Bioaerossóis bacterianos em um hospital

Microbial contamination of an enclosed area may come from outside or be generated within the area itself. In the study described here, bioaerosol levels in hospital air were quantified and related to those found in the air outside, taking into account some of the environmental variables that affect air quality, such as the number of occupants of a room and the type of ventilation. Airborne bacteria were collected for five minute by blowing air at 500 L min -1 in high speed jets on to the surface on plates culture in a single-stage bioaerosol impactor. The mean viable count of bacteria in the air outside in the hospital, São Paulo State, was 77 ± 4 CFU m -3, while in the air inside the hospital it was 302 ± 260 CFU m-3. The operating theatre was the only space sampled with a controlled environment and, after orthopedic surgery, it had the highest bioaerosol count recorded (867 ± 482 CFU m-3). In the enclosed environments, nine bacterial species were identified. Despite the difficulty in establishing precise numbers of bacteria in the bioaerosols in hospital environments, the values obtained demonstrate a need to instigate suitable programs to keep the microbial density low in these environments, and eliminate microorganisms presenting a significant risk to their occupants. It is also recommended that such programs include the monitoring of hospital air, with the aim of defining standards for acceptable numbers of bacteria in the bioaerosol.

Effectiveness of microwave irradiation on the disinfection of complete dentures

Purpose: The purpose of this study was to evaluate the effectiveness of microwave irradiation on the disinfection of simulated complete dentures. Materials and Methods: Eighty dentures were fabricated in a standardized procedure and subjected to ethylene oxide sterilization. The dentures were individually inoculated (10 7 cfu/mL) with tryptic soy broth (TSB) media containing one of the tested microorganisms (Candida albicans, Streptoccus aureus, Bacillus subtilis, and Pseudomonas aeruginosa). After 48 hours of incubation at 37°C, 40 dentures were individually immersed in 200 mL of water and submitted to microwave irradiation at 650 W for 6 minutes. Forty nonirradiated dentures were used as positive controls. Replicate aliquots (25 μL) of suspensions were plated at dilutions of 10 -3 to 10 -6 on plates of selective media appropriate for each organism. All plates were incubated at 37°C for 48 hours. TSB beakers with the microwaved dentures were incubated at 37°C for 7 more days. After incubation, the number of colony-forming units was counted and the data were statistically analyzed by Kruskal-Wallis test (α = .05). Results: No evidence of growth was observed at 48 hours for S aureus, B subtilis, and C albicans. Dentures contaminated with P aeruginosa showed small growth on 2 plates. After 7 days incubation at 37°C, no growth was visible in the TSB beakers of S aureus and C albicans. Turbidity was observed in 3 broth beakers, 2 from P aeruginosa and 1 from B subtilis. Conclusion: Microwave irradiation for 6 minutes at 650 W produced sterilization of complete dentures contaminated with S aureus and C albicans and disinfection of those contaminated with P aeruginosa and B subtilis.

Candida albicans inactivation and cell membrane integrity damage by microwave irradiation

In indicating the microwave irradiation for disinfecting dentures it is necessary to see how this procedure influences Candida albicans integrity and viability. The aim of this study was to evaluate the ability of microwaves to inactivate C. albicans and damage cell membrane integrity. Two 200-ml C. albicans (ATCC 10231) suspensions were obtained. A sterile denture was placed in a beaker containing the Experimental (ES) or the Control suspension (CS). ES was microwaved at 650 W for 6 min. Suspensions were optically counted using methylene blue dye uptake as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550 nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca++ (Cresolftaleine complexone method); DNA (spectrophotometer measurements at 260 nm) and K + (selective electrode technique). Data were analysed by Student's t- or Wilcoxon z-tests (α = 0.05). All ES cells demonstrated cell membrane damage. Viable cells were non-existent in the ES ASD plates. No significant difference in optical density between ES and CS was observed (P = 0.272). ES cells released significantly high protein (P < 0.001, Bradford; P = 0.005, Pyrogallol red), K+ (P < 0.001), Ca++ (P = 0.012) and DNA (P = 0.046) contents. Microwaves inactivated C. albicans and damaged cell membrane integrity. © 2007 The Authors.

