Effects of 6 months use of an antiseptic mouthrinse on supragingival dental plaque microflora.

This study was undertaken to determine whether long-term use (6-months) of an antiseptic mouthrinse (Listerine Antiseptic, Warner Lambert Co., Morris Plains, NJ, USA) led to an undesirable succession of oral pathogens or the emergence of resistant microbial forms. Supragingival plaque was collected from 83 subjects before treatment and after either 3 or 6 months use of either the active antiseptic or a 5% hydroalcohol control. Subjects rinsed with their assigned mouthrinse twice daily under supervision. The plaque samples were analyzed for microbial content by darkfield microscopy, culture on a series of nonselective and selective bacterial media, and by recognition of microbial forms by recognition of distinct colony on a nonselective medium. Statistical analysis of the results revealed no significant microbial shifts including no significant increases in presumptive oral pathogens, spirochetes, black-pigmented Bacteroides, Streptococcus mutans, or Candida albicans. Additionally, no detectable rise in either staphylococci or enteric bacteria, potential opportunistic pathogens, was observed.

Long-term effects of Listerine antiseptic on dental plaque and gingivitis.

Chemotherapeutic mouthrinses are useful adjuncts to normal oral hygiene and regular professional care for patients whose mechanical plaque removal is less than optimal. Recognizing this, the American Dental Association Council on Dental Therapeutics published guidelines for evaluating the safety and efficacy of products for the control of gingivitis. Four 6-month or longer controlled clinical trials have shown Listerine to be significantly effective in helping prevent the development of both supragingival plaque and gingivitis. Two microbiology studies have demonstrated that no resistant microorganisms, opportunistic microorganisms, or presumptive oral pathogens emerge as a result of long-term, daily Listerine use. Listerine is the first nonprescription mouthrinse to receive the Council on Dental Therapeutics Seal of Acceptance as safe and effective in helping to prevent and reduce supragingival plaque accumulation and gingivitis when used in a conscientiously applied program of oral hygiene and regular professional care.

Comparison of the antimicrobial capability of an abrasive paste and chemical-soak denture cleaners.

The objective of this research was to compare the ability of the two most popular methods for denture cleaning to remove plaque microorganisms from dentures. Dentu-Creme abrasive denture paste and Efferdent alkaline peroxide denture-cleanser soak were selected for study. Two trials were completed in which these materials were used alone and in combination along with a no-treatment control to determine the level of recoverable plaque bacteria from removable dentures. Plaque was allowed to accumulate for 48 or 72 hours in individuals with healthy oral mucosa during which time they refrained from all denture hygiene procedures. The results of two studies following similar double-blind cross-over designs were consistent in that soaking with the denture cleanser caused a significantly greater reduction of microorganisms than did brushing with the denture paste. Further, combining brushing with the soak did not reduce the level of recoverable microorganisms significantly more than soaking alone. Overall, brushing alone did not consistently remove more microorganisms than were observed in the no-treatment group. The denture-cleanser soak displayed broad antimicrobial activity against gram-negative anaerobic rods (Fusobacterium sp.), gram-positive facultative cocci (streptococci), and gram-negative anaerobic cocci (Veillonella sp.), as well as total recoverable microorganisms, which were all equally reduced by the denture-cleanser treatment. These results support the need for use of a denture cleanser in addition to brushing with a denture paste for proper denture hygiene.

Regulation of hexitol catabolism in Streptococcus mutans.

Regulation of hexitol catabolism was investigated in Streptococcus mutans, a cariogenic human dental plaque bacterium. Induction of hexitol catabolic enzymes and phosphoenolpyruvate:hexitol phosphotransferase and hexitol phosphate dehydrogenase activities was regulated by an inducer exclusion mechanism initiated by D-glucose and 2-deoxy-D-glucose. Kinetic analysis of the inhibitory effect of 2-deoxy-D-glucose on initial hexitol uptake illustrated that this was a noncompetitive type of inhibition. In mutant strains of S. mutans lacking phosphoenolpyruvate:glucose phosphotransferase activity, 2-deoxy-D-glucose was unable to inhibit hexitol uptake. These observations provide evidence for possible molecular mechanisms for the exclusion process.

