In vitro effects of commercial mouthwashes on several virulence traits of Candida albicans, viridans streptococci and Enterococcus faecalis colonizing the oral cavity

Abstract

Oral microbiota consists of hundreds of different species of bacteria, fungi, protozoa and archaea, important for oral health. Oral mycoses, mostly affecting mucosae, are mainly caused by the opportunistic pathogen Candida albicans. They become relevant in denture-wearers elderly people, in diabetic patients, and in immunocompromised individuals. Differently, bacteria are responsible for other pathologies, such as dental caries, gingivitis and periodontitis, which affect even immune-competent individuals. An appropriate oral hygiene can avoid (or at least ameliorate) such pathologies: the regular and correct use of toothbrush, toothpaste and mouthwash helps prevent oral infections. Interestingly, little or no information is available on the effects (if any) of mouthwashes on the composition of oral microbiota in healthy individuals. Therefore, by means of in vitro models, we assessed the effects of alcohol-free commercial mouthwashes, with different composition (4 with chlorhexidine digluconate, 1 with fluoride, 1 with essential oils, 1 with cetylpyridinium chloride and 1 with triclosan), on several virulence traits of C. albicans, and a group of viridans streptococci, commonly colonizing the oral cavity. For the study here described, a reference strain of C. albicans and of streptococci isolates from pharyngeal swabs were used. Chlorhexidine digluconate- and cetylpyridinium chloride-containing mouthwashes were the most effective in impairing C. albicans capacity to adhere to both abiotic and biotic surfaces, to elicit proinflammatory cytokine secretion by oral epithelial cells and to escape intracellular killing by phagocytes. In addition, these same mouthwashes were effective in impairing biofilm formation by a group of viridans streptococci that, notoriously, cooperate with the cariogenic S. mutans, facilitating the establishment of biofilm by the latter. Differently, these mouthwashes were ineffective against other viridans streptococci that are natural competitors of S. mutans. Finally, by an in vitro model of mixed biofilm, we showed that mouthwashes-treated S. salivarius overall failed to impair C. albicans capacity to form a biofilm. In conclusion, the results described here suggest that chlorhexidine- and cetylpyridinium-containing mouthwashes may be effective in regulating microbial homeostasis of the oral cavity, by providing a positive balance for oral health. On the other side, chlorhexidine has several side effects that must be considered when prescribing mouthwashes containing this molecule.

Effect of Listerine Mouthwash with Green Tea on the Inhibition of Streptococcus Mutans: A Microbiologic Study

“…Many studies on oral microorganisms have reported that CHX is the best mouthwash [14,15], deeming it the gold standard in the chemical treatment against SM and dental caries [1]. Consistent with the present study, other authors showed that CHX-containing mouthwashes (0.2% and 0.06% concentrates) and Total Care Listerine Zero inhibited the formation of plaque by different species of Streptococci [16]. They also reported that CHX-containing mouthwashes were more effective than Total Care Listerine Zero mouthwash.…”

Oral Microbiome and SARS-CoV-2: Beware of Lung Co-infection

“…Povidone iodine (PV-I, 0.23∼1%), cetylpyridinium chloride (CPC, 0.05∼0.10%), and hydrogen peroxide (0.5∼1.5%) all effectively reduce the number of oral microbiota ( Ardizzoni et al, 2018 ; Eggers et al, 2018 ; Li and Meng, 2020 ). Studies have also shown that SARS-CoV, MERS-CoV, and influenza virus A (H1N1) can be efficiently inactivated by these compounds within 1 min ( Kariwa et al, 2006 ; Eggers et al, 2015 , 2018 ; Kampf et al, 2020 ; Li and Meng, 2020 ).…”

Candida spp./Bacteria Mixed Biofilms

“…In what concerns mouthwashes, Ardizzoni et al [132] evaluated the antimicrobial activity of alcohol-free commercial mouthwashes with chlorhexidine digluconate (CHX), fluoride, essential oils, cetylpyridinium chloride (CC), and triclosan. Candida albicans and a cluster of viridans streptococci (frequently present in the oral cavity) were isolated from pharyngeal swabs and tested.…”

“…Additionally, they were effective in damaging biofilm formation by viridans streptococci that cooperate with the cariogenic S. mutans, and ineffective against viridans streptococci that are natural competitors of S. mutans. On the contrary, in a mixed biofilm, the mouthwashes eradicated S. salivarius but failed to impair C. albicans' biofilm forming ability [132]. Likewise, Tan et al [133] showed that the combination activity of curcumin and 2-aminobenzimidazole against single-and mixed-species biofilms of C. albicans and S. aureus was curiously most potent on mixed biofilms.…”