Modulation of Candida albicans virulence in in vitro biofilms by oral bacteria.

Candida-associated denture stomatitis presents as erythema of the palatal mucosa and is caused by biofilms containing the fungus Candida albicans that co-reside with oral bacteria on the denture-fitting surface. This study aimed to assess the effect of several frequently encountered oral bacteria on the expression of C. albicans virulence factors in in vitro polymicrobial biofilms. Biofilms containing C. albicans and selected bacterial species were grown on denture acrylic, and analysed by microscopy and by qPCR for expression of putative virulence genes. Candida albicans-only biofilms showed limited hyphal production. Hyphal development was significantly (P < 0·001) increased when biofilms also contained four species of oral bacteria (Streptococcus sanguinis, Streptococcus gordonii, Actinomyces odontolyticus and Actinomyces viscosus), as was the expression of virulence genes (P < 0·05). Importantly, inclusion of Porphyromonas gingivalis in the biofilm consortium resulted in significant (P < 0·05) inhibition of virulence gene expression and production of hyphae. The in vitro expression of C. albicans virulence factors was modulated in polymicrobial biofilms. The complexity of this modulation was highlighted by the reversal of effects following introduction of a single bacterial species into a biofilm community. SIGNIFICANCE AND IMPACT OF THE STUDY: The impact of individual bacterial species on Candida albicans virulence highlights both the complexity of predicting infection mediated by polymicrobial communities and the potential for management through pro- or prebiotic therapy. The possibility to selectively modulate microbial virulence by addition of, or treatment with pro- or prebiotics avoids the use of conventional antimicrobial compounds, thus reducing the contribution to potential drug resistance. Understanding which bacterial species modulate virulence, and the mechanisms by which this occurs, particularly in biofilms, provides excellent foundations for further research questions, and the potential for novel clinical interventions.

Continuing dental education: evaluation of the effectiveness of a disinfection and decontamination course.

AIM: To evaluate a disinfection and decontamination dental postgraduate course run by the Wales Dental Postgraduate Deanery between 2008 and 2010. METHODS: Pre- and post-course multiple choice questionnaires were completed by 1177 course attendees. Mean scores before and after participation on the training course were compared and analysed. RESULTS: Mean pre-course score was 45.3%, rising to 87.0% in the post-course assessment, reflecting an improvement of 41.8%. Prior to training, 30.7% achieved a satisfactory score of 13/20 (65%) compared to 98.3% on completion of training. Dental technicians were found to score significantly lower than other occupation groups both before and after course attendance. Decade of graduation had no effect on results. Theoretical microbiology was the question area which showed least improvement. CONCLUSION: Attending the disinfection and decontamination course significantly improved participants' knowledge. Theoretical microbiology, as a topic area, may be targeted for improvements in future courses to improve results further.

In vitro susceptibility of the Streptococcus milleri group to antimicrobial peptides.

AIM: To determine the susceptibility of strains of the Streptococcus milleri group (SMG) to commercially available antimicrobial peptides. METHODOLOGY: Thirty strains of SMG from a range of sources were assessed for their susceptibility to 10 antimicrobial peptides of either human, animal or insect origin, using a double layer diffusion assay. RESULTS: The majority of the test strains were sensitive to the amidated peptides, mastoparan (100%; n = 30), magainin 2 amide (95%; n = 21) and indolicin (91%; n = 23). Some strains were susceptible to cecropin B (30%; n = 30) and histatin (10%; n = 30), whilst no activity was observed for the defensins HNP-1 and HNP-2, histatin 8, cecropin P1 and magainin 2. CONCLUSIONS: The majority of strains were resistant to the human derived peptides. The ability to resist such peptides may be a factor in the colonisation of the oral cavity and the survival and initiation of infection in the pulp and root canal environment. Interestingly, the present study indicated that amidated and alpha helical peptides exhibit antimicrobial activity against SMG. Structural modification of these peptides may allow a targeted approach for the development of these substances as preventative or therapeutic agents.

Dermatitis artefacta of the lip in an adolescent.

