Oral Colonization Research Articles

Isolation and Characterization of a Novel Alpha-Hemolytic Streptococcus spp. from the Oral Cavity and Blood of Septicemic Periparturient Immunodeficient Mice.

MISTRG is an immunodeficient mouse strain that expresses multiple human cytokines that support hematopoietic stem cell maintenance and myelopoiesis. While establishing a breeding colony of MISTRG mice in a dedicated barrier room, 6 cases of death or disease occurred in pregnant or postpartum mice. Clinically, this manifested as hunched posture, dyspnea, and 1 case of emaciation with ataxia. Pathologic analysis of 7 mice revealed multisystemic necrosuppurative inflammation variably affecting the uterus and placenta, joints, meninges, inner and middle ears, kidneys, and small intestine. Bacteria cultured from the blood of septic mice were identified with 89% probability by the Vitek 2 identification system as Streptococcus sanguinuswith atypical biochemical parameters; the API 20E/NE system fully differentiated the isolates as a novel Streptococcusspecies. MALDI Biotyper-based mass spectrometry also indicated that the phenotype represented a novel Streptococcusspp. Sequencing revealed that the full-length 16S rRNA gene identity was below 97% with known Streptococcus species, including the 2 closest species Streptococcus acidominimus and Streptococcus azizii. We propose the name Streptococcus murisepticum spp. nov to our novel isolates. All male mice in this colony remained healthy despite their association with diseased female mice. Overall, 19% of the colony carried the novel Streptococcus in their oral cavity, but it could not be detected in feces. The organism was sensitive to amoxicillin, which was administered via drinking water throughout pregnancy and weaning to establish a colony of pathogen-negative future breeders. The colony remained disease-free and culture-negative for Streptococcus murisepticum spp. nov after treatment with amoxicillin. We suspect that oral colonization of MISTRG mice with the novel Streptococcus species and its associated unique pathology in periparturient mice is potentially the principal cause of loss of this strain at several institutions. Therefore, screening the oral cavity for α-hemolytic streptococci followed by targeted antibiotic treatment may be necessary when establishing MISTRG and allied immunodeficient mouse strains.

Interferon Gamma Response in Human Saliva Following Exposure to the Oral Probiotic Streptococcus salivarius BLIS K12.

Streptococcus salivarius BLIS K12 is a probiotic strain developed for application to the oral cavity. The strain was originally characterised for its in vitro antibacterial activity against the prominent oral pathogen Streptococcus pyogenes. More recent research has expanded its applications to include reducing halitosis, preventing otitis media and protecting against virus infections of the respiratory tract. A potential mechanism for this anti-viral activity could be the stimulation of salivary interferon gamma (IFN-γ) production in the oral cavity. The aim of this study was to investigate whether the ingestion of and oral cavity colonisation by S. salivarius BLIS K12 is associated with enhancement of IFN-γ levels in saliva. Application of ELISA demonstrated that consumption of S. salivarius BLIS K12 effected an increase in salivary IFN-γ, and this response was more consistent with use of viable cells than following ingestion of heat-killed S. salivarius BLIS K12. Interestingly, those subjects who more successfully colonised with S. salivarius BLIS K12 did not experience a relatively larger increase in their IFN-γ levels, indicating that the observed IFN-γ response occurs independently of colonisation efficacy. In summary, the consumption of S. salivarius BLIS K12 increases salivary levels of IFN-γ, an effect that may contribute to protection of the host against certain virus infections.

The Rate of Nasal and Oral Colonization and Expression Levels of Hyphal Adhesin Als3p and mecA Genes in Methicillin-Resistant Staphylococcus aureus and Candida spp. Isolated From Patients With Lung Cancer

Background: Patients with cancer is considered highly susceptible group to both nosocomial and community-acquired infections. Objectives: In the present research, we aimed to determine the rate of nasal and oral colonization and expression level of Als3p and mecA genes among Candida spp. and methicillin-resistant Staphylococcus aureus (MRSA) in co-colonization and single colonization conditions. Materials and Methods: In total, 110 oral swab samples and 110 nasal swab samples were gathered from patients with lung cancer. The frequency of MRSA isolates (oxacillin-resistant Staphylococcus aureus) was determined using the disk diffusion method. In addition, the frequency and expression levels of Als3p and mecA genes among MRSA and Candida spp. isolates were determined and compared using PCR and qRT-PCR methods, respectively. Results: Candida spp. and S. aureus were found in 42.7% (n=47/110), and 9.1% (n=10/110) of oral samples, respectively, while Candida spp. and S. aureus were found in 5.5% (n=6/110) and 16.4% (n=18/110) of nasal samples, respectively. Additionally, 55.5% (n=10/18) of S. aureus isolates obtained from nasal samples were MRSA. Candida albicans (n=23/110; 20.9%) had the highest frequency among Candida species. In all MRSA and Candida spp. isolates, the Als3p and mecA gene expression increased two and three times in co-colonization condition compared to single colonization condition, respectively. Conclusion: The present study revealed that co-colonization has a synergistic effect on the expression level of mecA and Als3p genes. Our finding suggested that co-colonization can facilitate the invasion of S. aureus and leads to systemic and severe infections in co-colonized patients.

