Fungicidal activity of human antimicrobial peptides and their synergistic interaction with common antifungals against multidrug-resistant Candida auris / Actividad fungicida de péptidos antimicrobianos humanos y su interacción sinérgica con antifúngicos comunes contra Candida auris multirresistente

Emergence of Candida auris, a multidrug-resistant yeast, demonstrates the urgent need for novel antifungal agents. Human antimicrobial peptides (AMPs) are naturally occurring molecules with wide spectrum antimicrobial activity, particularly against a variety of fungi. Therefore, this study examined the antifungal activity of seven different human AMPs against C. auris following the CLSI guidelines. The antifungal activity was further assessed using time kill curve and cell viability assays. For combination interaction, effectiveness of these peptides with three antifungals, fluconazole, amphotericin B, and caspofungin was done following standard protocols. To elucidate the antifungal mechanism, the effects of peptides on membrane permeability were investigated using propidium iodide staining method and confocal imaging. Antifungal susceptibility results showed that all the examined peptides possessed fungicidal effect against C. auris at different levels, with human β-defensin-3 being the most potent antifungal with MIC values ranging from 3.125 to 12.5 µg/ml. Time kill curves further confirmed the killing effect of all the tested peptides. Viability assay showed a significant decrease in the percentage of viable cells exposed to different inhibitory and fungicidal concentrations of each peptide (p < 0.01). Furthermore, peptides showed mostly synergistic interaction when combined with conventional antifungal drugs, with caspofungin showing 100% synergy when combined with different AMPs. As antifungal mechanism, peptides disrupted the membrane permeability at concentrations that correlated with the inhibition of growth. Overall, the findings of this study point towards the application of the tested peptides as a monotherapy or as a combination therapy with antifungal drugs to treat multidrug-resistant C. auris infections.(AU)

Fungicidal activity of human antimicrobial peptides and their synergistic interaction with common antifungals against multidrug-resistant Candida auris.

Emergence of Candida auris, a multidrug-resistant yeast, demonstrates the urgent need for novel antifungal agents. Human antimicrobial peptides (AMPs) are naturally occurring molecules with wide spectrum antimicrobial activity, particularly against a variety of fungi. Therefore, this study examined the antifungal activity of seven different human AMPs against C. auris following the CLSI guidelines. The antifungal activity was further assessed using time kill curve and cell viability assays. For combination interaction, effectiveness of these peptides with three antifungals, fluconazole, amphotericin B, and caspofungin was done following standard protocols. To elucidate the antifungal mechanism, the effects of peptides on membrane permeability were investigated using propidium iodide staining method and confocal imaging. Antifungal susceptibility results showed that all the examined peptides possessed fungicidal effect against C. auris at different levels, with human ß-defensin-3 being the most potent antifungal with MIC values ranging from 3.125 to 12.5 µg/ml. Time kill curves further confirmed the killing effect of all the tested peptides. Viability assay showed a significant decrease in the percentage of viable cells exposed to different inhibitory and fungicidal concentrations of each peptide (p < 0.01). Furthermore, peptides showed mostly synergistic interaction when combined with conventional antifungal drugs, with caspofungin showing 100% synergy when combined with different AMPs. As antifungal mechanism, peptides disrupted the membrane permeability at concentrations that correlated with the inhibition of growth. Overall, the findings of this study point towards the application of the tested peptides as a monotherapy or as a combination therapy with antifungal drugs to treat multidrug-resistant C. auris infections.

Oral Cavity and Candida albicans: Colonisation to the Development of Infection.

Candida colonisation of the oral cavity increases in immunocompromised individuals which leads to the development of oral candidiasis. In addition, host factors such as xerostomia, smoking, oral prostheses, dental caries, diabetes and cancer treatment accelerate the disease process. Candida albicans is the primary causative agent of this infection, owing to its ability to form biofilm and hyphae and to produce hydrolytic enzymes and candialysin. Although mucosal immunity is activated, from the time hyphae-associated toxin is formed by the colonising C. albicans cells, an increased number and virulence of this pathogenic organism collectively leads to infection. Prevention of the development of infection can be achieved by addressing the host physiological factors and habits. For maintenance of oral health, conventional oral hygiene products containing antimicrobial compounds, essential oils and phytochemicals can be considered, these products can maintain the low number of Candida in the oral cavity and reduce their virulence. Vulnerable patients should be educated in order to increase compliance.