UNLABELLED: Self-inflicted trauma is found in several patient groups including those with learning and developmental delay, the very young and those suffering from psychiatric disturbance. The diagnosis of artefactual disease can only be made when all possible organic disease has been excluded by specific investigations. The case presented is that of a 15-year-old girl complaining of persistent bleeding and crusting of her lips. Investigations provided no real information as to the cause of the allegedly spontaneous bleeding. The diagnosis of artefactual disease was finally decided upon and a referral to a child and adolescent psychiatrist made. CLINICAL RELEVANCE: Patients with unusual clinical signs may be examined regularly by their GDP. This case clearly illustrates the importance of considering a psychological disorder and referral in the differential diagnosis of conditions appearing with unusual clinical signs.

Mouth cancer: presentation, detection and referral in primary dental care.

Mouth cancer can present as a variety of abnormalities and visible changes affecting the oral mucosa, including ulceration, swelling and areas of erythema. The five-year survival from mouth cancer is poor at approximately 50%. Detection of the cancer while less than 2 cm in diameter with no metastasis greatly improves the outcome for the patient. Although many cancers in the mouth develop from what was previously an apparently normal mucosa, some arise in pre-existing conditions that are therefore regarded as potentially malignant. Regular assessment of the soft tissues within the mouth and the neck for the presence of abnormalities is an essential component of primary dental care. Any persistent and unexplained abnormality requires referral for definitive diagnosis and specialist management.

Antifungal susceptibility of Candida species using the Clinical and Laboratory Standards Institute disk diffusion and broth microdilution methods.

There are conflicting reports on the agreement between the Clinical and Laboratory Standards Institute disk diffusion (M44-A) and reference broth microdilution (M27-A) methods for determination of antifungal susceptibility of yeasts. The antifungal susceptibility of 541 yeasts, the majority of which were from the oral cavity, was determined using these two methods and the accuracy of the disk diffusion method assessed for clinical testing of various Candida species. Of the strains tested, Candida albicans predominated (390 out of 541). The classification of susceptibility determined by the disk diffusion method was largely in concordance with that obtained using the broth dilution method, regardless of species within Candida genus. The overall observed agreement between these two methods was 94.7% for fluconazole and 96.7% for voriconazole was with a 'very major' discrepancy level of 1.5% and 1.7% respectively. This study demonstrates a strong agreement of the simple disk diffusion method with the more labour intensive 'gold standard' broth microdilution method. These findings would support the use of the disk diffusion method in a routine mycology service.

Diagnosis and management of oral candidosis.

Candida is a fungus (yeast) that is generally regarded as a normal and harmless member of the oral microbiome in humans. Should host defences against these commensals be compromised in any way then Candida can cause clinical signs and symptoms, which manifest as distinct forms of oral candidosis (candidiasis). Candida albicans is the most frequently isolated candidal species from the oral cavity, although a range of non-C. albicans Candida species are being increasingly encountered. The basic principle of the management of candidosis is to identify and eliminate any underlying host predisposing factor. However, in many cases, antifungal therapy will also be required as part of initial management. This article will provide an overview of the isolation, identification and pathogenicity of Candida species encountered within the mouth and relate these to clinical management of oral candidosis.

A randomised controlled trial of clinical outreach education to rationalise antibiotic prescribing for acute dental pain in the primary care setting.