Oral Candida colonization and anti-fungal susceptibility pattern in patients with hematological malignancy.

Candidiasis is regarded as one of the most important fungal infections and a cause of disease and mortality in patients with hematological malignancy. Accordingly, antifungal prophylaxis is of significant importance in this regard. This study aimed to identify the epidemiology of Candida colonization and evaluate its antifungal susceptibility pattern in patients with hematological malignancy. In this study, the samples were collected from the oral cavity of 100 patients, and Candida colonization was confirmed by fungal culture. Candida strains were also identified by ITS-PCR. In vitro antifungal susceptibility tests against fluconazole, amphotericin B, and caspofungin were performed according to CLSI M60. Demographic characteristics, comorbidities, distribution of Candida species (spp.), and antifungal susceptibility were analyzed in this study. The study participants included 100 patients with a mean age of 15.48%±48.74 years (age range: 17-84 years). Regarding gender distribution, the majority (64%) of the patients were male. In terms of the distribution of underlying hematologic malignancy, 27% of the cases had lymphoma. The most commonly isolated species among patients were C. albicans complex (49%; n=49), C. glabrata (39%; n=39), and co-colonization of C. albicans complex and C. with C. glabrata (10%; n=10). The overall resistance of C. albicans complex was 5% to fluconazole (n=5) and 2% to amphotericin B (n=2). Furthermore, C. glabrata showed 11% (n=11) resistance to fluconazole and was susceptible to amphotericin B. All Candida spp. isolated from patients who were susceptible to caspofungin. The high rate of colonization of Candida spp., especially the significant increase in the frequency of C. glabrata in patients with blood malignancies and the gradual increase in resistance to fluconazole, necessitate a change in the use of antifungal drugs for the prevention and experimental treatment of hematological malignancy.

Species distribution and susceptibility profiles of oral candidiasis in hematological malignancy and solid tumor patients.

Oral colonization and infection by Candida species are common in cancer patients receiving chemoradiotherapy, which has significantly increased in recent years. This study aimed to evaluate the frequency, distribution, and antifungal susceptibility profiles of Candida species isolates in patients with hematological malignancy and solid tumors. This study was conducted on a total of 45 cancer patients undergoing treatment with concurrent chemoradiotherapy within 2019-2020. The identification of Candida species was accomplished based on conventional examination and molecular assays. The minimum inhibitory concentrations were determined based on the guidelines of Clinical and Laboratory Standards Institute. The highest prevalence rates of oral candidiasis were observed in patients with chronic lymphoid leukemia (24.4%) and lymphoma (20%). The majority of the patients had oral candidiasis caused by non-albicans Candida species (64.4%). The results of the multiplex PCR for the identification of Candida glabrata, Candida nivariensis, Candida bracarensis, and species-specific Candida parapsilosis complex showed that all isolate amplification products at 397 bp and 171 bp were related to C. glabrata and C. parapsilosis, respectively. There was a significant difference in the Candida species distribution between the hematological malignancies and solid tumors patients. The results of MIC showed that clotrimazole, voriconazole, and caspofungin were the most effective antifungal drugs against oral non-Candida albicans isolates. An understanding of the epidemiology of oral candidiasis among hematological malignancies and solid tumors patients is currently imperative to guide optimal empirical treatment strategies for affected patients.

Distribution and antifungal susceptibility profiles of Candida species isolated from people living with HIV/AIDS in a public hospital in Goiânia, GO, Brazil.

