Biophysical Society Thematic Meeting | Stockholm 2022

Physical and Quantitative Approaches to Overcome Antibiotic Resistance

Thursday Speaker Abstracts

INTRACELLULAR LOCALISATION OF MYCOBACTERIUM TUBERCULOSIS AFFECTS EFFICACY OF THE ANTIBIOTIC PYRAZINAMIDE Pierre Santucci 1 ; 1 The Francis Crick Institute, Host-Pathogen Interactions in Tuberculosis Laboratory, London, United Kingdom To be effective, chemotherapy against tuberculosis (TB) must kill the intracellular population of the pathogen, Mycobacterium tuberculosis. However, how host cell microenvironments affect antibiotic accumulation and efficacy remains unclear. By combining, high-content fluorescence microscopy with correlative light, electron, and ion microscopy (CLEIM), we investigate how various microenvironments within human macrophages affect the activity of pyrazinamide (PZA), a key antibiotic against TB. We show that PZA accumulates heterogeneously among individual bacteria in multiple host cell environments. We also demonstrate that correlative SEM-NanoSIMS imaging can be used to identify anti-TB drugs distribution and interaction at a subcellular resolution. Finally, by developing a dual-live imaging approach with pharmacological and genetic perturbations, we show that Mtb can maintain its intracellular pH independently of the surrounding pH in primary human macrophages. We show that unlike bedaquiline (BDQ), isoniazid (INH) or rifampicin (RIF), the front-line drug pyrazinamide (PZA) displays antibacterial efficacy by acting as protonophore which disrupts intrabacterial pH homeostasis in cellulo. By using Mtb mutants with different subcellular localisation, we confirmed that intracellular acidification is a prerequisite for PZA efficacy in cellulo. Our results may explain the potent in vivo efficacy of PZA, compared to its modest in vitro activity, and its critical contribution to TB combination chemotherapy.

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