Post-translational modification by the Pgf glycosylation machinery modulates Streptococcus mutans OMZ175 physiology and virulence.

Streptococcus mutans is commonly associated with dental caries and the ability to form biofilms is essential for its pathogenicity. We recently identified the Pgf glycosylation machinery of S. mutans, responsible for the post-translational modification of the surface-associated adhesins Cnm and WapA. Since the four-gene pgf operon (pgfS-pgfM1-pgfE-pgfM2) is part of the S. mutans core genome, we hypothesized that the scope of the Pgf system goes beyond Cnm and WapA glycosylation. In silico analyses and tunicamycin sensitivity assays suggested a functional overlap between the Pgf machinery and the rhamnose-glucose polysaccharide synthesis pathway. Phenotypic characterization of pgf mutants (ΔpgfS, ΔpgfE, ΔpgfM1, ΔpgfM2, and Δpgf) revealed that the Pgf system is important for biofilm formation, surface charge, membrane stability, and survival in human saliva. Moreover, deletion of the entire pgf operon (Δpgf strain) resulted in significantly impaired colonization in a rat oral colonization model. Using Cnm as a model, we showed that Cnm is heavily modified with N-acetyl hexosamines but it becomes heavily phosphorylated with the inactivation of the PgfS glycosyltransferase, suggesting a crosstalk between these two post-translational modification mechanisms. Our results revealed that the Pgf machinery contributes to multiple aspects of S. mutans pathobiology that may go beyond Cnm and WapA glycosylation.

Oral colonization by gram-negative bacilli in patients with hematologic malignancies and solid tumors compared with healthy controls.

BACKGROUND: Colonization of the oropharynx with gram-negative bacilli (GNB) is considered a negative prognostic factor in immunocompromised individuals. Hemato-oncologic patients represent a high-risk group due to their immunodeficiencies and associated treatments. This study aimed to determine the rates of oral colonization by GNB, associated factors, and clinical outcomes in patients with hematologic malignancies and solid tumors compared with healthy subjects. METHODS: We conducted a comparative study of hemato-oncologic patients and healthy subjects from August to October 2022. Swabs were taken from the oral cavity; specimens with GNB were identified and tested for antimicrobial susceptibility. RESULTS: We included 206 participants (103 hemato-oncologic patients and 103 healthy subjects). Hemato-oncologic patients had higher rates of oral colonization by GNB (34% vs. 17%, P = 0.007) and GNB resistant to third-generation cephalosporins (11.6% vs. 0%, P < 0.001) compared to healthy subjects. Klebsiella spp. was the predominant genus in both groups. The factor associated with oral colonization by GNB was a Charlson index ≥ 3, while ≥ 3 dental visits per year were a protective factor. Regarding colonization by resistant GNB in oncology patients, antibiotic therapy and a Charlson index ≥ 5 were identified as associated factors, while better physical functionality (ECOG ≤ 2) was associated with less colonization. Hemato-oncologic patients colonized with GNB had more 30-day infectious complications (30.5% vs. 2.9%, P = 0.0001) than non-colonized patients. CONCLUSION: Oral colonization by GNB and resistant GNB are prevalent in cancer patients, especially those with higher scores on the severity scales. Infectious complications occurred more frequently in colonized patients. There is a knowledge gap about dental hygiene practices in hemato-oncologic patients colonized by GNB. Our results suggest that patients' hygienic-dietary habits, especially frequent dental visits, are a protective factor against colonization.

Novel Two-Component System of Streptococcus sanguinis Affecting Functions Associated with Viability in Saliva and Biofilm Formation.