Oropharyngeal candidiasis (OPC) is the most common opportunistic fungal infection of the oral cavity and is a significant clinical problem, particularly in immunocompromised individuals, such as people living with HIV/AIDS (PLWHA). Although Candida albicans is the most frequent pathogen, at least 30 species capable of causing infection have been described. Identifying the infecting organism is necessary because the species respond differently to therapy, and antifungal susceptibility testing is important to determine the appropriate treatment. This study aimed to determine the epidemiological, clinical, and mycological profiles of OPC in hospitalized PLWHA. Clinical samples were collected from 103 PLWHA with suspected candidiasis admitted to the Hospital Estadual of Doenças Tropicais/Hospital Anuar Auad of Goiania, Goias, Brazil, for 14months. Candida species were identified using phenotypic microbiological techniques and molecular analysis performed by PCR using species-specific primers. The antifungal susceptibility pattern of the isolates against the six antifungal agents was determined using the broth microdilution method. Here, female individuals were the most affected by OPC, presenting a higher risk of oral colonization by Candida spp. The main clinical manifestation was pseudomembranous candidiasis. The number of cases of candidiasis was 87.3% (90/103), with C. albicans being the most common species, followed by C. tropicalis and C. glabrata. In the susceptibility pattern, non-albicans Candida showed higher resistance to than C. albicans. The fast and accurate identification of Candida spp. is very important to identify therapeutic agents for the treatment of oral candidiasis in PLWHA.

Oral and Rectal Colonization by Antimicrobial-Resistant Gram-Negative Bacteria and Their Association with Death among Residents of Long-Term Care Facilities: A Prospective, Multicenter, Observational, Cohort Study

Introduction: The prevalence of antimicrobial-resistant bacteria (ARB) in long-term care facilities (LTCFs) remains unclear. Furthermore, the effect of ARB colonization on the clinical outcomes of LTCF residents has not been explored. Methods: We conducted a prospective multicenter cohort study and investigated the residents (N = 178) of six Japanese LTCFs (three Welfare Facilities for the Elderly Requiring Long-term Care and three Geriatric Health Service Facilities) for oral and rectal carriage of ARB. The clinical outcomes of the residents were evaluated based on isolating bacterial strains and subjecting them to whole-genome sequencing. Results: Of the 178 participants, 32 belonging to Geriatric Health Service Facilities with no information on their clinical outcome were excluded, and the remaining 146 were followed up for at most 21 months. Extended-spectrum β-lactamases (ESBL)-producing Enterobacterales and Pseudomonas aeruginosa were detected in 42.7% (n = 76) and 2.8% (n = 5) of the rectal swabs and 5.6% (n = 10) and 3.4% (n = 6) of the oral swabs, respectively. Detection of ARB in the oral and rectal cavities showed remarkable association with enteral nutrition. Further, P. aeruginosa was significantly associated with an increase in mortality of the residents, but there were not significant association between ESBL-producing Enterobacterales and mortality. Core-genome phylogeny of P. aeruginosa revealed a wide-spread distribution of the isolated strains across the phylogeny, which included a cluster of ST235 strains with substantially higher biofilm formation ability than the other isolated P. aeruginosa strains. Discussion/Conclusion: This study is the first to investigate the carriage of both oral and rectal ARB, genomic relatedness and determinants of antimicrobial resistance in isolated strains, and clinical outcomes of LTCF residents. Our study provides the first direct evidence for the burden of antimicrobial resistance in LTCFs.

Frequency of Candida spp. in the Oral Cavity of Asymptomatic Preschool Mexican Children and Its Association with Nutritional Status.

Malnutrition is a public health problem in developing countries, affecting the child population, which favors the appearance of infections such as oral candidiasis. In Mexico, information on the presence of oral colonization by Candida spp. in asymptomatic children is scarce. The present study aimed to determine the presence of Candida spp. in the oral cavity of asymptomatic preschool Mexican children and its association with their nutritional status. A sample of oral mucosa was obtained using a sterile swab and then inoculated in Sabouraud dextrose agar with antibiotics, and the yeast growth was phenotypically identified. The anthropometric profile of children was performed based on the guidelines of the International Society for the Advancement of Kinanthropometry. In addition, eating habits were investigated. The possible associations between the variables were determined through the chi-square test (IC95%, p < 0.05) (GraphPad Prism 8.0). Among the 743 assessed children (403 boys and 340 girls), the average age was 4.6 years, and the average nutritional status was normal (53.7%), followed by undernutrition (28.4%), overweight (12.4%) and obesity (5.5%). In 52 children, Candida was isolated, and the identified species were C. albicans (87.8%), C. glabrata (11.5%), C. krusei (5.8%) and C. parapsilosis (1.9%). The frequency of colonization was greater in males of six years (69.23%). There was no significant association between the colonization by Candida spp. and the nutritional status; however, a relation was observed with a high intake of simple carbohydrates.

