Dose-response evaluation of a copaiba-containing varnish against streptococcus mutans in vivo.

INTRODUCTION: Dental caries is the most prevalent disease in humans and its incidence is particularly high during childhood. The use of medicinal plants is a common practice in Brazil. OBJECTIVE: To evaluate the optimal antimicrobial concentration of Copaifera langsdorffii (copaiba) oil-resin, in the form of dental varnish, against Streptococcus mutans (S. mutans) in children. METHODS: Twenty-four children, caries-free, aged until 6 years old, were selected to participate in this study. The varnish was applied to the occlusal surfaces of all deciduous molars. The antimicrobial activity was analyzed in saliva, whose collection was conducted in two phases: before applying the copaiba varnish and after use to verify the instantaneous effectiveness of Copaifera langsdorffii dental varnish in the reduction of S. mutans. The microbiological analysis was repeated twice, establishing dilutions of 1:10 mL and 1:100 mL. RESULTS: Comparisons between different times within the same dilution were carried out by repeated measures analysis of variance (ANOVA) associated with Tukey's multiple comparisons test. Comparisons of conditions prior to and after treatment were performed using the t test for paired samples and it indicated that the 1% formulation promoted a more significant decrease in the number of S. mutans colonies (p = 0,0026). CONCLUSION: Copaiba oil-resin, in the form of dental varnish, has antimicrobial activity against S. mutans in all the concentrations studied. Further studies to identify the long-term activity and anticaries effect of this varnish are required to establish its use in caries prevention.

A MLST Clade 2 Clostridium difficile strain with a variant TcdB induces severe inflammatory and oxidative response associated with mucosal disruption.

The epidemiology of Clostridium difficile infections is highly dynamic as new strains continue to emerge worldwide. Here we present a detailed analysis of a new C. difficile strain (ICC-45) recovered from a cancer patient in Brazil that died from severe diarrhea. A polyphasic approach assigned a new PCR-ribotype and PFGE macrorestriction pattern to strain ICC-45, which is toxigenic (tcdA(+), tcdB(+) and ctdB(+)) and classified as ST41 from MLST Clade 2 and toxinotype IXb. Strain ICC-45 encodes for a variant TcdB that induces a distinct CPE in agreement with its toxinotype. Unlike epidemic NAP1/027 strains, which are also classified to MLST Clade 2, strain ICC-45 is susceptible to fluoroquinolones and does not overproduce toxins TcdA and TcdB. However, supernatants from strain ICC-45 and a NAP1/027 strain produced similar expression of pro-inflammatory cytokines, epithelial damage, and oxidative stress response in the mouse ileal loop model. These results highlight inflammation and oxidative stress as common features in the pathogenesis of C. difficile Clade 2 strains. Finally, this work contributes to the description of differences in virulence among various C. difficile strains.

In vitro effect of antibiotics on biofilm formation by Bacteroides fragilis group strains isolated from intestinal microbiota of dogs and their antimicrobial susceptibility.

The Bacteroides fragilis group strains colonize the intestinal tract of dogs as commensal bacteria. Nevertheless, they can be opportunistic pathogens responsible for significant morbidity and mortality rates in dogs, like in oral infections, abscesses and wound infections. The purpose of this study was to evaluate antimicrobial susceptibility in B. fragilis strains isolated from dogs intestinal microbiota and to evaluate the effect of subinhibitory concentrations of some antimicrobials on biofilm formation. A total of 30 B. fragilis group strains were tested for susceptibility to ten antimicrobial agents by broth microdilution method. Thirteen B. fragilis strains were tested for biofilm formation and the biofilm producer strains were chosen to evaluate the effect of subinhibitory concentrations of six antimicrobials on biofilm formation. The isolates were susceptible to amoxicillin-clavulanic acid, metronidazole, imipenem and chloramphenicol. Tetracycline and clindamycin were active against 50% and 33% of the strains, respectively. When biofilm-forming strains were grown in the presence of sub-MICs of imipenem and metronidazole, the inhibition of biofilm formation was observed. In contrast, enrofloxacin at ½ MIC caused a significant increase in biofilm formation in two of four strains examined. In conclusion, the B. fragilis group strains isolated were susceptible to most of the antimicrobials tested and the sub-MIC concentrations of imipenem, metronidazole and clindamycin were able to inhibit the biofilm formation.