Tolerance of Listeria monocytogenes to biocides used in food processing environments.

Listeria monocytogenes is a foodborne pathogen that causes a life-threatening disease in humans known as listeriosis. Contamination of food during processing is the main route of transmission of Listeria monocytogenes. Therefore, biocides play a crucial role in food processing environments as they act as the first line of defense in the prevention and control of L. monocytogenes. Residues of biocides may be present at sublethal concentrations after disinfection. This, unfortunately, subjects L. monocytogenes to selection pressure, giving rise to tolerant strains, which pose a threat to food safety and public health. This review will give a brief description of L. monocytogenes, the clinical manifestation, treatment of listeriosis as well as recently recorded outbreaks. The article will then discuss the current literature on the ability of L. monocytogenes strains to tolerate biocides especially quaternary ammonium compounds as well as the mechanisms of tolerance towards biocides including the activation of efflux pump systems.

Infection control in dentistry during COVID - 19 pandemic: what has changed?

The novel coronavirus (COVID-19) pandemic has emerged disrupting many socio-economical and healthcare aspects across the world. This virus can be transmitted by symptomatic and asymptomatic individuals through saliva and contact. Due to its airborne transmission, aerosols created by natural activities and during dental treatment of infected individuals have become a potential vehicle of transmission and threat. The objective of this review was to assess the existing infection control measures taken in dental health-care settings and suggest modifications to reduce the transmission of novel coronavirus. This is a general review publication. Literature search was made at National Library of Medicine, Pubmed using key words such as "dentistry and COVID", "dentistry and COVID and infection control". Publications related to behaviour, education, ethics, treatment and childcare were excluded. Publications describing general aspects of infection control were reviewed. Keyword "Dentistry and COVID and Infection control" generated 70 publications which were reviewed. Infection control measures in dentistry are designed to minimise cross transmission mainly of blood borne pathogens. The unique nature of COVID-19 including highly infectious and transmissibility, and the ability to survive for a long time in the environment requires special attention and modification to the existing infection control measures which are highlighted here. In conclusion, a modified infection prevention and control (IPC) regime will protect the dental practitioner, assistant and staff, patients and the community. During the pandemic, drastic measures are necessary, however, during an endemic period measures can be remodified as necessary.

Mezoneuron benthamianum inhibits cell adherence, hyphae formation, and phospholipase production in Candida albicans.

The aim of this study was to evaluate the phytochemical constituents, antioxidant, antifungal, and anti-virulence activities of traditionally used Mezoneuron benthamianum leaves. Extracts were prepared using acetone and methanol, and the preliminary phytochemical screening was performed. The antioxidant activity was studied using the DPPH method. Anti-Candida albicans activity was established and the effect on the germ tube and phospholipase production, as well as on the host cell adherence was assessed. The extracts showed the presence of anthraquinones, cardiac glycosides, flavonoids, reducing sugars, saponins, steroids, tannins, and terpenoids. Gallic acid and trans-resveratrol were among the predominant phytochemicals found in M. benthamianum. The crude extracts presented significantly higher antioxidant activity than the ascorbic acid standard. At 0.39 mg/mL, acetone extract inhibited the growth of Candida albicans. At lower concentrations (200-50 µg/mL), it significantly inhibited the adherence ability (up to 51%), formation of hyphae (up to 65%), and the production of phospholipase. In conclusion, at high concentrations, M. benthamianum kills C. albicans, and at lower concentrations, it can inhibit the virulence properties of this pathogen. This study on crude extract validates the traditional use of this plant. However, further research is required to establish the anti-virulence activity of the two compounds and their therapeutic potential.

Quantitative Analysis of Selected Microorganisms Present at Various Sites in a Prosthetics Clinic and Dental Laboratory during Complete Denture Fabrication.

