Efficacy of a Mouthwash Containing CHX and CPC in SARS-CoV-2-Positive Patients: A Randomized Controlled Clinical Trial

Genomic and Transcriptomic Adaptation to Chlorhexidine in Streptococcus spp

Antiseptics such as chlorhexidine digluconate (CHX) are widely used in clinical dental practice, but their potential risks, particularly regarding antimicrobial resistance (AMR), are not yet known. This study explores the genomic and transcriptomic mechanisms of CHX adaptation in 3 clinical isolates of Streptococcus spp. and their adapted counterparts. The genomic analysis revealed mutations in genes related to membrane structure, DNA repair, and metabolic processes. Mutations include those in diacylglycerol kinase that occurred in Streptococcus salivarius and the autolysin N-acetylmuramoyl-L-alanine amidase homologues in both Streptococcus mitis and Streptococcus vestibularis, which may contribute to enhanced CHX resistance. Our findings showed stress response genes constantly expressed in all 3 CHX-adapted strains, regardless of acute CHX exposure. Commonly upregulated genes were related to oxidative stress, DNA repair, and metabolic pathway changes, especially amino acid related metabolism. In addition, cell surface restructuring, multiple ABC transporter genes, as well as antimicrobial resistance-associated genes were constitutively expressed. Homologue genes that were significantly upregulated across all 3 species after mutation included recD (DNA repair), potE (amino acid transport), and groEL (stress response). In addition, we saw an increase in a gene associated with the penicillin-binding protein PBP2a in all strains. Beyond these conserved adaptations, we observed species-specific shifts under prolonged CHX exposure. In S. vestibularis, glutathione synthesis genes increased while fatty acid metabolism genes were downregulated. S. salivarius showed elevated expression of genes related to organic anion transport and RNA modification. S. mitis exhibited changes in pyrimidine metabolism, ion homeostasis, and pyruvate dehydrogenase complex genes. Uniquely, S. mitis also showed acute CHX response with upregulation of carbohydrate metabolism and phosphotransferase system genes. These findings highlight the complexity of CHX-induced adaptation, suggesting connections to genetic mutations and emphasizing the need for further research to understand and mitigate AMR risks.

Effectiveness of Preprocedural Mouthwashes: A Triple-Blind Randomised Controlled Clinical Trial

OBJECTIVES

Bioaerosols generated during dental treatment are considered to be potentially carriers of infectious respiratory pathogens. The use of preprocedural mouthwashes has been suggested to reduce microbial load prior to dental surgery procedures. However, limited evidence on the effectiveness of preprocedural mouthwashes regarding mitigating respiratory pathogens exists. The aim of this clinical trial is to determine and compare the effectiveness of 3 preprocedural mouthwashes recommended by the Department of Health of the Hong Kong Special Administrative Region in the mitigation of respiratory pathogens during dental care in pandemic times.

METHODS

In all, 228 participants were block-randomised to three groups based on preprocedural mouthwash used: povidone-iodine, hydrogen peroxide, and chlorhexidine digluconate. Participants, operators, and assessors were blinded to the assigned mouthwashes (triple-blind). Saliva was assessed for the presence of a number of respiratory pathogens (19 viruses including SARS-CoV-2). Changes in the prevalence and mean number of "any" pathogen present following mouthwash use were determined.

RESULTS

Overall, the prevalence of any detected respiratory viral pathogens in the preprocedural saliva was 3.5% as compared to the postprocedural saliva: 1.3% (P = .034). The mean (SD) number of viruses was significantly lower following preprocedural mouthwash use, from 0.04 (0.18) to 0.01 (0.11) (P = .025). No significant differences were observed in the downward change (∆) of any detected virus (prevalence) (P = .155) or in the reduction of the mean number (∆) of any detected virus in the postprocedural saliva compared to preprocedural saliva of participants with respect to mouthwash used (P = .375).

CONCLUSIONS

The practice of using preprocedural mouthwash, as recommended by the government of Hong Kong, was effective in reducing the number of respiratory pathogens present during dental aerosol-generating treatment. This study lends support for official policy on use of preprocedural mouthwashes, which has significant implications for practice and policy during pandemics.

