José Liébana

Evaluation of the capacity of oral streptococci to produce hydrogen peroxide

The capacity of 11 strains of oral streptococcal species (Streptococcus sanguis, S. oralis, S. mitis and S. sobrinus) to produce hydrogen peroxide (H2O2) was studied in vitro. Detection of this property in solid media, particularly with trypticase soy agar-benzidine-peroxidase, was more sensitive than in liquid media. The addition of carbohydrates (arabinose, xylose, mannose, sorbose and lactose), sorbitol and saccharine to buffered trypticase soy broth increased H2O2 production in S. oralis NCTC 11427, although the concentrations obtained with some substrates (glucose, galactose, mannitol and xylitol) were lower than those obtained in controls. In S. sanguis NCTC 7863, H2O2 production was detected only with galactose, sorbitol, lactose and saccharin.

Horizontal transmission of streptococcus mutans in schoolchildren

Objetive: The aim of this study was to analyze possible horizontal transmission patterns of S. mutans among 6-7-yr-old schoolchildren from the same class, identifying genotypes and their diversity and relationship with caries disease status. Study Design: Caries indexes and saliva mutans streptococci and lactobacilli counts were recorded in 42 schoolchildren. Mutans streptococci colonies were identified by means of biochemical tests and all S. mutans strains were genotyped by arbitrarily primed polymerase chain reaction. A child was considered free of S. mutans when it could not be isolated in 3 samples at 1-week intervals. Results: S. mutans was isolated in 30 schoolchildren: 20 having one genotype and 10 two genotypes. Higher mutans streptococci and caries index values were found in those with two genotypes. Five genotypes were isolated in more than 1 schoolchild and one of these was isolated in 3 schoolchildren. Our results suggest that horizontal transmission may take place. Conclusion: Schoolchildren aged 6-7 yrs may be the source of mutual transmission of S. mutans. Key words:Streptococcus mutans, Horizontal transmission, AP-PCR, genotyping

Genotypes of Streptococcus mutans in saliva versus dental plaque

OBJECTIVE The aim of this study was to investigate whether genotypes of Streptococcus mutans strain can be detected as effectively in saliva samples as in plaque samples from buccal surfaces and occlusal surface fissures of permanent first molars. DESIGN The study included 20 school children aged 6-7 years who were positive for mutans streptococci. Samples of stimulated saliva and of dental plaque on buccal surfaces and occlusal surface fissures of permanent first molars were collected. Samples were cultivated in MSB agar. Up to nine isolates compatible with mutans streptococci were obtained and identified by means of biochemical tests. All isolates identified as S. mutans were genotyped by arbitrarily primed polymerase chain reaction. RESULTS A total of 28 genotypes of S. mutans were isolated: 23 in saliva samples, 23 in buccal surface plaque samples, and 16 in plaque samples from occlusal surface fissures. CONCLUSIONS Although, saliva sampling did not reveal all genotypes isolated, it was equally as effective as plaque sampling from the buccal surfaces of permanent first molars, and more effective than plaque sampling from fissures on their occlusal surfaces.

Activity of Daptomycin Against Multiresistant Clinical Isolates of Staphylococcus aureus and Streptococcus agalactiae

The activity of daptomycin against 141 Staphylococcus aureus and 63 Streptococcus agalactiae isolates was assessed. The isolates were previously characterized and showed resistance to the antibiotics normally used against gram-positive cocci. Daptomycin was active against 100% of the isolates (minimum inhibitory concentration [MIC(90)] = 0.5 microg/ml, for both species). This antibiotic shows good in vitro activity; therefore, it is an excellent therapeutic alternative against these isolates.

Evaluation of the Automicrobic System for the identification ofStreptococcus mutans

The performance of the Automicrobic System with the Vitek gram-positive identification card (bioMérieux, France) in identifying strains ofStreptococcus mutans was studied. Of 160 strains assayed, 72.5% were confirmed to beStreptococcus mutans; the remainder were identified as other species of streptococci (Streptococcus bovis, Streptococcus uberis, Streptococcus anginosus, Streptococcus sanguis I and II,Streptococcus intermedius, andStreptococcus constellatus).

In vitro activity of macrolides and lincosamides against oral streptococci: a therapeutic alternative in prophylaxis for infective endocarditis.

Susceptibility to macrolides and lincosamides was tested in a total of 446 strains of oral streptococci belonging to eleven species, all isolated from dental plaque and/or saliva in 1991. Minimum inhibitory concentrations (MIC) were determined by the double serial dilutions method in agar. Clindamycin was the most effective antibiotic against all species tested. The results of nearly all parameters (range, mean, MIC(50), MIC(90)) in all species showed erythromycin to be less effective than josamycin, making the latter antibiotic a possible alternative to erythromycin in prophylaxis for infective endocarditis caused by oral streptococci, not only in patients allergic to penicillin, but also in all patients with low-risk lesions, who will be treated with low-risk dental procedures. In these latter patients, antibiotic prophylaxis may be indicated if, after careful evaluation of the individuals situation, no other alternatives are available.