Background: Contamination with oral commensals and pathogenic microorganisms, and cross contamination between clinic and laboratory can occur. The amount of contamination has not been determined. Methods: Samples from different clinical and laboratory stages before and after disinfection (17 sites, 10 samples per stage) were collected. Laboratory surfaces and equipment were swabbed for 10 days (11 sites). Swabs were cultured for total mixed flora, Streptococci, Lactobacilli, Staphylococcus aureus, aerobic Gram-negative bacteria (AGNB) and Candida. Knowledge of infection control among staff and students was assessed. Results: Clinic: In total, 30-40% of the samples overall were contaminated with mixed flora and Streptococci of >100 cfu/swab; >100 cfu of AGNB and Candida were present on 6% and 1% of samples; 2% contained <100 cfu of S. aureus. Laboratory: In total, 17-48% of the samples overall were contaminated with mixed flora and Streptococci of >100 cfu/swab; >100 cfu of AGNB were present on 11% of samples; none contained >100 cfu of Candida. Disinfection significantly reduced the level of all organisms. Knowledge of infection control was sufficient, but compliance was poor. Conclusion: Although the count of mixed flora was high, potential pathogens such as S. aureus and Candida were low. In immunocompromised patients, this can become a problem.

Dodonaea viscosa var angustifolia derived 5,6,8-trihydroxy-7,4' dimethoxy flavone inhibits ergosterol synthesis and the production of hyphae and biofilm in Candida albicans.

ETHNOPHARMACOLOGICAL RELEVANCE: Candida albicans is developing resistance to existing drugs increasing morbidity and mortality, which elevates an immediate need to explore new antifungal agents. Phytochemicals are an excellent source of therapeutic agents. We previously reported the antifungal activity of the crude extract of Dodonaea viscosa var. angustifolia Jacq. (DVA) from which a beneficial compound flavone: 5,6,8-trihydroxy-7,4' dimethoxy flavone (5,6,8-trihydroxy-7-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one) abbreviated as TMMC, was extracted. AIM OF THE STUDY: The present study evaluated the effect of a TMMC subfraction on biofilms, membrane stability, ergosterol biosynthesis and germ tube (GT) formation in Candida albicans. MATERIALS AND METHODS: Extracts were prepared and fractionated to obtain purified TMMC. Minimum inhibitory concentrations of TMMC were obtained and subinhibitory concentrations were selected for further studies. Confocal laser scanning microscopy (CLSM) was performed to assess the effect of TMMC on membrane permeability and sterol deposition using propidium iodide (PI) and filipin stains, respectively. RESULTS: Minimum inhibitory concentrations (MIC) and Minimum Fungicidal concentrations (MFC) of TMMC were 0.39 mg/mL and 1.56 mg/mL, respectively. TMMC inhibited biofilm formation and damaged mature biofilms at 0.39 mg/mL and 1.56 mg/mL, respectively. CLSM further confirmed the disruption and architectural changes in biofilms following treatment with TMMC. TMMC also inhibited GT formation and ergosterol biosynthesis in a concentration dependent manner, which was further confirmed by varying sterol distribution and membrane disruption in treated and untreated cells. CONCLUSIONS: With the multiple targets at different concentrations, TMMC warrants its potential use as antifungal drug against C. albicans. However further studies using animal models and more mechanistic approaches will be required.

Improved efficacy of antifungal drugs in combination with monoterpene phenols against Candida auris.

Emergence of Candida auris has been described as a global health threat due to its ability to cause invasive infections with high mortality rate and multidrug resistance. Novel drugs and therapies are required to target this organism and its pathogenicity. Anti-virulence approach and combination therapy have been proposed as alternatives in recent years. This study evaluated the virulence factors in C. auris, combination antifungal activity of phenolic compounds with antifungal drugs and determined effect of the most active compound on positive pathogenicity markers of C. auris. Antifungal susceptibility profile of 25 clinical isolates of C. auris against antifungal agents as well as against phenolic compounds was obtained using CLSI guidelines. Combination of the most active phenolic compound with antifungal drugs was determined. Effect of carvacrol on the virulence factors was also studied. Carvacrol was the most active phenol with median MIC of 125 µg/ml and its combination with fluconazole, amphotericin B, nystatin and caspofungin resulted synergistic and additive effects in 68%, 64%, 96% and 28%, respectively. Combination also reduced the MIC values of the drugs. All test strains showed adherence ability to epithelial cells and 96% of strains produced proteinase. None of the strains produced hyphae and phospholipase. At low concentrations, carvacrol significantly inhibited the adherence ability and proteinase production (both p < 0.01). Carvacrol has antifungal and anti-virulence activity against C. auris. It also showed an enhanced antifungal activity in combination with antifungal agents. Therefore it has potential to be developed into a novel antifungal agent.