Streptococcus sanguinis is a pioneer species of teeth and a common opportunistic pathogen of infective endocarditis. In this study, we identified a two-component system, S. sanguinis SptRS (SptRS Ss ), affecting S. sanguinis survival in saliva and biofilm formation. Isogenic mutants of sptRSs (SKsptR) and sptSSs (SKsptS) showed reduced cell counts in ex vivo assays of viability in saliva compared to those of parent strain SK36 and complemented mutants. Reduced counts of the mutants in saliva were associated with reduced growth rates in nutrient-poor medium (RPMI) and increased susceptibility to the deposition of C3b and the membrane attach complex (MAC) of the complement system, a defense component of saliva and serum. Conversely, sptRSs and sptSSs mutants showed increased biofilm formation associated with higher levels of production of H2O2 and extracellular DNA. Reverse transcription-quantitative PCR (RT-qPCR) comparisons of strains indicated a global role of SptRS Ss in repressing genes for H2O2 production (2.5- to 15-fold upregulation of spxB, spxR, vicR, tpk, and ackA in sptRSs and sptSSs mutants), biofilm formation, and/or evasion of host immunity (2.1- to 11.4-fold upregulation of srtA, pcsB, cwdP, iga, and nt5e). Compatible with the homology of SptR Ss with AraC-type regulators, duplicate to multiple conserved repeats were identified in 1,000-bp regulatory regions of downstream genes, suggesting that SptR Ss regulates transcription by DNA looping. Significant transcriptional changes in the regulatory genes vicR, spxR, comE, comX, and mecA in the sptRSs and sptSSs mutants further indicated that SptRS Ss is part of a regulatory network that coordinates cell wall homeostasis, H2O2 production, and competence. This study reveals that SptRS Ss is involved in the regulation of crucial functions for S. sanguinis persistence in the oral cavity.

Concordance in bacterial colonization profiles between voice prostheses and oral microbiota post-laryngectomy: An experimental study.

OBJECTIVE: Knowledge about voice prosthesis microbial colonization is vital in laryngectomized patients' quality of life (QoL). Herein, we aimed to explore the relationship between oral microbial patterns, demographic variables and voice prosthesis performance. METHODS: Thirty laryngectomy patients were assessed for microbial colonization in their voice prostheses and oral cavities. Factors like age, proton pump inhibitor (PPI) usage, and alcohol consumption were considered. RESULTS: Participants' average age was 74.20 ± 7.31 years, with a majority on PPIs. Staphylococcus aureus was the most common bacterium in prostheses (53 %), followed by Pseudomonas aeruginosa (27 %). Candida albicans was the primary fungal colonizer (67 %). A statistically significant moderate correlation was found between fungal species before and after oral rinsing (p = 0.035, Phi=0.588, Cramer's V = 0.416). Voice prosthesis and oral cavity microbiota profiles showed significant concordance (kappa=0.315, p < 0.004). Among subgroup analyses, bacterial patterns of colonization did not significantly influence VHI (p = 0.9555), VrQoL (p = 0.6610), or SF-36 (p = 0.509) scores. Conversely, fungal patterns of VP colonization significantly impacted subjective voice scores, with Candida krusei demonstrating better VHI (35.25 ± 3.63 vs. 44.54 ± 6.33; p = 0.008), VrQoL (7.13 ± 1.69 vs. 10.73 ± 2.00; p = 0.001), and SF-36 (69.36 ± 7.09 vs. 76.50 ± 7.73; p = 0.051) scores compared to C. albicans. CONCLUSIONS: There was a significant correlation between the oral microbiota and voice prosthesis colonization. These insights can inform improved care strategies for voice prostheses, enhancing patient outcomes.

Prevalence of yeast other than Candida albicans in denture wearers.

PURPOSE: The isolation of yeast species other than Candida albicans from the oral mucosa has been increasing in frequency, suggesting that those may constitute emerging potential oral colonizers. The purpose of this work was to determine whether yeast species other than C. albicans are associated with factors related to wearing of dental prostheses. MATERIALS AND METHODS: tRNA-PCR fingerprinting and sequencing of the 26S rDNA D1/D2 domain were used to identify all yeasts isolated from CHROMagar™ Candida cultures of oral swabs collected from 178 patients. RESULTS: Besides C. albicans, 13 other species were identified, corresponding to 34% of the yeast isolates. The majority of the non-C. albicans species were not detected as single colonizers but rather in co-colonization with one or two other yeasts, often with C. albicans. No significant associations were found with non-C. albicans species. On the contrary, the best-fitted logistic regression model predicts that either wearing a denture (adjusted odds = 4.6) or insufficient oral hygiene (adjusted odds = 2.3) are risks for colonization by yeast, in general. CONCLUSIONS: The colonization with non-C. albicans species and co-colonization were not independently associated with any of the analyzed host-related factors. In particular, neither wearing a removable denture nor being elderly were significant predictors.

A preliminarily Investigation on Oral Colonization and Counts of Streptococcus mutans and Streptococcus mitis in a Group of Predentate Infants in Relation to Some Maternal and Infant Factors (A Longitudinal Observational study).

