Fig. 4: IleRS silencing enhances pyrazinamide (PZA) sensitivity in M. abscessus and M. marinum.

IleRS-silenced (IleRS_KD) strains were compared with empty vector strains (PLJR962_KD) under four treatment conditions: untreated, PZA without ATC (no IleRS silencing), ATC alone (silencing control), and ATC + PZA. A Bar charts demonstrates the synergistic bactericidal effect of IleRS silencing and PZA on M. abscessus and M. marinum under acidic conditions (pH 5.0 and 5.5), with greater killing when ATC + PZA are combined than with either treatment alone (n = 3). B In the NR medium (non-replicating stress model; see Methods), IleRS silencing further enhances PZA activity, indicating a synergistic interaction under stress (n = 3). C alamarBlue microplate assay determining minimum inhibitory concentrations (MICs) of isoniazid (INH), rifampicin (RFP), ethambutol (EMB), pyrazinamide (PZA), amikacin (AMK), moxifloxacin (MXF), ethionamide (ETH), D-cycloserine (DCS), sodium para-aminosalicylic acid (PAS), linezolid (LZD), bedaquiline (BDQ), meropenem (MEM), clofazimine (CFZ), and clarithromycin (CLA). Drugs were tested at 0.004×–0.5× MIC. Empty vector strains and IleRS-silenced strains were tested with or without ATC induction. D Survival of M. abscessus and M. marinum in RAW 264.7 and THP-1 macrophage infected at MOI = 1. At 24 and 72 h post-infection, macrophages were washed, extracellular bacteria were removed with gentamicin (see Methods), cells were lysed with 0.01% SDS, and lysates were plated on 7H10 to quantify viable bacteria (n = 3). Error bars represent mean ± SD. Statistical significance was determined by two-way ANOVA. Differences were considered statistically significant at P < 0.05 (*), P < 0.01 (**), P < 0.001 (***), and P < 0.0001 (****). “ns” denotes no significant difference.