Efficacy of ultrasonic, electric and manual toothbrushes in patients with fixed orthodontic appliances

Objective: This crossover study compared the efficacy of an ultrasonic toothbrush for the reduction of plaque, gingival inflammation, and levels of Streptococcus mutans, in relation to an electric and a manual toothbrush. Materials and Methods: Twenty-one patients with orthodontic appliances were divided into three groups. All patients were evaluated by a periodontist and samples of saliva were collected for quantification of S mutans. The patients received their first brushes with appropriate instructions. For each crossover leg, patients used each toothbrush for a period of 30 days. At the end of each washout period, participants received a periodontal evaluation and new samples of saliva were collected. After 15 days of using their own toothbrushes, patients received the next toothbrushes in the experimental sequence. Results: The ultrasonic brush group presented significant improvement in the reduction of visible plaque on the buccal surfaces (-6.36%, P = .007). The counts of S mutans decreased in the electric (2.04 × 105 to 1.36 × 105 colony-forming units [CFU]/mL) and ultrasonic (2.98 × 105 to 1.84 × 105 CFU/mL) groups. There were no statistical differences among the three brushes for the clinical and microbiological parameters evaluated. Conclusions: This study did not demonstrate that the ultrasonic toothbrush was better in reducing gingival inflammation in adolescent orthodontic patients, but plaque scores were lowered on buccal surfaces of teeth with orthodontic brackets. In addition, S mutans counts were markedly decreased in the electric and ultrasonic groups, which should be related to a reduced risk of oral disease. © 2006 by The EH Angle Education and Research Foundation, Inc.

Comparative study of the clinical and anti-microbial efficacy of tongue cleaners

Candida species have frequently been isolated from the oral cavities of a variety of patients, such as elderly people, dentures users, immunocompromised and health patients. Yeasts may be associated with immune response and local factors such as poor oral hygiene. It was evaluated effectiveness of tongue cleaner showing which types would be preferred by patients, changes in tongue coating and in saliva yeasts counting. Thirty patients were selected and randomly distributed into three groups. This crossover blind study evaluated the effect of tongue cleaning using: a plastic and a steel tongue scraper and a nylon soft-bristle toothbrush. All patients were instructed to use the cleaners twice a day for one week (fifteen-day wash-out period). Saliva and tongue coating samples were collected from each patient from each test period, the yeasts were counted by colony forming units per mL (CFU/ mL) and the species were identified. The patients were questioned about cleaner preference. An increase in the percentage of patients with no tongue coating after scraping was observed. A reduction in the mean number of Candida species in tongue coating was observed only after nylon soft-bristle toothbrush cleaner. Candida albicans was the prevalent species. Volunteers preferred to the steel tongue scraper (60%). Tongue cleaners reduced the tongue coating and the mean number of saliva's yeasts. Degree of tongue coating favors the Candida species colonization.

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.

Interleukin-15: Its role in microbial infections

Interleukin-15 (IL-15) is a pleiotropic cytokine which regulates the proliferation, survival and the secretory activities of many distinct cell types in the body. This cytokine is produced by macrophages and many other cell types in response to infectious agents; it controls growth and differentiation of T and B lymphocytes, activation of Natural Killer (NK) and phagocytic cells, and contributes to the homeostasis of the immune system. The present review focuses on the biological and modulatory effects of IL-15 in microbial infections and shows that this cytokine may play a role in the host defense against infections by inducing activation of effector cells from both innate and adaptive immune system.

Transmission of Aggregatibacter actinomycetemcomitans between Brazilian women with severe chronic periodontitis and their children

This study evaluated the transmission of Aggregatibacter actinomycetemcomitans (Aa) in women with severe chronic periodontitis and their children. Thirty women (mean age = 36.1±6.0 years) who were mothers of at least one child aged 7 to 16 years were enrolled. In order to investigate mother-child transmission of Aa, the children were also evaluated when their mothers were colonized by the bacterium. Subgingival plaque samples of each woman were collected from 3 sites (mean probing depth of 7.3±1.2 mm and mean clinical attachment level of 7.9±1.5 mm) and pooled in reduced transport fluid (RTF). These samples were processed, inoculated onto TSBVagar selective medium and incubated at 37°C in microaerophilic atmosphere for 5 days. Aa was identified on the basis of colony morphology, Gram staining, catalase and oxidase reactions. Aa was found in 8 out of 30 women. Therefore, 8 children from these women (mean age= 12 ± 3.7 years) were evaluated, but Aa was found only in 2 of them. Aa strains of the two mother-child pairs were evaluated by arbitrarily-primed polymerase chain reaction (AP-PCR), although it was not found similarity between the amplitypes of each pair. No Aa transmission was found between Brazilian women with severe chronic periodontitis and their children.

