# Additive Effects of N-Acetylcysteine and [R4W4] Combination Treatment on Mycobacterium avium

## TL;DR

This study shows that combining NAC and [R4W4] improves the treatment of Mycobacterium avium infections by enhancing bacterial inhibition.

## Contribution

The paper demonstrates the additive antimycobacterial effects of combining NAC and [R4W4] against M. avium.

## Key findings

- NAC and [R4W4] together disrupted M. avium membrane potential more effectively than individually.
- Combination treatment significantly reduced M. avium survival in cultures and infected macrophages.
- The combination showed additive antibacterial activity with the lowest MIC compared to individual treatments.

## Abstract

Mycobacterium avium is an opportunistic pathogen and a leading contributor to nontuberculous mycobacterial infections in immunocompromised individuals. However, treatment duration, antibiotic toxicity, and resistance present challenges in the management of mycobacterium infections, prompting the need for novel treatment. N-acetylcysteine (NAC) has demonstrated potent antimycobacterial activity, while antimicrobial peptides such as the cyclic [R4W4] have shown additive effects when combined with first-line antibiotics. This study aimed to investigate the mechanism and efficacy of NAC and [R4W4] combination therapy against M. avium. A membrane depolarization assay was used to evaluate the effects of NAC and [R4W4] on M. avium cell membrane integrity. Antimycobacterial activity was assessed by treating cultures with varying concentrations of NAC, [R4W4], a combination, or a sham treatment. The same regimens were applied to M. avium-infected THP-1-derived macrophages to assess intracellular efficacy. NAC and [R4W4] each disrupted the M. avium membrane potential, with enhanced effects in combination. The combination treatment significantly reduced M. avium survival in both the culture and infected macrophages compared with NAC alone and untreated controls. [R4W4] and NAC also demonstrated potent antibacterial activity, while the lowest MIC and the combination of [R4W4] and NAC displayed additive effects, indicating an improved bacterial inhibition compared to individual treatments. These findings demonstrate the additive activity of NAC and [R4W4] against M. avium in vitro and suggest that combining antioxidant compounds with antimicrobial peptides may represent a promising strategy for treating mycobacterial infections.