Aim: Bacterial colonization of infants' oral cavities is a key factor for future caries risk. This study sought to longitudinally assess oral bacterial colonization in a group of predentate infants in relation to some mother and infant factors. Materials and methods: A total of 50 mother-infant pairs were enrolled. When infants were 3-month-old, data were collected about some infant and mother factors; additionally, maternal Decayed, Missing, and Filled Teeth (DMFT) scores and salivary samples of mothers and infants were obtained. At 6 months of infant's age, another infants' salivary samples were obtained. Saliva was cultured to detect and quantify Streptococcus mutans (S. mutans) and Streptococcus mitis (S. mitis). Results: Streptococcus mitis (S. mitis) was detected in all infants at 3 months. 74 and 96% of infants acquired S. mutans at 3 and 6 months, respectively. S. mutans detection was significantly higher with higher maternal DMFT scores, salivary S. mutans counts, and lower S. mitis counts, as well as when infants were given sugar-containing complementary foods/drinks. At 3-6 months, infants' S. mutans counts were significantly positively correlated with maternal S. mutans counts and DMFT scores and negatively correlated with maternal S. mitis counts. The opposite was evident for infants' S. mitis counts. Regression analysis showed that increased maternal DMFT scores and S. mutans counts, and Cesarean delivery were strong predictors for increased infant's S. mutans counts. While increased DMFT scores and maternal S. mutans counts were strong predictors for reduced infant's S. mitis counts. Conclusion: Poor maternal oral health, early introduction of sugars in the diet, and probably Cesarean delivery can negatively impact infants' oral bacterial colonization and possibly future caries risk. Clinical significance: Understanding factors associated with oral colonization of both caries-producing and protective flora in infants of different populations is important for caries prevention. This, in turn, can aid tailoring oral health promotion programs for expectant mothers. How to cite this article: Wassel MO, Salman NS, Metwalli NE. A preliminarily Investigation on Oral Colonization and Counts of Streptococcus mutans and Streptococcus mitis in a Group of Predentate Infants in Relation to some Maternal and Infant Factors (A Longitudinal Observational study). Int J Clin Pediatr Dent 2023;16(1):79-86.

High oral carriage of multidrug resistant Gram-negative bacilli in adolescents: the SOPKARD-Junior study.

Introduction: The colonization of the oral cavity by potentially pathogenic antimicrobial-resistant bacteria in adolescents and its consequences is very poorly understood. The present study focused on the occurrence of oral colonization by Gram-negative bacilli (GNB) and their multidrug resistance, including the production of extended-spectrum ß-lactamases (ESBLs) and carbapenemases, among healthy adolescents and risk factors associated with GNB colonization. Materials and methods: This study was conducted as part of "A program for the early detection of risk factors for lifestyle diseases SOPKARD-Junior" (SOPKARD-Junior). Oral samples were collected from 182 adolescents from four public elementary schools in Sopot, Poland, aged 13-14 years. Bacterial strains were identified by the MALDI-TOF MS method. Screening of antimicrobial resistance was performed using a disk diffusion method. The NG-Test® CARBA-5 was used to detect and differentiate the five most widely distributed carbapenemases. Demographic and clinical data were collected and statistical analysis of risk factors was performed. Results: A total of 68 out of 182 (37.4%) healthy adolescents was documented oral colonization with Gram-negative bacilli, including 50/182 (27.5%) multidrug resistant (MDR-GNB) strains. Over 60% of oral carriage concerned three main genera Enterobacter spp., Pseudomonas spp., and Serratia spp., which were detected in 22.1%, 19.1%, and 19.1% of participants, respectively. Citrobacter spp., Escherichia coli, Klebsiella spp., Hafnia spp., Aeromonas spp., Acinetobacter spp., and Stenotrophomonas spp. were also isolated. The antimicrobial resistance to ampicillin (100%), ceftazidime (69.1%), meropenem (60.3%), gentamycin (60.3%), piperacillin/tazobactam (52.9%), and piperacillin (45.6%) were the most common. Among 73.5% GNB strains multidrug resistance was observed, including all Pseudomonas spp. strains. Among MDR-GNB, 30.4% were resistant to four groups of antibiotics, half of the MDR Pseudomonas spp. strains were resistant to 10 groups of antibiotics. Extended-spectrum ß-lactamases were produced by Enterobacter cloacae, Klebsiella spp., and Serratia spp. (7.4%). Colonization by ESBLs-positive GNB strains was significantly associated with recurrent respiratory infections, nasal congestion, and bronchitis (p<0.05). Conclusion: Our study revealed high oral carriage of multi-drug resistant Gram-negative bacilli in healthy adolescents and the association of ESBL-producing strains with respiratory infections. Further studies on oral colonization with GNB are necessary due to the possibility of distinct infections and the acquisition of antibiotic resistance by resident microbiota.