Anti-acidogenic, anti-biofilm and slow release properties of Dodonaea viscosa var. angustifolia flavone stabilized polymeric nanoparticles.

OBJECTIVE: Dental caries is caused by plaque associated oral bacteria including a pioneer species Streptococcus mutans. It has ability to form biofilm and produce acids in the oral cavity. Many oral hygiene products containing plant derived compounds have been investigated for their anti-S. mutans activity. Dodonaea viscosa var. angustifolia (DVA), has been found to have this property. However, beneficial concentrations are difficult to maintain in the oral cavity due to continual saliva flow which can be overcome using nanotechnology. The aim of this study was to investigate the anti-acidogenic, anti-biofilm and slow release properties of DVA derived flavone stabilized polymeric nanoparticles. METHODS: Crude extract prepared from DVA leaves was fractionated to produce subfractions and the beneficial subfraction (F5.1) was obtained. Polymeric nanoparticles (PLGA-PEG) were prepared, stabilized with the DVA subfraction (F5.1/NPs) and characterized. Anti-S. mutans, anti-acidogenic and antibiofilm properties were determined. The subfraction release profile (substantivity) and cytotoxicity was determined. Results were analyzed using the Wilcoxon sum test (Mann-Whitney). RESULTS: F5.1/NPs showed anti-S. mutans property (MIC 1.56 mg/ml). Subinhibitory concentrations of these nanoparticles significantly reduced the acid production in S. mutans (p < 0.01) and also reduced the biofilm formation by 92%. The retention and slow release of the beneficial compound was detected up to 12 h, reaching 0.1 mg/ml concentration at pH 7.4 after 4 h and at pH 5.5 after 5 h. IC50 of F5.1/NPs was 62.5 µg/ml. CONCLUSION: the DVA flavone containing nanoparticles showed anticariogenic activity with improved substantivity. Therefore, they have potential for use to control dental caries.

Viability of Candida albicans in Denture Base Resin After Disinfection: A Preliminary Study.

PURPOSE: To quantify the depth of penetration of Candida albicans (C albicans) into a denture base resin and to investigate its viability after disinfection. MATERIALS AND METHODS: Heat-polymerizing polymethyl methacrylate plates were contaminated with C albicans, then washed, dried, and prepared for scanning electron microscopy (SEM). Vertical surfaces were cut, and the depth of any penetration was measured. For viability after disinfection, plates were contaminated, subjected to one of two disinfection techniques, and subcultures were taken to determine viability. RESULTS: The results showed that at 7, 14, and 21 days after exposure, the mean depth of penetration of C albicans was 33.9, 96.9, and 97.0 µm, respectively. The depth of penetration was time dependent, with the deepest being 631 µm at 21 days. Daily subcultures for 10 days revealed that penetrated cells remained viable and were not affected by the disinfectant. CONCLUSION: To the present authors' knowledge, this is the first time that the viability of denture base-penetrated C albicans has been shown, even after disinfection. The implication of these results is that denture resin is likely to be penetrated, especially in patients with chronic or recurrent denture stomatitis. If the C albicans remain viable, then the infected denture-fitting surfaces may have to be replaced by removing at least a 1-mm layer of contaminated resin.

Anti-acidogenic and anti-biofilm activity of 5,6,8-trihydroxy-7-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one.

OBJECTIVES: Crude extracts of Dodonaea viscosa var. angustifolia (DVA), has shown to have anticariogenic property. However the compound responsible for this activity has not been identified. The aim of this study was to investigate anti-acidogenic and anti-biofilm activity of a flavone 5,6,8-Trihydroxy-7-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one isolated from D. viscosa var. angustifolia (DVA) in cariogenic bacteria Streptococcus mutans. METHODS: The crude extract from DVA leaves was fractionated into six fractions (F1-F6) using chromatography. The Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentration (MBC) were determined. The effect of the six fractions on biofilm formation and acid production were investigated. The most active fraction (F5) was further fractionated, purified, identified and elucidated using GC-MS and NMR. The anticariogenic property of this purified compound was established. Results were analyzed using Wilcoxon rank-sum test (Mann-Whitney). RESULTS: The MIC and MBC of the fractions (F1-F6) and crude extract ranged from 0.39 to 12.5 mg/ml. F5 showed the lowest MBC. At 0.2 mg/ml, F5 reduced biofilm formation by 93.3% and reduced acid production in S. mutans. Subfraction F5.1 showed higher antimicrobial activity compared to the crude extract and F5. Purified F5.1 was identified as 5,6,8-Trihydroxy-7-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one (TMMC). TMMC inhibited biofilm formation at both 6 h (94% reduction) and 24 h (99% reduction), which was higher compared to the crude extract (87% reduction at 0.78 mg/ml after 6 h). TMMC also exhibited a higher inhibitory effect on acid production compared to the crude extract. CONCLUSION: Flavone 5,6,8-Trihydroxy-7-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one derived from DVA has anti-S. mutans, anti-biofilm and anti-acidogenic activity therefore it has a potential for use in the oral cavity to prevent dental caries.