OBJECTIVE: To assess the effect of educational outreach visits on antibiotic prescribing for acute dental pain in primary care. STUDY DESIGN: RCT. SETTING: General dental practices in four health authority areas in Wales. SUBJECTS AND METHODS: General dental practitioners were recruited to the study and randomly allocated to one of the three study groups (control group, guideline group or intervention group). Following the intervention, practitioners completed a standardised questionnaire for each patient that presented with acute dental pain. INTERVENTIONS: The control group received no intervention. The guideline group received educational material by post. The intervention group received educational material by post and an academic detailing visit by a trained pharmacist. The educational material included evidence-based guidelines on prescribing for acute dental pain and patient information leaflets. MAIN OUTCOME MEASURES: The number of antibiotic prescriptions issued to patients presenting with dental pain and the number of 'inappropriate' antibiotic prescriptions. Antibiotics were considered to be inappropriate if the patient did not have symptoms indicative of spreading infection. RESULTS: A total of 1,497 completed questionnaires were received from 23, 20 and 27 general dental practitioners in the control, guideline and intervention group respectively. Patients in the intervention group received significantly fewer antibiotic prescriptions than patients in the control group (OR (95% CI) 0.63 (0.41, 0.95)) and significantly fewer inappropriate antibiotic prescriptions (OR (95% CI) 0.33 (0.21, 0.54)). However, antibiotic and inappropriate antibiotic prescribing were not significantly different in the guideline group compared to the control group (OR (95% CI) 0.83 (0.55, 1.21) and OR (95% CI) 0.82 (0.53, 1.29) respectively). CONCLUSIONS: Strategies based upon educational outreach visits may be successfully employed to rationalise antibiotic prescribing by dental practitioners.

Antimicrobial prescribing by dentists in Wales, UK: findings of the first cycle of a clinical audit.

Objective To describe the findings of the first cycle of a clinical audit of antimicrobial use by general dental practitioners (GDPs).Setting General dental practices in Wales, UK.Subjects and methods Between April 2012 and March 2015, 279 GDPs completed the audit. Anonymous information about patients prescribed antimicrobials was recorded. Clinical information about the presentation and management of patients was compared to clinical guidelines published by the Scottish Dental Clinical Effectiveness Programme (SDCEP).Results During the data collection period, 5,782 antimicrobials were prescribed in clinical encounters with 5,460 patients. Of these 95.3% were antibiotic preparations, 2.7% were antifungal agents, and 0.6% were antivirals. Of all patients prescribed antibiotics, only 37.2% had signs of spreading infection or systemic involvement recorded, and 31.2% received no dental treatment. In total, 79.2% of antibiotic, 69.4% of antifungal, and 57.6% of antiviral preparations met audit standards for dose, frequency, and duration. GDPs identified that failure of previous local measures, patient unwillingness or inability to receive treatment, patient demand, time pressures, and patients' medical history may influence their prescribing behaviours.Conclusions The findings of the audit indicate a need for interventions to support GDPs so that they may make sustainable improvements to their antimicrobial prescribing practices.

Reduced adherence of Candida to silane-treated silicone rubber.

Silicone rubber is widely used in the construction of medical devices that can provide an essential role in the treatment of human illness. However, subsequent microbial colonization of silicone rubber can result in clinical infection or device failure. The objective of this study was to determine the effectiveness of a novel silane-treated silicone rubber in inhibiting microbial adherence and material penetration. Test material was prepared by a combination of argon plasma discharge treatment and fluorinated silane coupling. Chemicophysical changes were then confirmed by X-ray photoelectron spectroscopy, contact-angle measurement, and atomic force microscopy. Two separate adherence assays and a material penetration assay assessed the performance of the new material against four strains of Candida species. Results showed a significant reduction (p < 0.01) of Candida albicans GDH 2346 adherence to silane-treated silicone compared with untreated controls. This reduction was still evident after the incorporation of saliva into the assay. Adherence inhibition also occurred with Candida tropicalis MMU and Candida krusei NCYC, although this was assay dependent. Reduced penetration of silane-treated silicone by Candida was evident when compared to untreated controls, plaster-processed silicone, and acrylic-processed silicone. To summarize, a novel silicone rubber material is described that inhibits both candidal adherence and material penetration. The clinical benefit and performance of this material remains to be determined.

An outcome audit of the treatment of acute dentoalveolar infection: impact of penicillin resistance.

