Comparison between Clinical Aspects and Salivary Microbial Profile of Children with and without Early Childhood Caries: A Preliminary Study.

PURPOSE: To compare the clinical aspects and microbial profile of children with and without early childhood caries (ECC). STUDY DESIGN: 14 patients (7 without caries and 7 with ECC) were submitted to anamnesis, clinical exam and saliva collection for microbiological analyses. Counts of Streptococcus mutans, Lactobacillus spp. Candida spp., and total microorganisms were performed by culture methods. Microbial diversity was characterized by PCR-DGGE. Demographic/clinical data and salivary microbial counts were compared between groups. RESULTS: Habits of hygiene and breastfeeding presented no association with ECC. Use of pacifiers was associated with absence of caries (p=0.035). Counts of total microorganisms and Candida spp. did not differ between the groups. The ECC group presented larger quantity of S. mutans (p=0.026) and Lactobacillus spp. (p=0.002). There was no correlation between microorganisms and breastfeeding and pacifier use. The dmf-t of ECC Group was 10.5 ± 1.9 and the modified dmf-t was 11.3 ± 3.6. The DGGE demonstrated difference in the pattern of bands between the groups. CONCLUSION: Pacifiers usage was associated with the absence of ECC and microorganism number was higher in the caries group. The PCR-DGGE revealed a characteristic microbial diversity in the ECC Group, being an excellent tool for observing the dynamics of the salivary microbial community in these patients.

Antimicrobial resistance of strains of the Bacteroides fragilis group isolated from the intestinal tract of children and adults in Brazil.

The results of this study show that there is a high frequency of resistant species in the Bacteroides fragilis group in the intestinal tract of children and adults in Brazil. B. fragilis was not studied. Of the 73 strains examined, B. distasonis was the most resistant species to penicillin, cefoxitin, cefotaxime and clindamycin. High rates of multiresistance were found, most commonly to penicillin and clindamycin (18 of 36 strains). High levels of beta-lactamase production were detected in isolates showing high resistance to penicillin and multiresistance to the cephamycins, suggesting a widespread dissemination of such resistance.

Resistance profile of Bacteroides fragilis isolated in Brazil. Do they shelter the cfiA gene?

The epidemiology of antimicrobial resistance of clinical isolates and human intestinal strains of Bacteroides fragilis has assumed great importance in the last few years since this microorganism, like other members of the B. fragilis group, can be responsible for the spread of resistance determinants. It is possible that the presence of B. fragilis in polluted aquatic environments might contribute to the spread of resistance. The antimicrobial resistance profile of 44 clinical B. fragilis strains isolated from 1981-1988 and 1991-1998 from the University hospital of Rio de Janeiro, and of 17 faecal and 17 polluted aquatic environmental B. fragilis strains isolated between 1991 and 1998 was determined. The susceptibility tests against penicillin, cefoxitin, imipenem, meropenem, clindamycin, chloramphenicol and metronidazole were performed by Etest in Wilkins-Chalgren agar enriched with 5% sheep blood. Motivated by some high MIC values for cefoxitin and meropenem, the cfiA gene, which codes for a metallo-beta-lactamase, was investigated among all strains, using PCR amplification. The resistance to penicillin was high in the samples from 1981 to 1988 (92.9%) and also in those from 1991 to 1998 (100%), although the MIC90 decreased from 256 mg/L to 24 mg/L. An increase in the resistance level to clindamycin and cefoxitin was seen from one decade to the other, the MIC90 values changing from 4 mg/L to 12 mg/L and from 8 mg/L to 32 mg/L, respectively. The susceptibility profile for metronidazole, chloramphenicol, imipenem and meropenem remained stable, although two clinical strains showed MICs of 6 mg/L and 8 mg/L against meropenem. Almost all human intestinal strains were resistant to penicillin and all of them were susceptible to imipenem, meropenem, chloramphenicol and metronidazole. The MICs of meropenem against two strains isolated from a polluted aquatic environment were 6 mg/L and 32 mg/L. The cfiA gene was detected in five strains, two of which were isolated from clinical specimens against which the MIC values of cefoxitin were high and three from an aquatic environment, whose susceptibility to both cefoxitin and meropenem ranged from sensitive to resistant.

Production of bacteriocin by Bacteriodes fragilis and partial characterization.

The ability of Bacteroides fragilis strains, isolated from various sources, to produce bacteriocin was evaluated. All strains isolated from intestinal infections were producers in high levels and less susceptible to the others. Strains from other origins were found to produce bacteriocin at a medium level and they were variably susceptible. Some properties of one bacteriocin produced by the Bact. fragilis 079298-3 strain were analysed, providing evidence of its protein nature, with stability over a wide range of pH and retained inhibitory activity after heating. This variability seems to suggest that bacteriocin typing is a good method for this species.