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Biomedical subjects

C G Emilson

Publications and source records attributed to C G Emilson.

At least 91 records · Page 5Linked to original sources
PubMed1980

Effects of chlorhexidine and iodine on in vitro plaques of Streptococcus mutans and Streptococcus sanguis.

Both chlorhexidine and iodine showed greater antimicrobial effect on in vitro grown S. mutans plaque than on plaque composed of S. sanguis. One treatment with iodine for 8 min inhibited the acid production of S. Mutans plaque whereas S. sanguis plaque required 20 min to be similarly affected. In contrast one treatment with chlorhexidine for up to 20 min did not completely inhibit the acid production of plaque of either microorganism. Repeated short term exposures increased the bactericidal effect of chlorhexidine but not that of iodine. The difference in antimicrobial effect between chlorhexidine and that of iodine on S. mutans and S. sanguis should be investigated in persons heavily infected by S. mutans.

Acids↗
PubMed1980

In vitro development of chlorhexidine resistance in Streptococcus sanguis and its transmissibility by genetic transformation.

Three chlorhexidine-sensitive strains of Streptococcus sanguis developed resistance to chlorhexidine when grown as continuous cultures in a fermenter containing medium with increasing concentrations of the drug. The MIC of the test strains increased by between two and three dilution steps and these high values were maintained after daily transfer in drug-free medium for at least 15 d. In addition, the resistance of one of the strains persisted for more than 1 month of continuous growth in drug-competent sensitive S. sanguis to increased chlorhexidine resistance, thus proving that resistance to this drug is an inheritable trait. Immunoelectrophoretic experiments showed that certain changes in the antigenic pattern of the Chxr variants had occurred as compared with their sensitive wild-type strains. Antigenic extracts of the Chxr variants and all Chxr recombinants tested contained consistently less protein than those of the sensitive wild-types.

Antigens, Bacterial↗
PubMed1979

Effect of chlorhexidine on the relative proportions of Streptococcus mutans and Streptococcus sanguis in hamster plaque.

The effect of chlorhexidine on the proportions of Streptococcus mutans and Streptococcus sanguis in plaque was studied in hamsters fed a diet containing 28% sucrose. In animals given chlorhexidine in their drinking water for 10 d a decrease in the population of S. mutans and an increase of S. sanguis occurred in the plaque. Following the removal of chlorhexidine the population of S. mutans increased again in the presence of sucrose and the number of S. sanguis returned to initial values. When animals were given a sucrose-free diet the low proportion of S. mutans observed following the short-term chlorhexidine period persisted. These data indicate that there is an inverse relationship between the number of S. sanguis and S. mutans in plaque and that the sensitivity in vivo of S. mutans to chlorheximide can be used to suppress the population of S. mutans with a concomitant rise in the proportion of S. sanguis.

Animals↗
PubMed1977

Outlook for Hibitane in dental caries.

The association between S. mutans and dental caries in humans has focused the interest on the possiblity to suppress or eliminate this microorganism from the oral cavity. In this respect chlorhexidine seems to be a valuable adjunct, since S. mutans is highly sensitive to the drug. In hamsters and rats infected with S. mutans topical applications of chlorhexidine have been highly effective in lowering the caries activity. In long-term studies in students, a certain caries inhibiting effect has also been demonstrated. The decrease in the prevalence of S. mutans by chlorhexidine treatment suggests that the drug can be used for directed and controlled antimicrobial therapy in subjects highly infected with S. mutans.

Administration, Topical↗
PubMed1977

Susceptibility of various microorganisms to chlorhexidine.

The susceptibility to chlorhexidine of bacteria in aerobic, facultatively anaerobic and anaerobic isolates from clinical specimens of wounds, urine, saliva, and dental plaque was studied. Agar diffusion tests using 50 microng chlorhexidine discs and agar dilution tests were performed and the MIC values correlated with inhibition zone diameters. Anaerobic plaque strains were isolated and tested by the agar dilution method in an anaerobic glove box. Regression lines obtained for five agar media demonstrated a good correlation between zone diameters and MIC values. There was a broad range of susceptibility to chlorhexidine among both Gram-positive and Gram-negative strains. Low MIC values were noted for staphylococci, S. mutans, S. salivarius and E. coli, while strains of Proteus, Pseudomonas and Klebsiella were less susceptible. S. sanguis showed intermediate susceptibility with both low and high MIC values. Among the anaerobic isolates tested, the strains most susceptible to chlorhexidine were Propionibacterium and Selenomonas, While the least susceptible strains were Gram-negative cocci resembling Veillonella.

