The effect of a polyhexamethylene biguanide mouthrinse compared with a triclosan rinse and a chlorhexidine rinse on bacterial counts and 4-day plaque re-growth

Preparation and Antimicrobial Activity of a Film-Forming Polyhexamethylene Biguanide Teat Disinfectant

Bovine mastitis caused by infectious pathogens can lead to a decline in production performance and an increase in elimination rate, resulting in huge losses to the dairy industry. This study aims to prepare a novel dairy cow teat disinfectant with polyhexamethylene biguanide (PHMB) as the main bactericidal component and to evaluate its bactericidal activity in vitro and its disinfection effect in dairy cow teats. PHMB disinfectant with a concentration of 3 g/L was prepared with PVA-1788, propylene glycol and glycerol as excipients. When the dilution ratio is 1:4800 and the action time is 5 min, the PHMB teat disinfectant can reduce the four types of bacteria (S. agalactiae ATCC 12386, S. dysgalactiae ATCC 35666, S. aureus ATCC 6538, and E. coli ATCC 8099) by 99.99%. PHMB teat disinfectant applied on the skin of rabbits with four bacteria types achieved an average log10 reduction greater than 4. After 30 s of PHMB teat disinfectant dipping, the bacteria of cow teats were counted prior to disinfection. The mean log10 reduction in bacteria on the skin surface of 12 cows ranged from 0.99 to 3.52 after applying the PHMB teat disinfectant for 10 min. After 12 h, the PHMB teat disinfectant achieved an average log10 reduction in bacteria from 0.27 to 0.68 (compared with that prior to disinfection). These results suggested that PHMB teat disinfection has the potential to prevent and treat mastitis-causing bacteria in dairy herds.

Could polyhexanide and chlorine dioxide be used as an alternative to chlorhexidine? A systematic review

BACKGROUND

Maintenance of oral microbiota balance is the simplest way to prevent infectious oral diseases, through controlling dental biofilm. Combined use of mouthwash and mechanical removal has been shown to be a very effective way for this.

OBJECTIVES

To identify clinical studies comparing the antimicrobial effect and possible adverse effects and/or side effects of chlorhexidine-based mouthwashes with those of mouthwashes containing chlorine dioxide and/or polyhexanide, for controlling oral microbiota.

DESIGN AND SETTING

Systematic review designed by the stomatology sector of postgraduation in applied dental sciences of Bauru Dentistry School, University of São Paulo, Brazil.

METHODS

A systematic review was conducted using online databases (PubMed, Embase, Web of Science and Science Direct) up to April 8, 2020. The search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

The studies included comprised eight articles published between 2001 and 2017. A total of 295 young adults, adults and elderly people were evaluated (males 44.75% and females 55.25%). Three articles compared polyhexanide with chlorhexidine and five articles compared chlorine dioxide with chlorhexidine. No studies comparing all three mouthwashes were found. The concentrations of the study solutions were quite varied, and all rinses had an antimicrobial effect. In four studies, it was stated that no side effects or adverse effects had been found. Three studies did not address these results and only one study addressed side effects and/or adverse effects.

CONCLUSION

Mouthwashes containing chlorine dioxide and polyhexanide are viable alternatives to chlorhexidine, since they reduce oral biofilm and have little or no reported side or adverse effects.

Effect of Polyhexamethylene Biguanide in Combination with Undecylenamidopropyl Betaine or PslG on Biofilm Clearance

