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Antimicrobial activity of alexidine alone and associated with N-acetylcysteine against Enterococcus faecalis biofilm

2013; Springer Nature; Volume: 5; Issue: 3 Linguagem: Inglês

10.1038/ijos.2013.58

2049-3169

Luiz Fernando Machado Silveira, Pilar Baca, María Teresa Arias‐Moliz, Alberto Rodríguez-Archilla, Carmen Marı́a Ferrer-Luque,

Bacterial biofilms and quorum sensing

The purpose of this study was to assess the efficacy of alexidine (ALX), alone and combined with N-acetylcysteine (NAC), in eradicating two Enterococcus faecalis strain biofilms. The biofilms of E. faecalis ATCC 29212 and the clinical isolate E. faecalis D1 were grown in the MBEC-high-throughput device for 24 h and were exposed to five twofold dilutions of ALX (2%–0.007 8%) alone and combined with 100 mg⋅mL−1 NAC, for 1 and 5 min. Eradication was defined as 100% kill of biofilm bacteria. The Student's t-test was used to compare the efficacy of the associations of the two irrigants. After 1-min contact time, ALX eradicated the biofilms at all concentrations except for 0.007 8% and 0.015 6%–0.007 8% with E. faecalis ATCC 29212 and E. faecalis D1, respectively. Similar results for eradication and concentration were obtained when it was combined with 100 mg⋅mL−1 NAC. After 5 min of contact time, ALX alone and combined with NAC eradicated all enterococci biofilms. ALX showed antimicrobial properties against the two E. faecalis strain biofilms tested at very low concentrations, and its combined use with NAC was not seen to enhance its activity. An analysis of different treatment combinations has revealed an optimal strategy for eliminating bacteria that take up residence inside teeth. Bacteria that infiltrate the root canal system establish dense communities known as biofilms, which are challenging to eradicate. Treatment typically entails irrigation of the canal with drugs such as chlorhexidine, a bisbiguanide. Researchers led by Carmen María Ferrer-Luque of the University of Granada in Spain compared the efficacy of alexidine, another bisbiguanide in killing Enterococcus faecalis biofilm. They determined that this drug efficiently kills off two different strains of E. faecalis within one minute at very low concentrations. The researchers also tested a combination of alexidine with N-acetylcysteine, a mucolytic agent that disrupts the extracellular polysaccharide matrix of biofilms, but observed that the combination did not meaningfully improve on the performance of alexidine alone.