Electrolyzed Saline Prevents Virus Transmission in Dental Procedures: An In Vitro Study

In dentistry, disinfection with antimicrobials is employed under different conditions and at different time points. During the COVID-19 pandemic, the use of disinfectant dental sprays was proposed, among other measures, to help prevent the transmission of infections during dental procedures that require highly effective antiseptics at particularly short contact times. The study aimed to evaluate the efficacy of electrolyzed saline (EOS) compared with other antiseptics in terms of the spread of enveloped and nonenveloped viruses by ultrasonic scaler (USS)-generated dental spray. Suspension tests were performed to evaluate the antiviral efficacy of EOS against herpes simplex virus 1 (HSV-1) and human adenovirus (HAdV), which served as models for enveloped and nonenveloped viruses, respectively. EOS, mostly composed of hypochlorous acid (HOCl), reduced the amount of both virus types in the presence or absence of artificial saliva by > 4 log10 50% tissue culture infectious dose (P < 0.001). In addition, the mechanism of virucidal effect was investigated using transmission electron microscopy. Following this assessment, a virus-laden dental spray transmission model was used to simulate virus-infected patients undergoing dental procedures with USS. Attenuation was achieved by substituting the USS coolant with one of the effective, pretested antiseptics. Due to safety concerns, nonhuman viral pathogens-equine arteritis virus (EAV) and feline calicivirus (FCV)-served as enveloped and nonenveloped virus models, respectively. Viral infection was evaluated by direct droplet/aerosol infection of RK-13 or CRFK cells. In addition, the biocompatibility of the antiseptics was tested with exposure to human oral keratinocytes. EOS demonstrated strong virucidal activity against both enveloped and nonenveloped viruses and was able to absolutely prevent airborne transmission of EAV and FCV through dental spray in the splatter and droplet/aerosol samples. The study emphasized that EOS, a chlorine-based antiseptic, is a promising, reasonably safe, broad-spectrum agent for preventing dental spray-mediated viral transmission.

A Cetylpyridinium Chloride Oral Rinse Reduces Salivary Viral Load in Randomized Controlled Trials

INTRODUCTION

Evaluating the antiviral potential of commercially available mouthrinses on SARS-CoV-2 holds potential for reducing transmission, particularly as novel variants emerge. Because SARS-CoV-2 is transmitted primarily through salivary and respiratory secretions and aerosols, strategies to reduce salivary viral burden in an antigen-agnostic manner are attractive for mitigating spread in dental, otolaryngology, and orofacial surgery clinics where patients may need to unmask.

METHODS

Patients (n = 128) with confirmed COVID-19-positive status within 10 days of symptom onset or positive test result were enrolled in a double-blind randomized controlled trial of Food and Drug Administration-approved mouthrinses containing active ingredients ethanol, hydrogen peroxide, povidone iodine, chlorhexidine gluconate, cetylpyridinium chloride (CPC), or saline. The CPC, ethanol, and sterile water rinses were followed in a second double-blind randomized controlled trial (n = 230). Participants provided a saliva sample before rinsing (baseline) and again at 30 and 60 min after rinse. Quantitative polymerase chain reaction was used to determine salivary SARS-CoV-2 viral load at all time points. An adjusted linear mixed-effect model was employed to compare viral load after rinsing relative to baseline.

RESULTS

The rinse containing CPC significantly reduced salivary SARS-CoV-2 viral load 30 min postrinse relative to baseline (P = .015), whereas no other rinse significantly affected viral load at 30 min after rinsing. At 60 min postrinsing, no group had a significant reduction in SARS-CoV-2 copy number relative to baseline, indicating a rebound in salivary viral load over a 1-hour window. Participants indicated a fair to good rinsing experience with the CPC product and high willingness to use oral rinses before and during dental and medical health care visits.

CONCLUSIONS

Our findings suggest that preprocedural oral rinsing could be implemented as a feasible, inexpensive approach to mitigate spread of SARS-CoV-2 and potentially other enveloped viruses for short periods, which is relevant to clinical procedures involving the nasal and oropharyngeal region.

KNOWLEDGE TRANSFER STATEMENT

Rinsing with a cetylpyridinium chloride-containing mouthrinse can significantly reduce salivary SARS-CoV-2 viral load for up to 30 min; patients are willing to use mouthrinses in medical and dental settings to limit transmission risk in clinics.

A MULTICENTER, RANDOMIZED, OPEN-LABEL, PLACEBO-CONTROLLED CLINICAL TRIAL OF THE EFFECT OF CETYLPYRIDINIUM CHLORIDE (CPC) MOUTHWASH AND ON-DEMAND AQUEOUS CHLORINE DIOXIDE MOUTHWASH ON SARS-COV-2 VIRAL TITER IN PATIENTS WITH MILD COVID-19

OBJECTIVES

The established effect of cetylpyridinium chloride (CPC) mouthwash on SARS-CoV-2 viral titers is unclear. No clinical trial has examined the impact of on-demand aqueous chlorine dioxide mouthwash on SARS-CoV-2 viral titer.