Hospital-acquired infection is a great challenge for clinical treatment due to pathogens’ biofilm formation and their antibiotic resistance. Here, we investigate the effect of antiseptic agent polyhexamethylene biguanide (PHMB) and undecylenamidopropyl betaine (UB) against biofilms of four pathogens that are often found in hospitals, including Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli, Gram-positive bacteria Staphylococcus aureus, and pathogenic fungus, Candida albicans. We show that 0.02% PHMB, which is 10-fold lower than the concentration of commercial products, has a strong inhibitory effect on the growth, initial attachment, and biofilm formation of all tested pathogens. PHMB can also disrupt the preformed biofilms of these pathogens. In contrast, 0.1% UB exhibits a mild inhibitory effect on biofilm formation of the four pathogens. This concentration inhibits the growth of S. aureus and C. albicans yet has no growth effect on P. aeruginosa or E. coli. UB only slightly enhances the anti-biofilm efficacy of PHMB on P. aeruginosa biofilms. However, pretreatment with PslG, a glycosyl hydrolase that can efficiently inhibit and disrupt P. aeruginosa biofilm, highly enhances the clearance effect of PHMB on P. aeruginosa biofilms. Meanwhile, PslG can also disassemble the preformed biofilms of the other three pathogens within 30 min to a similar extent as UB treatment for 24 h.

Adjunctive Antiseptic Irrigation of Periodontal Pockets: Effects on Microbial and Cytokine Profiles

To evaluate the effect of adjunctive antiseptic irrigation of periodontal pockets on microbial and cytokine profiles. Fifty-nine patients with severe periodontitis were allocated to one of three groups for scaling and root planing facilitated with different adjunctive antiseptics: 1% polyhexamethyleneguanidine phosphate (PHMG-P) (n = 19), 0.2% chlorhexidine (CHX) (n = 21) or distilled water (n = 19). Gingival crevicular fluid and subgingival bacterial samples were collected at baseline, and at 2 weeks, and 1 and 4 months. The levels of interleukin (IL)-1β, IL-8, IL-10, and IL-17A, matrix metalloproteinase (MMP)-8, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum,Aggregatibacter actinomycetemcomitans, and Prevotella intermedia were determined. There were no intergroup differences in cytokine concentrations and bacterial counts at any follow-up, however, varying patterns were observed. In the PHMG-P and water groups IL-1β expression peaked at 2 weeks and then gradually declined. In all three groups, the dynamics of MMP-8 concentration were non-linear, increasing by 2 weeks and then declining to below baseline (p > 0.05). P. gingivalis and T. forsythia declined within the first month and increased thereafter, not regaining the baseline level. Adjunctive antiseptic treatment was associated with changes in biomarkers and bacterial counts in the course of the study. The effects of adjunctive antiseptic irrigation were limited in the applied protocol.

Monitoring and controlling bacteria in pharmaceutical industries water system

AIM

This research aimed to monitor pharmaceutical water system by sampling water from all treatment stages, identify bacterial isolates from each phase and determine the most suitable methods to control them.

METHODS AND RESULTS

Water samples were collected and examined from pharmaceutical water system in a pharmaceutical factory in Giza, Egypt during 12 months, once per month (from December 2017 to November 2018) from 15 points covering all stages of the treatment process starting from wells, pre-treatment points; treatment points ending with purified points which are the main source of water used in all pharmaceutical process. In all, 216 water samples were collected and examined, 156 isolates were selected according to morphological characteristics. VITEK system 2 (BioMérieux) was used for identification of all isolates resulting in 24 different identified bacteria. Antibiotic assay test using disc diffusion methods were carried out using seven antibiotics from different groups. Several disinfectants were also examined for efficacy against the isolates to control micro-organisms in water treatment stage and manufacturing area. The effect of different preservatives (parabens, acids and alcohols) in various pharmaceutical formulas was also tested on bacterial isolates, 63% of formulas were effective against all bacterial isolates.

CONCLUSION

Ciprofloxacin was the most effective antibiotic, mixture of 0·45% peracetic acid plus 2·2% of hydrogen peroxide (Minncare 1%) was maximally effective disinfectant, and Cronobacter sakazakii was the most resistant micro-organism against 22·7% of tested preservatives.

SIGNIFICANCE AND IMPACT OF THE STUDY

Controlling pharmaceutical manufacturing operation from pathogenic bacteria that affect the quality of drugs.

