A bacterial tyrosine phosphatase modulates cell proliferation through targeting RGCC.

Tyrosine phosphatases are often weaponized by bacteria colonizing mucosal barriers to manipulate host cell signal transduction pathways. Porphyromonas gingivalis is a periodontal pathogen and emerging oncopathogen which interferes with gingival epithelial cell proliferation and migration, and induces a partial epithelial mesenchymal transition. P. gingivalis produces two tyrosine phosphatases, and we show here that the low molecular weight tyrosine phosphatase, Ltp1, is secreted within gingival epithelial cells and translocates to the nucleus. An ltp1 mutant of P. gingivalis showed a diminished ability to induce epithelial cell migration and proliferation. Ltp1 was also required for the transcriptional upregulation of Regulator of Growth and Cell Cycle (RGCC), one of the most differentially expressed genes in epithelial cells resulting from P. gingivalis infection. A phosphoarray and siRNA showed that P. gingivalis controlled RGCC expression through Akt, which was activated by phosphorylation on S473. Akt activation is opposed by PTEN, and P. gingivalis decreased the amount of PTEN in epithelial cells. Ectopically expressed Ltp1 bound to PTEN, and reduced phosphorylation of PTEN at Y336 which controls proteasomal degradation. Ltp-1 induced loss of PTEN stability was prevented by chemical inhibition of the proteasome. Knockdown of RGCC suppressed upregulation of Zeb2 and mesenchymal markers by P. gingivalis. RGCC inhibition was also accompanied by a reduction in production of the proinflammatory cytokine IL-6 in response to P. gingivalis. Elevated IL-6 levels can contribute to periodontal destruction, and the ltp1 mutant of P. gingivalis incited less bone loss compared to the parental strain in a murine model of periodontal disease. These results show that P. gingivalis can deliver Ltp1 within gingival epithelial cells, and establish PTEN as the target for Ltp1 phosphatase activity. Disruption of the Akt1/RGCC signaling axis by Ltp1 facilitates P. gingivalis-induced increases in epithelial cell migration, proliferation, EMT and inflammatory cytokine production.

The use of antimicrobial photodynamic therapy in oral injuries of a pediatric patient with myelodysplastic syndrome: case report.

AIM: To report a case of a pediatric patient carrier of myelodysplastic syndrome (MDS) with severe oral infectious disease, in which antimicrobial photodynamic therapy (aPDT) was used as a therapeutic choice to support systemic treatment. METHODS AND RESULTS: This case report refers to a 1-year-old male patient with MDS and hospitalized for investigation and treatment of complications at a Pediatric Oncology and Hematology Center in Recife/PE, Brazil. The intraoral examination revealed a violaceous lesion surrounding the lower incisor teeth, which progressed with alteration of color to milky yellowish white, compromising the entire lower gingival border, leading to tooth mobility and consequent loss of teeth 71 and 81. The patient was treated under systemic antimicrobial therapy and aPDT was also performed, using a photosensitizing agent (methylene blue, 0.01%) and a low-intensity laser in the visible red spectrum. Oral clinical improvement was observed, but the patient died after 45 days of hospitalization in the Pediatric ICU due to other systemic complications. CONCLUSION: MDS may present limiting oral repercussions interfering in patients' quality of life. The aPDT is presented as an adjuvant therapeutic modality in oral infections with satisfactory results.

Chronic paracoccidioidmycosis in a woman with Crohn Disease.

We report a rare case of chronic paracoccidioidomycosis(PCM) in a woman with Crohn disease in the setting of treatment with azathioprine and mesalazine. Serum tests for antigens to Paracoccidioides brasiliensis, Histoplasma capsulatum, and Aspergillus fumigatus were negative. An incisional biopsy of an oral lesion with periodic acid-schiff and Grocott-methenamine silver stains revealed chronic granulomatous inflammation with multinucleated giant cells with Paracoccidioides brasiliensis within the cytoplasm, confirming the diagnosis of PCM.

Assessment of Photodynamic Inactivation against Periodontal Bacteria Mediated by a Chitosan Hydrogel in a 3D Gingival Model.

