Oral microbial ecology and the role of salivary immunoglobulin A

Bacterial interactions in dental biofilm

Biofilms are masses of microorganisms that bind to and multiply on a solid surface, typically with a fluid bathing the microbes. The microorganisms that are not attached but are free floating in an aqueous environment are termed planktonic cells. Traditionally, microbiology research has addressed results from planktonic bacterial cells. However, many recent studies have indicated that biofilms are the preferred form of growth of most microbes and particularly those of a pathogenic nature. Biofilms on animal hosts have significantly increased resistance to various antimicrobials compared to planktonic cells. These microbial communities form microcolonies that interact with each other using very sophisticated communication methods (i.e., quorum-sensing). The development of unique microbiological tools to detect and assess the various biofilms around us is a tremendously important focus of research in many laboratories. In the present review, we discuss the major biofilm mechanisms and the interactions among oral bacteria.

Salivary protein profiles and sensitivity to the bitter taste of caffeine

The interindividual variation in the sensitivity to bitterness is attributed in part to genetic polymorphism at the taste receptor level, but other factors, such as saliva composition, might be involved. In order to investigate this, 2 groups of subjects (hyposensitive, hypersensitive) were selected from 29 healthy male volunteers based on their detection thresholds for caffeine, and their salivary proteome composition was compared. Abundance of 26 of the 255 spots detected on saliva electrophoretic patterns was significantly different between hypo- and hypersensitive subjects. Saliva of hypersensitive subjects contained higher levels of amylase fragments, immunoglobulins, and serum albumin and/or serum albumin fragments. It also contained lower levels of cystatin SN, an inhibitor of protease. The results suggest that proteolysis occurring within the oral cavity is an important perireceptor factor associated to the sensitivity to the bitter taste of caffeine.

Perialveolar bacterial microbiota and bacteraemia after dental alveolitis in adult rats that had been subjected to neonatal malnutrition

The aim of the present study was to analyse the bacteriological factors during the process of dental alveolitis, relating it to a higher incidence of bacteraemia in adult rats subjected to neonatal malnutrition. We used forty male Wistar rats, suckled by mothers fed a diet during lactation containing 17 % protein in the nourished group (N) or 8 % protein in the undernourished group (UN). After weaning, the animals were given the Labina standard diet. After 90 d, these animals underwent upper right incisor extraction and induction of alveolitis. The oral microbiota was obtained using a swab and blood culture through venous blood. These procedures were performed before the extraction, 5 min after extraction, on the 21st day after alveolitis for groups N-21 and UN-21 and on the 28th day after alveolitis for groups N-28 and UN-28. Data were expressed as means and standard deviations for parametric data, and as medians and interquartile intervals for non-parametric data. Statistical significance was considered by assuming a critical level of 5 %. Before and after extraction, lower bacterial growth was observed per colony-forming unit (CFU) in the perialveolar region of the upper right incisors of undernourished animals, while the opposite was true after alveolitis, when a larger number of CFU was observed in these animals. The percentage of positive blood cultures obtained after alveolitis was greater in the undernourished animals. The present study thus demonstrated the influence of neonatal malnutrition in the perialveolar microbiota and in the development of bacteraemia after dental alveolitis.

Prevention of aspiration pneumonia (AP) with oral care

AP is a major cause of morbidity and mortality in elderly patients, especially frail elderly patients. The aim of this article is to review effect of oral care, including oral hygiene and improvement of oral function, on the prevention of AP among elderly people in hospitals and nursing homes. There is now a substantial body of work studying the effect of oral care on the prevention of respiratory diseases. Oral hygiene, consisting of oral decontamination and mechanical cleaning by dental professionals, has resulted in significant clinical effects (decreased incidence of pneumonia and decreased mortality from respiratory diseases) in clinical randomized trials. Moreover, studies examining oral colonization by pneumonia pathogens have shown the effect of oral hygiene on eliminating these pathogens. In addition, swallowing training has been shown to improve the movement and function of swallowing-related muscles, also resulting in decreased incidence of pneumonia. These findings support the contention that oral care is effective in the prevention of AP.

[Streptococcus mutans and oral streptococci in dental plaque]

The human oral microbial biota represents a highly diverse biofilm. Twenty-five species of oral streptococci inhabit the human oral cavity and represent about 20 % of the total oral bacteria. Taxonomy of these bacteria is complex and remains provisional. Oral streptococci encompass friends and foes bacteria. Each species has developed specific properties for colonizing the different oral sites subjected to constantly changing conditions, for competing against competitors, and for resisting external agressions (host immune system, physico-chemical shocks, and mechanical frictions). Imbalance in the indigenous microbial biota generates oral diseases, and under proper conditions, commensal streptococci can switch to opportunistic pathogens that initiate disease in and damage to the host. The group of "mutans streptococci" was described as the most important bacteria related to the formation of dental caries. Streptococcus mutans, although naturally present among the human oral microbiota, is the microbial species most strongly associated with carious lesions. This minireview describes the oral streptococci ecology and their biofilm life style by focusing on the mutans group, mainly S. mutans. Virulence traits, interactions in the biofilm, and influence of S. mutans in dental caries etiology are discussed.

Gingival disease and secretory immunoglobulin a in non-stimulated saliva in children

AIM

To find the relationship of secretory immunoglobulin A (SIgA) to gingival diseases in childhood and adolescence by quantitative study of these antibodies in non-stimulated saliva.