Potential of Novel Bacterial Cellulose Dressings Chemisorbed with Antiseptics for the Treatment of Oral Biofilm Infections

Infections of the oral cavity are caused by multicellular communities of microbes, referred to as biofilms. Due to the high tolerance of biofilms to antibiotics and specific conditions within the oral cavity, there is an ongoing search for carriers that are able to deliver high local concentrations of potent antimicrobials that can eradicate pathogenic biofilms. Bacterial cellulose, owing to its high flexibility, absorbance, and release potential, meets these demands. In this work we chemisorbed bacterial cellulose with antiseptics containing povidone-iodine or polihexanide and analyzed their ability to eradicate in vitro biofilms formed by oral pathogens, such as Aggregatibacter actinomycetemcomitans, Enterococcus faecalis, Candida albicans, Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa. In tests performed by means of standard laboratory methods and with a long contact time (24 h), all antiseptics released from the cellulose dressings displayed a very high antibiofilm efficacy. On the other hand, when conditions imitating the oral cavity were used and cellulose dressings were applied for a 0.5–1 h contact time, the antiseptics released from the dressings displayed lower, though still acceptable, activity. Our findings indicate that besides species-specific resistance to particular antiseptic agents, environmental and experimental settings play an essential role in outcomes. Finally, in a proof-of-concept experiment performed in an oral cavity typodont model, we demonstrated the high flexibility and adhesiveness of antiseptic-containing cellulose dressings. Our novel findings, if developed in further studies, may lead to the introduction of new types of dressings that are able to efficiently deal with biofilm infections of the oral cavity.

A novel zinc oxide eugenol modified by polyhexamethylene biguanide: Physical and antimicrobial properties

This study was to prepare and screen a novel root canal sealing agent modified by polyhexamethylene biguanide (PHMB) that was in accordance with the ISO 6876:2001 standard and to study its physical and antimicrobial properties. The modified sealers were produced by mixing a certain amount of zinc oxide with eugenol containing different concentrations of PHMB (0.05, 0.1, 0.2, 0.4, 0.6 and 0.8%) at a ratio of 1:1 (w/v). The setting time, flow, film thickness, solubility and dimensional change after solidifying were assessed to screen out the modified sealing agents that the physical properties met the mentioned standards. The modified direct contact test (DCT) was used to evaluate the antimicrobial activity against Enterococcus faecalis. The results suggested that when the concentrations of PHMB were 0.05, 0.1 and 0.2%, the modified root canal sealers showed the best performance in physical and antimicrobial properties.

Polyhexamethylene guanidine phosphate irrigation as an adjunctive to scaling and root planing in the treatment of chronic periodontitis

OBJECTIVE

To evaluate the efficacy of adjunctive polyhexamethylene guanidine (PHMG) phosphate irrigation in periodontal treatment.

MATERIALS AND METHODS

The subjects comprised 59 patients with severe chronic periodontitis. Plaque index, bleeding on probing (BOP) and pocket probing depths (PPD) were recorded. The subjects were randomly allocated to one of three groups for scaling and root planning, with different adjunctive irrigants: 1% PHMG phosphate (19 subjects), 0.2% chlorhexidine (21 subjects) and distilled water (19 subjects). Patients were recalled after two weeks, one month and then after 4, 6 and 12 months.

RESULTS

In all groups, treatment resulted in considerable improvement of the observed clinical parameters. There were no intergroup differences in plaque index and BOP at any time point, but significant differences in PPD at one, four and six months. By the end of the study no intergroup differences in PPDs persisted. While post study surgical treatment needs decreased in all three groups, no intergroup differences were observed in the number of deep periodontal pockets.

CONCLUSIONS

Irrigation with PHMG phosphate significantly reduces PPDs in the short-term, but has no significant long-term effect on the mean pocket depth.