METHODS

In this multicenter, 3-armed, randomized, open-label, placebo-controlled clinical trial involving mildly symptomatic COVID-19 patients, we randomly assigned them to receive 20 mL of 0.05% CPC, 10 mL of 0.01% on-demand aqueous chlorine dioxide, or 20 mL of purified water as a placebo mouthwash in a 1:1:1 ratio. The primary measurement was the SARS-CoV-2 viral titer in saliva, evaluated by a mixed-effects linear regression model.

RESULTS

49 patients received CPC mouthwash (n=16), on-demand aqueous chlorine dioxide mouthwash (n=16), and placebo (n=17) between January 14, 2024, and February 20, 2024. 0.05% CPC mouthwash significantly reduced salivary viral titer at 10 minutes postuse (-0.97 log10 PFU/mL; 95% CI, -1.64 to -0.30; P = .004), while no such effect was observed at 30 minutes (difference vs placebo, -0.26 log10 PFU/mL; 95% CI, -0.92 to 0.40; P = .435) or 60 minutes (difference vs. placebo, -0.05 log10 PFU/mL; 95% CI, -0.68 to 0.58; P = .877). 0.01% on-demand chlorine dioxide mouthwash did not reduce salivary viral titer at 10 minutes, 30 minutes, or 60 minutes compared to placebo.

CONCLUSIONS

10 minutes after using a 0.05% CPC mouthwash, the salivary viral titer of SARS-CoV-2 decreased compared to placebo. 0.01% on-demand aqueous chlorine dioxide mouthwash and placebo had no significant difference in SARS-CoV-2 viral titers.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (jRCT): jRCTs031230566.

Oral mouthwashes for asymptomatic to mildly symptomatic adults with COVID-19 and salivary viral load: a randomized, placebo-controlled, open-label clinical trial

BACKGROUND

Recent randomized clinical trials suggest that the effect of using cetylpyridinium chloride (CPC) mouthwashes on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load in COVID-19 patients has been inconsistent. Additionally, no clinical study has investigated the effectiveness of on-demand aqueous chlorine dioxide mouthwash against COVID-19.

METHODS

We performed a randomized, placebo-controlled, open-label clinical trial to assess for any effects of using mouthwash on the salivary SARS-CoV-2 viral load among asymptomatic to mildly symptomatic adult COVID-19-positive patients. Patients were randomized to receive either 20 mL of 0.05% CPC, 10 mL of 0.01% on-demand aqueous chlorine dioxide, or 20 mL of placebo mouthwash (purified water) in a 1:1:1 ratio. The primary endpoint was the cycle threshold (Ct) values employed for SARS-CoV-2 salivary viral load estimation. We used linear mixed-effects models to assess for any effect of the mouthwashes on SARS-CoV-2 salivary viral load.

RESULTS

Of a total of 96 eligible participants enrolled from November 7, 2022, to January 19, 2023, 90 were accepted for the primary analysis. The use of 0.05% CPC mouthwash was not shown to be superior to placebo in change from baseline salivary Ct value at 30 min (difference vs. placebo, 0.640; 95% confidence interval [CI], -1.425 to 2.706; P = 0.543); 2 h (difference vs. placebo, 1.158; 95% CI, -0.797 to 3.112; P = 0.246); 4 h (difference vs. placebo, 1.283; 95% CI, -0.719 to 3.285; P = 0.209); 10 h (difference vs. placebo, 0.304; 95% CI, -1.777 to 2.385; P = 0.775); or 24 h (difference vs. placebo, 0.782; 95% CI, -1.195 to 2.759; P = 0.438). The use of 0.01% on-demand aqueous chlorine dioxide mouthwash was also not shown to be superior to placebo in change from baseline salivary Ct value at 30 min (difference vs. placebo, 0.905; 95% CI, -1.079 to 2.888; P = 0.371); 2 h (difference vs. placebo, 0.709; 95% CI, -1.275 to 2.693; P = 0.483); 4 h (difference vs. placebo, 0.220; 95% CI, -1.787 to 2.226; P = 0.830); 10 h (difference vs. placebo, 0.198; 95% CI, -1.901 to 2.296; P = 0.854); or 24 h (difference vs. placebo, 0.784; 95% CI, -1.236 to 2.804; P = 0.447).