Chitosan hydrogels containing hydroxypropyl methylcellulose (HPMC) and toluidine blue O were prepared and assessed for their mucoadhesive property and antimicrobial efficacy of photodynamic inactivation (PDI). Increased HPMC content in the hydrogels resulted in increased mucoadhesiveness. Furthermore, we developed a simple In Vitro 3D gingival model resembling the oral periodontal pocket to culture the biofilms of Staphylococcus aureus (S. aureus), Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), and Porphyromonas gingivalis (P. gingivalis). The PDI efficacy of chitosan hydrogel was examined against periodontal biofilms cultured in this 3D gingival model. We found that the PDI effectiveness was limited due to leaving some of the innermost bacteria alive at the non-illuminated site. Using this 3D gingival model, we further optimized PDI procedures with various adjustments of light energy and irradiation sites. The PDI efficacy of the chitosan hydrogel against periodontal biofilms can significantly improve via four sides of irradiation. In conclusion, this study not only showed the clinical applicability of this chitosan hydrogel but also the importance of the light irradiation pattern in performing PDI for periodontal disease.

Oral ulcer by Sphingomonas paucimobilis: first report.

The first case of an oral infection caused by Sphingomonas paucimobilis is reported. A 73-year-old man presented with a gingival ulcer with bone exposure affecting the attached gingiva in the anterior maxillary region. He reported pain during chewing and the presence of fever. Since the first case of S. paucimobilis infection was reported in 1977, involving a leg ulcer, the number of reports related to this organism has been increasing, indicating that the bacterium should be considered an emerging pathogen. It is possible that other non-classical pathogens of the oral cavity may be responsible for infectious lesions, which represents a diagnostic and therapeutic challenge.

Primary Gingival Tuberculosis Diagnosed Based on Genetic Identification.

A case of primary gingival tuberculosis in a 71-year-old Japanese woman is herein presented. A serous saliva culture was positive for tuberculosis, and we recognized that the origin of the tuberculosis infection was the gingiva based on the genetic identification in gingival biopsy tissue. The definitive diagnosis was facilitated by the genetic identification, a useful modern tool for diagnosing infectious diseases. The location and clinical presentation of this lesion were unusual, which underlines the importance of considering tuberculosis in the differential diagnosis of oral lesions that affect the gingiva.

Alterations of the Subgingival Microbiota in Pediatric Crohn's Disease Studied Longitudinally in Discovery and Validation Cohorts.

BACKGROUND: Oral manifestations are common in Crohn's disease (CD). Here we characterized the subgingival microbiota in pediatric patients with CD initiating therapy and after 8 weeks to identify microbial community features associated with CD and therapy. METHODS: Pediatric patients with CD were recruited from The Children's Hospital of Pennsylvania. Healthy control subjects were recruited from primary care or orthopedics clinic. Subgingival plaque samples were collected at initiation of therapy and after 8 weeks. Treatment exposures included 5-ASAs, immunomodulators, steroids, and infliximab. The microbiota was characterized by 16S rRNA gene sequencing. The study was repeated in separate discovery (35 CD, 43 healthy) and validation cohorts (43 CD, 31 healthy). RESULTS: Most subjects in both cohorts demonstrated clinical response after 8 weeks of therapy (discovery cohort 88%, validation cohort 79%). At week 0, both antibiotic exposure and disease state were associated with differences in bacterial community composition. Seventeen genera were identified in the discovery cohort as candidate biomarkers, of which 11 were confirmed in the validation cohort. Capnocytophaga, Rothia, and TM7 were more abundant in CD relative to healthy controls. Other bacteria were reduced in abundance with antibiotic exposure among CD subjects. CD-associated genera were not enriched compared with healthy controls after 8 weeks of therapy. CONCLUSIONS: Subgingival microbial community structure differed with CD and antibiotic use. Results in the discovery cohort were replicated in a separate validation cohort. Several potentially pathogenic bacterial lineages were associated with CD but were not diminished in abundance by antibiotic treatment, suggesting targets for additional surveillance.

Extensive Inflammatory Gingival Tumor in a Young Nonsmoking Woman: Back to Basics.

Tuberculous lesions of the oral cavity are rare and can be a diagnostic challenge, particularly in young immunocompetent patients. Most of the cases in the literature are secondary to pulmonary disease, whereas primary form is uncommon. This paper presents a case of gingival tuberculosis in a 26-year-old Indian female patient, manifesting as a rapidly extensive ulcer. The diagnosis was confirmed by histopathology and immunological investigations. Although oral manifestations of tuberculosis are rare, clinicians should include them in the differential diagnosis of various types of oral ulcers. An early diagnosis with a prompt treatment can prevent complications and potential contaminations.