Effect of polyhexamethylene biguanide functionalized silver nanoparticles on the growth of Staphylococcus aureus

Polyhexamethylene biguanide (PHMB) was used as a stabilizing ligand to synthesize uniform silver nanoparticles (Ag NPs). The effects and action mechanism of PHMB functionalized Ag NPs (Ag NPs-PHMB) on the growth of the Gram-positive bacteria Staphylococcus aureus were investigated. The results showed that a high concentration Ag NPs-PHMB could be obtained and prepared particles were fairly uniform. Prepared Ag NPs-PHMB enhanced the bactericidal effect and the log kill reached 5.06 when S. aureus was exposed to Ag NPs-PHMB for 20 min. Ag NPs-PHMB caused damage to cell wall, a decrease in the membrane fluidity, and leakage of K+, Mg2+, ATP and proteins from the cell, eventually leading to the death of S. aureus.

Toxicological assessment of polyhexamethylene biguanide for water treatment

Polyhexamethylene biguanide (PHMB) is an antiseptic with antiviral and antibacterial properties used in a variety of products including wound care dressings, contact lens cleaning solutions, perioperative cleansing products, and swimming pool cleaners. There are regulatory concerns with regard to its safety in humans for water treatment. We decided to assess the safety of this chemical in Sprague-Dawley rats. PHMB was administered in a single dose by gavage via a stomach tube as per the manufacturer's instruction within a dose range of 2 mg/kg to 40 mg/kg. Subchronic toxicity studies were also conducted at doses of 2 mg/kg, 8 mg/kg and 32 mg/kg body weight and hematological, biochemical and histopathological findings of the major organs were assessed. Administration of a dose of 25.6 mg/kg, i.e. 1.6 mL of 0.4% PHMB solution (equivalent to 6.4x10(3) mg/L of 0.1% solution) resulted in 50% mortality. Histopathological analysis in the acute toxicity studies showed that no histopathological lesions were observed in the heart and kidney samples but 30% of the animals had mild hydropic changes in zone 1 of their liver samples, while at a dosage of 32 mg/kg in the subchronic toxicity studies, 50% of the animals showed either mild hepatocyte cytolysis with or without lymphocyte infiltration and feathery degeneration. Lymphocyte infiltration was, for the first time, observed in one heart sample, whereas one kidney sample showed mild tubular damage. The acute studies showed that the median lethal dose (LD50) is 25.6 mg/kg (LC50 of 1.6 mL of 0.4% PHMB. Subchronic toxicological studies also revealed few deleterious effects on the internal organs examined, as seen from the results of the biochemical parameters evaluated. These results have implications for the use of PHMB to make water potable.

Novel negative pressure wound therapy with instillation and the management of diabetic foot infections

PURPOSE OF REVIEW

The use of negative pressure wound therapy with instillation (NPWTi) in complex or difficult-to-treat acute and chronic wounds has expanded rapidly since the introduction of commercially available NPWTi systems. We summarize the evidence related to NPWTi and particularly focus on the application of this technology in diabetic foot ulcers, diabetic foot infections and postoperative diabetic wounds.

RECENT FINDINGS

The benefits of negative pressure wound therapy (NPWT) are well documented in the treatment of complex acute and chronic wounds, including noninfected postoperative diabetic wounds and diabetic foot ulcers. Combining intermittent wound irrigation with NPWT may offer additional benefits compared to NPWT alone, including further reduction of wound bed bioburden, increased granulation tissue formation and provision of wound irrigation in a sealed environment, thus preventing potential cross-contamination events. Recently, available evidence suggests that adjunctive NPWTi may be superior to standard NPWT in the management of diabetic infections following surgical debridement and may promote granulation tissue formation in slow-to-heal wounds.

SUMMARY

Available evidence relating to the utilization of NPWTi in diabetic foot infections is promising but limited in quality, being derived mostly from case series or small retrospective or prospective studies. In order to confirm or refute the potential benefits of NPWTi in this patient cohort, well designed randomized controlled studies are required that compare NPWTi to NPWT or standard wound care methodologies.