Significance of pleural effusion detected by metagenomic next-generation sequencing in the diagnosis of aspiration pneumonia.

Objective: Using metagenomic next-generation sequencing (mNGS) to profile the bacterial pathogen of pleural infection in aspiration pneumonia for therapeutic decision-making. Methods: Collection and analysis of the clinical and laboratory data of aspiration pneumonia patients who underwent mNGS detection of pleural effusion at the Second Hospital of Jilin University from November 2020 and March 2022. Results: Nine males and one female were included, aged 33 to 69 years. All patients had chest pain, fever, cough, and hypoxemia symptoms; 90% had expectoration. The laboratory tests revealed that all patients had elevated white blood cell, neutrophil, and C-reactive protein (CRP) levels. Furthermore, erythrocyte sedimentation rate (ESR) increased in 8 patients, and procalcitonin increased in only one patient. Chest CT indicated different degrees of lobar pneumonia and pleural effusion in all patients, and biochemical results implied exudative effusion according to Light criteria. Most routine culture results were negative. Among bacteria identified by mNGS, Fusobacterium nucleatum (n=9) was the most common, followed by Parvimonas micra (n=7) and Filifactor alocis (n=6). Three patients underwent surgical treatment after applying targeted antibiotics, thoracic puncture and drainage, and fibrinolytic septum treatment. After the adjusted treatment, the number of white blood cells, neutrophils, and lymphocytes decreased significantly, indicating the eradication of the infection. Conclusions: Improving the vigilance of atypical people suffering from aspiration pneumonia is essential. The mNGS detection of pleural effusion clarified the microbial spectrum of aspiration pneumonia, allowing targeted antibiotic administration.

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 colonization of Acinetobacter baumannii in intensive care units: Risk factors, incidence, molecular epidemiology, association with the occur of pneumonia and sepsis, and infection control measures.

Objectives: Oral colonization of Acinetobacter baumannii can lead to infections such as pneumonia and sepsis. We aimed to evaluate oral colonization of hospitalized patients in ICUs and to examine risk factors for oral colonization, molecular epidemiology, and incidence of pneumonia and sepsis. Materials and Methods: The study began in February 2021. Oral cultures were taken. The microorganisms were identified by a Maldi-tof MS mass spectrometry device. Colistin resistance genes were investigated by polymerase chain reaction. Clonal relationships were determined by pulsed-field gel electrophoresis. Results: A. baumannii was found in 21 of 96 patients' oral cultures. Pneumonia and sepsis due to A. baumannii were detected in 14 and 5 patients, respectively. The mean growth time of A. baumannii from oral cultures was 11.8 days, and the meantime for the occurrence of pneumonia after oral growth was 5.2 days. We determined a plasmid mediated mcr-2 colistin resistance gene in a colistin susceptible A. baumannii strain. It is the first report of the plasmid mediated mcr-2 colistin resistance gene in our country. In total, fourteen different A. baumannii genotypes were determined in PFGE. It was determined that the effects of antibiotic use, oral motor dysfunction, mechanical ventilation, intubation, orogastric tube use, and total parenteral nutrition intake on oral colonization were statistically significant. Conclusion: Oral colonization of A. baumannii is a significant concern in ICUs. We believe that it is important to take oral cultures and follow the risk factors and take infection control measures to prevent oral colonization of resistant isolates in ICUs.

Meticillin-susceptible Staphylococcus aureus transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions investigated using whole-genome sequencing.