Synergistic antifungal effect of cyclized chalcone derivatives and fluconazole against Candida albicans.

The occurrence of invasive fungal diseases, particularly in immunocompromised patients, is life-threatening and increases the economic burden. The rising problem of multi-drug resistance is becoming a major concern for clinicians. In addition, a repertoire of antifungal agents is far less in number than antibacterial drugs. To combat these problems, combination therapy has gained a lot of interest. We previously reported the synergistic interaction of some mono- and bis-dihydropyrimidinone and thione derivatives with fluconazole and amphotericin B for combination antifungal therapy. In this study we used the same approach and synthesized different azole and non-azole derivatives of mono-(M) and bis-(B) chalcones and evaluated their antifungal activity profile alone and in combination with the most commonly used antifungal drug - fluconazole (FLC) - against seven FLC susceptible and three FLC resistant clinically isolated Candida albicans strains. Based on the minimum inhibitory concentration results, the bis-derivatives showed lower MIC values compared to their mono-analogues. Both fractional inhibitory concentration index and isobologram results revealed mostly synergistic, additive or indifferent interactions between the tested compounds and FLC against different Candida isolates. None of the tested compounds showed any effect on energy dependent R6G efflux, revealing that they do not reverse the mechanism of drug efflux. However, surprisingly, these compounds profoundly decreased ergosterol biosynthesis and showed down regulation of ERG11 gene expression, which is the possible mechanism of reversal of azole drug resistance by these compounds. These results provide a platform for further research to develop pyrimidinone/thione ring containing compounds as promising new antifungal agents, which could be used in antifungal combination therapy.

Challenges in the Development of Antifungal Agents Against Candida: Scope of Phytochemical Research.

BACKGROUND: Infections caused by Candida have become a major source of morbidity and mortality. Limited numbers of drugs are available to treat these infections. Phytochemicals can be the major source of antifungal compounds. The aim of this publication was to review the current literature to assess the challenges and scope of phytochemical research in the development of new antifungal drugs. METHODS: Literature describing cellular nature of Candida, the development of drug resistance and target sites for the new drugs were assessed. Publications reporting antifungal activities of crude extracts of plants, their essential oils and identified chemical constituents were also summarised. RESULTS: The results showed that the development of new antifungal agents from natural sources is a complex process due to the cellular nature of Candida and the types of infections caused, such as superficial to life threatening systemic mycosis which necessitate systemic and topical use of drugs. Efficacy of the drugs in the presence of body fluids, normal flora and medical devices can also pose a challenge. Synthetic, semi-synthetic and natural compounds can be screened for their antifungal activities against emerging target sites using new cost effective techniques to increase throughput. Their efficacy, substantivity and site specific desired drug delivery can be enhanced using nanotechnology, hydrogel formulation and bio-adhesive technology. Finally, partnership between academic research laboratories and pharmaceutical industries is also necessary. CONCLUSION: Many challenges are identified in the development of new antifungal drugs, however phytochemicals are still the major source of new antifungal drugs and should be strategically explored.

Effect of Punica granatum on the virulence factors of cariogenic bacteria Streptococcus mutans.