PATIENTS AND METHODS

The survey included 30 somatically healthy children (mean age 15.37 +/- 1.06 yrs) with clinically healthy gingiva and another 30 children (somatically healthy) (mean age 15.07 +/- 0.69 yrs) with manifested plaque-induced gingivitis. The diagnosis of periodontal status was made on the basis of clinical criteria, the oral-hygiene index of Silness & Loe, the papilla bleeding index (PBI) of Saxer & Mulheman and the periodontal screening index for evaluation--Periodontal Screening and Registration (PSR, after ADA--American Dental Association). SIgA in saliva was quantified by ELISA with salivary secretory IgA kit of SalimetricsLLC--USA.

RESULTS

In children with gingivitis the mean SIgA was 41.07 +/- 32.14 microg/ml; it was higher in healthy children - 48.3 +/- 32.41 microg/ml. A correlation was found between SIgA and the oral-hygiene index of Silness & Loe, (P < 0.05) and lack of dependence on the degree of gingival bleeding.

CONCLUSIONS

SIgA is a factor characterizing the local specific immunity which depends on local antigenic stimuli (plaque biofilm), but it does not affects the gingival pathology directly. SIgA can be considered an important part of an integrated assessment of oral risk environments.

Osteomyelitis of the mandible in a group of 33 pediatric patients with congenital insensitivity to pain with anhidrosis

OBJECTIVE

To determine the frequency of mandibular osteomyelitis (OM) in patients with congenital insensitivity to pain with anhidrosis (CIPA) and to relate its appearance to possible risk factors.

METHODS

The records of 33 patients were reviewed for data concerning events of jaw OM, oral trauma, maxillofacial interventions, or OM of long bones.

RESULTS

Eighteen percent of the patients had mandibular OM. Of the six patients, preceding oral laceration was documented in one and tooth extraction in two. Seventy percent of the patients had OM of the limbs, but only 15% overlapped, having both jaw and limb OM. Half of the patients with mandibular OM had also OM of the limbs during the following year. There seems to be a correlation between high frequency of limb OM (at least 5 events per patient) and appearance of mandibular OM.

CONCLUSION

The incidence of mandibular OM is very high among patients with CIPA and can result in pathologic fracture and the need for open reduction and internal fixation. The reason for this phenomenon is presently not clear. Preventive and therapeutic strategy for CIPA patients should be undertaken to minimize this severe complication.

Opportunistic respiratory pathogens in the oral cavity of the elderly

The oral cavity of the hospitalized or bedridden elderly is often a reservoir for opportunistic pathogens associated with respiratory diseases. Commensal flora and the host interact in a balanced fashion and oral infections are considered to appear following an imbalance in the oral resident microbiota, leading to the emergence of potentially pathogenic bacteria. The definition of the process involved in colonization by opportunistic respiratory pathogens needs to elucidate the factors responsible for the transition of the microbiota from commensal to pathogenic flora. The regulatory factors influencing the oral ecosystem can be divided into three major categories: the host defense system, commensal bacteria, and external pathogens. In this article, we review the profile of these categories including the intricate cellular interaction between immune factors and commensal bacteria and the disturbance in homeostasis in the oral cavity of hospitalized or bedridden elderly, which facilitates oral colonization by opportunistic respiratory pathogens.

Salivary IgA and IgE levels in healthy subjects: relation to age and gender

It has been reported that the immune system undergoes age and gender changes. The aim of this study was to investigate the age- and gender-dependent changes of salivary IgA and IgE levels among healthy subjects. A total of 203 healthy individuals (aged 1-70 years) were enrolled in the study. Two milliliters of saliva were collected from all participants, and salivary IgA and IgE levels were measured by the ELISA technique. Mean salivary IgA levels were significantly higher in subjects aged 11-20 years as compared to subjects aged 1-10 years (P < 0.01). Mean salivary IgA levels increased with age up to the age of 60 years, and then slightly decreased in subjects aged 61-70 years. The frequency of subjects with detectable levels of salivary IgE and mean salivary IgE levels gradually increased with age, with maximum levels being observed in the 31-40 years age group and not changing significantly thereafter. The mean levels of salivary IgA and IgE in adults were significantly higher than those observed in children (P < 0.00001 and P < 0.05, respectively). No significant differences were observed between men and women regarding both salivary immunoglobulins. These results showed age-dependent changes of the salivary IgA and IgE levels. Gender had no effect on the salivary levels of IgA and IgE.

Investigation of lectinized liposomes as M-cell targeted carrier-adjuvant for mucosal immunization

In the present investigation hepatitis B surface antigen (HBsAg) encapsulated liposomes were developed and coupled with Ulex europaeus agglutinin 1 (UEA-1) to increase transmucosal uptake by M-cells of the Peyer's patches. The liposomes were characterized for shape, size, polydispersity and encapsulation efficiency. Bovine submaxillary mucin (BSM) was used as a biological model for the in vitro determination of lectin activity and specificity. Dual staining technique was used to investigate targeting of lectinized liposomes to the M-cells. Anti-HBsAg IgG response in serum and anti-HBsAg sIgA level in various mucosal fluids was estimated by using ELISA, following oral immunization with lectinized and non-lectinized liposomes in Balb/c mice. Additionally, interleukin-2 (IL-2) and interferon-γ (IFN-γ) level in the spleen homogenates was determined. The results suggest that lectinized liposomes were successfully developed, exhibited increased activity with BSM as compared to non-lectinized liposomes and α-l-fucose specificity of the lectinized liposomes was also maintained. The lectinized liposomes were predominantly targeted to the M-cells. The serum anti-HBsAg IgG titre obtained after 3 consecutive days oral immunizations with HBsAg encapsulated lectinized liposomes and boosting after third week was comparable with the titre recorded after single intramuscular prime and third week boosting with alum-HBsAg. Moreover, lectinized liposomes induced higher sIgA level in mucosal secretions and cytokines level in the spleen homogenates. The results showed that the developed surface modified liposomes could be a potential module for the development of effective mucosal vaccines.