Gingival response in orthodontic patients: comparative study between self-ligating and conventional brackets

Orthodontic brackets contribute to the accumulation of bacterialplaque on tooth surfaces because they hinder oral hygiene.In contrast to conventional brackets, self-ligating brackets donot require additional parts to support the arches, thus improvingdental hygiene. The aim of this study was to compare thegingival response in orthodontic patients wearing self-ligatingor conventional brackets. A sample of 22 patients aged 16 to 30years was divided into two groups: Group A, treated with selfligatingbrackets (Damon system) and Group B, treated withconventional brackets (Roth technique). The following wereassessed during the treatment: Plaque Index (PI), GingivalIndex (GI) and Probing Depth (PD), and sub-gingival sampleswere taken from teeth 14/24 for microbiological observation.No statistically significant difference was found between GroupsA and B; p>0.05 (sign-ranked) or between PI, GI and PD at thedifferent times (Friedman’s Analysis of Variance), even thoughthe indices were found to increase at 14 days, particularly forself-ligating brackets. The quantity and quality of microorganismspresent were compatible with health on days 0, 28 and 56.As from day 14 there is a predominance of microbiota compatiblewith gingivitis in both groups. In the samples studied,orthodontic treatment increases bacterial plaque and inflammatorygingival response, but gingival-periodontal health canbe maintained with adequate basic therapy...

bacteriana en las superficies dentarias, debido a que dificultanla higiene oral. A diferencia de los brackets convencionales, losbrackets autoligables no requieren elementos adicionales parasujetar los arcos, lo cual favorecería la higiene dentaria. Elobjetivo del presente trabajo fue comparar la respuesta gingivalen pacientes ortodóncicos, utilizando brackets autoligablesy brackets convencionales. Se estudiaron 22 pacientes, entre 16y 30 años, divididos en dos grupos: A, tratado con bracketsautoligables, Sistema Damon) y B, tratado con brackets convencionales,Técnica de Roth. Durante el tratamiento, seevaluaron los Índices de Placa (IP), Índice Gingival (IG) y Profundidadde Sondaje (PS) y se tomaron muestras subgingivalesde las piezas 14/24 para su observación microbiológica. En laevaluación estadística no se encontraron diferencias estadísticamentesignificativa entre los grupos A y B; p>0.05 (de losrangos con signo) y ni en los IP, IG y PS en los diferentes tiemposevaluados (Análisis de varianza de Friedman), sin embargose observa un aumento en los índices a los 14 días, sobre todoen autoligables. Los microorganismos se presentaron en cantidady calidad compatible con salud el día 0, 28 y 56; a partirdel día 14 predomina microbiota compatible con gingivitis paraambos grupos. En las muestras estudiadas el tratamientoortodóncicos produce incremento de placa bacteriana yrespuesta gingival inflamatoria, pero con terapia básica adecuadapuede mantenerse la salud gingivo-lperiodontal. Losbrackets autoligables y los o convencionales, produjeronrespuesta gingival simila...

Primary gingival tuberculosis diagnosis: a difficult endeavor.

AIM: To highlight the importance of considering tuberculosis in the differential diagnosis even in the absence of confirmation from several investigations and diagnostic aides. BACKGROUND: Tuberculosis is a common infectious granulomatous disease caused by various strains of mycobacteria. An oral lesion when seen in association with tuberculosis is very rare and in most cases is noticed secondary to pulmonary forms. CASE REPORT: We report a case of primary gingival tuberculosis in 20-year-old female patient who presented with treatment resistant gingivitis. Patient had no evidence of disease elsewhere in the body and several diagnostic tests also failed to reveal the presence of the causative organism. Resolution of gingivitis was noted following a therapeutic trial of antitubercular drugs. CONCLUSION: Therefore the importance of including tuberculosis in the differential diagnosis of inflammatory disorder of the gingiva is very essential in order to avoid one of the most lethal forms of infections often overlooked. CLINICAL SIGNIFICANCE: It is essential to consider tuberculosis as one of the differential diagnosis in India even when several diagnostic tests are negative for tuberculosis.

Arteriovenous malformation (AVM) of the maxilla complicated by a local pathogen infection.

Arteriovenous malformations (AVM) are usually observed on the skin, but they can also rarely affect the visceral organs and the maxillofacial area. In the maxillofacial area, these lesions can spread and they are potentially dangerous, as a biopsy or even a simple tooth extraction can lead to a catastrophic haemorrhage that may eventually cause death. There are several indications for the treatment, including age, size and type of vascular malformation. The purpose of this report is to describe an AVM on the maxilla, first diagnosed as an epulis, which has been treated for several years as a chronic local periodontitis. The lesion was finally stabilised after an antibiotic therapy. Improved knowledge of the development of these lesions and collaboration between dentists, radiologists and surgeons are necessary to improve the diagnosis and treatment of vascular malformations.

