Inhibitory Effect of N-Acetylcysteine on Adherence of <i>Streptococcus pneumoniae</i> and <i>Haemophilus influenzae</i> to Human Oropharyngeal Epithelial Cells in vitro

Abstract

Background: Bacterial adherence to mucosal and epithelial cell structures is of importance for the persistence of bacteria in the airways. Cigarette smoking and chronic bronchitis are associated with increased bacterial adherence. N-Acetylcysteine (NAC) medication reduces the number of infectious exacerbations in patients with chronic bronchitis, and NAC medication has been associated with low intrabronchial bacterial numbers. Objective: We investigated whether NAC influences bacterial adherence as a possible mechanism behind its clinical effects. Methods: Highly adhering test strains of Streptococcus pneumoniae and Haemophilus influenzae were used to investigate the influence of four pharmacological compounds on adherence to oropharyngeal epithelial cells in vitro. Adhesion assays were performed both during short-term exposure to, as well as after long-time incubation with, NAC, lidocaine, hydrocortisone and terbutaline at concentrations not inhibiting bacterial growth. Results: Only NAC showed a significant inhibitory effect on adhesion of H. influenzae during short-term incubation. After long-term incubation, both NAC and hydrocortisone inhibited bacterial adhesion for both strains in a dose-dependent manner. When NAC’s effect on three different strains of S. pneumoniae and four strains of H. influenzae was studied, inhibition of bacterial adhesion was found for three strains of each species. Conclusions: NAC lowers bacterial adhesion in vitro to oropharyngeal epithelial cells in doses equivalent to that is being used clinically. This effect might be a contributory mechanism behind the reduction of infectious exacerbations in chronic bronchitis patients.

Antioxidant properties of N-acetylcysteine: their relevance in relation to chronic obstructive pulmonary disease

“…In addition, 600 mg?day -1 NAC in COPD patients reduced sputum eosinophil cationic protein concentrations and the adhesion of PMNs [65]. In vitro, NAC reduced adhesion of Haemophilus influenzae and Streptococcus pneumoniae to oropharyngeal epithelial cells [66].…”

N -Acetyl- l -Cysteine Affects Growth, Extracellular Polysaccharide Production, and Bacterial Biofilm Formation on Solid Surfaces

“…Perez-Giraldo et al (32) showed that NAC reduced the formation of biofilms of Staphylococcus epidermidis on a polystyrene surface but did not distinguish between the effects on bacteria and bacterial EPS. Recently, it was shown that NAC reduced adhesion of Streptococcus pneumoniae and Haemophilus influenzae to oropharyngeal epithelial cells in vitro (36). Similarly, NAC also reduced attachment of Moraxella catarrhalis to pharyngeal epithelial cells, possibly by removing a layer of ruthenium red-positive extracellular material from the epithelial cells (49).…”

“…N-Acetyl-L-cysteine (NAC), which is used in medical treatment of chronic bronchitis, cancer, and paracetamol intoxication (36,43), is one of the smallest drug molecules in use (28), and it has antibacterial properties. The molecule is a thiolcontaining antioxidant that disrupts disulfide bonds in mucus (3,41) and competitively inhibits amino acid (cysteine) utilization (46,50).…”

Evidence-Based Treatment of Acute Respiratory Infections in Children

“…Влияние на антиоксидантные системы способствует защите клеток от свободнорадикального повреждения, что приводит к снижению воспаления на слизистых оболочках дыха-тельных путей и улучшению клинической симптоматики [41]. Ацетилцистеин уменьшает адгезию патогенных бак-терий к эпителиальным клеткам слизистой оболочки дыха-тельных путей и тем самым снижает колонизацию дыха-тельных путей патогенными микробами [11,42]. Препарат приводит к уменьшению образования биопленок грам-положительными и грамотрицательными бактериями и грибами; уменьшает продукцию экстрацеллюлярного полисахаридного матрикса, что способствует разруше-нию зрелых биопленок [43][44][45].…”