# Biofilm Associated Persistence and Drug Tolerance in Mycobacteria Within Host Microenvironments

## TL;DR

Mycobacteria in biofilms are hard to treat because they resist drugs and hide from the immune system, leading to persistent and recurring tuberculosis.

## Contribution

This review integrates current understanding of mycobacterial biofilm drug tolerance and evaluates novel therapeutic strategies to combat it.

## Key findings

- Mycobacterial biofilms create drug-tolerant microenvironments by restricting antibiotic access and shielding bacteria.
- Biofilm-associated persistence is linked to TB treatment failure and disease relapse in clinical and experimental settings.
- Peptide–antibiotic therapies and synergistic drug combinations show promise in overcoming biofilm-induced drug tolerance.

## Abstract

Biofilms formed by mycobacteria, particularly
Mycobacterium tuberculosis
(Mtb), represent a major challenge in tuberculosis (TB) treatment due to their highly organized structure and their capacity to induce phenotypic drug tolerance. These three‐dimensional bacterial aggregates are embedded in a self‐produced extracellular matrix that restricts antibiotic penetration and shields bacilli from host immune responses. The resulting spatial and physiological heterogeneity within biofilms generates microenvironments that favor slow‐growing or non‐replicating cells, markedly reducing the efficacy of conventional antimicrobial therapies. Increasing experimental and clinical evidence supports the presence of biofilm‐like mycobacterial communities in TB lesions, linking this growth mode to disease chronicity, treatment failure, and relapse. This review aims to provide an integrated overview of the biological and physiological states adopted by mycobacteria within biofilm microenvironments, with particular emphasis on the mechanisms underlying biofilm‐associated drug tolerance. In addition, it critically discusses therapeutic strategies designed to overcome this tolerance, focusing on synergistic antibiotic combinations and peptide–antibiotic therapies that directly disrupt biofilm architecture, enhance drug penetration, or sensitize biofilm‐embedded bacilli to antimicrobial killing.