Oral Candida spp. Colonisation Is a Risk Factor for Severe Oral Mucositis in Patients Undergoing Radiotherapy for Head & Neck Cancer: Results from a Multidisciplinary Mono-Institutional Prospective Observational Study.

Simple SummaryThis study aims to find a correlation between Candida spp. oral colonisation prior to radiotherapy and (i) the development of severe oral mucositis (OM) (grade 3/4) and (ii) early development of severe OM (EOM). Candida spp. in the oral cavity appears to be a predictive factor of EOM. Preventive treatment could aid in reducing incidence of EOM. Further clinical trials are required to confirm our findings.Background: This study aims to find a correlation between Candida spp. oral colonisation prior to radiotherapy (RT) and (i) the development of severe oral mucositis (OM) (grade 3/4) and (ii) early development of severe OM (EOM). Methods: The protocol was registered on ClinicalTrials.gov (ID: NCT04009161) and approved by the ethical committee of the ‘Fondazione Policlinico Universitario Gemelli IRCCS’ (22858/18). An oral swab was obtained before RT to assess the presence of Candida spp. Severe OM occurring before a dose of 40 Gy was defined as EOM. Results: No patient developed G4 OM, and only 36/152 patients (23.7%) developed G3 OM. Tumour site and lymphocytopenia were risk factors for severe OM (OR for tumour site: 1.29, 95% CI: 1–1.67, p = 0.05; OR for lymphocytopenia: 8.2, 95% CI: 1.2–55.8, p = 0.03). We found a correlation between Candida spp. and EOM (OR: 5.13; 95% CI: 1.23–21.4 p = 0.04). Patients with oral colonisation of Candida spp. developed severe OM at a mean dose of 38.3 Gy (range: 28–58; SD: 7.6), while negative patients did so at a mean dose of 45.6 Gy (range: 30–66; SD: 11.1). Conclusions: Candida spp. in the oral cavity appears to be a predictive factor of EOM.

P494 Comparison of Candida colonization in intensive care unit patients with and without COVID-19: First prospective cohort study from Turkey

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PMObjectives Candida species, as the main component of human mycobiome, are the most common cause of fungal infections in intensive care units (ICU). ICU patients with COVID-19 are more prone to fungal infections, due to various causes like mechanical ventilation, use of steroids, or long-term hospitalization. There is yet no extended prospective study examining Candida colonization rates, epidemiology of species, and predisposing factors in this population. This is the first prospective cohort study comparing the time-varying colonization features of Candida species in ICU patients with and without COVID-19.MethodsThis study was performed between March 2021-December 2021 in ICUs of Istanbul University, Istanbul Faculty of Medicine, Department of Anesthesiology and Reanimation. COVID-19 and non-COVID-19 ICU patients who were ≥ 18 years and expected to stay in the ICU for at least 7 days were included in the study.Samples were taken at certain time intervals from different body parts of the patients [mouth, skin (axilla), rectal, and urine] (Table 1) and evaluated at Istanbul University, Istanbul Faculty of Medicine, Department of Medical Microbiology, Mycology Laboratory. All specimens were inoculated on CHROMagar Candida media (CHROMagar Candida, France) to detect mixed growth and CHROMagar Candida Plus media (CHROMagar Candida Plus, France) to avoid missing Candida auris.Cultures were incubated at 35-37⁰C for 48 h and phenotypically different colonies on primary media were subcultured on corn meal-tween-80 agar for determining their morphology. All strains were identified to the species level using MALDI-TOF MS (Version 4.1.80; Biotyper Bruker) in Yeditepe University, Faculty of Engineering, Genetics and Bioengineering Department. Patient groups were compared statistically in terms of isolated Candida species and distribution according to regions.ResultsThe study consisted of 122 ICU patients including 62 COVID-19 (25 female; 37 male; mean age:63.29 years) and 60 non-COVID-19 (24 female; 36 male; mean age:63.9 years).A total of 1464 samples (756 COVID-19 and 708 non-COVID-19 patients) were taken (Table 1) and fungi grew in 340 (23.2%) samples. Mixed growth was observed in 108 cultures; was more frequently in COVID-19 patients (P < .05), and significantly higher in oral specimens (P < .05).Out of a total of 471 strains that were obtained from fungal cultures, C. albicans (42.25%) and C. glabrata (24.2%) were most frequently isolated. Candida auris was not observed in this period (Table 2).Patients with COVID-19 were found more frequently colonized in oral (P < .001), rectal (P < .05) regions and urine (P < .001) compared with non-COVID-19 patients. There was no growth in the axillary region in any of the patients.Non-albicans Candida strains were found significantly more frequent in patients with COVID-19 in oral (P < .001) and rectal regions (P < .05).ConclusionIn this study, we found significantly higher oral, rectal, and urine Candida colonization rates in COVID-19 ICU patients compared with non-COVID-19 individuals. Increased oral Candida colonization can be the result of insufficient oral care application to these patients in the ICUs due to infection control anxiety, and also mechanical ventilation.Because non-albicans Candida strains were found significantly more frequent in COVID-19 patients, intrinsically resistant isolates should be kept in mind before administering antifungals.The high mixed growth rate detected in all individuals and especially in COVID-19 patients will affect the antifungal therapy and therefore emphasized the importance of using chromogenic media for routine evaluation.