Back massage therapy promotes psychological relaxation and an increase in salivary chromogranin A release

Massage therapy promotes psychosocial relaxation, reduces stress and has been reported to improve the immune function. As such, massage therapy is currently used in palliative care for the relief of anxiety and pain. Although psychosocial status has been evaluated using subjective psychological tests, such as State-Trait Anxiety Inventory (STAI), subjective psychological tests are of limited value if the subjects fail to report reliably. Salivary biomarkers have been recently suggested as useful objective markers for assessing psychosocial status. To determine whether salivary biomarkers are useful objective indices for assessing the effects of back massage on the mental status of 25 young healthy female volunteers, we measured heart rate and salivary biomarkers (α-amylase activity, cortisol, and chromogranin A) and assessed the STAI score before and after the back massage. Back massage significantly reduced the heart rate and STAI; however, salivary amylase and cortisol levels did not change. In contrast, the level of salivary chromogranin A significantly increased. We therefore conclude that changes in the salivary biomarkers tested here may not indicate changes in psychological status following massage therapy. However, the increase in chromogranin A release may contribute to the immunologically beneficial effects of massage therapy as chromogranin A has antibacterial and antifungal activity.

Bacterial interactions in dental biofilm development

Recent analyses with ribosomal RNA-based technologies have revealed the diversity of bacterial populations within dental biofilms, and have highlighted their important contributions to oral health and disease. Dental biofilms are exceedingly complex and multispecies ecosystems, where oral bacteria interact cooperatively or competitively with other members. Bacterial interactions that influence dental biofilm communities include various different mechanisms. During the early stage of biofilm formation, it is known that planktonic bacterial cells directly attach to surfaces of the oral cavity or indirectly bind to other bacterial cells that have already colonized. Adherence through co-aggregation may be critical for the temporary retention of bacteria on dental surfaces, and may facilitate eventual bacterial colonization. It is likely that metabolic communication, genetic exchange, production of inhibitory factors (e.g., bacteriocins, hydrogen peroxide, etc.), and quorum-sensing are pivotal regulatory factors that determine the bacterial composition and/or metabolism. Since each bacterium can easily access a neighboring bacterial cell and its metabolites, genetic exchanges and metabolic communication may occur frequently in dental biofilms. Quorum-sensing is defined as gene regulation in response to cell density, which influences various functions, e.g., virulence and bacteriocin production. In this review, we discuss these important interactions among oral bacteria within the dental biofilm communities.

Study of human neutrophil peptides in saliva by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is used to rapidly characterize the human neutrophil peptides - HNP 1, 2, and 3 - in saliva. The saliva excreted from the parotid and sublingual/submandibular glands of 70 individuals were collected and examined using MALDI-TOF. The MALDI approach requires no sample pretreatment other than mixing the saliva-absorbing material with the matrix and drying under ambient conditions. Tissue paper was the best material for collecting the saliva samples because of its strong texture and high absorbance, and sinapinic acid was the best MALDI matrix for the analysis of the HNPs. HNPs were detected in almost all the samples collected from the parotid glands, with no obvious differences among age or gender. In contrast, the distribution of the HNPs in the samples collected from the sublingual/submandibular glands was age-dependent: no HNPs were detected for those collected from individuals younger than 30, but the HNPs were present in all of the samples collected from those older than 60 years. The increased probability of detecting saliva HNPs with age suggests that HNPs may function as a biomarker for aging.

The effectiveness of the Uchida-Kraepelin test for psychological stress: an analysis of plasma and salivary stress substances

Background

The hypothalamic-pituitary-adrenocortical (HPA) axis and sympathetic adrenomedullary (SAM) system are the major stress-response pathways. Plasma adrenocorticotropic hormone (ACTH) represents HPA axis activity, while plasma catecholamines are used as markers of the SAM system. Salivary alpha amylase (AA), chromogranin A (CgA), and immunoglobulin A (IgA) are candidate markers of stress activation, although their role has not been established. The Uchida-Kraepelin (U-K) test is a questionnaire that requires intense concentration and effort, and has been used as a tool to induce mental stress. However, it is not clear whether or not the test is effective as a psychological/mental stressor.

Methods

In this study, normal young women took the U-K test and serial measurements of plasma ACTH and catecholamines (dopamine, noradrenaline, and adrenaline) (n = 10), as well as salivary AA, CgA, and IgA (n = 16) before, during and after the test.

Results

We found no changes in any of these parameters at any time point during or after the U-K test.

