title: Role of antibiofilm-antimicrobial agents in controlling device-related infections.
abstract: OBJECTIVE
  To assess the effects of N-acetylcysteine (NAC) on organism viability in planktonic and biofilm phases, biofilm thickness, and extracellular polysaccharide content.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Infectious Diseases, University of California San Diego, San Diego, CA, USA. saslam@ucsd.edu
authors.forename: Saima
authors.initials: S
authors.lastname: Aslam
authors.forename: Rabih O
authors.initials: RO
authors.lastname: Darouiche
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D018613:Microscopy, Confocal; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D016459:Prosthesis-Related Infections / Q000188:drug therapy* / Q000382:microbiology; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D011135:Polysaccharides, Bacterial; D000111:Acetylcysteine
references.citation: Int J Antimicrob Agents. 2003 Oct;22 Suppl 2:95-100
references.pmid: 14527779
references.citation: J Clin Microbiol. 1977 Jan;5(1):58-61
references.pmid: 401831
references.citation: Eur J Clin Pharmacol. 1989;37(5):501-6
references.pmid: 2598989
references.citation: Appl Environ Microbiol. 2003 Aug;69(8):4814-22
references.pmid: 12902275
references.citation: Infect Control Hosp Epidemiol. 2008 Sep;29(9):894-7
references.pmid: 18643743
references.citation: J Infect Dis. 1993 Aug;168(2):400-7
references.pmid: 8335977
references.citation: Antimicrob Agents Chemother. 2007 Apr;51(4):1556-8
references.pmid: 17220399
references.citation: Ann Emerg Med. 2003 Dec;42(6):741-50
references.pmid: 14634597
references.citation: Am J Infect Control. 2008 Dec;36(10):S175.e9-11
references.pmid: 19084156