P350 Oropharyngeal candidiasis in HIV infected patients: associated risk factors and antifungal susceptibility testing of candida species by disc diffusion method

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM ObjectivesTo isolate and identify Candida species by the standard microbiological method.To estimate the frequency of oral Candidiasis according to age, sex, and other factors [CD4 + count, ART, tobacco consumption, diabetes, upper respiratory tract infection (URTI), recent antibiotic consumption] in HIV-positive patients.To determine the Antifungal Susceptibility pattern of the Candida species by Disc Diffusion Method.MethodologyA hospital-based cross-sectional study was conducted for 6 months in the Department of Microbiology of Sukraraj Tropical and Infectious Disease Hospital, Kathmandu, Teku, Nepal. A total of 408 HIV-positive patients attending the ART center of the hospital of different age and sex were included in the study. Study variables like CD4 + count, tobacco consumption, diabetes, URTI, and recent antibiotic consumption were noted.Standard microbiological guidelines were followed for the oral swab collection and transportation. Specimen was seeded on SDA agar plates (SDA with chloramphenicol and cycloheximide). Preliminary identification of the Candida was done on the basis of colony characteristics, gram staining, and germ tube test. Further for the speciation of Candida species, HiCrome™ Candida Differential Agar (HImedia, India) was applied where on the basis of coloration and colony morphology speciation was done. Similarly, Cornmeal Agar (Dalmau plate culture technique) and sugar Fermentation test were applied to confirm the Candida species.Muller-Hinton agar supplemented with 2% glucose and 0.5 μg/ml methylene blue dye (GMB) medium was used to perform the antifungal susceptibility testing of Candida isolates. Antifungal susceptibility testing (AST) of isolates was performed and interpreted according to Clinical and Laboratory Standards Institute (CLSI) M44-A document. Candida albicans ATCC 90028 was taken as the reference strain. All the data were entered in Microsoft excel and Chi-square was used to find out the association between the frequency of oral candidiasis and study variables.ResultsAmong 408 studied subjects, 225 (55.1%) were males and 183 (44.9%) were females. Of the participants, 116 (28.4%) had regular tobacco smoking habit, diabetes 10 (2.5%), URTIs 30 (7.4%), antibiotic consumption 44 (10.8%) and ART use 394 (96.6%). The CD4 + cell count of respondents ranged from 12 - 2425 cells/mm³. Candida albicans 53 (81.5%) was the most frequently encountered species followed by C. tropicalis 3 (4.6%), C. krusei 2 (3.1%), C. glabrata 1 (1.5%) and 6 (9.2%) other Candida species. A total of 26 patients had CD4+ ≤200 cells/mm3 and 39 patients had CD4+ >200 cells/mm3. There was no significant association in the occurrence of oral candidiasis among males and females (P = .966), tobacco consumption (P = .051), ART use (P = .188), diabetes (P = .722). Whereas, there was a significant association between oral Candida carriage and CD4 + cell count ≤ 200 cells/mm3 (P <.001), URTI (P = .029), and recent antibiotic consumption (P = .002). Amphotericin B was the most potent antifungal followed by voriconazole, itraconazole, and conversely fluconazole the most resistant.Conclusion Candida albicans was the common species isolated in our study. Candida Chrome Agar can be used as a routine media for rapid identification and Candida speciation. AST needs to be done routinely to know the susceptibility pattern of isolates and initiate proper treatment of patients. Since oral yeast colonization was associated with low CD4 + count (<200 cells/mm3). Thus, oral lesions can serve as early markers for HIV infection.