CONCLUSIONS

In asymptomatic to mildly symptomatic adults with COVID-19, compared to placebo, the use of 0.05% CPC and 0.01% on-demand aqueous chlorine dioxide mouthwash did not lead to a significant reduction in SARS-CoV-2 salivary viral load. Future studies of the efficacy of CPC and on-demand aqueous chlorine dioxide mouthwash on the viral viability of SARS-CoV-2 should be conducted using different specimen types and in multiple populations and settings.

Cetylpyridinium chloride and chlorhexidine show antiviral activity against Influenza A virus and Respiratory Syncytial virus in vitro

BACKGROUND

The oral cavity is the site of entry and replication for many respiratory viruses. Furthermore, it is the source of droplets and aerosols that facilitate viral transmission. It is thought that appropriate oral hygiene that alters viral infectivity might reduce the spread of respiratory viruses and contribute to infection control.

MATERIALS AND METHODS

Here, we analyzed the antiviral activity of cetylpyridinium chloride (CPC), chlorhexidine (CHX), and three commercial CPC and CHX-containing mouthwash preparations against the Influenza A virus and the Respiratory syncytial virus. To do so the aforementioned compounds and preparations were incubated with the Influenza A virus or with the Respiratory syncytial virus. Next, we analyzed the viability of the treated viral particles.

RESULTS

Our results indicate that CPC and CHX decrease the infectivity of both the Influenza A virus and the Respiratory Syncytial virus in vitro between 90 and 99.9% depending on the concentration. Likewise, CPC and CHX-containing mouthwash preparations were up to 99.99% effective in decreasing the viral viability of both the Influenza A virus and the Respiratory syncytial virus in vitro.

CONCLUSION

The use of a mouthwash containing CPC or CHX alone or in combination might represent a cost-effective measure to limit infection and spread of enveloped respiratory viruses infecting the oral cavity, aiding in reducing viral transmission. Our findings may stimulate future clinical studies to evaluate the effects of CPC and CHX in reducing viral respiratory transmissions.

Optimal effective concentration combinations (OPECCs) for binary application of membrane-targeting antiseptics and TMPyP-mediated antimicrobial photodynamic therapy

The widespread occurrence of multi-resistant bacteria is a health problem of global dimension. Infections caused by multi-resistant pathogens are difficult to treat and often associated with high mortality. Therefore, new treatment strategies are of interest, such as the use of differently acting antibacterial concepts. One of these new concepts is the use of antiseptics in combination with the antibacterial photodynamic therapy (aPDT). Currently, no method has yet been established as a standard procedure for investigating combined effects and evaluating them in a generally valid and unambiguous manner. The focus of this study was on how cationic antiseptics benzalkonium chloride (BAC) and chlorhexidine digluconate (CHX) behave in a combined application with aPDT using the photosensitizer TMPyP. For this purpose, BAC and CHX were applied in combination with the aPDT using TMPyP in non-lethal concentrations to the three bacteria Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. The results of the combination experiments with sublethal concentrations of BAC or CHX with the aPDT showed that the binary application had a lethal effect. Irrespective of the bacteria, the reduction in concentrations in OPECC, compared to individual concentrations, was more than 50% for TMPyP, 23-40% for BAC, and 18-43% for CHX. Furthermore, the optimal effective concentration combinations (OPECCs) could be determined. The latter showed that the combined application allowed the reduction of both concentrations compared to the single application.

Efficacy of different mouthwashes against COVID-19: A systematic review and network meta-analysis

To evaluate the effectiveness of antiseptic mouthwashes in reducing SARS-CoV-2 load clinically and in vitro. A systematic electronic search (MEDLINE/Scopus/Cochrane) was conducted to identify prospective clinical and in vitro studies published between 2019 included and 16 June 2023 assessing the effectiveness of mouthwashes in reducing SARS-CoV-2 load in saliva or surrogates. Data were summarized in tables and a network meta-analysis was performed for clinical trials. Thirty-five studies (14 RCTs, 21 in vitro) fulfilled the inclusion criteria. The risk of bias was judged to be high for 2 clinical and 7 in vitro studies. The most commonly test product was chlorhexidine alone or in combination with other active ingredients, followed by povidone-iodine, hydrogen peroxide and cetylpyridinium chloride. Overall, the descriptive analysis revealed the effectiveness of the mouthwashes in decreasing the salivary viral load both clinically and in vitro. Network meta-analysis demonstrated a high degree of heterogeneity. Among these studies, only chlorhexidine 0.20% was associated to a significant Ct increase in the saliva 5 min after rinsing compared to non-active control (p = 0.027). Data from clinical and in vitro studies suggested the antiviral efficacy of commonly used mouthwashes. Large well-balanced trials are needed to identify the best rinsing protocols.