Anticariogenic effect of fluoride-releasing elastomers in orthodontic patients

This in vivo experimental study evaluated the efficacy of fluoride-releasing elastomers in the control of Streptococcus mutans levels in the oral cavity. Forty orthodontic patients were recruited and divided into two groups of 20. Fluoride-releasing elastomeric ligature ties (Fluor-I-Ties, Ortho Arch Co. Inc., USA) were used in the experimental group, and conventional elastomeric ligature ties (D. Morelli, Brazil), in the control group. Two initial samples of saliva were collected at a 14-day interval to determine the number of colony forming units (CFU) of Streptococcus mutans. Immediately after collecting the second sample, fluoride-releasing elastomeric ligature ties were placed in the patients of the experimental group, and conventional ligature ties, in the patients of the control group. Seven, 14 and 28 days after placement of the elastomeric ligature ties, saliva and plaque surrounding the orthodontic appliance were collected for microbiologic analysis. There were no significant differences in the number of Streptococcus mutans CFUs in saliva or plaque in the area surrounding the fluoride-releasing or conventional elastomeric ligature ties. Thus, fluoride-releasing elastomeric ligature ties should not be indicated to reduce the incidence of enamel decalcification in orthodontic patients. Since there was no significant reduction in S. mutans in saliva or plaque, other means of prevention against enamel decalcification should be indicated for these patients.

SEM analysis of the in situ early bacterial colonization on two novel feldspathic ceramics submitted to different types of glazing

Aim: The aim of this study was to evaluate in situ, the early bacterial colonization on feldspar-ceramics submitted to different glazing. Methods and Materials: Fourteen standardized disc specimens (diameter: 5 mm, thickness: 1.5 mm) of each of two micro-particulate feldspathic ceramics (VM7 and VM13, Vita) were produced according to manufacturers' specifications for a total of 28 specimens (24 for the analysis of biofilm and 4 for topographic analysis analyzing the ceramic surfaces). Specimens from each type of ceramic were submitted to two different glazing methods composing four groups: VM7 glazed using glazing liquid Vita Akzent® 25 (G1) and glaze firing (G2), VM13 glazed using glazing liquid (G3) and glaze firing (G4). Six individuals (n=6) wore oral appliances with four ceramic specimens, fixed on the buccal face of the appliances. After 8 hours, each sample was evaluated for the presence (1) or absence (0) of bacterial colonization under a scanning electron microscope (SEM) on five randomly selected fields. The value for each sample was cumulative of the results observed in the fields. One sample from each group was evaluated under a SEM to verify the topographic pattern. Results: There was no difference with regard to bacterial colonization between the feldspar-ceramics and between the glazing types (Kruskal-Wallis non-parametric test). Conclusion: Feldspar-ceramics submitted to firing or glaze firing with Vita Akzent® 25 present a similar condition for in situ bacterial colonization. The similar topographic pattern of the ceramic surfaces seems to have influenced the bacterial colonization.

Effect of different exposure times on microwave irradiation on the disinfection of a hard chairside reline resin

Purpose: This study evaluated the effectiveness of different exposure times of microwave irradiation on the disinfection of a hard chairside reline resin. Materials and Methods: Sterile specimens were individually inoculated with one of the tested microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Bacillus subtilis) and incubated for 24 hours at 37°C. For each microorganism, 10 specimens were not microwaved (control), and 50 specimens were microwaved. Control specimens were individually immersed in sterile saline, and replicate aliquots of serial dilutions were plated on selective media appropriate for each organism. Irradiated specimens were immersed in water and microwaved at 650 W for 1, 2, 3, 4, or 5 minutes before serial dilutions and platings. After 48 hours of incubation, colonies on plates were counted. Irradiated specimens were also incubated for 7 days. Some specimens were prepared for scanning electron microscopic (SEM) analysis. Results: Specimens irradiated for 3, 4, and 5 minutes showed sterilization. After 2 minutes of irradiation, specimens inoculated with C. albicans were sterilized, whereas those inoculated with bacteria were disinfected. One minute of irradiation resulted in growth of all microorganisms. SEM examination indicated alteration in cell morphology of sterilized specimens. The effectiveness of microwave irradiation was improved as the exposure time increased. Conclusion: This study suggests that 3 minutes of microwave irradiation can be used for acrylic resin sterilization, thus preventing cross-contamination. © 2008 by The American College of Prosthodontists.