S6.3d Candida albicans commensalism in the oral mucosa is favored by limited virulence and metabolic adaptation

S6.3 Fungal adaptation and evolution, September 22, 2022, 4:45 PM - 6:15 PM ObjectivesAs part of the human microbiota, the fungus Candida albicans colonizes the oral cavity and other mucosal surfaces. Commensalism is tightly controlled by complex fungus-host interactions that preclude fungal elimination but also fungal overgrowth and invasion that would result in disease. As such, defects in antifungal T cell immunity render individuals susceptible to oral thrush due to interrupted immunosurveillance. The factors that promote commensalism and ensure persistence of C. albicans in a fully immunocompetent host remain less clear. In this study, we aimed at identifying determinants of C. albicans commensalism in the oral cavity.MethodsWe used an experimental model of C. albicans oral colonization in mice, profiled the transcriptome of the fungus in the mucosal tissue, and conducted functional studies with the prototypical commensal isolate 101 in host-free and host-involving conditions.Results C. albicans commensalism is associated with a characteristic metabolic profile tailored to the nutrient-poor conditions in the stratum corneum of the epithelium where the fungus resides. Metabolic adaptation of the commensal isolate 101 was also reflected in enhanced nutrient acquisition when grown on oral mucosa substrates. Persistent colonization of the oral mucosa by C. albicans also correlated inversely with the capacity of the fungus to induce epithelial cell damage and to elicit an inflammatory response. These immune evasive properties of isolate 101 are explained by a strong attenuation of numerous virulence genes, including those linked to filamentation. De-repression of the hyphal program by deletion or conditional repression of the transcriptional repressor NRG1 abolished the commensal behavior of isolate 101.ConclusionsThis study establishes a central role of NRG1 in the commensal lifestyle of C. albicans in the oral niche of the host.

Cytokine array analysis of mediators produced by human macrophages stimulated with Trichomonastenax

The incidence of oral colonization by the protozoan Trichomonas tenax correlates with gingival inflammation and periodontitis in humans. To determine whether T. tenax might contribute to inflammation by eliciting cytokines from human cells, differentiated THP-1 (dTHP-1) macrophages were cultured with live or sonicated T. tenax trophozoites, and the conditioned media were assayed for 36 different mediators by a membrane-based cytokine array. Scanning densitometry of the membranes revealed that live T. tenax trophozoites stimulated secretion of interleukin-8 (IL-8), macrophage migration inhibitory factor (MIF), IL-1β, intercellular adhesion molecule-1 (ICAM-1), and IL-1 receptor antagonist (IL-1ra) from dTHP-1 macrophages. T. tenax lysates stimulated release of IL-8, MIF, and IL-1ra. Despite often being classified as a commensal organism, T. tenax elicited a wider variety of cytokines than the human urogenital pathogen, T. vaginalis, which elicited only IL-8 and MIF production from dTHP-1 cells.

Streptococcus mutans glutamate binding protein (GlnH) as antigen target for a mucosal anti-caries vaccine.

In recent years, several studies have demonstrated that bacterial ABC transporters present relevant antigen targets for the development of vaccines against bacteria such as Streptococcus pneumoniae and Enterococcus faecalis. In Streptococcus mutans, the glutamate transporter operon (glnH), encoding an ABC transporter, is associated with acid tolerance and represents an important virulence-associated factor for the development of dental caries. In this study, we generated a recombinant form of the S. mutans GlnH protein (rGlnH) in Bacillus subtilis. Mice immunized with this protein antigen elicited strong antigen-specific antibody responses after sublingual administration of a vaccine formulation containing a mucosal adjuvant, a non-toxic derivative of the heat-labile toxin (LTK63) originally produced by enterotoxigenic Escherichia coli (ETEC) strains. Serum anti-rGlnH antibodies reduced adhesion of S. mutans to the oral cavity of naïve mice. Moreover, mice actively immunized with rGlnH were partially protected from oral colonization after exposure to the S. mutans NG8 strain. Our results indicate that S. mutans rGlnH is a potential target antigen capable of inducing specific and protective antibody responses after immunization. Overall, these observations raise the prospect of the development of mucosal anti-caries vaccines.

