug therapy, suggesting potential for the use of beta-lactams for tuberculosis treatment. Molecular analyses have shown regulatory links between genes involved in beta-lactam sensitivity and drug resistance, supporting continued exploration of beta-lactams for drug-resistant tuberculosis strains.