Factors related to maternal transmission of mutans streptococci in high-risk children-pilot study.

PURPOSE: The purpose of this study was to investigate virulence factors associated with maternal transmission of mutans streptococci (MS). METHODS: Saliva samples were collected from 10 mothers with active caries and their 2- to 5-year-old children. Ten MS colonies were isolated from each subject. Transmission of MS was identified by arbitrarily primed polymerase chain reactions. Biofilm formation and mutacin production of the isolates against Streptococcus gordonii 10558, Streptococcus sanguinis 10557, Streptococcus mutans 25175, and Streptococcus sobrinus 6715 were analyzed. RESULTS: All mothers and children had MS colonization. Only 7 of the 36 maternal genotypes (33 Streptococcus mutans genotypes and 3 Streptococcus sobrinus genotypes) were transmitted. Maternal transmission was found in 4 mother-child pairs, whereas 9 children had nonmaternal genotypes. There was no difference in biofilm formation between transmitted and nontransmitted genotypes (P>.05). Transmitted genotypes, however, produced more mutacin against Streptococcus sobrinus 6715 than nontransmitted genotypes. CONCLUSIONS: This pilot study showed that there may be nonmaternal as well as maternal mutans streptococci transmission.

Lipopolysaccharide biosynthesis-related genes are required for colony pigmentation of Porphyromonas gingivalis.

The periodontopathic bacterium Porphyromonas gingivalis forms pigmented colonies when incubated on blood agar plates as a result of accumulation of mu-oxo haem dimer on the cell surface. Gingipain-adhesin complexes are responsible for production of mu-oxo haem dimer from haemoglobin. Non-pigmented mutants (Tn6-5, Tn7-1, Tn7-3 and Tn10-4) were isolated from P. gingivalis by Tn4351 transposon mutagenesis [Hoover & Yoshimura (1994), FEMS Microbiol Lett 124, 43-48]. In this study, we found that the Tn6-5, Tn7-1 and Tn7-3 mutants carried Tn4351 DNA in a gene homologous to the ugdA gene encoding UDP-glucose 6-dehydrogenase, a gene encoding a putative group 1 family glycosyltransferase and a gene homologous to the rfa gene encoding ADP heptose-LPS heptosyltransferase, respectively. The Tn10-4 mutant carried Tn4351 DNA at the same position as that for Tn7-1. Gingipain activities associated with cells of the Tn7-3 mutant (rfa) were very weak, whereas gingipain activities were detected in the culture supernatants. Immunoblot and mass spectrometry analyses also revealed that gingipains, including their precursor forms, were present in the culture supernatants. A lipopolysaccharide (LPS) fraction of the rfa deletion mutant did not show the ladder pattern that was usually seen for the LPS of the wild-type P. gingivalis. A recombinant chimera gingipain was able to bind to an LPS fraction of the wild-type P. gingivalis in a dose-dependent manner. These results suggest that the rfa gene product is associated with biosynthesis of LPS and/or cell-surface polysaccharides that can function as an anchorage for gingipain-adhesin complexes.

A novel approach in assessment of coronal leakage of intraorifice barriers: a saliva leakage and micro-computed tomographic evaluation.

The efficacy of amalgam, Fuji-Plus, Geristore, and mineral trioxide aggregate (MTA) as intraorifice barriers was compared in a simulated saliva leakage model. Fifty teeth were divided into 4 experimental (n = 10 each) and 2 control groups (n = 5 each). Two millimeters of the materials was placed as intraorifice barriers and brought into contact with human saliva in a coronal reservoir. Bacterial leakage into the apical reservoir was assessed daily for 3 months. Geristore barriers leaked significantly more often (5/10) than Fuji-Plus (0/10, P < .05) at 60 days. The first Fuji-Plus sample leaked after 70 days; after 90 days, 3 (Fuji-Plus), 4 (MTA, amalgam), and 6 (Geristore) samples leaked. There were no significant differences between the experimental groups at that time point. Three-dimensional gap volumes in the barrier-dentin interface and the porosity of the barrier materials were compared by using micro-computed tomography (microCT). A measurable gap was evident in only 1 specimen with an MTA barrier. MTA was significantly less porous than Fuji-Plus and Geristore (P < or = .05), whereas amalgam was too radiopaque to allow microCT measurements. In conclusion, Fuji-Plus might be an effective intraorifice barrier (up to 70 days in vitro), but all 4 materials showed leakage in some specimens at 90 days.