Antimicrobial activity of polyhexamethylene guanidine phosphate in comparison to chlorhexidine using the quantitative suspension method

Background

Polyhexamethylene guanidine phosphate (PHMG-P) belongs to the polymeric guanidine family of biocides and contains a phosphate group, which may confer better solubility, a detoxifying effect and may change the kinetics and dynamics of PHMG-P interactions with microorganisms. Limited data regarding PHMG-P activity against periodontopathogenic and cariogenic microorganisms necessitates studies in this area. Aim is to evaluate polyhexamethylene guanidine phosphate antimicrobial activity in comparison to chlorhexidine.

Methods

Quantitative suspension method was used enrolling Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Streptococcus mutans and Lactobacillus acidophilus.

Results

Both tested antiseptics at their clinically-used concentrations, of 0.2% (w/v) and 1% (w/v), correspondingly provided swift bactericidal effects against S. aureus, P. aeruginosa, E. coli andC. albicans, A. actinomycetemcomitans and P. gingivalis with reduction factors higher than 6.0. Diluted polyhexamethylene guanidine phosphate and chlorhexidine to 0.05% continued to display anti-bacterial activity and decreased titers of standard quality control, periopathogens to below 1.0 × 10³ colony forming units/ml, albeit requiring prolonged exposure time. To achieve a bactericidal effect against S. mutans, both antiseptics at all concentrations required a longer exposure time. We found that a clinically-used 1% of polyhexamethylene guanidine phosphate concentration did not have activity against L. acidophilus.

Conclusion

High RF of polyhexamethylene guanidine phosphate and retention of bactericidal effects, even at 0.05%, support the use of polyhexamethylene guanidine phosphate as a biocide with sufficient anti-microbial activity against periopathogens. Polyhexamethylene guanidine phosphate displayed bactericidal activity against periopathogens and S. mutans and could potentially be applied in the management of oral diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12941-015-0097-x) contains supplementary material, which is available to authorized users.

An effective and biocompatible antibiofilm coating for central venous catheter

The aim of this study was to investigate the in vitro and in vivo efficacy and the tissue reaction of an antibiofilm coating composed of xylitol, triclosan, and polyhexamethylene biguanide. The antimicrobial activity was analyzed by a turbidimetric method. Scanning electron microscopy was used to evaluate the antiadherent property of central venous catheter (CVC) fragments impregnated with an antibiofilm coating (I-CVC) in comparison with noncoated CVC (NC-CVC) fragments. Two in vivo assays using subcutaneous implantation of NC-CVC and I-CVC fragments in the dorsal area of rats were performed. The first assay comprised hematological and microbiological analysis. The second assay evaluated tissue response by examining the inflammatory reactions after 7 and 21 days. The formulation displayed antimicrobial activity against all tested strains. A biofilm disaggregation with significant reduction of microorganism's adherence in I-CVC fragments was observed. In vivo antiadherence results demonstrated a reduction of early biofilm formation of Staphylococcus aureus ATCC 25923, mainly in an external surface of the I-CVC, in comparison with the NC-CVC. All animals displayed negative hemoculture. No significant tissue reaction was observed, indicating that the antibiofilm formulation could be considered biocompatible. The use of I-CVC could decrease the probability of development of localized or systemic infections.

Mucoadhesive system formed by liquid crystals for buccal administration of poly(hexamethylene biguanide) hydrochloride

Antimicrobial approaches are valuable in controlling the development of buccal diseases, but some antibacterial agents have a short duration of activity. Therefore, the development of prolonged delivery systems would be advantageous. Liquid crystalline systems comprising monoolein (GMO)/water have been considered to be a potential vehicle to deliver drugs to the buccal mucosa because of the phase properties that allow for controlled drug release as well as its mucoadhesive properties. Therefore, the aim of this study was to develop a GMO/water system for the slow release of poly(hexamethylene biguanide) hydrochloride (PHMB) on the buccal mucosa and test the properties of this system with regard to swelling, release profile, antimicrobial activity, and strength of mucoadhesion, with the overall goal of treating buccal infections. The tested systems were capable of modulating drug release, which is controlled by diffusion of the drug throughout the system. Furthermore, PHMB appeared to improve the mucoadhesive properties of the system and may synergistically act with the drug to promote antimicrobial activity against S. mutas and C. albicans, indicating that liquid crystals may be suitable for the administration of PHMB on the buccal mucosa. Therefore, this system could be proposed as a novel system for mucoadhesive drug delivery.