BACKGROUND: The role of meticillin-susceptible Staphylococcus aureus (MSSA) colonization of healthcare workers (HCWs), patients and the hospital environment in MSSA transmission events (TEs) is poorly understood. AIMS: The role of meticillin-resistant Staphylococcus aureus (MRSA) was investigated recently under non-outbreak conditions in a large hospital with a history of endemic MRSA over 2 years using whole-genome sequencing (WGS). Numerous potential MRSA TEs were identified. The present study investigated MSSA TEs from the same sources during the same 2-year hospital study. METHODS: HCW (N=326) and patient (N=388) volunteers on nine wards were tested for nasal and oral MSSA colonization over 2 years. Near-patient environment (N=1164), high-frequency touch sites (N=810) and air (N=445) samples were screened for MSSA. Representative MSSA and clinical isolates were sequenced and analysed by core genome multi-locus sequence typing. Closely related isolates (≤24 allelic differences) were segregated into related isolate groups (RIGs). Potential TEs involving MSSA in RIGs from HCWs, patients and patient infections were identified in combination with epidemiological data. FINDINGS: In total, 635 MSSA were recovered: clinical isolates (N=82), HCWs (N=170), patients (N=120), and environmental isolates (N=263). Twenty-four clonal complexes (CCs) were identified among 406/635 MSSA sequenced, of which 183/406 segregated into 59 RIGs. Numerous potential HCW-to-patient, HCW-to-HCW and patient-to-patient TEs were identified, predominantly among CC5-MSSA, CC30-MSSA and CC45-MSSA. HCW, patient, clinical and environmental isolates were identified in 33, 24, six and 32 RIGs, respectively, with 19/32 of these containing MSSA related to HCW and/or patient isolates. CONCLUSIONS: WGS detected numerous potential hospital MSSA TEs involving HCWs, patients and environmental contamination under non-outbreak conditions.

A Comparison of the Prevalence Rate of Oral Candida Colonization between Opium Users and Cigarette Smokers in Kerman, Iran.

BACKGROUND: Candidiasis is the most common opportunistic oral infection and smoking is considered as one of its well-known risk factors. However, it remains unknown whether opium users are susceptible to increased oral candida colonization. The aim of the present study is to compare the prevalence rate of oral candida colonization between opium users and cigarette smokers in Kerman, Iran. METHODS: This case-control study included 75 healthy male respondents divided into three groups (25 in each group): cigarette smokers, cigarette and opium users, and non-smokers as control group. The samples were obtained from oral mucosa by scraping the mucosa with a sterile cotton swab then inoculated into Sabouraud Dextrose Agar (SDA) and CHROMagar plates and also examined with the light microscope. FINDINGS: Candida was identified in 38.70% of respondents. The most frequently isolated species was Candida albicans (90.66%). The highest prevalence of candida carriage was found in cigarette smokers (52.00%). The difference of candida carriage between the two groups of cigarette smokers and cigarette plus opium users and the control group was statistically significant (P = 0.007 and P = 0.015, respectively). CONCLUSION: In the present study, it was revealed that the prevalence of oral candida carriage was significantly higher among cigarette and opium users in comparison to the non-users.

Host Age and Denture Wearing Jointly Contribute to Oral Colonization with Intrinsically Azole-Resistant Yeasts in the Elderly.

In elderly patients, several morbidities or medical treatments predisposing for fungal infections occur at a higher frequency, leading to high mortality and morbidity in this vulnerable patient group. Often, this is linked to an innately azole-resistant yeast species such as Candida glabrata or C. krusei. Additionally, host age per se and the wearing of dentures have been determined to influence the mix of colonizing species and, consequently, the species distribution of invasive fungal infections. Since both old age and the wearing of dentures are two tightly connected parameters, it is still unclear which of them is the main contributor. Here, we performed a cross-sectional study on a cohort (N = 274) derived from three groups of healthy elderly, diseased elderly, and healthy young controls. With increasing host age, the frequency of oral colonization by a non-albicans Candida species, mainly by C. glabrata, also increased, and the wearing of dentures predisposed for colonization by C. glabrata irrespectively of host age. Physically diseased hosts, on the other hand, were more frequently orally colonized by C. albicans than by other yeasts. For both C. albicans and C. glabrata, isolates from the oral cavity did not generally display an elevated biofilm formation capacity. In conclusion, intrinsically azole-drug-resistant, non-albicans Candida yeasts are more frequent in the oral cavities of the elderly, and fungal cells not contained in biofilms may predispose for subsequent systemic infection with these organisms. This warrants further exploration of diagnostic procedures, e.g., before undergoing elective abdominal surgery or when using indwelling devices on this patient group.

Oral Candidal Colonization in Patients with Different Prosthetic Appliances.