Dental caries is caused by acids produced by biofilm-forming Streptococcus mutans from fermentable carbohydrates and bacterial byproducts. Control of these bacteria is important in the prevention of dental caries. This study investigated the effect of the fruit peel of Punica granatum on biofilm formation, acid and extracellular polysaccharides production (EPS) by S. mutans. Pomegranate fruit peels crude extracts were prepared. The Minimum bactericidal concentrations (MBC) were determined against S. mutans. At 3 sub-bactericidal concentrations, the effect on the acid production, biofilm formation and EPS production was determined. The results were analysed using Kruskal-Wallis and Wilcoxon Rank Sum Tests. The lowest MBC was 6.25 mg/mL. Punica granatum significantly inhibited acid production (p < 0.01). After 6 and 24 h, it significantly reduced biofilm-formation by 91% and 65% respectively (p < 0.01). The plant extract did not inhibit the production of soluble EPS in either the biofilm or the planktonic growth. However, it significantly reduced the insoluble EPS in the biofilm and the plantktonic (p = < 0.01) form of S. mutans. The crude extract of P. granatum killed cariogenic S. mutans at high concentrations. At sub-bactericidal concentrations, it reduced biofilm formation, acid and EPS production. This suggests that P. granatum extract has the potential to prevent dental caries.

Detection of cfxA2, cfxA3, and cfxA6 genes in beta-lactamase producing oral anaerobes.

Purpose The aim of this study was to identify ß-lactamase-producing oral anaerobic bacteria and screen them for the presence of cfxA and BlaTEM genes that are responsible for ß-lactamase production and resistance to ß-lactam antibiotics. Material and Methods Periodontal pocket debris samples were collected from 48 patients with chronic periodontitis and anaerobically cultured on blood agar plates with and without ß-lactam antibiotics. Presumptive ß-lactamase-producing isolates were evaluated for definite ß-lactamase production using the nitrocefin slide method and identified using the API Rapid 32A system. Antimicrobial susceptibility was performed using disc diffusion and microbroth dilution tests as described by CLSI Methods. Isolates were screened for the presence of the ß-lactamase-TEM (BlaTEM) and ß-lactamase-cfxA genes using Polymerase Chain Reaction (PCR). Amplified PCR products were sequenced and the cfxA gene was characterized using Genbank databases. Results Seventy five percent of patients carried two species of ß-lactamase-producing anaerobic bacteria that comprised 9.4% of the total number of cultivable bacteria. Fifty one percent of ß-lactamase-producing strains mainly Prevotella, Porphyromonas, and Bacteroides carried the cfxA gene, whereas none of them carried blaTEM. Further characterization of the cfxA gene showed that 76.7% of these strains carried the cfxA2 gene, 14% carried cfxA3, and 9.3% carried cfxA6. The cfxA6 gene was present in three Prevotella spp. and in one Porphyromonas spp. Strains containing cfxA genes (56%) were resistant to the ß-lactam antibiotics. Conclusion This study indicates that there is a high prevalence of the cfxA gene in ß-lactamase-producing anaerobic oral bacteria, which may lead to drug resistance and treatment failure.

Detection of cfxA2, cfxA3, and cfxA6 genes in beta-lactamase producing oral anaerobes

ABSTRACT Purpose The aim of this study was to identify β-lactamase-producing oral anaerobic bacteria and screen them for the presence of cfxA and BlaTEM genes that are responsible for β-lactamase production and resistance to β-lactam antibiotics. Material and Methods Periodontal pocket debris samples were collected from 48 patients with chronic periodontitis and anaerobically cultured on blood agar plates with and without β-lactam antibiotics. Presumptive β-lactamase-producing isolates were evaluated for definite β-lactamase production using the nitrocefin slide method and identified using the API Rapid 32A system. Antimicrobial susceptibility was performed using disc diffusion and microbroth dilution tests as described by CLSI Methods. Isolates were screened for the presence of the β-lactamase-TEM (BlaTEM) and β-lactamase-cfxA genes using Polymerase Chain Reaction (PCR). Amplified PCR products were sequenced and the cfxA gene was characterized using Genbank databases. Results Seventy five percent of patients carried two species of β-lactamase-producing anaerobic bacteria that comprised 9.4% of the total number of cultivable bacteria. Fifty one percent of β-lactamase-producing strains mainly Prevotella, Porphyromonas, and Bacteroides carried the cfxA gene, whereas none of them carried blaTEM. Further characterization of the cfxA gene showed that 76.7% of these strains carried the cfxA2 gene, 14% carried cfxA3, and 9.3% carried cfxA6. The cfxA6 gene was present in three Prevotella spp. and in one Porphyromonas spp. Strains containing cfxA genes (56%) were resistant to the β-lactam antibiotics. Conclusion This study indicates that there is a high prevalence of the cfxA gene in β-lactamase-producing anaerobic oral bacteria, which may lead to drug resistance and treatment failure.