In vitro efficacy of cold atmospheric pressure plasma on S. sanguinis biofilms in comparison of two test models

Dental plaque critically affects the etiology of caries, periodontitis and periimplantitis. The mechanical removal of plaque can only be performed partially due to limited accessibility. Therefore, plaque still represents one of the major therapeutic challenges. Even though antiseptic mouth rinses reduce the extent of biofilm temporarily, plaque removal remains incomplete and continuous usage can even result in side effects. Here we tested argon plasma produced by kinpen09 as one option to inactivate microorganisms and to eliminate plaque. S. sanguinis biofilms cultivated in either the European Biofilm Reactor (EUREBI) or in 24 well plates were treated with argon plasma. In both test systems a homogeneous, good analyzable and stable biofilm was produced on the surface of titan plates within 72 h (>6,9 log10 CFU/ml). Despite the significantly more powerful biofilm production in EUREBI, the difference of 0.4 log10 CFU/ml between EUREBI and the 24 well plates was practically not relevant. For that reason both test models were equally qualified for the analysis of efficacy of cold atmospheric pressure plasma. We demonstrate a significant reduction of the biofilm compared to the control in both test models. After plasma application of 180 s the biofilm produced in EUREBI or in 24 well plates was decreased by 0.6 log10 CFU/ml or 0.5 log10 CFU/ml, respectively. In comparison to recently published studies analyzing the efficacy of kinpen09, S. sanguinis produces a hardly removable biofilm. Future investigations using reduced distances between plasma source and biofilm, various compositions of plasma and alternative plasma sources will contribute to further optimization of the efficacy against S. sanguinis biofilms.

Antimicrobial penetration and efficacy in an in vitro oral biofilm model

The penetration and overall efficacy of six mouthrinse actives was evaluated by using an in vitro flow cell oral biofilm model. The technique involved preloading biofilm cells with a green fluorescent dye that leaked out as the cells were permeabilized by a treatment. The loss of green color, and of biomass, was observed by time-lapse microscopy during 60 min of treatment under continuous flow conditions. The six actives analyzed were ethanol, sodium lauryl sulfate, triclosan, chlorhexidine digluconate (CHX), cetylpyridinium chloride, and nisin. Each of these agents effected loss of green fluorescence throughout biofilm cell clusters, with faster action at the edge of a cell cluster and slower action in the cluster center. The time to reach half of the initial fluorescent intensity at the center of a cell cluster, which can be viewed as a combined penetration and biological action time, ranged from 0.6 to 19 min for the various agents. These times are much longer than the predicted penetration time based on diffusion alone, suggesting that anti-biofilm action was controlled more by the biological action time than by the penetration time of the active. None of the agents tested caused any removal of the biofilm. The extent of fluorescence loss after 1 h of exposure to an active ranged from 87 to 99.5%, with CHX being the most effective. The extent of fluorescence loss in vitro, but not penetration and action time, correlated well with the relative efficacy data from published clinical trials.

Antimicrobial efficacy of 3 oral antiseptics containing octenidine, polyhexamethylene biguanide, or Citroxx: can chlorhexidine be replaced?

BACKGROUND

Use of oral antiseptics decreases the bacterial load in the oral cavity.

OBJECTIVE

To compare the antimicrobial activity of 3 novel oral antiseptics with that of chlorhexidine, which is considered the "gold standard" of oral hygiene.

DESIGN

Comparative in vitro study.