Oral infections caused by Candida species are becoming more common, which may be related to an increase in the number of immunologically compromised patients as well as favorable conditions in the oral cavity that often include removable prosthetic appliances. The purpose of this study was to determine the presence of a particular Candida species in patients with PMMA and Cr-Co prosthetic appliances, as well as the salivary flow rate, and oral signs and symptoms. This investigation included a total of 120 subjects with different kinds of removable dentures. A sample of concentrated oral rinse was collected from all subjects in order to detect Candida colonization and identify the Candida species, a quantum of salivation was measured, and subjects were examined clinically. Candida spp. was predominant among the subjects who were denture wearers (p < 0.0001). In all subjects, the most frequently detected species was C.albicans. A statistically significant difference was found between the prevalence of C.albicans (p < 0.001) and C.krusei (p < 0.001) in denture wearers. Subjects with PMMA-based removable prosthetic appliances mostly demonstrated a significant decrease in salivation (p < 0.001), an increase in burning sensations (p < 0.001), and dry mouth (p < 0.001) compared to the subjects who wore partial dentures with Co-Cr metallic frameworks. Red oral lesions were more frequently found among the subjects with partial dentures with Co-Cr metallic frameworks (p < 0.001). Regardless of the material used for the denture, patients must be regularly checked by their dentists in order to prevent the development of oral lesions.

Influence of delivery and feeding mode in oral fungi colonization - a systematic review.

Postnatal acquisition of microorganisms from maternal and environmental sources contributes to the child microbiome development. Several studies showed that the mode of delivery and breastfeeding may have impact on the oral bacterial colonization, however, the influence on oral fungal colonization is still unknown. We performed a systematic literature review on mother to child oral fungi transmission, namely regarding the association between the mode of delivery and breastfeeding in oral yeast colonization. Our analysis revealed no significant differences between the oral mycobiome of breastfed and bottle-fed children. As for the delivery mode, the majority of studies found a relation between fungal colonization and vaginal delivery. Candida albicans was the most commonly isolated fungi species. Our analysis suggests that maternal breastfeeding does not seem to influence oral mycology, but vaginal delivery appears to promote oral yeast colonization in early life.

Oral Candida albicans colonization in healthy individuals: prevalence, genotypic diversity, stability along time and transmissibility.

In this study, 181 healthy individuals, including 29 couples, were analysed regarding oral yeast colonization using a culture-based approach. Results showed that 39% of the individuals were yeast carriers, 89% being colonized with Candida albicans, 5% with C. guilliermondi, 3% with C. lusitaniae and 3% with C. parapsilosis. Sixty-two percent of the couples had at least one member colonized. Colonization and CFU counts were higher in the couples´ group. Eighty percent of the volunteers were colonized with C. albicans strains with only one CAI genotype, while two but similar CAI genotypes inhabited the oral cavity of the remaining 20% individuals. The same CAI genotypes were found in 66.6% of the couples when both were colonized. Our results indicate that the intimacy among couples increases the probability of heavy cross-colonization, which is potentiated when one member of the couple is a smoker.

Oral Candida colonization in patients with chronic periodontitis. Is there any relationship?

BACKGROUND: Candida can be implicated in the pathology of chronic periodontitis. AIMS: To analyze the oral Candida carriage in patients suffering from chronic periodontitis (CP) and its correlation with the severity of this condition. METHODS: Microbiological samples were taken from 155 patients using the oral rinse (OR) technique and by using paper points in the periodontal pockets (GPP). These patients were divided into 3 groups: 89 patients without CP (control), 47 with moderate CP, and 19 with severe CP. Samples were cultured in a Candida chromogenic agar for Candida. Species were identified by microbiological and molecular methods. RESULTS: Candida was isolated in the OR of 45 (50.6%), 21 (44.7%), and 11 (57.9%) patients, respectively, and in the GPP of 32 (36%), 14 (29.2%), and 10 (42.6%) patients from the control, moderate CP and severe CP groups, respectively. Candida was isolated more frequently and in a greater burden in OR than in GPP (p<0.01). Candida albicans was the most prevalent species. GPP of patients with CP had poor fungal biodiversity (p<0.01). CONCLUSIONS: Colonization by Candida was present in the samples of patients without CP, and with both moderate and severe CP. Nonetheless, patients with severe CP had a higher rate of Candida colonization, especially by C. albicans.