OBJECTIVES: The aim of this audit was to measure the outcome of treatment of acute dentoalveolar infection and to determine if this was influenced by choice of antibiotic therapy or the presence of penicillin-resistance. SUBJECTS AND METHODS: A total of 112 patients with dentoalveolar infection were included in the audit. All patients underwent drainage, either incisional (n=105) or opening of the pulp chamber (n=7) supplemented with antibiotic therapy. A pus specimen was obtained from each patient for culture and susceptibility. Clinical signs and symptoms were recorded at the time of first presentation and re-evaluated after 48 or 72 h. RESULTS: A total of 104 (99%) of the patients who underwent incisional drainage exhibited improvement after 72 h. Signs and symptoms also improved in five of the seven patients who underwent drainage by opening of the root canal although the degree of improvement was less than that achieved by incisional drainage. Penicillin-resistant bacteria were found in 42 (38%) of the 112 patients in this study. Of the 65 patients who were given penicillin, 28 had penicillin-resistant bacteria. There was no statistical difference in the clinical outcome with regard to the antibiotic prescribed and the presence of penicillin-resistant bacteria. Strains of penicillin-resistant bacteria were isolated more frequently in patients who had previously received penicillin (p<0.05). CONCLUSION: Incisional drainage appeared to produce a more rapid improvement compared to drainage by opening of the root canal. The presence of penicillin-resistant bacteria did not adversely affect the outcome of treatment. The observations made support surgical drainage as the first principle of management and question the value of prescribing penicillin as part of treatment.

Evaluation of a phenotypic scheme for identification of the 'butyrate-producing' Peptostreptococcus species.

Gram-positive anaerobic cocci (GPAC) are isolated from approximately one quarter of all infections involving anaerobic bacteria. However, studies of the significance of this group of pathogens have been hindered by an inadequate taxonomy and the lack of a valid identification scheme. In the present study, a phenotypic scheme for the identification of 'butyrate-producing' GPAC based on the analysis of volatile fatty acid profiles by gas-liquid chromatography, biochemical profiles (including the use of the rapid ID 32 A commercial kit) and carbohydrate fermentation reactions, was evaluated. The identity of 68 clinical isolates of GPAC was determined by application of the scheme published by Murdoch. The scheme was found to be easy to apply and only four of the test isolates could not be readily assigned to a species or well-defined group. The species most frequently identified in the test collection were Peptostreptoccoccus vaginalis, P. tetradius and the betaGAL group. A large number of strains was assigned to the heterogeneous 'prevotii/tetradius' group. Some species regarded as being restricted to particular clinical sites were shown to be more widespread than previously thought. The clinical source of the isolates did not show any consistent correlation with species identity.

Phenotypic characterisation of Candida albicans isolated from chronic hyperplastic candidosis.

The phenotypes of 35 Candida albicans isolates from 19 patients with chronic hyperplastic candidosis (CHC) and 35 isolates from 30 patients with non-CHC infections were compared. Typing was based on carbohydrate assimilation, chemical sensitivity and serology. Eight carbohydrate assimilation profiles were evident with the API-20C system and a single profile predominated for isolates from CHC (17 of 19 patients; 89%) and non-CHC (18 of 30 patients; 63%). Chemical sensitivity tests revealed four profiles with no significant difference between CHC and non-CHC isolates. Serotype A predominated for isolates from both CHC (15 of 19 patients; 79%) and non-CHC (25 of 30 patients; 83%) infections. Boric acid resistance was more prevalent in CHC isolates, although a significant difference was not apparent. In summary, there was no overall difference in the phenotypes of isolates from CHC and non-CHC patients, and clonal restriction of CHC isolates was not demonstrated.

Direct detection of Prevotella intermedia and P. nigrescens in suppurative oral infection by amplification of 16S rRNA gene.

A specific 16S rDNA PCR and subsequent hybridisation reaction was designed to discriminate between strains of Prevotella intermedia (n = 15) and P. nigrescens (n = 15). This technique was then used to detect the presence of these two bacterial species in acute suppurative oral infection. A total of 36 pus samples aspirated from 26 peri-apical abscesses, three root canals, three periodontal abscesses, two cases of refractory periodontitis, one cyst and one haematoma was examined. A portion of the pus sample was processed by PCR and the remainder of the specimen was subjected to routine culture. The PCR-based technique gave an identical pattern of detection of P. intermedia or P. nigrescens to that obtained by culture for 30 of the 36 specimens. Either P. intermedia or P. nigrescens was present in 14 samples and neither species was detected in 16 samples. In the remaining six samples the PCR method indicated the presence of one (n = 3) or both (n = 3) of the Prevotella species but neither or only one species was isolated by culture. It is concluded that the presence of P. intermedia and P. nigrescens in pus can be detected rapidly and specifically by direct PCR amplification of 16S rDNA. P. nigrescens was detected more frequently than P. intermedia in suppurative peri-apical infection both by culture and PCR.