Oral Colonization by Entamoeba gingivalis in the Biofilm and Saliva from Patients with Periodontal Disease

Background: In addition to human cells, healthy gums contain a variety of bacteria, fungi, and protozoa that may contribute to unhealthy sites. The effect of pathogens lysis or other immune cell lysis needs to be clarified in order to expand the current pathophysiological pattern of periodontitis. The purpose of this study was to survey the prevalence of E. gingivalis among patients with periodontitis and healthy individuals in order to support public health action. In addition, we investigated the relationship between the incidence rate and some parameters, such as patient age and gender. Methods and Results: This study enrolled 51 subjects divided into two groups: The case group involved 31 patients (15 females and 16 males) with periodontal disease; the control group included 20 people (10 females and 10 males) with healthy oral cavities. Biofilm and saliva samples were collected and examined for the presence of E. gingivalis. A total of 22(71.0%) patients of various ages with periodontal disease were infected with E. gingivalis. Male patients were more likely to have the amoeba than female patients. E. gingivalis was also found in the control group, albeit at a lower frequency (P=0.005). Conclusion: Infections with E. gingivalis should be considered as a potential pathological factor associated with the development of periodontal diseases. More research should be conducted to determine whether E. gingivalis is the primary cause of tissue destruction and disease progression, or if it is acting synergistically with the current pathogenic bacteria that should be investigated further.

The high frequency of mecA and Als3p genes among Staphylococcus aureus and Candida species isolated from patients with malignancies on chemotherapy

The present study aimed to survey the prevalence of methicillin-resistant Staphylococcus aureus and Candida species oral and nasal co-colonization among patients with malignancies on chemotherapy in Tehran, Iran. In a cross-sectional single-center study performed from October until the end of December 2020, oral and nasal specimens were collected using dry sponge swabs from patients with different malignancies under chemotherapy in Masih Daneshvari Hospital, Tehran, Iran. We used the disk diffusion method to the screening of oxacillin (methicillin) resistance among S. aureus isolates. The final identification of MRSA strains and the frequency of hyphal adhesin Als3p was performed using the PCR method with a specific primer that targeted mecA and Als3p genes, respectively. A total of 170 oral and nasal specimens were collected from 170 adult patients. Oral colonization by S. aureus, MRSA, and Candida species was found in 20 (11.8%), 11 (6.5%), and 68 (40%) patients, respectively, while nasal colonization by S. aureus and MRSA and Candida species was found in 26 (15.3%), 17 (10%) and 7 (4.1%) patients, respectively. The total colonization of MRSA and Candida spp. in both oral and nasal was 14.7% (n = 25/170) and 41.2% (n = 70/170), respectively. All MRSA isolates and Candida species were positive for mecA and Als3p genes, respectively. The present study revealed the importance of polymicrobial infection among patients with different malignancies and presumed that S. aureus can use Candida adhesion Als3p to create systemic infections in immunocompromised patients.

Impacts of Delivery Mode and Maternal Factors on Neonatal Oral Microbiota.

ObjectivesInitial oral microbial colonization has complicatedly interacted with growth and development. The aim of our study was to discover links between oral microbiota community structure and mode of delivery, maternal factors, such as systemic diseases, abortion history, and pregnancy complications.MethodsA total of 177 pregnant women and their neonates were enrolled at Peking university people’s hospital. We collected oral samples, medical history, and development phenotype and used a 16S rRNA gene sequence to analyze microbial diversity at all taxonomic levels, network structure, and metabolic characteristics.ResultsFirmicutes, Proteobacteria, and Actinobacteriota were the most predominant bacteria of neonatal oral samples among these phyla. Alpha-diversity of pregnant women with gestational diabetes mellitus (GDM), abortion history, and without immune diseases was higher than in control groups, and no significant dissimilarity in beta-diversity was observed between different maternal factors. Obvious separation or trend failed to be seen in different development phenotype groups. Besides, Oscillospirales were significantly more abundant in a natural delivery group than in the cesarean section group.ConclusionOur study indicated that maternal factors and mode of delivery influenced the oral microbial structure, but longitudinal studies were indispensable for capturing the long-term effects on neonatal development phenotype and oral microbiota.

Leuconostoc mesenteroides LVBH107 Antibacterial Activity against Porphyromonas gingivalis and Anti-Inflammatory Activity against P. gingivalis Lipopolysaccharide-Stimulated RAW 264.7 Cells.