Antibacterial treatment needed for severe early childhood caries.

OBJECTIVES: To assess the effects of a single 10% povidone iodine application as an adjunct to extensive surgical procedures in the clinical treatment of children with early childhood caries. METHODS: Twenty-two children scheduled for dental treatment under general anesthesia were randomized into either an intervention group (10% povidone iodine), or a control group (phosphate buffered saline). Either povidone iodine or phosphate buffered saline was applied to teeth and soft tissues after prophylaxis and all operative dental procedures, followed by 1.23% acidulated phosphate fluoride gel. Saliva samples taken at baseline, and after 1 hour, 3 weeks and 3 months were assayed for mutans streptococci, lactobacilli and total viable bacteria. Caries lesions were recorded at baseline and at one year. RESULTS: Mutans streptococci and lactobacilli levels in the povidone iodine group were significantly reduced relative to baseline at 1 hour, 3 weeks and 3 months. At one year at least 60% of subjects had new caries lesions in each group, and there was no significant difference in caries increment between the two groups. CONCLUSIONS: Even prophylaxis, fluoride gel application and complete surgical treatment of caries at baseline were insufficient to prevent new caries in over 60% of the patients in these high caries risk infants. Although the one-time treatment with povidone iodine reduced mutans streptococci and lactobacilli levels for up to 3 months this therapy failed to additionally reduce future caries formation over one year, indicating that repeated antibacterial treatments will be needed to control high levels of cariogenic bacteria.

A laboratory model biofilm fermenter: design and initial trial on a single species biofilm.

BACKGROUND: The minimum inhibitory concentration (MIC) does not provide information on the efficacy of antimicrobial agents against infections involving biofilms, which are many times more resistant than planktonic forms of bacteria. This report is on the design and initial trial of a device for growing standard biofilms and testing antimicrobial agents. METHODS: We constructed a durable, autoclaveable laboratory model biofilm fermenter (LMBF) that holds hydroxyapatite discs 300 microm below a surface onto which an artificial saliva medium drips at a rate comparable to human salivary flow. Inoculated with Streptococcus sanguinis, the device formed biofilms that were swept with a Teflon wiper under aerobic conditions. Five-day-old biofilm-coated discs were aseptically removed and placed in 3 ml of sterile saline, 0.12% chlorhexidine gluconate, or 0.1% phosphate-buffered chlorine dioxide mouthwash for 1 minute. The discs and test agent were immediately diluted with saline to 10 ml, vortexed for 30 seconds, serially diluted, plated on blood agar, and incubated anaerobically 2 days. Bacterial counts were done, and the MIC of each mouthwash was determined. RESULTS: In tests with sterile water and sterile medium, the device maintained a closed system. After inoculation with S. sanguinis, a steady state was reached at day 5. Chlorhexidine at stock concentration achieved about a 2 log10 reduction (P = 0.002), but never achieved complete killing. Chlorine dioxide had no significant effect. The MIC against planktonic S. sanguinis was 112.8 microg/ml for chlorhexidine and 9.0 microg/ml for chlorine dioxide. CONCLUSIONS: The LMBF generates and maintains a single-species oral model biofilm to a steady state and enables in vitro tests of disinfectant mouthwashes in simulated clinical use. It should be usable for more advanced tests of multiple species biofilms.

Bacterial, behavioral and environmental factors associated with early childhood caries.

The goals of this cross-sectional study were to characterize and compare demographic, behavioral, and environmental factors potentially associated with early childhood caries (ECC) and to assess salivary levels of mutans streptococci (MS) and lactobacilli (LB) in underserved, predominantly Hispanic children. One hundred forty-six children aged 3 to 55 months with a range of caries experience were identified and examined. ECC was primarily associated with the presence of MS and lack of access to dental care. Salivary MS levels among young children with ECC were higher than would be expected in a dentally healthy population, but lower than levels reported among older children at high risk for caries. After adjustment for age, children with log10 MS > or = 3.0 or log10 LB > or = 1.5 were about five times as likely (OR=4.9, 95% CI=2.0, 12.0) to have ECC than those with lower bacterial levels. This study demonstrated a significant association between relatively low cariogenic bacterial levels and dental caries in infants and toddlers. Antibiotic use, exposure to lead, and anemia were not significantly associated with the number of decayed and filled surfaces or decayed and filled teeth. ECC correlated significantly with child's age and lack of dental insurance of the children, as well as inversely with both family income and the educational level of the mother of the child.