Bacteria↗
PubMed1976

Effect of a fluoride-containing chlorhexidine gel on bacteria in human plaque.

The effect on the plaque flora of a fluoride-containing chlorhexidine gel in mouthpieces was studied in seven subjects. Use of the gel during a 3-month period resulted in a change in the pattern of sensitivity to cholorhexidine in the plaque flora as displayed by determination of the minimal inhibitory amount (MIA) of the drug in agar diffusion assays. Three months after the use of gel was discontinued, the MIA value for plaque bacteria had returned to its original level. The relative proportions of S. mutans and S. sanguis in plaque changed during the chlorhexidine period. Thus S. mutans could not be detected in plaque samples after 3-month use of the gel, and the frequency of S. sanguis was altered.

Adult↗
PubMed1976

Effect of toothbrushing with chlorhexidine gel on salivary microflora, oral hygiene, and caries.

The effect of daily toothbrushing with 0.5% chlorhexidine-containing gel for 12 months was evaluated in a double-blind study in 37 dental students. The active gel did not markedly influence plaque formation, gingival conditions, or caries as compared with placebo gel treatment. Salivary bacterial counts were performed on subgroups of six subjects using chlorhexidine gel and on six using placebo gel. No differences in the effect of treatment on the microorganisms studied in the two subgroups could be detected except for S. sanguis. The percentage of this species decrease in the placebo group and increased in the chlorhexidine group. The difference became significant after 2 weeks. A tendency to a greater reduction of S. mutans noted in the chlorhexidine group was most marked in individuals who had high initial counts of this species. The proportion of S. sanguis, which could grow on chlorhexidinei-containing mitis salivarius medium, increased and after 12 months of chlorhexidine treatment averaged 34% of cultivable S. sanguis compared with 0.002% prior to treatment. The number of less sensitive S. sanguis decreased in the 12 months following termination of treatment. There was no observed tendency for the selection or proliferation of other streptococci, gram-negative rods, yeasts, or staphylococci.

Adult↗
PubMed1976

Growth of Streptococcus mutans on various selective media.

The ability of Streptococcus mutans to grow on mitis-salivarius (MS) agar, MC agar, mitis-sucrose-bacitracin (MSB), BCY agar, and MM10 sucrose agar was studied. Batch cultures of S. mutans serotype a demonstrated no growth on MSB agar. Certain serotype d and g strains did not grow on MC agar. The yield for most strains of other serotypes on these selective media was lower compared with that on MS agar. The number of total colony-forming units on BCY and MM10 sucrose agar was similar to the blood agar results. Similar data were obtained when fermenter-grown strains, harvested in the middle or the end of the logarithmic growth phase, were used for inoculation of the various media. Enumeration of S. mutans from plaque samples plated on MC and MSB agar yielded about 75% of the counts obtained on MS or the nonselective medium. When the proportions of S. mutans were expressed as a percentage of the total cultivable flora, the selective media (MC and MSB agar) showed approximately 10% lower values than the MS, BCY, and MM10 sucrose agar.

Agar↗
PubMedDate not supplied

Colonization of Streptococcus mutans and Streptococcus sobrinus genotypes and caries development in children to mothers harboring both species.

The major route of early acquisition of mutans streptococci in humans is a vertical transmission from mother to child. The purpose of this longitudinal study was to examine the acquisition, distribution and persistence of Streptococcus mutans and Streptococcus sobrinus in children whose mothers harbored both species and to study the caries incidence in relation to colonization of these bacteria. Fifteen mother-child pairs were followed during the child's first 7 years. Stimulated salivary samples were taken from the mothers and the children. Plaque samples were also collected from the teeth and the tongue of the children. The samples were analyzed by cultivating techniques together with genomic fingerprinting and hybridizing. The caries experience was evaluated on the sampling occasions and retrospectively using the records of caries registrations from the community clinics. During the 7-year period 10 of the 15 children acquired mutans streptococci. Only 4 of them were colonized by both S. mutans and S. sobrinus despite the fact that their mothers harbored both species. In 2 of the children S. sobrinus was found later than S. mutans. A total of 26 genotypes were found in the children and 9 of them were identical to their mothers. New genotypes and a gain-loss pattern were noted especially in the children but also in their mothers. The groups of teeth first positive for the two species were the deciduous molars. The caries experience was low during the study period with 8 children showing no caries.

Child↗