Survival of an Aggregatibacter actinomycetemcomitans quorum sensing luxS mutant in the mouths of Rhesus monkeys: insights into ecological adaptation.

Experiments were designed to explore a prominent autoinducer-2 (AI-2) producing gene (luxS) related to colonization and survival of Aggregatibacter actinomycetemcomitans, a low abundance member of the indigenous flora, that forms a key component of the dysbiotic flora in localized aggressive periodontitis. The luxS gene was disrupted in a primate strain of A. actinomycetemcomitans before implantation into the oral cavity of Rhesus monkeys (Rh). The colonization efficiency of the luxS mutant (RhAa-VS4) was compared with the parental wild-type strain (RhAa3) (positive control) and a ltxA mutant (RhAa-VS2) (negative control). The in vivo results showed that the luxS mutation had minimal impact on A. actinomycetemcomitans colonization compared with the wild-type RhAa3 strain. In vitro studies revealed that there was a significant upregulation of attachment-related genes aae, apiA, and flp in the RhAa-VS4 strain compared with RhAa3. Biofilm forming ability was also significantly increased in the RhAa-VS4 strain compared with RhAa3, whereas the AI-2 signal was ablated. The exogenous addition of the AI-2 precursor dihydroxy pentanedione allowed the RhAa-VS4 strain to achieve RhAa3 biofilm levels. This is the first primate study to test the relevance of LuxS in vivo. In vitro assessment suggests that in vivo survival of the RhAa-VS4 strain was due to the production of signaling AI-2 molecules derived from other members of the flora as well as the upregulation of genes related to attachment and biofilm formation.

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus colonization among human immunodeficient virus-infected outpatients in Taiwan: oral Candida colonization as a comparator.

Human immuodeficency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) and community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) have increased in recent years in Taiwan. This study was undertaken to determine the prevalence of and risk factors for nasal and oral S. aureus and MRSA colonization among contemporary HIV-infected populations. Clinical variables for S. aureus and MRSA colonization among HIV-infected outpatients from three hospitals were analyzed and compared with those for oral Candida colonization. Genetic characteristics of MRSA isolates were analyzed. A total of 714 patients were screened for nasal S. aureus colonization, and a subset of 457 patients were also screened for oral S. aureus colonization. Of all patients, 79.4% were receiving HAART, and their mean CD4 count was 472 cells/mm3. The colonization rates in the oral cavity, nasal cavity, and at either site were 18.8%, 31.7%, and 36.8%, respectively, for S. aureus, and 3.1%, 4.4%, and 5.5%, respectively, for MRSA. These rates were all much lower than the previously reported rate of oral Candida colonization (52.4%). By multivariate analysis, a suppressed viral load (<200 copies/mL) protected against oral S. aureus, MRSA, and Candida colonization, and recent use of antibacterial agents protected against oral and nasal S. aureus colonization. Recent incarceration increased the risk of nasal MRSA colonization, while recent hospitalization, tuberculosis, older age, and intravenous drug use increased the risk of oral Candida colonization. Candida spp. did not augment S. aureus or MRSA colonization in the oral cavity. Most of the 41 MRSA isolates recovered belonged to the SCCmec IV/pvl-negative (51.2%) and VT/pvl-positive (26.8%) ST59 local prevalent CA-MRSA clones. Distinct carriage rates demonstrated here suggested that mucosal immunity against colonization might differ in terms of microbes and sites. A decreased risk in oral carriage of MRSA and Candida might be a benefit of HAART.

Oral Colonization by Nosocomial Pathogens During Hospitalization in Intensive Care Unit and Prevention Strategies.

BACKGROUND: Critically ill patients are very susceptible to a variety of disorders and infections during hospitalization in Intensive Care Units [ICU]. Among these problems, nosocomial infections are major causes of morbidity and mortality. METHODS: Nosocomial pneumonias, specifically ventilator associated pneumonias have become a major health care issue. The implication of oral care in hospital presents challenges that can prevent or reduce the risk of nosocomial pneumonias in ICU. In this review article, we reviewed the most important nosocomial pathogens which colonize the oral cavity and causes severe infections during hospitalization in ICU. CONCLUSION: Finally, we discuss that the prevention strategies against oral colonization of nosocomial pathogens include classical methods and novel methods such as Photodynamic therapy, NO based therapy, anti-virulence therapy and other new under investigation antimicrobial strategies.