Intrinsic acidity of N-acetylcysteine mediates enhanced inhibition of Klebsiella pneumoniae and its biofilms by polymyxin B.
Intrinsic Acidity of N-Acetylcysteine Mediates Enhanced Inhibition ofand Its Biofilms by Polymyxin B.
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Key Findings
Abstract
This study investigated the combined antibacterial and anti-biofilm activity of polymyxin B (PB) with intrinsically acidic N-acetylcysteine (NAC) against. The minimum inhibitory concentrations (MICs) of PB, acidic NAC, and neutralized NAC against 34strains were determined using the broth microdilution. Drug interactions were assessed by checkerboard assays and the fractional inhibitory concentration index (FICI), while biofilm inhibition was quantified using crystal violet staining. Polymyxin B resistance was identified in the reference multidrug-resistant strainATCC BAA-1705. The PB-NAC combination showed an additive effect (FICI 0.53-0.63) against PB-resistant and PB-intermediately susceptible strains, whereas indifferent interactions were observed in PB-susceptible strains. Furthermore, sub-inhibitory concentrations of the combination produced significantly stronger biofilm inhibition than either agent alone. Neutralization of NAC markedly reduced its antibacterial and anti-biofilm activities, with substantial inhibition observed only at concentrations≥32 mg/mL. These findings demonstrate that the combination of PB and acidic NAC exerts additive antibacterial effects, particularly against resistantstrains, and enhances biofilm inhibition. Notably, the intrinsic acidity of NAC is essential for its antimicrobial and anti-biofilm activity.
Affiliation
Fei Wang
External References
- PubMed ID:
- 41753798
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