Mouthwash Effects on the Oral Microbiome: Are They Good, Bad, or Balanced?

This narrative review describes the oral microbiome, and its role in oral health and disease, before considering the impact of commonly used over-the-counter (OTC) mouthwashes on oral bacteria, viruses, bacteriophages, and fungi that make up these microbial communities in different niches of the mouth. Whilst certain mouthwashes have proven antimicrobial actions and clinical effectiveness supported by robust evidence, this review reports more recent metagenomics evidence, suggesting that mouthwashes such as chlorhexidine may cause "dysbiosis," whereby certain species of bacteria are killed, leaving others, sometimes unwanted, to predominate. There is little known about the effects of mouthwashes on fungi and viruses in the context of the oral microbiome (virome) in vivo, despite evidence that they "kill" certain viral pathogens ex vivo. Evidence for mouthwashes, much like antibiotics, is also emerging with regards to antimicrobial resistance, and this should further be considered in the context of their widespread use by clinicians and patients. Therefore, considering the potential of currently available OTC mouthwashes to alter the oral microbiome, this article finally proposes that the ideal mouthwash, whilst combatting oral disease, should "balance" antimicrobial communities, especially those associated with health. Which antimicrobial mouthwash best fits this ideal remains uncertain.

Chlorhexidine Resistance or Cross-Resistance, That Is the Question

Chlorohexidine (CHX) is a widely used biocide in clinical and household settings. Studies over the last few decades have reported CHX resistance in different bacterial species, but at concentrations well below those used in the clinical setting. Synthesis of these findings is hampered by the inconsistent compliance with standard laboratory procedures for biocide susceptibility testing. Meanwhile, studies of in vitro CHX-adapted bacteria have reported cross-resistance between CHX and other antimicrobials. This could be related to common resistance mechanisms of CHX and other antimicrobials and/or the selective pressure driven by the intensive use of CHX. Importantly, CHX resistance and cross-resistance to antimicrobials should be investigated in clinical as well as environmental isolates to further our understanding of the role of CHX in selection of multidrug resistance. Whilst clinical studies to support the hypothesis of CHX cross-resistance with antibiotics are currently lacking, we recommend raising the awareness of healthcare providers in a range of clinical disciplines regarding the potential adverse impact of the unfettered use of CHX on tackling antimicrobial resistance.

Preprocedural mouthwashes for infection control in dentistry-an update

OBJECTIVES

Aerosols and splatter are routinely generated in dental practice and can be contaminated by potentially harmful bacteria or viruses such as SARS-CoV-2. Therefore, preprocedural mouthwashes containing antiseptic agents have been proposed as a potential measure for infection control in dental practice. This review article aims to summarize the clinical (and, if insufficient, preclinical) evidence on preprocedural mouthwashes containing antiseptic agents and to draw conclusions for dental practitioners.

METHODS

Literature on preprocedural mouthwashes for reduction of bacterial or viral load in dental aerosols was searched and summarized.

RESULTS

Preprocedural mouthwashes, particularly those containing chlorhexidine digluconate (CHX), cetylpyridinium chloride (CPC), or essential oils (EO), can significantly reduce the bacterial load in dental aerosols. With respect to viruses such as HSV-1, there are too little clinical data to draw any clear recommendations. On the other hand, clinical data is consolidating that CPC-containing mouthwashes can temporarily reduce the intraoral viral load and infectivity in SARS-CoV-2 positive individuals. Nevertheless, potential risks and side effects due to regular antiseptic use such as ecological effects or adaptation of bacteria need to be considered.

CONCLUSIONS

The use of preprocedural mouthwashes containing antiseptics can be recommended according to currently available data, but further studies are needed, particularly on the effects on other viruses besides SARS-CoV-2. When selecting a specific antiseptic, the biggest data basis currently exists for CHX, CPC, EO, or combinations thereof.

CLINICAL RELEVANCE

Preprocedural mouthwashes containing antiseptics can serve as part of a bundle of measures for protection of dental personnel despite some remaining ambiguities and in view of potential risks and side effects.