Probiotics, active microorganisms benefiting human health, currently serve as nutritional supplements and clinical treatments. Periodontitis, a chronic infectious oral disease caused by Porphyromonas gingivalis (P. gingivalis), activates the host immune response to release numerous proinflammatory cytokines. Here, we aimed to clarify Leuconostoc mesenterica (L. mesenteroides) LVBH107 probiotic effects based on the inhibition of P. gingivalis activities while also evaluating the effectiveness of an in vitro P. gingivalis lipopolysaccharide-stimulated RAW 264.7 cell-based inflammation mode. L. mesenteroides LVBH107 survived at acid, bile salts, lysozyme, and hydrogen peroxide conditions, auto-aggregated and co-aggregated with P. gingivalis, exhibited strong hydrophobicity and electrostatic action, and strongly adhered to gingival epithelial and HT-29 cells (thus exhibiting oral tissue adherence and colonization abilities). Moreover, L. mesenteroides LVBH107 exhibited sensitivity to antibiotics erythromycin, doxycycline, minocycline, ampicillin, and others (thus indicating it lacked antibiotic resistance plasmids), effectively inhibited P. gingivalis biofilm formation and inflammation (in vitro inflammation model), reduced the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) and inflammatory mediators (NO and PGE2), and decreased the expression levels of inflammation related genes. Thus, L. mesenterica LVBH107 holds promise as a probiotic that can inhibit P. gingivalis biofilm formation and exert anti-inflammatory activity to maintain oral health.

Oral Microbes in Hospital-Acquired Pneumonia: Practice and Research Implications.

Hospital-acquired pneumonia accounts for 25% of all health care-associated infections and is classified as either ventilator-associated or non-ventilator-associated pneumonia. Hospital-acquired pneumonia most frequently results from aspiration of oropharyngeal secretions into the lungs. Although preventive measures for ventilator-associated pneumonia are well established, few preventive measures exist for the nonventilator type. To (1) explore oral microbes associated with ventilator-associated and non-ventilator-associated pneumonia in acutely ill, adult hospitalized patients, and (2) provide evidence-based recommendations for measures to prevent pneumonia in hospitalized patients. A literature search was conducted using CINAHL, Academic Search Premier, Medline, and the Cochrane Library. Ten studies were found that identified common oral microbes in ventilator-associated and non-ventilator-associated pneumonia, including Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, S aureus, and Streptococcus pneumoniae. Collectively, oral colonization with E coli, P aeruginosa, methicillin-resistant S aureus, and S aureus increased the risk of nonventilator pneumonia. Findings also suggested microaspiration of colonized oral microbes into the lungs. Non-ventilator-associated pneumonia had similar colonization rates of gram-positive and gram-negative bacteria, whereas ventilator-associated pneumonia had greater colonization with gram-negative bacteria. The literature did not indicate a standard of oral care effective in all patient populations. Oral care is an effective intervention to prevent hospital-acquired pneumonia by reducing pathogenic oral microbial colonization. The impact of different methods and timing of oral care on oral microbes should be further explored, particularly in patients not receiving mechanical ventilation. Findings reaffirm the importance of consistent oral care in hospitalized patients. In addition, practices should be different in patients receiving mechanical ventilation versus patients not receiving ventilation. Results may also provide knowledge to inform future preventive measures for pneumonia, particularly for nonventilator pneumonia.

Photoactivation of Curcumin Doped Poly-Lactic-Co-Glycolic Acid Nanoparticles in Rat Model with Fixed Orthodontic Appliances.

This study aimed to evaluate the antimicrobial effect of curcumin doped poly-lactic-co-glycolic acid nanoparticles (Cur-PLGA-Nps)-mediated antimicrobial photodynamic therapy (aPDT), as well as the probiotics on S. mutans in rats with fixed orthodontic appliances. Orthodontic appliances were ligated to the right maxillary of the rats. After the oral colonization of S. mutans, the rats were then treated in four groups including Cur-PLGA-Nps, light-emitting diode, Cur-PLGA-Nps-mediated aPDT, and probiotic (Lactobacillus acidophilus). After that, the S. mutans counts and the gtfB gene expression of S. mutans were determined on days 4, 7, 15, and 30. Probiotic and Cur-PLGA-Nps-mediated aPDT groups significantly reduced the count of S. mutans in a time-dependent manner (P < 0.05). So, probiotics and Cur-PLGA-Nps-mediated aPDT were able to reduce S. mutans more than other groups on the 30th day. Also, there was no considerable difference between Cur-PLGA-Nps-mediated aPDT and probiotic groups in bacterial growth inhibition. The expression level of gtfB gene was significantly downregulated at all-time intervals after exposure to Cur-PLGA-Nps-mediated aPDT compared with untreated bacteria (P < 0.05). According to the results, simultaneous use of Cur-PLGA-Nps-mediated aPDT and probiotic therapeutic approaches can be suggested to increase effectiveness.