Serologic control against hepatitis B virus among dental students of the University of Granada, Spain

Background To evaluate the immunological situation against hepatitis B virus (HBV) of a cohort of dentistry students, to analyze the behavior of the levels of hepatitis B surface antigen (anti-HBs) after the administration of one or three vaccine doses, and to determine the influence of age and sex on the immune response. Material and Methods This retrospective cohort study included students attending the School of Dentistry of the institution where the study was performed from 2005 to 2012 who had completed the public health vaccination calendar for HBV at the age of 12-13. Data on age, sex, basal anti-HBs levels, post-vaccination anti-HBs results and final anti-HBs levels were collected. Comparisons of the basal and final levels, as well as associations regarding age and sex, were performed by means of the Student t and Chi-square tests. Results Of the 359 students, 97 (27.02%) had basal antibody concentrations <10 mIU/ml, whereas in 262 the levels of anti-HBs were ≥10 mIU/ml (72.98%). Of the 288 participating students who completed the School´s protocol for immunization, 287 (99.65%) attained a level of protection ≥10 mIU/ml. Globally, there were statistically significant differences between the basal antibody levels and those achieved after administration of the vaccine and booster, but no association with age or sex was observed. Conclusions About 70% of dental students vaccinated as preadolescents had serologic evidence of protection against HBV. Administering a booster is associated with the presence of an excellent immune memory. There is clearly a need to reinforce control of the antibody levels in groups at risk, such as Dentistry students. Key words:Dental students, hepatitis B virus, serologic control.

Two cases of an atypical presentation of necrotizing stomatitis

Purpose The purpose of this report was to describe the clinical and microbiological characteristics of two rare cases of necrotizing stomatitis, and the outcomes of a non-invasive treatment protocol applied in both cases. Methods We report two cases of necrotizing stomatitis in a rare location in the hard palate of a 40-year-old woman and a 28-year-old man. Neither had a relevant medical history and both presented with highly painful ulceration in the palate and gingival margin that was accompanied by suppuration and necrosis. 3% hydrogen peroxide was applied to the lesions using sterile swabs, and antibiotic and anti-inflammatory treatment was prescribed to both patients in addition to two daily oral rinses of 0.2% chlorhexidine. Results In both cases, radiological examination ruled out bone involvement, and exfoliative cytology revealed a large inflammatory component and the presence of forms compatible with fusobacteria and spirochetes. There was a rapid response to treatment and a major improvement was observed after 48 hours, with almost complete resolution of the ulcerated lesions and detachment of necrotic areas with partial decapitation of gingival papillae. Conclusions Necrotizing periodontal lesions can hinder periodontal probing and the mechanical removal of plaque in some cases due to the extreme pain suffered by the patients. We present a non-invasive treatment approach that can manage these situations effectively.

In vitro immune modulation of polymorphonuclear leukocyte adhesiveness by sodium fluoride.

Abstract. We investigated the influence of sodium fluoride on polymorphonuclear leukocyte (PMN) adhesiveness in a healthy subject with low serum levels of fluoride. The PMN were separated from venous blood, and the percentages of adhered and unadhered cells were determined in vitro in plastic culture plates. The cells were cultured with five different fluoride concentrations ranging from 6.25 10‐2μM to 4.0 μM in the presence and absence of autologous serum.

Análisis mediante una prueba de ELISA de la respuesta de anticuerpos frente a Fusobacterium nucleatum y Eikenella corrodens en sujetos con enfermedad periodontal

Fundamento Se estudia, mediante ELISA, la sintesis de IgG, IgA e IgM frente a Fusobacterium nucleatum y Eikenella corrodens en el suero, el liquido crevicular y la saliva con sujetos con enfermedad periodontal. Pacientes y metodo Se estudiaron 26 enfermos con alta predisposicion a la enfermedad y menores de 35 anos, y 30 sujetos de edad comparable y con escasa predisposicion a la enfermedad. Resultados No se encontraron diferencias para la IgG y la IgM entre los grupos, excepto para la IgM frente a E. corrodens. En el caso de la IgA se encontraron diferencias significativas cuan-do se estudiaron la saliva y el liquido crevicular para ambas bacterias, al igual que en el caso de la IgA en suero frente a E. corrodens. En todos los casos la diferencia estadistica encontrada se refirio a unos valores de anticuerpos mas bajos en los enfermos. Conclusiones La menor sintesis de IgM e IgA, fundamentalmente de esta ultima, frente a F. nuclearum y E. corrodens en los sujetos con enfermedad periodontal podria contribuir a la patogenia de esta enfermedad.