Heterogeneity within the gram-positive anaerobic cocci demonstrated by analysis of 16S-23S intergenic ribosomal RNA polymorphisms.

Peptostreptococci are gram-positive, strictly anaerobic bacteria which, although regarded as members of the commensal human microflora, are also frequently isolated from sites of clinical infection. The study of this diverse group of opportunist pathogens has been hindered by an inadequate taxonomy and the lack of a valid identification scheme. Recent re-classification of the Peptostreptococcus family into five distinct genus groups has helped to clarify the situation. However, this has been on the basis of 16S rRNA sequence determinations, which are both time-consuming and expensive. The aim of the present study was to evaluate the use of PCR-amplified ribosomal DNA spacer polymorphisms for the rapid differentiation of the currently recognised taxa within the group of anaerobic gram-positive cocci. A collection comprising 19 reference strains with representatives of each of the 15 species, two close relatives and two of the well-characterised groups, together with 38 test strains was studied. All strains were identified to species group level by phenotypic means. Amplification of the 16S-23S intergenic spacer region (ISR) with universal primers produced distinct banding patterns for all the 19 reference strains and the patterns could be differentiated easily visually. However, of the 38 test strains, less than half could be speciated from ISR analysis alone. Only five groups produced correlating banding patterns for all members tested (Peptoniphilus lacrimalis, P. ivorii, Anaerococcus octavius, Peptostreptococcus anaerobius and Micromonas micros). For other species, either the type strain differed significantly from other species members (e.g., A. hydrogenalis) or there appeared to be considerable intra-species variation (e.g., A. vaginalis). Partial 16S rRNA gene sequences for the 'trisimilis' and 'betaGAL' groups showed that both are most closely related to the Anaerococcus group. This work highlights the heterogeneous nature of a number of Peptostreptococcus species and hence the need for still further revision of the taxonomy of this important group of pathogens.

Herpes simplex virus: an occupational hazard in dentistry.

Approximately 70% of the population in the western world become infected with the herpes simplex virus type 1 (HSV-1) by the second decade of life. This review discusses the role of the HSV-1 as a potential occupational hazard for dental workers, focusing on herpes labialis, herpetic whitlow and keratitis. The risks associated with the dental treatment of patients with HSV-1, both from the perspective of the clinician and the patient are presented. Procedures for minimising the impact of HSV-1 within the dental practice, in particular infection control, delivery of treatment and patient education, are addressed. The management options for recurrent herpes labialis are also reviewed.

Antimicrobial activity of Citrox bioflavonoid preparations against oral microorganisms.

BACKGROUND: Citrox is a formulation of soluble bioflavonoids obtained from citrus fruits. The non-toxic and antimicrobial properties of natural bioflavonoids are well documented, and consequently there has been interest in the therapeutic application of these substances. OBJECTIVE: To determine the antimicrobial activity of two Citrox formulations (BC30 and MDC30) with different bioflavonoid combinations against a range of oral microorganisms. METHODS: The antimicrobial activity of both formulations was tested against 14 bacterial species and six Candida species. The two Citrox formulations (dilution range 0.007-8% v/v) were firstly evaluated by determining the in vitro Minimal Inhibitory Concentration (MIC) against planktonic microorganisms in a broth microdilution assay. Secondly, the ability of the same serial dilutions to inhibit microbial growth was assessed in a modified microtitre biofilm assay. RESULTS: Both Citrox formulations exhibited antimicrobial activity. The BC30 formulation demonstrated greater activity than MDC30 and significantly inhibited growth of all bacterial species and most candidal species tested at a concentration of 1% (v/v) in both the broth and the biofilm assay. CONCLUSION: Bioflavonoid preparations of Citrox have a broad-spectrum of antimicrobial activity against oral microorganisms, and as such have the potential to be used within therapeutic preparations for the control of the oral microflora.

