In vitro effects of N-acetyl cysteine alone and in combination with antibiotics on Prevotella intermedia

Abstract

N-acetyl cysteine (NAC) is an antioxidant that possesses anti-inflammatory activities in tissues. In the field of dentistry, NAC was demonstrated to prevent the expression of LPS-induced inflammatory mediators in phagocytic cells and gingival fibroblasts during the inflammatory process, but the effect of NAC on oral pathogens has been rarely studied. Here, we examined the effect of NAC against planktonic and biofilm cells of Prevotella intermedia, a major oral pathogen. NAC showed antibacterial activity against the planktonic P. intermedia with MIC value of 3 mg/ml and significantly decreased biofilm formation by the bacterium even at sub MIC. NAC did not affect the antibiotic susceptibility of planktonic P. intermedia, showing indifference (fractional inhibitory concentration index of 0.5-4) results against the bacterium in combination with ampicillin, ciprofloxacin, tetracycline or metronidazole. On the other hand, viability of the pre-established bacterial biofilm exposed to the antibiotics except metronidazole was increased in the presence of NAC. Collectively, NAC may be used for prevention of the biofilm formation by P. intermedia rather than eradication of the pre-established bacterial biofilm. Further studies are required to explore antibacterial and anti-biofilm activity of NAC against mixed population of oral bacteria and its modulatory effect on antibiotics used for oral infectious diseases.

In Vitro Effects of Polyphosphate against Prevotella intermedia in Planktonic Phase and Biofilm

“…The biofilm formation assay was performed as described previously (35,36). Briefly, P. intermedia was grown to exponential phase and then adjusted to an optical density at 600 nm (OD 600 ) of approximately 0.1.…”

“…The viability of the preestablished P. intermedia biofilms exposed to polyP3 (0.05 to 0.4%) was further examined by CLSM. The biofilms were stained with a LIVE/DEAD BacLight bacterial viability kit consisting of green fluorescent SYTO 9, which stains live bacteria, and red fluorescent propidium iodide, which only penetrates nonviable bacterial cells with damaged or perturbed cell membranes (35). While unexposed control biofilm was shown to be predominantly green (vi- able), the fraction of red color (nonviable) increased in the polyP3-exposed biofilm (Fig.…”

“…Effect of polyP3 on EPS. EPS is the primary matrix material of biofilm, and viscosity of culture supernatant is an indication of the relative amount of EPS production in the culture (35,37,38). Yamanaka et al (39,40) reported that clinical isolates of P. intermedia designated strain 17 and strain OD1-16 produced mannose-rich EPSs, as revealed by the increased viscosity of the spent culture media.…”

Adverse Influences of Antimicrobial Strategy against Mature Oral Biofilm

“…In the field of dentistry, it has also been reported that sub-MICs of antimicrobial agents or compounds can inhibit bacterial attachment [54,56,57], biofilm formation [54,55,57,58], and downregulate virulence genes [54,56,59,60]. Moon et al reported N-acetyl cysteine (NAC) that is an antioxidant possessing anti-inflammatory activities, showed a significant decrease of Prevotella intermedia biofilm formation in the presence of sub-MIC [55].…”

“…Moon et al reported N-acetyl cysteine (NAC) that is an antioxidant possessing anti-inflammatory activities, showed a significant decrease of Prevotella intermedia biofilm formation in the presence of sub-MIC [55]. NAC was demonstrated to present the expression of LPS-induced inflammatory mediators in phagocytic cells and gingival fibroblasts during the inflammatory process.…”