Conclusion

Our findings indicate that the U-K test is not a suitable for measuring the psychological/mental stress of young women because the plasma data showed that it did not affect the HPA axis and SAM system. The U-K test should be employed carefully as a psychological/mental stressor due to insufficient scientific evidence of its effectiveness. In addition, salivary AA, CgA, and IgA should not simply be compared with previous reports, because the mechanism of secretion and normal range of each salivary parameter remain unknown. Salivary AA, CgA, and IgA may not be suitable candidate markers of psychological/mental stress.

Polymicrobial interactions stimulate resistance to host innate immunity through metabolite perception

Bacteria in the human oral cavity often grow in an attached multispecies biofilm community. Members of this community display defined interactions that have an impact on the physiology of the individual and the group. Here, we show that during coculture growth with streptococci, the oral pathogen Aggregatibacter actinomycetemcomitans displays enhanced resistance to killing by host innate immunity. The mechanism of resistance involves sensing of the streptococcal metabolite hydrogen peroxide by A. actinomycetemcomitans, which stimulates a genetic program resulting in enhanced expression of the complement resistance protein ApiA. The oxidative stress response regulator OxyR mediates induction of apiA transcription, and this induction is required for coculture resistance to killing by human serum. These findings provide evidence that interaction between community members mediates prokaryotic resistance to host innate immunity and reinforce the need to understand how polymicrobial growth affects interaction with the host immune system.

Vaccines and photodynamic therapies for oral microbial-related diseases

The mouth is a favorable habitat for a great variety of bacteria. Microbial composition of dental plaque is the usual cause of various oral diseases in humans, including dental caries, periodontal disease and halitosis. In general, oral antibacterial agents such as antibiotics are commonly used to treat oral bacterial infection. Traditional periodontal surgery is painful and time-consuming. In addition, bacterial resistance and toxicity of antibiotics have become a global pandemic and unavoidable. Recently, vaccines for dental caries and periodontal disease have been developed and applied. Moreover, the use of photodynamic therapy has become an alternative to antibiotic drugs. The purpose of this article is to highlight the advantages of vaccine therapy and photodynamic therapy for oral microbial-related diseases compared to treatments with antimicrobial agents and traditional periodontal surgery.

Recurrent blocked duct(s) in a mother with immunoglobulin A deficiency

Abstract Secretory immunoglobulin A (sIgA) is the dominant immunoglobulin in human milk, and apart from the obvious contribution it makes towards the protection of the infant, sIgA may also form an important part of the defense of the mammary gland. This report involves a mother (M8) who participated in a research study investigating the relationships between symptoms and changes in the physiology of the lactating breast during mastitis. Breastmilk samples were collected on Days 14, 30, 60, and 90 postpartum, to establish the normal reference range of biochemical markers, and during periods of breast inflammation. M8 experienced seven episodes of blocked duct(s) during the first 19 weeks, five of which occurred within the 90-day reference sample collection period. On analysis, it was found there was no detectable sIgA present in her milk samples. Medical referral and further testing resulted in a diagnosis of selective IgA deficiency, of which the mother had not been previously aware. M8 showed little variation in her milk composition even when suffering with blocked duct(s), although there was an increase in the concentration of lactoferrin in both breasts at reference collection days 14-90. Lactoferrin concentration was also unusually high at Day 14 (15 g/L) in the left breast and continued to be increased in this breast until Day 60. The absence of sIgA in this mother's breastmilk may have been a contributing factor in her experiencing recurrent blocked ducts.

Dental caries and allergic disorders in Japanese children: the Ryukyus Child Health Study

BACKGROUND

Dental caries is an infectious disease and is highly prevalent among children. In the etiology of allergic diseases, the hygiene hypothesis contends that infections might confer protection against the development of allergic diseases. The aim of this cross-sectional study was to investigate the association between dental caries and the prevalence of allergic disorders.

METHODS

Study subjects were 21,792 children 6 to 15 years of age in Okinawa, Japan. Outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Data on dental caries were obtained from school records. Children were classified as having dental caries if one or more teeth had decayed and/or had been filled. Adjustment was made for sex, age, region of residence, number of siblings, smoking in the household, paternal and maternal history of asthma, atopic eczema, or allergic rhinitis, and paternal and maternal educational level.

RESULTS

The prevalence of wheeze, asthma, atopic eczema, and allergic rhinoconjunctivitis in the previous 12 months was 10.8%, 7.6%, 6.8%, and 7.6%, respectively. In an overall analysis, no measurable relationship was found between dental caries and the prevalence of wheeze, asthma, atopic eczema, or allergic rhinoconjunctivitis. However, dental caries was significantly inversely associated with the prevalence of allergic rhinoconjunctivitis only among children with a positive parental allergic history: The adjusted odds ratio was 0.84 (95% confidence interval: 0.72, 0.99).

CONCLUSIONS

The present findings do not support the hypothesis that dental caries was protective against allergic diseases. However, a parental allergic history may affect the association between dental caries and allergic rhinoconjunctivitis.

