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

Abstract

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.

N-acetyl-cysteine exhibits potent anti-mycobacterial activity in addition to its known anti-oxidative functions

“…High concentrations of NAC have been shown to directly inhibit extracellular growth of a number of bacterial species [24, 25, 46]. Indeed, NAC inhibits biofilm formation of a variety of medically important gram-positive and gram-negative bacteria, e.g.…”

“…Indeed, NAC inhibits biofilm formation of a variety of medically important gram-positive and gram-negative bacteria, e.g. P. aeruginosa, K. pneumoniae, S. epidermidis, S. aureus and Escherichia coli [25, 26, 46–48]. Interestingly, NAC does not inhibit growth of methicillin-sensitive and resistant S. aureus strains at 49 mM (8 mg/mL) [49], suggesting that bacterial species may diverge in susceptibility to the effects of this drug.…”

Identification of α-tocopherol as a bioactive component ofDicranopteris lineariswith disrupting property against preformed biofilm ofStaphylococcus aureus

“…Besides that, a potent thiol‐containing antioxidant, N‐acetyl cysteine (NAC) have been reported to decrease biofilm formation of Enterococcus faecalis, Escherichia coli and Klebsiella pneumoniae, and may reduce the production of extracellular polysaccharide matrix while promoting the disruption of mature biofilm (Silveira et al . ; Dinicola et al . ).…”

Irrigants Used in Endodontic Treatment – Review of the Literature

“…Alexidine is similar to chlorhexidine but proven to have a faster bactericidal action and bacterial permeabilization because of the presence of two hydrophobic ethylhexyl groups in its structure [27]. Alexidine has higher affinity for bacterial lipopolysaccharide and LTA than chlorhexidine.…”

“…Consequently, the new irrigant has greater antimicrobial action at a lower concentration [28]. 1% ALX can be as effective against Enterococcus faecalis infections as 2% CHX [27]. Both agents observed eradicated the same amount of bacteria from dentin [29].…”