METHODS

Four common oral microorganisms (Streptococcus sanguinis, Streptococcus mutans, Candida albicans, and Fusobacterium nucleatum) were tested under standard conditions and at different concentrations, by use of a broth dilution assay and an agar diffusion assay and by calculating the log10 reduction factor (RF). The antimicrobial activity of each antiseptic was assessed by counting the difference in bacterial densities (ie, the log10 number of colony-forming units of bacteria) before and after the disinfection process.

RESULTS

The oral antiseptics containing octenidine (with an RF in the range of 7.1-8.24 CFU/mL) and polyhexamethylene biguanide (with an RF in the range of 7.1-8.24 CFU/mL) demonstrated antimicrobial activity comparable to that of chlorhexidine (with an RF in the range of 1.03-8.24 CFU/mL), whereas the mouth rinse containing Citroxx (Citroxx Biosciences; with an RF in the range of 0.22-1.36 CFU/mL) showed significantly weaker antimicrobial efficacy. Overall, octenidine and polyhexamethylene biguanide were more active at lower concentrations.conclusion. Oral antiseptics containing the antimicrobial agent octenidine or polyhexamethylene biguanide may be considered as potent alternatives to chlorhexidine-based preparations.

Effect of lactoperoxidase on the antimicrobial effectiveness of the thiocyanate hydrogen peroxide combination in a quantitative suspension test

BACKGROUND

The positive antimicrobial effects of increasing concentrations of thiocyanate (SCN-) and H2O2 on the human peroxidase defence system are well known. However, little is known about the quantitative efficacy of the human peroxidase thiocyanate H2O2 system regarding Streptococcus mutans and sanguinis, as well as Candida albicans. The aim of this study was to evaluate the effect of the enzyme lactoperoxidase on the bactericidal and fungicidal effectiveness of a thiocyanate-H2O2 combination above the physiological saliva level. To evaluate the optimal effectiveness curve, the exposure times were restricted to 1, 3, 5, and 15 min.

RESULTS

The bactericidal and fungicidal effects of lactoperoxidase on Streptococcus mutans and sanguinis and Candida albicans were evaluated by using two test mixtures of a 2.0% (w/v; 0.34 M) thiocyanate and 0.4% (w/v; 0.12 M) hydrogen peroxide solution, one without and one with lactoperoxidase. Following the quantitative suspension tests (EN 1040 and EN 1275), the growth of surviving bacteria and fungi in a nutrient broth was measured. The reduction factor in the suspension test without lactoperoxidase enzyme was < 1 for all three tested organisms. Thus, the mixtures of 2.0% (w/v; 0.34 M) thiocyanate and 0.4% (w/v; 0.12 M) hydrogen peroxide had no in vitro antimicrobial effect on Streptococcus mutans and sanguinis or Candida albicans. However, the suspension test with lactoperoxidase showed a high bactericidal and fungicidal effectiveness in vitro.

CONCLUSION

The tested thiocyanate and H2O2 mixtures showed no relevant antimicrobial effect. However, by adding lactoperoxidase enzyme, the mixtures became not only an effective bactericidal (Streptococcus mutans and sanguinis) but also a fungicidal (Candida albicans) agent.

Maximum inhibitory dilution of mouthwashes containing chlorhexidine and polyhexamethylene biguanide against salivary Staphylococcus aureus

Objective:

The aim of the present study was to determine the in vitro maximum inhibitory dilution (MID) of two chlorhexidine-based oral mouthwashes (CHX): Noplak®, Periogard®, and one polyhexamethylene biguanide-based mouthwash (PHMB): Sanifill Premium® against 28 field Staphylococcus aureus strains using the agar dilution method.

Materials and Methods:

For each product, decimal dilutions ranging from 1/10 to 1/655,360 were prepared in distilled water and added to Mueller Hinton Agar culture medium. After homogenization, the culture medium was poured onto Petri dishes. Strains were inoculated using a Steers multipoint inoculator and dishes were incubated at 37°C for 24hours. For reading, MID was considered as the maximum dilution of the mouthwash still capable of inhibiting microbial growth.