Effect of an alcoholic diet on dental caries and on Streptococcus of the mutans group. Study in rats

The objective of this study was to evaluate the effects of an alcohol diet on Streptococcus of the mutans group and on dental caries in the oral cavity of rats. Forty animals were divided into 3 groups according to the following liquid diets: 20% ethanol solution (Alcohol Group, AG), 27% sucrose solution (Isocaloric Group, IG), and water (Control Group, CG). After 56 days, samples were collected and plated on Mitis Salivarius Bacitracin agar to assess the number of colony forming units (CFU/mL) of Streptococcus of the mutans group. The animals were sacrificed and the jaws were removed in order to assess the occurrence of dental caries on the smooth and occlusal surfaces using stereomicroscopy. The data were submitted to ANOVA and Tukey test. The average numbers of CFU/mL (10(3)) were: 8.17 (AG), 9.78 (IG), and 5.63 (CG). There was no significant difference among the groups for the occurrence of occlusal caries. Regarding smooth surface caries, in the upper jaw, the caries number in the IG (1.58) was similar to that in the AG (2.06) and in the CG (1.14), and the number of caries in the AG was higher than in the CG; in the lower jaw there was significant difference among the 3 groups: AG (1.14), IG (2.00) and CG (0.43). The diets with the alcohol and sucrose solutions presented a tendency of increasing the colonization by Streptococcus of the mutans group and of increasing the occurrence of smooth surface dental caries in rat molars when compared to the control diet.

Predominant bacteria recovered from a periodontitis site in a hamster model raised by silk-ligature with Porphyromonas gingivalis infection

We isolated oral bacteria that coexisted with Porphyromonas gingivalis in a hamster periodontitis model. As predominant bacteria in the periodontitis site, Collinsella-reltaed strains, Eubacterium-reltaed strains, Streptococcus suis-related strains, and Veillonella parvula-reltaed strains were detected. In addition, Actinomyces, Bacteroides, and P. gingivalis were also isolated predominantly. The results suggest that the bacterial composition of the periodontitis site in hamsters is complex, as in human periodontitis.

Reduction of vitamin K concentration by salivary Bifidobacterium strains and their possible nutritional competition with Porphyromonas gingivalis

AIMS

To assess the possibility that bifidobacteria compete with Porphyromonas gingivalis for their mutual growth factor vitamin K. This study also examined whether salivary Bifidobacterium species decrease vitamin K concentration in the growth medium.

METHODS AND RESULTS

Sixty-five strains of Bifidobacterium were obtained from 20 of 24 periodontally healthy subjects. Bifidobacterium dentium was most frequently detected in the saliva of subjects, followed by Bifidobacterium adolescentis, Bifidobacterium longum, and Bifidobacterium urinalis. The growth of most Bifidobacterium isolates, except that of B. urinalis, was stimulated by vitamin K. Moreover, the isolates were capable of decreasing vitamin K after incubation, which suggests that bifidobacteria compete with P. gingivalis for vitamin K. In a co-culture, a representative strain -B. adolescentis S2-1 - inhibited the growth of P. gingivalis if it was inoculated in the medium before P. gingivalis.

CONCLUSIONS

B. adolescentis S2-1 decreased vitamin K concentration and inhibited the growth of P. gingivalis by possibly competing for the growth factor.

SIGNIFICANCE AND IMPACT OF THE STUDY

Salivary bifidobacteria may possess the potential to suppress the growth of P. gingivalis by reducing the growth factor(s) in the environment.

Whole Saliva has a Dual Role on the Adherence of Candida albicans to Polymethylmetacrylate

Adhesion of Candida albicans to acrylic of dental prostheses or to salivary macromolecules adsorbed on their surface is believed to be a critical event in the development of denture stomatitis. In previous studies our group has shown that adhesion of C. albicans germ tubes to polystyrene is decreased by saliva whereas C. albicans yeast cells adhesion to the same material is enhanced. The results presented in this study confirm this dual role played by whole saliva, since it decreased the adhesion of germ tubes but increased the adhesion of yeast cells to polymethylmetacrylate (PMMA). These effects mediated by whole saliva do not seem to be related to an inhibition of the germination of C. albicans, since similar levels of filamentation were observed in presence and absence of saliva. These results may give new insights into the conflicting role of saliva in the adhesion of C. albicans to acrylic resins of dental prostheses.

Desnutrição neonatal e microbiota normal da cavidade oral em ratos

OBJETIVO: Avaliar a influência da desnutrição neonatal sobre o padrão e o crescimento de bactérias aeróbias, da microbiota normal da cavidade oral, em ratos Wistar adultos. MÉTODOS: O material da cavidade oral foi coletado através de swabs embebidos em 40µL de solução salina estéril e colocados em tubos estéreis contendo 960µL de brain heart infusion. Posteriormente, fez-se homogeneização de cada uma amostra. Então, destes 1.000µL, retirou-se 1µL e este foi semeado em placas de Petri contendo Agar-sangue e Levine para isolamento e identificação de bactérias Gram+ e Gram-, respectivamente. Essas placas foram incubadas em estufa bacteriológica a 37ºC, 48 horas, e as unidades formadoras de colônias que cresceram foram contadas e seus percentuais calculados. Para a bacterioscopia foram confeccionadas lâminas coradas pelo método de Gram. RESULTADOS: Do 5º ao 21º dia de vida os pesos corporais do grupo desnutrido (33,6g:42,8g, desvio-padrão=27,2g) foram menores (p<0,001) que os do grupo nutrido (52,5g:56,3g, desvio-padrão=24,0g). Dos 60 aos 120 dias de vida os pesos foram reduzidos no grupo desnutrido (248,2g:290,2g, desvio-padrão=220,2g), quando comparados aos do grupo nutrido (306,2g:319,4g, desvio-padrão=219,5g) teste Mann Whitney, p<0,05. A microbiota foi composta de menor número de bactérias no grupo nutrido (4,2x10(6) unidades formadoras de colônias, desvio-padrão=1,2x10(6) unidades formadoras de colônias de bactérias/mL), comparado ao grupo desnutrido (7,4x10(6) unidades formadoras de colônias, desvio-padrão=1,0x10(6) unidades formadoras de colônias de bactérias/mL) teste "t", (p=0,026). Das bactérias isoladas em culturas, observou-se um padrão bacteriano semelhante nos dois grupos, com 70% de bactérias gram-positivas e 30% de bactérias gram-negativas. CONCLUSÃO: A desnutrição neonatal foi efetiva em reduzir o peso corporal e aumentar o crescimento bacteriano. Embora o padrão bacteriano não tenha sido alterado, o aumento do crescimento bacteriano pode induzir a um desequilíbrio na microbiota oral desfavorecendo assim, o hospedeiro.