Adherence of Streptococcus mutans to uncoated and saliva-coated glass-ceramics and composites

This study sought to investigate the surface roughness and the adherence of Streptococcus mutans (in the presence and absence of saliva) to ceramics and composites. The early dental biofilms formed in situ on the materials were illustrated, using scanning electron microscopy (SEM). Feldspathic and leucite/feldspathic ceramics and microhybrid and microfilled composites were evaluated. Human dental enamel was used as the control. Standardized specimens of the materials were produced and surface roughness was analyzed. The adhesion tests were carried out in 24-well plates and colony forming units (CFU/mL) were evaluated. Values of roughness (μm) and adherence (CFU/mL) were analyzed statistically. Of all the surfaces tested, enamel was the roughest. Leucite/feldspathic ceramics were rougher than the feldspathic ceramic, while composites were similar statistically. Enamel offered the highest level of adherence to uncoated and saliva-coated specimens, while the leucite/feldspathic ceramic demonstrated greater adherence than the feldspathic ceramic and the composites were similar statically. The rougher restorative materials increased the adherence of S, mutans on the material surfaces.

Influence of local tetracycline on the microbiota of alveolar osteitis in rats

The aim of the present study was to evaluate the effects of local tetracycline on the occurrence of alveolar osteitis in rats, and on the microbiota associated to this infection. Forty Wistar rats were randomly assigned to 4 groups (n=10): I - the rats had the maxillary right incisor extracted and the alveolar wound did not receive any treatment; II - adrenaline and Ringer-PRAS were introduced into the alveolar wound; III - the alveolar wound was irrigated with sterile saline; and IV - the alveolar wound was irrigated with an aqueous solution of tetracycline. Microbial samples from the alveolar wounds were collected 2 days after surgery and inoculated on blood agar (with and without 8 μg/mL of tetracycline) and other selective media, and were incubated in either aerobiosis or anaerobiosis at 37°C, for 2 to 14 days. It was verified that tetracycline reduced the occurrence of alveolar osteitis in the rats and caused significant changes in the microbiota of the surgical sites, decreasing the number of anaerobes and increasing the participation of tetracycline-resistant and multi-resistant microorganisms.

Microbial distribution in the root canal system after periapical lesion induction using different methods

The aim of this study was to evaluate the microbial distribution in the root canal system after periapical lesion induction in dogs' teeth using different methods. Fifty-two root canals were assigned to 4 groups (n=13). Groups I and II: root canals were exposed to the oral cavity for 180 days; groups III and IV: root canals were exposed for 7 days and then the coronal openings were sealed for 53 days. The root apices of groups I and III were perforated, while those of groups II and IV remained intact. After the experimental periods, the animals were euthanized and the anatomic pieces containing the roots were processed and stained with the Brown & Brenn method to assess the presence and distribution of microorganisms. The incidence of microorganisms at different sites of the roots and periapical lesions was analyzed statistically by the chi-square test at 5% significance level. All groups presented microorganisms in the entire root canal system. A larger number of microorganisms was observed on the root canal walls, apical delta and dentinal tubules (p<0.05), followed by cementum and cemental resorption areas. In spite of the different periods of exposure to the oral environment, the methods used for induction of periapical periodontitis yielded similar distribution of microorganisms in the root canal system.

Antimicrobial activity of endodontic sealers based on calcium hydroxide and MTA.

The aim of this study was to evaluate the antimicrobial activity of a new root canal sealer containing calcium hydroxide (Acroseal) and the root canal sealer based on MTA (Endo CPM Sealer), in comparison with traditional sealers (Sealapex, Sealer 26 and Intrafill) and white MTA-Angelus, against five different microorganism strains. The materials and their components were evaluated after manipulation, employing the agar diffusion method. A base layer was made using Müller-Hinton agar (MH) and wells were made by removing agar. The materials were placed into the wells immediately after manipulation. The microorganisms used were: Micrococcus luteus (ATCC9341), Staphylococcus aureus (ATCC6538), Pseudomonas aeruginosa (ATCC27853), Candida albicans (ATCC 10231), and Enterococcus faecalis (ATCC 10541). The plates were kept at room temperature for 2 h for prediffusion and then incubated at 37 degrees C for 24 h. The results showed that Sealapex and its base paste, Sealer 26 and its powder, Endo CPM Sealer and its powder, white MTA and its powder all presented antimicrobial activity against all strains. Intrafill and its liquid presented antimicrobial activity against all strains except P. aeruginosa and Acroseal was effective only against M. luteus and S. aureus.