Retrospective investigation of gingival invaginations: Part II: microbiological findings and genetic risk profile.

BACKGROUND AND OBJECTIVE: Gingival invaginations are a frequent finding during tooth extraction and following orthodontic space closure. Based on the interdental localization and sometimes pronounced depth, it has been suggested that a gingival invagination may impede oral hygiene. In Part I of this series, the time until active tooth movement and the localization of extraction were identified as potential risk factors for the development of gingival invagination. The aims of the present study were the analysis of the microbial spectrum of a gingival invagination in comparison with pool samples of the sulcus of Ramfjord teeth, on the one hand, and the importance of genetic variations of the pro-inflammatory mediator interleukin-1 (IL-1) and its receptor antagonist (IL-1-RN), on the other hand. In addition, a possible role of smoking as a risk factor was evaluated. SUBJECTS AND METHODS: A total of 30 patients with (n=16) and without (n=14) gingival invagination were examined for the presence of eleven periodontal pathogen bacterial species with a commercially available test (micro-IDent®Plus, Hain Lifescience, Nehren, Germany). The genetic evaluation was performed with the GenoType® IL-1 test (Hain Lifescience). RESULTS: The results of the microbiological analysis of gingival invaginations showed that the bacterial flora might differ or even be higher than the pool sample from sulcus regions. The genetic evaluation demonstrated that in the group without gingival invagination only 14% showed an IL-1 polymorphism, whereas this value was twice as high (35%) in the group with gingival invagination. In addition, a combination of both polymorphisms IL-1 and IL-1-RN was only found in patients with gingival invagination (25%). Interestingly, smoking patients showed a significant increase of the severity of the gingival invagination. CONCLUSION: This retrospective study demonstrated that gingival invagination might be accompanied with an altered microbiological bacterial spectrum and a genetic IL-1 polymorphism. In addition, smoking was identified as another potential risk factor for the severity of gingival invaginations.

Lipoproteins of Actinomyces viscosus induce inflammatory responses through TLR2 in human gingival epithelial cells and macrophages.

Actinomyces viscosus has been suggested to be associated with periodontal disease. However, the pathogenicity of this bacterium is not known. In this study, we examined inflammation-inducing activity by A. viscosus. Whole cells and a lipophilic fraction of A. viscosus ATCC19246 induced production of interleukin-8 and tumor necrosis factor alpha from both human oral epithelial cells and human monocytoid cells. This cytokine production was blocked by lipoprotein lipase treatment of the lipophilic fraction. In addition, anti-Toll-like receptor 2 antibody blocked the cytokine production. These results suggest that lipoprotein of A. viscosus triggers inflammatory responses in periodontitis by activation of Toll-like receptor 2.

A retrospective study of oral manifestations in patients with paracoccidioidomycosis.

South American blastomycosis, paracoccidioidomycosis (Pb mycosis) or Lutz disease is an endemically fungal infection in Latin America. It is caused by the dimorphic fungus Paracoccidioides brasiliensis and may cause oral mucosal lesions. The incidence of Pb mycosis oral lesions was evaluated in patients assisted at a Brazilian Dental School's Specialized Oral Diagnosis Service with special focus on the different clinical forms of these lesions, its location, patients' occupation, deleterious habits, and diagnosis methodology. Students' and professionals' initial diagnoses were compared with the definitive diagnosis. Lesions were detected 31 cases (18 patients). The results show that 88.8% of the patients were male with a mean age of 50 years and 39% work(ed) with activities related to agriculture. As much as 88.9% were smokers and 72.2% were alcohol users. Exfoliative cytology was performed in 66.6% of the patients. Oral mucosa (30%), gingiva (16.6%) and lips 16.6% were the most common sites of Pb mycosis oral lesions. Comparing the initial with the definitive diagnosis made by the professionals their accuracy was 33% (6 out of 18 patients). Students' diagnosis was more accurate demonstrating 72.5% of initial correct diagnosis (13 out of 18). Statistical analysis by ANOVA (α=0.05, SPSS WIN) demonstrated a significant difference between the diagnosis of Pb mycosis made by students and professionals when considering initial diagnosis and final diagnosis (after histopathological analysis) (p=0.25). Incisional biopsy and exfoliate cytology are efficient for an early diagnosis of this disease in mouth. Students' training in diagnosis of oral pathologies to recognize lesions is urgent to improve public health.

