Aslam Saima, Darouiche Rabih O
Division of Infectious Diseases, University of California San Diego, San Diego, CA, USA.
Int J Artif Organs. 2011 Sep;34(9):752-8. doi: 10.5301/ijao.5000024.
To assess the effects of N-acetylcysteine (NAC) on organism viability in planktonic and biofilm phases, biofilm thickness, and extracellular polysaccharide content.
We performed time-kill curves and broth macrodilution assays of bacterial and fungal clinical isolates with varying concentrations of NAC. We also created in vitro bacterial biofilms, incubated them with NAC or control, and then stained with propidium iodide and FITC-labeled concanavalin A. We measured biofilm thickness, number of non-viable cells, and fluorescent intensity as a marker of extracellular matrix via a confocal laser scanning microscope. All experiments were conducted in triplicate. Tested organisms included methicillin-sensitive and -resistant Staphylococcus aureus (MSSA, MRSA), S. epidermidis, vancomycin-resistant Enterococcus faecalis (VRE), Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella pneumoniae, Candida albicans and C. krusei.
NAC 80 mg/ml was uniformly bactericidal (>99.9% reduction) against all tested bacteria with no recoverable organisms after 30 minutes of incubation, but was fungistatic against candida species. Minimum inhibitory and bactericidal concentrations of NAC ranged from 5-10 mg/ml. Biofilm thickness was significantly decreased in NAC-treated biofilms for all organisms except VRE. The number of non-viable cells in NAC-treated Gram-positive biofilms was increased (p<0.05 for MRSA and VRE). NAC-treated Gram-negative biofilms had scant cellularity and lacked complex 3-dimensional structures that were characteristic of controls. Fluorescent intensity was similar in the experimental and control arms.
NAC is bactericidal against clinically relevant and drug-resistant bacteria and also leads to biofilm disruption. NAC has the potential for use as a novel agent for prevention or treatment of biofilm-related infections.
评估N-乙酰半胱氨酸（NAC）对浮游菌和生物膜阶段生物体活力、生物膜厚度及细胞外多糖含量的影响。
我们用不同浓度的NAC对细菌和真菌临床分离株进行了时间-杀菌曲线和肉汤稀释法检测。我们还构建了体外细菌生物膜，分别用NAC或对照进行孵育，然后用碘化丙啶和异硫氰酸荧光素标记的伴刀豆球蛋白A进行染色。通过共聚焦激光扫描显微镜测量生物膜厚度、非存活细胞数量以及作为细胞外基质标志物的荧光强度。所有实验均重复三次。受试生物体包括甲氧西林敏感和耐药金黄色葡萄球菌（MSSA、MRSA）、表皮葡萄球菌、耐万古霉素粪肠球菌（VRE）、铜绿假单胞菌、阴沟肠杆菌、肺炎克雷伯菌、白色念珠菌和克柔念珠菌。
80mg/ml的NAC对所有受试细菌均有一致的杀菌作用（孵育30分钟后细菌减少>99.9%），且无存活菌，但对念珠菌属为抑菌作用。NAC的最低抑菌浓度和杀菌浓度范围为5-10mg/ml。除VRE外，所有生物体经NAC处理的生物膜厚度均显著降低。经NAC处理的革兰氏阳性生物膜中非存活细胞数量增加（MRSA和VRE的p<0.05）。经NAC处理的革兰氏阴性生物膜细胞数量稀少，缺乏对照所具有的复杂三维结构。实验组和对照组的荧光强度相似。
NAC对临床相关及耐药细菌具有杀菌作用，还能导致生物膜破坏。NAC有潜力作为预防或治疗生物膜相关感染的新型药物。