The efficacy of disinfectants in the decontamination of dental unit water lines: an in vitro laboratory study.

OBJECTIVES/AIMS: This in vitro laboratory study compared the efficacy of water, sodium percarbonate (SPC) and chlorine dioxide (ClO2) solutions in the disinfection of dental unit water lines (DUWLs). MATERIALS AND METHODS: New DUWL tubes were cut, split open, and mono-culture and mixed-culture biofilms of Staphylococcus aureus, Enterococcus faecalis and Streptococcus mutans were grown. Harvested biofilms from the sectioned DUWL tubes were exposed to sterile distilled water, SPC or 5 and 10 p.p.m. ClO2 in both a stationary phase and through a constant flow. Bacterial counts were compared using the Kruskal-Wallis nonparametric rank test. RESULTS: In the mono-culture biofilms, SPC, 5 and 10 p.p.m. ClO2 significantly reduced all the test organisms (P<0.01). However, no significant difference was found between SPC and ClO2. In the mixed-culture biofilms exposed to disinfectant without flow, ClO2 significantly reduced the biofilm (P=0.02) compared with water and SPC. Similarly, in the constant flow study, ClO2 proved to be superior to water. CONCLUSION: At low concentrations, ClO2 with and without flow significantly reduced the mixed-culture biofilm grown in vitro on the sections of the DUWL tubes. Therefore, it has the potential to be used in the patient treatment water, as it is potable at these concentrations, and to decontaminate and limit the biofilm formation in the water lines.

Influence of cancer treatment on the Candida albicans isolated from the oral cavities of cancer patients.

PURPOSE: Cancer treatment causes mucositis and the manifestation of oral candidiasis. This study investigated the virulence properties and antifungal susceptibilities of Candida albicans isolated from cancer patients undergoing therapy. METHODS: C. albicans were isolated from 49 patients on cancer treatment and 21 healthy individuals and their virulence attributes measured. A correlation was determined between the length of treatment and the fungal counts and their virulence factors. RESULTS: Although Candida carriage was similar in all the study groups, high quantities of C. albicans and variety of Candida were found in cancer patients. Germ tubes were produced by all the strains. Significantly high number of yeast isolated from radiotherapy and chemotherapy produced large quantities of phospholipase compared to healthy individuals (p < 0.01). The length of chemotherapy was associated with an increase in the phospholipase production (p = 0.03) by the C. albicans. Proteinase production was seen in a significant number of isolates from the radiotherapy group (p < 0.01). Type of cancer treatment had no effect. Resistance to antifungal agents was low. CONCLUSIONS: High quantities of phospholipase were produced by C. albicans in cancer patients on therapy which also increased with the length of chemotherapy suggesting enhanced risk of oral and systemic infection. Therefore, during treatment, prophylactic topical antifungal therapy may be considered.

Virulence of oral Candida isolated from HIV-positive women with oral candidiasis and asymptomatic carriers.

OBJECTIVE: This study compared the virulence of oral Candida species isolated from human immunodeficiency virus (HIV)-positive women with and without oral candidiasis. STUDY DESIGN: Candida species were isolated from 197 women, and their virulence attributes were measured. RESULTS: Of the 197 women, 117 (59.4%) carried Candida. Of these, 15 (12.8%) had symptoms of oral candidiasis. Among highly active antiretroviral therapy (HAART)-naive patients, 33% were diagnosed with oral candidiasis, whereas 5.9% were asymptomatic carriers (P < .01). C. albicans was the predominant species, with higher virulence attributes than non-albicans Candida. Women diagnosed with oral candidiasis had higher levels of Candida (P = .02) than asymptomatic carriers. There was no difference in the CD4 counts and the virulence attributes of Candida from both the groups. CONCLUSIONS: This study indicates that oral candidiasis is mainly caused by high counts of C. albicans and suggests the importance of therapies targeting Candida counts in the oral cavity even in patients on HAART to reduce the development of infections.