Age-dependent deficiency in saliva and salivary antibodies secretion in Down's syndrome

OBJECTIVE

Down's syndrome (DS) individuals suffer from an increased susceptibility to infections. Here, we assessed age-related changes in the salivary-specific humoral immunity of DS subjects.

DESIGN

Parotid and whole saliva were collected from a young group of DS (YDS, n=30, 23.3+/-4 years), an older group of DS individuals (ODS, n=10, 51.9+/-8 years) and compared to two age-matched groups of healthy volunteers--a young group (YC, n=29, 22.8+/-5 years) and an older group (OC, n=10, 48.4+/-9 years). The levels of total IgA, and specific antibodies to three common oral pathogens (Porphyromonas gingivalis, Actinobacillus (Aggregatibacter) actinomycetemcomitans and Streptococcus mutans) were analysed.

RESULTS

The limited increases in IgA concentrations could not compensate the dramatic reduction in the salivary flow rate observed in DS individuals. Therefore, the median secretion rates of the specific antibodies in whole and parotid saliva were 70-77% and 34-60% (respectively) lower in YDS individuals as compared to YC and farther 77-100% and 75-88% (respectively) lower in ODS compared to YDS. In contrast, the antibody secretion rates were similar for parotid saliva, or even increased for whole saliva of OC, compared with YC. Consequently, a dramatic cumulative extreme reduction (>92%) in the bacterial specific salivary antibodies differentiated the adult DS individuals from to their age-matched controls.

CONCLUSIONS

Our results indicate a severe immunodeficiency in the secretion rate of the specific salivary IgA response of in DS individuals which intensifies with age.

A novel exclusion mechanism for carbon resource partitioning in Aggregatibacter actinomycetemcomitans

The bacterium Aggregatibacter actinomycetemcomitans is a common commensal of the human oral cavity and the putative causative agent of the disease localized aggressive periodontitis. A. actinomycetemcomitans is a slow-growing bacterium that possesses limited metabolic machinery for carbon utilization. This likely impacts its ability to colonize the oral cavity, where growth and community composition is mediated by carbon availability. We present evidence that in the presence of the in vivo relevant carbon substrates glucose, fructose, and lactate A. actinomycetemcomitans preferentially metabolizes lactate. This preference for lactate exists despite the fact that A. actinomycetemcomitans grows faster and obtains higher cell yields during growth with carbohydrates. The preference for lactate is mediated by a novel exclusion mechanism in which metabolism of lactate inhibits carbohydrate uptake. Coculture studies reveal that A. actinomycetemcomitans utilizes lactate produced by the oral bacterium Streptococcus gordonii, suggesting the potential for cross-feeding in the oral cavity.

Salivary -Amylase in Biobehavioral Research: Recent Developments and Applications

In the history of science, technical advances often precede periods of rapid accumulation of knowledge. Within the past three decades, discoveries that enabled the noninvasive measurement of the psychobiology of stress (in saliva) have added new dimensions to the study of health and human development. This widespread enthusiasm has led to somewhat of a renaissance in behavioral science. At the cutting edge, the focus is on testing innovative theoretical models of individual differences in behavior as a function of multilevel biosocial processes in the context of everyday life. Several new studies have generated renewed interest in salivary alpha-amylase (sAA) as a surrogate marker of the autonomic/sympathetic nervous system component of the psychobiology of stress. This article reviews sAA's properties and functions; presents illustrative findings relating sAA to stress and the physiology of stress, behavior, cognitive function, and health; and provides practical information regarding specimen collection and assay. The overarching intent is to accelerate the learning curve such that investigators avoid potential pitfalls associated with integrating this unique salivary analyte into the next generation of biobehavioral research.

Influence of Different Orthodontic Brackets on Adherence of Microorganisms In Vitro

OBJECTIVE

To define the capacity of different bracket materials to modify the growth and adherence of microorganisms.

METHODS

Three types of brackets from the right upper central incisor were used: metallic, ceramic, and composite. Streptococcus mutans and Candida albicans were studied. The association of both species was also evaluated. The brackets were placed in flat-bottomed vials containing basal medium with 20% sucrose added; the flasks were inoculated with each of the microbial suspensions. The samples were incubated at 37 degrees C for 48 hours, after which the brackets were removed. The supernatant was removed from the flasks, the cells adhering to the glass were counted, and the brackets were studied with electron microscopy.