The efficacy of three formulations of Lippia sidoides Cham. essential oil in the reduction of salivary Streptococcus mutans in children with caries: a randomized, double-blind, controlled study.

Essential oils of many plants have been previously tested in the treatment of oral diseases and other infections. This study was a randomized, double-blind, in parallel with an active control study, which aimed to evaluate the efficacy of three formulations of the Lippia sidoides Cham. essential oil (LSO) in the reduction of salivary Streptococcus mutans in children with caries. 81 volunteers, aged 6-12 years, both genders, with caries, were recruited to participate in this study, and randomly assigned to either one of five different groups. Each group received topical treatment with either 1.4% LSO toothpaste, 1.4% LSO gel, 0.8% LSO mouthwash, 1% chlorhexidine gel, or 0.12% chlorhexidine mouthwash. A 5-ml volume of each gel was placed inside disposable trays, and applied for 1 min, every 24h, for 5 consecutive days. The mouthwash groups used 5-ml volume of a mouthwash inside disposable syringes. In the toothpaste group, children brushed their teeth for 1 min, once a day for 5 days. Saliva was collected before and after treatment. MS colonies were counted, isolated and confirmed through biochemical tests. Differences in MS levels measured in different days within the same treatment group was only verified with LSO toothpaste, chlorhexidine gel and chlorhexidine mouthwash. Comparison between groups of LSO mouthwash, toothpaste and gel showed that the toothpaste group expressed significantly lower MS levels than the mouthwash and gel groups at day-30. Chlorhexidine significantly reduced MS levels after 5 days of treatment, but these levels returned to baseline in other periods of the study. LSO toothpaste reduced MS levels after 5 days of treatment, and MS levels remained low and did not return to baseline during subsequent analysis. Hence, LSO toothpaste demonstrated the most long-lasting MS reduction in saliva, whereas other LSO formulations did not effectively reduce MS levels in children with dental caries.

Efficacy of Plectranthus amboinicus (Lour.) Spreng in a Murine Model of Methicillin-Resistant Staphylococcus aureus Skin Abscesses.

The present work aimed to evaluate the effectiveness of Plectranthus amboinicus (Lour.) Spreng against MRSA clinical isolates. The in vitro antimicrobial activity of the hydroalcoholic extract (HE), the ethyl acetate (EA) fraction and its subfractions were determined by broth microdilution and bioautography against MRSA clinical isolates. The microdilution checkerboard method was used to assess in vitro drug combination studies. To induce abscess formation, bacterial suspensions were added to Citodex and inoculated subcutaneously into male Swiss mice. The treatment protocol consisted of 2 doses of HE, the EA fraction or vancomycin introduced intraperitoneally into mice 3 and 12 h after infection. The EA fraction and its subfractions presented the lowest minimal inhibitory concentrations (MIC, 0.25 to 0.5 mg/mL). The plant samples were bacteriostatic at 2x and 4x MIC and bactericidal at 100 mg/mL. The EA fraction presented synergism with vancomycin and an additive effect with ciprofloxacin. A significant reduction of abscess volume, bacterial cell counts in abscess slurries, and inflammatory scores was observed in the HE and EA fraction-treated groups. The samples were effective in treating the animals in a dose-dependent fashion. The present study proved the effectiveness of P. amboinicus fractions against MRSA using in vitro and in vivo assays.

Salivary peptide profile and its association with early childhood caries.

