Reactive Oxygen Detoxification Contributes to Mycobacterium abscessus Antibiotic Survival

Area of Science:

• Microbiology
• Bacteriology
• Molecular Biology

Background:

• Bactericidal antibiotics kill most bacteria, but a sub-population, persister cells, survive in a dormant state.
• Stress conditions like nutrient deprivation increase persister cell frequency, but the underlying mechanisms for viability and regulation remain unclear.

Purpose of the Study:

• To identify genetic factors enabling antibiotic persistence in mycobacteria.
• To compare spontaneous and stress-induced persister states in *Mycobacterium abscessus*.

Main Methods:

• Transposon mutagenesis high-throughput sequencing (Tn-Seq) screens were performed in *Mycobacterium abscessus*.
• Investigated the role of reactive oxygen species (ROS) and KatG catalase-peroxidase in persister cell survival.
• Assessed the impact of hypoxia on bacterial killing and persister cell viability.

Main Results:

• Tn-Seq identified genes crucial for both spontaneous and stress-induced persister cells.
• Multiple genes involved in reactive oxygen species (ROS) detoxification were unexpectedly identified.
• Endogenous ROS increased post-antibiotic exposure, with KatG essential for survival in spontaneous and starvation-induced persisters.
• Hypoxia reduced bacterial killing and rendered KatG dispensable, suggesting ROS accumulation amplifies antibiotic lethality.

Conclusions:

• Antibiotic persistence in mycobacteria involves ROS detoxification pathways.
• KatG catalase-peroxidase plays a significant role in persister cell survival, particularly under aerobic conditions.
• Hypoxia modulates antibiotic efficacy, highlighting the complex interplay between environmental factors and bacterial survival strategies.