A retrospective study of oral manifestations in patients with paracoccidioidomycosis

South American blastomycosis, paracoccidioidomycosis (Pb mycosis) or Lutz disease is an endemically fungal infection in Latin America. It is caused by the dimorphic fungus Paracoccidioides brasiliensis and may cause oral mucosal lesions. The incidence of Pb mycosis oral lesions was evaluated in patients assisted at a Brazilian Dental School's Specialized Oral Diagnosis Service with special focus on the different clinical forms of these lesions, its location, patients' occupation, deleterious habits, and diagnosis methodology. Students' and professionals' initial diagnoses were compared with the definitive diagnosis. Lesions were detected 31 cases (18 patients). The results show that 88.8% of the patients were male with a mean age of 50 years and 39% work(ed) with activities related to agriculture. As much as 88.9% were smokers and 72.2% were alcohol users. Exfoliative cytology was performed in 66.6% of the patients. Oral mucosa (30%), gingiva (16.6%) and lips 16.6% were the most common sites of Pb mycosis oral lesions. Comparing the initial with the definitive diagnosis made by the professionals their accuracy was 33% (6 out of 18 patients). Students' diagnosis was more accurate demonstrating 72.5% of initial correct diagnosis (13 out of 18). Statistical analysis by ANOVA (α=0.05, SPSS WIN) demonstrated a significant difference between the diagnosis of Pb mycosis made by students and professionals when considering initial diagnosis and final diagnosis (after histopathological analysis) (p=0.25). Incisional biopsy and exfoliate cytology are efficient for an early diagnosis of this disease in mouth. Students' training in diagnosis of oral pathologies to recognize lesions is urgent to improve public health.

A blastomicose sul americana, paracoccidiodomicose (Pb micose) ou doença de Lutz é uma infecção fúngica endêmica na América Latina. É causada pelo fungo dimórfico Paracoccidiodes brasiliensis, e pode causar lesões na mucosa oral. Nós avaliamos a incidência de lesões orais de Pb micose nos pacientes atendidos em um Centro Especializado em Diagnóstico Oral com foco principal nas diferentes formas clinicas das lesões, suas localidades, ocupação dos pacientes, hábitos deletérios e diagnóstico e metodologia, e foram detectados 31 casos (18 pacientes). Os resultados mostraram que 88,8% dos pacientes eram do sexo masculino com idade média de 50 anos de idade, e 39% trabalham, ou trabalhavam, com atividades relacionadas à agricultura. Observou-se que 88,9% eram fumantes e 72,2% ingeriam álcool. Citologia esfoliativa foi feita em 66,6%. Mucosa jugal foi acometida em 30%, gengiva, e lábios 16% (cada um) foram os locais mais comuns de lesões orais da Pb micose. Comparando o diagnóstico inicial com o definitivo feito pelos profissionais, a acurácia foi de 33%; o diagnóstico dos estudantes foi mais preciso demonstrando 72,5% do diagnóstico inicial correto com diferença estatística significante (p=0,25) através do teste ANOVA do SPSS WIN com nível de significância de 5%. Biópsia incisonal e citologia esfoliativa são eficientes para um diagnóstico precoce desta doença na boca; o treinamento dos estudantes em diagnóstico para reconhecer as patologias orais é urgente para melhorar a saúde pública.

Tuberculosis cutis orificialis with both gingival involvement and underlying pulmonary tuberculosis.

Tuberculosis cutis orificialis is a rare manifestation of cutaneous tuberculosis which occurs in the oral, perianal and adjacent mucosa. The most frequent orificial lesion location is the tongue. We report a case of a 35-year-old female with tuberculosis cutis orificialis with gingival involvement. She had a six-month history of a moderately painful gingival ulceration. Histopathological examination showed granulomatous infiltrates composed of epithelioid cells, Langhans giant cells and caseating necrosis. A purified protein derivative test was positive. Sputum culture was positive for Mycobacterium tuberculosis. Chest X-ray and high resolution computed tomography showed active pulmonary tuberculosis in both upper lung zones. The gingival specimen was positive for M. tuberculosis polymerase chain reaction. A complete resolution was achieved after six months of anti-tuberculosis therapy. Dental identification of M. tuberculosis may serve as an important aid in the first line of control of this dangerous infectious disease.