Results:

Sanifill Premium® inhibited the growth of all strains at 1/40 dilution and of 1 strain at 1/80 dilution. Noplak® inhibited the growth of 23 strains at 1/640 dilution and of all 28 strains at 1/320 dilution. Periogard® showed inhibited growth of 7 strains at 1/640 dilution and of all 28 strains at 1/320 dilution. Data were submitted to Kruskal-Wallis statistical test, showing significant differences between the mouthwashes evaluated (p<0.05). No significant difference was found between Noplak® and Periogard® (p>0.05). Sanifill Premium® was the least effective (p<0.05).

Conclusion:

It was concluded that CHX-based mouthwashes present better antimicrobial activity against S. Aureus than the PHMB-based mouthwash.

The Peritoneal Explant Test for Evaluating Tissue Tolerance to Mouthrinses

The tissue cultures of explants of neonatal rat peritoneum have been demonstrated to be a sensitive test for tissue compatibility with wound antiseptics. The present study investigated the suitability of this method to assess the relative toxicity of mouthrinses to tissue. Mouthrinses containing 0.1% chlorhexidine (Chlorhexamed Fluid 0.1%) (A), 0.3% triclosan (Colgate) (B), essential oil in ethanolic solution (Listerine) (C), and amine/stannous fluoride (Meridol) (D) were tested at use concentration and in dilutions of 10, 1, and 0.1% with exposure times of 1, 10, and 30 min, respectively. The mouthrinses (test) and Ringer's solutions (control) were applied to opened rat peritoneum. After thorough irrigation with Ringer's solution, a piece of peritoneum was removed and 1 x 1 mm explants were cut. The explants were cultivated with a bovine serum culture medium in 24-well plates at 37 degrees C in a CO2 incubator (95% air, 5% CO2). After 10 days, the tissue proliferation for the explants was assessed by a stereo microscope at 10x magnification after ethanol fixing and hemalaun staining. With 24 grafts per test, the proliferation rate was calculated relative to a control, which was run for each mouthrinse and concentration/time combination. Data were analyzed using ANOVA (SPSS 11.0) and post-hoc paired t test. Statistical significance of all correlations was tested by setting the significance level at p < 0.05. At most concentrations, D caused significantly less tissue damage than A or B. There was no difference between C and A or C and B at 100%. However, the toxicity of C was significantly less than A or B at 10, 1, and 0.1%. C and D behaved similarly except for the 10% (30 min) and the 1% (10 min) solutions in which C was significantly less toxic. We concluded that the rat peritoneum explant test was demonstrated to be a sensitive test to assess the relative toxicity of mouthrinses to tissue.

In vitro antimicrobial activity of the novel polymeric guanidine Akacid plus

The bactericidal and fungicidal activity of Akacid plus, a novel polymeric compound of the cationic family of disinfectants, was compared with chlorhexidine digluconate using quality control strains of Staphylococcus aureus, Enterococcus hirae, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. In vitro activity was determined using the quantitative suspension tests described by the European Committee for Standardization. These use concentrations of 0.01-0.5% against bacterial strains/C. albicans, with 0.5-4% against A. niger, and exposure times of 5, 15 and 60 min in the presence and absence of 0.3% bovine albumin and with dilution in distilled and hard water. In the basic quantitative suspension test, Akacid plus destroyed all bacterial pathogens at a concentration of 0.1% in < or =5 min. Chlorhexidine was also highly active against S. aureus, E. coli and P. aeruginosa, but failed to eliminate E. hirae within 5 min. A high organic load reduced the bactericidal activity of both disinfectants slightly. Akacid plus showed fungicidal activity against C. albicans within 15-60 min and eliminated A. niger at a concentration of 1% in 5 min of contact. Chlorhexidine was fungicidal against C. albicans, but not against A. niger.