Lívia Araújo Alves

Effect of Schinus terebinthifolius on Candida albicans growth kinetics, cell wall formation and micromorphology.

Abstract Objective: To evaluate the anti-fungal activity of a tincture from Schinus terebinthifolius (Brazilian pepper tree) on Candida albicans (ATCC 289065), a micro-organism associated with fungal infections of the oral cavity. Materials and methods: Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) were determined through microdilution technique, as well as the microbial growth curve of C. albicans promoted by S. terebinthifolius. In addition, this study investigated a possible activity of the product on the fungal cell wall and its biological activity on fungal morphology. Nystatin was used as control and all tests were performed in triplicate. Results: S. terebinthifolius showed MIC of 312.5 µg/mL and MFC of 2500 µg/mL upon the strain tested, while Nystatin showed MIC and MFC of 6.25 µg/mL. As regards the microbial growth curve, S. terebinthifolius was able to significantly reduce the number of CFU/mL when compared to growth control until the time of 60 min. In the times 120 and 180 min there was no statistically significant difference between the growth control and the experimental product. S. terebinthifolius possibly acts on the fungal cell wall, once the sorbitol test indicated a MIC of 1250 µg/mL. In the fungal morphology, a reduction was observed of pseudo-hyphae, chlamydoconidia and blastoconidia in the presence of the experimental product. Conclusion: S. terebinthifolius showed anti-fungal activity against C. albicans, inhibiting, probably, the fungal cell wall formation.

CovR Regulates Streptococcus mutans Susceptibility To Complement Immunity and Survival in Blood

ABSTRACT Streptococcus mutans, a major pathogen of dental caries, may promote systemic infections after accessing the bloodstream from oral niches. In this study, we investigate pathways of complement immunity against S. mutans and show that the orphan regulator CovR (CovR Sm ) modulates susceptibility to complement opsonization and survival in blood. S. mutans blood isolates showed reduced susceptibility to C3b deposition compared to oral isolates. Reduced expression of covRSm in blood strains was associated with increased transcription of CovR Sm -repressed genes required for S. mutans interactions with glucans (gbpC, gbpB, and epsC), sucrose-derived exopolysaccharides (EPS). Consistently, blood strains showed an increased capacity to bind glucan in vitro. Deletion of covRSm in strain UA159 (UAcov) impaired C3b deposition and binding to serum IgG and C-reactive protein (CRP) as well as phagocytosis through C3b/iC3b receptors and killing by neutrophils. Opposite effects were observed in mutants of gbpC, epsC, or gtfBCD (required for glucan synthesis). C3b deposition on UA159 was abolished in C1q-depleted serum, implying that the classical pathway is essential for complement activation on S. mutans. Growth in sucrose-containing medium impaired the binding of C3b and IgG to UA159, UAcov, and blood isolates but had absent or reduced effects on C3b deposition in gtfBCD, gbpC, and epsC mutants. UAcov further showed increased ex vivo survival in human blood in an EPS-dependent way. Consistently, reduced survival was observed for the gbpC and epsC mutants. Finally, UAcov showed an increased ability to cause bacteremia in a rat model. These results reveal that CovR Sm modulates systemic virulence by regulating functions affecting S. mutans susceptibility to complement opsonization.

A Randomized Clinical Trial of Schinus terebinthifolius Mouthwash to Treat Biofilm-Induced Gingivitis.

Objectives. This study aimed to investigate the efficacy of a Schinus terebinthifolius (ST) mouthwash in reducing gingival inflammation levels (GI) and biofilm accumulation (BA) in children with gingivitis. Methods. This was a randomized, controlled, triple blind, and phase II clinical trial, with children aged 9–13 years (n = 27) presenting with biofilm-induced gingivitis. The sample was randomized into experimental (0.3125% ST, n = 14) and control (0.12% chlorhexidine/CHX, n = 13) groups. Products were masked as regards color, flavor and aroma. Intervention protocol consisted in supervised rinsing of 10 mL/day for 01 minute for 10 days. Gingival bleeding and simplified oral hygiene indexes were used to assess the efficacy variables, measured at baseline and after intervention by calibrated examiners. Data were statistically treated with paired t-test, unpaired t-test, and Wilcoxon and Mann-Whitney tests (α = .05). Results. It was found that both ST and CHX were able to significantly reduce GI levels after 10 days (P < 0.001) and there was no significant difference between them (P > 0.05). CHX was the only product able to significantly reduce BA after 10 days when compared to baseline (P < 0.05). Conclusion. ST mouthwash showed significant anti-inflammatory activity (equivalent to CHX), but it was not able to reduce biofilm accumulation.

INTEGRAÇÃO ENSINO-SERVIÇO: EXPERIÊNCIA EXITOSA NA ATENÇÃO ODONTOLÓGICA À COMUNIDADE

Introduction: Curriculum guidelines have reinforced the need for introducing undergraduate students to real-practice scenarios at health care services as a strategy to diversify their actuation contexts as well as to develop their critical perception, social sensibility and humanism. Aim: To report an experience on a service-learning integration process between the curricular component ‘Supervised training IX’ of the School of Dentistry, Federal University of Paraiba (FUPB) and a Family Health Unit (FHU) in Joao Pessoa – PB. Results: It was possible to develop activities at the FHU concerning to health promotion and care in view of broadening interaction mechanisms between FUPB and the health service as a model for universal care, equitable and qualified, which may give feedback to the population’s demands. Conclusion: Learning in the services potentiates curricular development, favors an approach between higher education institutions and community, and provides a room for critical reflections on the search for solving actual health problems. DESCRIPTORS: Teaching. Health Services. Oral Health.

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

ABSTRACT 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 (SptRSSs), 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 SptRSSs 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 SptRSs with AraC-type regulators, duplicate to multiple conserved repeats were identified in 1,000-bp regulatory regions of downstream genes, suggesting that SptRSs 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 SptRSSs is part of a regulatory network that coordinates cell wall homeostasis, H2O2 production, and competence. This study reveals that SptRSSs is involved in the regulation of crucial functions for S. sanguinis persistence in the oral cavity.