BACKGROUND: As dietary management during early childhood is a great barrier in caries control, there is a need for the identification of intrinsic risk factors, capable of allowing the use of a more cost-effective approach to early childhood caries (ECC). OBJECTIVE: To evaluate the salivary peptide profile of children with and without ECC and its association with caries experience. METHODS: One hundred and six 10- to 71-month-old children participated in the study. Caries experience was determined through the visual/tactile method, based on the number of decayed, missing, and filled teeth, and surface scores (dmft/dmfs). Whole saliva was collected for mutans streptococci (MS) detection and peptide analysis. RESULTS: Chromatograms from CF (children without caries experience, n = 58) and CE (children with caries experience, n = 48) saliva pools expressed different patterns. Identification of molecular masses suggested the presence of nine peptides. Three of them were significantly related with caries experience. HNP-3 (α-defensin 3) (P = 0.019) and HBD-3 (ß-defensin 3) (P = 0.034) reduced the chances of experiencing ECC. Proline-rich peptides IB-4 significantly increased caries experience (P = 0.035). Age (P = 0.020) and MS counts (P = 0.036) increased caries experience; however, gender was not associated with dental caries (P = 0.877). CONCLUSION: Specific salivary peptides of CF or CE children in early childhood predispose to a higher or lower risk of caries experience.

Biofilm production by clinical staphylococci strains from canine otitis.

This study determined the species of 54 staphylococci isolates from canine otitis and their ability to produce biofilm through the Congo red agar method, confirmed by scanning electron microscopy. The most frequently identified species were S. intermedius and S. simulans. Results showed that 30% of the strains were biofilm producers.

Antibacterial effects of chemomechanical instrumentation and calcium hydroxide in primary teeth with pulp necrosis.

PURPOSE: This study's purposes were to: evaluate the antibacterial effect of chemomechanical instrumentation and a calcium hydroxide-based dressing in primary teeth with pulp necrosis secondary to trauma; and detect the presence of Fusobacterium nucleatum and black-pigmented rods in the canals of these teeth. METHODS: Microbiological sample collections (MSCs) were obtained: after coronal access to the canals of primary incisors (in 18 teeth; MSC 1); after chemomechanical instrumentation (in 10 teeth; MSC 2); and 72 hours after removal of intracanal medication (in 18 teeth; MSC 3). These samples were sent for microbiological processing. The results were analyzed statistically via chi-square, analysis of variance, and Games-Howell tests (P<.05). RESULTS: Micro-organisms were isolated in approximately 94%, 10%, and 83% of canals, respectively, in MSCs 1, 2, and 3. There was a statistically significant difference only between MSCs 1 and 2 (P<.03). F nucleatum and black-pigmented rods were detected in approximately 56% and 11% of canals in MSC 1, respectively. CONCLUSION: Chemomechanical instrumentation and calcium hydroxide-based dressing have an anti-bacterial effect by significantly reducing the number of micro-organisms in the main root canal. They showed a limited efficacy, however, and did not prevent bacterial regrowth after endodontic therapy in primary teeth with pulp necrosis secondary to trauma.

Dose-response evaluation of a novel essential oil against Mutans streptococci in vivo.

Research has demonstrated the need for identifying a novel antimicrobial agent for topical use in the pediatric dental population. The essential oil of Lippia sidoides Cham. (LSO) has been described as having favorable biological properties, and a broad in vitro and in vivo antimicrobial spectrum against bacteria and yeast infections. Our aim was to determine a dose and formulation of LSO, acceptable for clinical testing in a pediatric population with dental caries. Thirty-seven 6-12-year old children were selected to participate in this study, and randomly allocated to receive different concentrations of either a gel (0.8%, 1%, 1.2% and 1.4%) or a mouth rinse (0.6%, 0.8%, 1% and 1.2%) formulation. The highest percentage MS reduction was observed with 0.8% mouth rinse and 1.4% gel. The efficacy of these concentrations was compared with a Thy-Car mixture formulated as a mouth rinse and gel treatments in 11 children. Saliva was collected after a single application of the antimicrobial treatment to establish effectiveness against MS. Both rinse (p<0.001) and gel (p=0.02) formulations produced significant MS reduction. Mouth rinse concentrations above 0.8% were associated with a transient intra-oral burning sensation. In conclusion, mouth rinse and gel LSO formulations demonstrated effectiveness against MS and good acceptance among children. We suggest future randomized clinical trials to test its effectiveness against early childhood caries.