Microbial contamination of removable prosthodontic appliances from laboratories and impact of clinical storage.

Decontamination of dental instruments has recently been the subject of considerable debate. However, little information is available on the potential bacterial colonisation of dental appliances returning from dental laboratories and their need for decontamination. This study investigated the extent and nature of microbial contamination of removable prosthodontic appliances produced at different dental laboratories and stored in two clinical teaching units (CTU 1 and CTU 2) of a dental hospital and school. Forty consecutive dental prosthodontic appliances that were being stored under varying conditions in the two clinical teaching units were selected for study; the appliances having been produced 'in-house' (hospital laboratory) or 'out-of-house' (external commercial laboratory). Two appliances, that were known to have undergone decontamination before storage, were used as controls. Swabs were taken according to a standard protocol and transferred to the microbiological laboratory with bacterial growth expressed as colony forming units (cfu) per cm(2). Microbial sampling yielded growth from 23 (58%) of the 40 appliances studied (CTU 1, n = 22; CTU 2, n = 18), with 38% of these having a high level of contamination (>42,000 cfu/cm(2)). The predominant bacteria isolated were Bacillus spp. (57%), pseudomonads (22%) and staphylococci (13%). Fungi of the genus Candida were detected in 38% of the samples. There was no significant difference in contamination of the appliances in relation to either their place of production or the CTU (p >0.05). However, the level of contamination was significantly higher (p = 0.035) for those appliances stored in plastic bag with fluid (n = 16) compared to those stored on models (n = 19). No growth was recovered from the two appliances that had undergone decontamination before storage. The research showed that appliances received from laboratories are often contaminated and therefore there is a need for routine disinfection of such items before use and a review of storage conditions required.

A pilot study of bioaerosol reduction using an air cleaning system during dental procedures.

BACKGROUND: Bioaerosols are defined as airborne particles of liquid or volatile compounds that contain living organisms or have been released from living organisms. The creation of bioaerosols is a recognized consequence of certain types of dental treatment and represents a potential mechanism for the spread of infection. OBJECTIVES: The aims of the present study were to assess the bioaerosols generated by certain dental procedures and to evaluate the efficiency of a commercially available Air Cleaning System (ACS) designed to reduce bioaerosol levels. METHODS: Bioaerosol sampling was undertaken in the absence of clinical activity (baseline) and also during treatment procedures (cavity preparation using an air rotor, history and oral examination, ultrasonic scaling and tooth extraction under local anaesthesia). For each treatment, bioaerosols were measured for two patient episodes (with and without ACS operation) and between five and nine bioaerosol samples were collected. For baseline measurements, 15 bioaerosol samples were obtained. For bioaerosol sampling, environmental air was drawn on to blood agar plates using a bioaerosol sampling pump placed in a standard position 20 cm from the dental chair. Plates were incubated aerobically at 37°C for 48 hours and resulting growth quantified as colony forming units (cfu/m³). Distinct colony types were identified using standard methods. Results were analysed statistically using SPSS 12 and Wilcoxon signed rank tests. RESULTS: The ACS resulted in a significant reduction (p = 0.001) in the mean bioaerosols (cfu/m³) of all three clinics compared with baseline measurements. The mean level of bioaerosols recorded during the procedures, with or without the ACS activated respectively, was 23.9 cfu/m³ and 105.1 cfu/m³ (p = 0.02) for cavity preparation, 23.9 cfu/m³ and 62.2 cfu/m³ (p = 0.04) for history and oral examination; 41.9 cfu/m³ and 70.9 cfu/m³ (p = 0.01) for ultrasonic scaling and 9.1 cfu/m³ and 66.1 cfu/m³ (p = 0.01) for extraction. The predominant microorganisms isolated were Staphylococcus species and Micrococcus species. CONCLUSION: These findings indicate potentially hazardous bioaerosols created during dental procedures can be significantly reduced using an air cleaning system.