RESULTS

The adherence of Streptococcus mutans was not modified by the different brackets. The adherence of Candida albicans was increased by the composite bracket, whereas the use of metallic brackets decreased the number of colony-forming units (CFUs). By electron microscopy we demonstrated that the adherence of Streptococcus mutans plus Candida albicans together varied according to the bracket materials with composite > ceramic > metallic.

CONCLUSIONS

Orthodontic appliances serve as different impact zones and modify microbial adherence and colonization, acting as foreign reserves and possible sources of infection.

Digestive tract microbiota in healthy volunteers

PURPOSE

The aim of this study was to standardize the methods of sample collection of mucus from the digestive tract and to determine the microbiota in healthy volunteers from Brazil, collecting samples from the mouth, esophagus, stomach, duodenum, jejunum, ileum, colon, and rectum.

METHODS

Microbiota of selected healthy volunteers from the oral cavity (n=10), the esophagus (n=10), the upper digestive tract (n=20), and the lower digestive tract (n=24) were evaluated through distinct collection methods. Collection methods took into account the different sites, using basic scraping and swabbing techniques, stimulated saliva from the oral cavity, irrigation-aspiration with sterile catheters especially designed for the esophagus, a probe especially designed for upper digestive tract, and a special catheter for the lower digestive tract.

RESULTS

(i) Mixed microbiota were identified in the oral cavity, predominantly Gram-positive aerobic and anaerobic cocci; (ii) transitional flora mainly in the esophagus; (iii) Veillonella sp, Lactobacillus sp, and Clostridium sp in the stomach and duodenum; (iv) in the jejunum and upper ileum, we observed Bacteroides sp, Proteus sp, and Staphylococcus sp, in addition to Veillonella sp; (v) in the colon, the presence of "nonpathogenic" anaerobic bacteria Veillonella sp (average 10(5) UFC) indicates the existence of a low oxidation-reduction potential environment, which suggests the possibility of adoption of these bacteria as biological markers of total digestive tract health.

CONCLUSIONS

The collection methods were efficient in obtaining adequate samples from each segment of the total digestive tract to reveal the normal microbiota. These procedures are safe and easily reproducible for microbiological studies.

Pacifiers: A microbial reservoir

The permanent contact between the nipple part of pacifiers and the oral microflora offers ideal conditions for the development of biofilms. This study assessed the microbial contamination on the surface of 25 used pacifier nipples provided by day-care centers. Nine were made of silicone and 16 were made of latex. The biofilm was quantified using direct staining and microscopic observations followed by scraping and microorganism counting. The presence of a biofilm was confirmed on 80% of the pacifier nipples studied. This biofilm was mature for 36% of them. Latex pacifier nipples were more contaminated than silicone ones. The two main genera isolated were Staphylococcus and Candida. Our results confirm that nipples can be seen as potential reservoirs of infections. However, pacifiers do have some advantages; in particular, the potential protection they afford against sudden infant death syndrome. Strict rules of hygiene and an efficient antibiofilm cleaning protocol should be established to answer the worries of parents concerning the safety of pacifiers.

Salivary immunoglobulin A directed to oral microbial GroEL in patients with periodontitis and their potential protective role

The aim of this study was to identify salivary immunoglobulin A (IgA) directed to oral microbial GroEL in patients with periodontitis and to demonstrate their potential protective role through a reduction of inflammatory cytokine production induced by microbial GroEL. Using five different proteins belonging to the heat-shock protein 60 family, Western immunoblot analysis of salivary IgA from 63 subjects revealed immunoreactivities with Campylobacter rectus GroEL and Porphyromonas gingivalis GroEL in subjects with periodontitis (P < 0.05) compared to control subjects. Using the BIACORE 1000 to measure the salivary IgA titers directed towards C. rectus GroEL, high resonance unit (RU) values were observed in the saliva samples from patients with periodontitis (P < 0.01). Furthermore, the number of teeth with deep pocket depth (>or=5 mm) showed a high correlation coefficient with the RU value (r = 0.50, P < 0.01). C. rectus GroEL possessed the ability to stimulate the production of interleukin-6 by gingival fibroblasts. Interestingly, salivary IgA antibody directed to C. rectus GroEL caused a partial inhibition of interleukin-6 production. This study showed a relationship between high levels of salivary IgA directed to GroEL and periodontal disease severity. Although additional investigations are required, salivary IgA to GroEL may have a protective role by reducing the inflammatory response induced by GroEL derived from periodontopathogenic bacteria.

Therapeutic effect of llama derived VHH fragments against Streptococcus mutans on the development of dental caries

Streptococcus mutans is the main cause of dental caries. We evaluated the therapeutic effect of variable regions of a llama heavy chain antibody fragments directed against S. mutans named S36-VHH (S for Streptococcus) alone or fused with glucose oxidase (GOx) from Aspergillus niger. Western blot analysis and ELISA revealed binding of the S36-VHH to the streptococcal antigen I/II adhesin molecule of S. mutans serotype C. In a rat-desalivated caries model, daily administration of S36-VHH significantly reduced the development of smooth surface caries. No additional therapeutic effect of GOx was observed. Our results suggest that llama VHH antibodies may be a potential benefit as prophylaxis against dental caries.