Effect of serine-type protease of Candida spp. isolated from linear gingival erythema of HIV-positive children: critical factors in the colonization.

BACKGROUND: There are several kinds of oral soft tissue lesions that are common manifestations observed in human immunodeficiency virus (HIV)-infected children; for example, linear gingival erythema (LGE) that is a distinctive fiery red band along the margin of the gingivae. The etiology and pathogenesis of LGE are questionable, but a candidal origin has been suggested. Proteases are key virulence attributes produced by a variety of pathogenic fungi, including Candida. The objective of the present study is to identify the protease production in Candida species including, C. albicans (n=5), C. dubliniensis (n=1) and C. tropicalis (n=1), isolated directly from typical LGE lesions observed in six HIV-positive children, and also to test the effect of a serine protease inhibitor on the interaction of Candida spp. and epithelial cells in vitro. METHODS: The ability of Candida strains to release proteases in the culture supernatant fluids was visualized by gelatin-SDS-PAGE. Gel strips containing 30-fold concentrated supernatant (1.5×10(8) yeasts) were incubated at 37°C for 48 h in 50 mM sodium phosphate buffer, pH 5.5. The concentrated supernatants were also incubated with fibronectin, laminin, immunoglobulin G, bovine serum albumin and human serum albumin. The effect of serine protease inhibitor on the interaction of Candida spp. and epithelial cells (MA 104) was measured after pre-treatment of fungi with the inhibitor (phenylmethylsulphonyl fluoride, PMSF). RESULTS: All the extracellular proteases were completely inhibited by PMSF, identifying these activities as serine-type proteases. Interestingly, a common 62-kDa serine protease was observed in all Candida strains. The culture supernatants, rich in serine protease activities, cleaved several soluble proteinaceous substrates. Additionally, we demonstrated that pre-treatment of C. albicans, C. dubliniensis and C. tropicalis with PMSF diminished the interaction with epithelial cells. CONCLUSIONS: Collectively, our results show that Candida spp. isolated from LGE lesions produced and secreted serine proteases and these enzymes may be involved in the initial colonization events.

Invasive oral aspergillosis in a patient with acute myeloid leukaemia.

Aspergillosis (a fungal infection by an organism of the Aspergillus species) of the oral cavity is an uncommon condition which most frequently occurs in immunocompromised patients, such as those with haematological malignancies. In such patients, prolonged neutropenia secondary to chemotherapeutic agents enables the spread of invasive aspergillosis, which is unaffected by anatomical barriers. Early detection and treatment of the condition is essential to avoid more serious complications, such as disseminated infection, which results in increased morbidity and mortality. This case report describes a patient with acute myeloid leukaemia who developed localized invasive Aspergillus flavus of the palate. High-dose antifungal therapy was instituted along with surgical removal of the involved tissues. Aspergillosis of the palate was successfully eradicated with no long-term ill effects from the treatment. Management of invasive aspergillosis includes early aggressive antifungal medication combined with surgical removal of the involved tissues.

Microbiological findings in subjects with asymptomatic oral lichen planus: a cross-sectional comparative study.

BACKGROUND: The bacterial colonization of the oral mucosa was evaluated in patients with asymptomatic oral lichen planus (OLP) and compared to the microbiologic status in mucosally healthy subjects. METHODS: Bacteria from patients with clinically and histopathologically diagnosed OLP from the Stomatology Service, Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, were collected with a non-invasive swab system. Samples were taken from OLP lesions on the gingiva and from non-affected sites on the contralateral side of the mouth. The control population did not have OLP and was recruited from the student clinic. All samples were processed with the checkerboard DNA-DNA hybridization method using well-defined bacterial species for the analysis. RESULTS: Significantly higher bacterial counts of Bacteroides ureolyticus (P = 0.001), Dialister species (sp.) (P = 0.006), Staphylococcus haemolyticus (P = 0.007), and Streptococcus agalactiae (P = 0.006) were found in samples taken from OLP lesions compared to sites with no clinical evidence of OLP. Significantly higher bacterial counts were found for Capnocytophaga sputigena, Eikenella corrodens, Lactobacillus crispatus, Mobiluncus curtisii, Neisseria mucosa, Prevotella bivia, Prevotella intermedia, and S. agalactiae at sites with lesions in subjects with OLP compared to sites in control subjects (P <0.001). CONCLUSIONS: Microbiologic differences were found between sites with OLP and sites in subjects without a diagnosis of OLP. Specifically, higher counts of staphylococci and S. agalactiae were found in OLP lesions.