Effect of saliva collection method on the concentration of protein components in saliva

In order to clarify how we collect saliva for analyzing salivary protein in aged subjects who can not eat well, we compared the effects of suction, spitting and the swab saliva collection method on the yield of protein components in saliva samples from normal volunteers. The saliva collected by suction, spitting and the swab method were designated as, Saliva I, II and III, respectively. The saliva volume collected by Saliva I was about 2-fold greater than that by of Saliva II and III. This is mainly due to the fact that saliva secretion was stimulated by the suction itself. The content of total protein, S-IgA, trypsin-like activity and human airway trypsin-like protease (HAT) were almost the same in Saliva I and II, and significantly lower in Saliva III than in Saliva I and II. Kallikrein activity was almost the same in Saliva I, II and III. The concentration of each total protein, S-IgA, kallikrein activity, trypsin activity and HAT in Saliva I were significantly positively correlated with that in Saliva II. These results indicate that we can obtain information of change of salivary protein by analyzing saliva collected by suction method, although this method caused the stimulation of saliva to some extent.

Oral lactobacilli in chronic periodontitis and periodontal health: species composition and antimicrobial activity

BACKGROUND/AIMS

Lactobacilli are known to play an important role in the maintenance of health by stimulating natural immunity and contributing to the balance of microflora. However, their role in chronic periodontitis is unclear. We aimed to identify oral lactobacilli in chronic periodontitis and periodontally healthy subjects, and to determine their antimicrobial activity against putative oral pathogens.

METHODS

A total of 238 Lactobacillus isolates from the saliva and subgingival sites of 20 chronic periodontitis and 15 healthy subjects were collected. In all, 115 strains were identified using rapid amplified ribosomal DNA restriction analysis. Antimicrobial activity against Streptococcus mutans, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia was assessed.

RESULTS

Lactobacilli belonging to 10 species were identified. The most prevalent strains in healthy persons were Lactobacillus gasseri and Lactobacillus fermentum and in chronic periodontitis patients, Lactobacillus plantarum. Obligately homofermentatives, particularly L. gasseri, were less prevalent in chronic periodontitis patients compared with healthy subjects (8% vs. 64% for L. gasseri, P < 0.01). Sixty-nine percent of tested lactobacilli inhibited S. mutans, 88% A. actinomycetemcomitans, 82% P. gingivalis and 65% P. intermedia. The strongest antimicrobial activity was associated with Lactobacillus paracasei, L. plantarum, Lactobacillus rhamnosus, and Lactobacillus salivarius. The strains from periodontally healthy patients showed a lower antimicrobial activity against S. mutans than the strains from chronic periodontitis patients.

CONCLUSION

The composition of oral lactoflora in chronic periodontitis and healthy subjects differs, with a higher prevalence of homofermentative lactobacilli, particularly L. gasseri, in the latter group. Both homo- and heterofermentative oral lactobacilli suppress the growth of periodontal pathogens, but the antimicrobial properties are strain, species and origin specific.

Identification of Actinobacillus suis genes essential for the colonization of the upper respiratory tract of swine

Actinobacillus suis has emerged as an important opportunistic pathogen of high-health-status swine. A colonization challenge method was developed, and using PCR-based signature-tagged transposon mutagenesis, 13 genes belonging to 9 different functional classes were identified that were necessary for A. suis colonization of the upper respiratory tract of swine.

Facilitated production of secretory IgA against Shiga toxin B subunits by intranasal application of antigen-coated polystyrene microspheres

We examined the effects of microspheres as antigen carriers in mucosal immunization. Shiga toxin B subunits (Stx1B) were adsorbed on 6 mum polystyrene microspheres, which were then intranasally administered to mice together with cholera toxin (CT). Stx1B-specific serum IgG production and secretory IgA production at local mucosal sites were enhanced by the use of microspheres. When OVA was used as a model antigen, secretory IgA production but not serum IgG production was enhanced on the use of microspheres. These results indicated that microspheres provide a useful means of potentiating the immune response against Stx1B with weak immunogenicity.

Growth characteristics of and virulence factor production by group A Streptococcus during cultivation in human saliva

Group A Streptococcus (GAS) commonly infects the human oropharynx, but the initial molecular events governing this process are poorly understood. Saliva is a major component of the innate and acquired immune defense in this anatomic site. Although landmark studies were done more than 60 years ago, investigation of GAS-saliva interaction has not been addressed extensively in recent years. Serotype M1 GAS strain MGAS5005 cultured in human saliva grew to approximately 10(7) CFU/ml and, remarkably, maintained this density for up to 28 days. Strains of several other M-protein serotypes had similar initial growth patterns but did not maintain as high a CFU count during prolonged culture. As revealed by analysis of the growth of isogenic mutant strains, the ability of GAS to maintain high numbers of CFU/ml during the prolonged stationary phase in saliva was dependent on production of streptococcal inhibitor of complement (Sic) and streptococcal pyrogenic exotoxin B (SpeB). During cultivation in human saliva, GAS had growth-phase-dependent production of multiple proven and putative extracellular virulence factors, including Sic, SpeB, streptococcal pyrogenic exotoxin A, Mac protein, and streptococcal phospholipase A(2). Our results clearly show that GAS responds in a complex fashion to growth in human saliva, suggesting that the molecular processes that enhance colonization and survival in the upper respiratory tract of humans are well under way before the organism reaches the epithelial cell surface.