Regulation of lactose transport by the phosphoenolpyruvate-sugar phosphotransferase system in membrane vesicles of Escherichia coli.

Regulation of lactose uptake by the phosphoenolpyruvate-sugar phosphotransferase system (PTS) has been demonstrated in membrane vesicles of Escherichia coli strain ML 308-225. Substrates of the phosphotransferase system inhibited D-lactate energized uptake of lactose but did not inhibit uptake of either L-alanine or L-proline. This inhibition was reversed by intravesicular (but not extravesicular) phosphoenolpyruvate. Lactose uptake was also inhibited by enzyme IIIglc preparations that were shocked into the vesicles, and this inhibition was reversed by phosphoenolpyruvate. Intravesicular HPr and enzyme I stimulated methyl alpha-glycoside uptake but did not inhibit or stimulate lactose accumulation. Vesicles maintained at 0 degree C for several days partially lost 1) the ability to take up lactose, 2) the ability to accumulate PTS substrates, and 3) PTS-mediated regulation. Phosphoenolpyruvate addition restored all of these activities. These results support a mechanism in which the relative proportions of phosphorylated and nonphosphorylated forms of a phosphotransferase constituent regulate the activity of the lactose permease.

Phosphoenolpyruvate-dependent sugar phosphotransferase activity in Megasphaera elsdenii.

Megasphaera elsdenii was found to possess an inducible phosphoenolpyruvate:sugar phosphotransferase system for glucose and fructose but not for other hexoses, hexosamines, or hexitols. The complexity of the Megasphaera phosphoenolpyruvate:sugar phosphotransferase system lies intermediate to systems found in photoautotrophic bacteria and enteric bacteria. Megasphaera elsdenii phosphotransferase proteins exhibited enzymatic cross-reactivity with those from Escherichia coli; however, differences were found in substrate specificities and the physical characteristics of the proteins from these organisms. Sugar uptake was reduced in M. elsdenii stationary-phase as compared with log-phase cells and this loss correlated with a reduction in enzyme II function.

Cyclic adenosine 3',5'-monophosphate regulation of the bacteriophage T6/colicin K receptor in Escherichia coli.

Mutant strains of Escherichia coli unable to synthesize cyclic adenosine 3',5'-monophosphate (cAMP) or the cyclic adenosine monophosphate receptor protein (CRP) were more resistant than wild-type cells to infection by bacteriophage T6. This resistance was found to be associated with the decreased production of specific T6 receptor protein (also the colicin K receptor) located in the outer membrane protein fraction of these cells. Transcription of this particular outer membrane protein was regulated by the cAMP-CRP complex. A novel affinity technique coupled with sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used in these investigations.

Glucose-triggered germination of Bacillus megaterium spores.

Triggering of germination in Bacillus megaterium QM B1551 spores with D-glucose was studied. First, the interaction of glucose with spores for less than 1 min resulted in triggering almost 90% of the spores after the glucose was removed by dilution. Therefore only a brief time is needed for glucose to trigger germination, and then the continuous presence of glucose is not necessary. Detectable uptake of glucose began 2 to 3 min after absorbance loss started, and a non-metabolizable glucose analog, methyl-alpha-D-glucopyranoside, triggered germination in the absence of detectable uptake. Several inhibitors that reduced or eliminated glucose uptake did not block triggering of germination. Therefore, glucose uptake may be a relatively late event and not a prerequisite for triggering of germination.

An evaluation of respiration chain-associated functions during initiation of germination of Bacillus megaterium spores.

In Bacillus megaterium QM B1551, spore germination could be initiated by glucose in the absence of detectable oxygen consumption, ATP synthesis or a pH decrease in the external media, suggesting that none of those reactions were mandatory. In addition, initiation of germination was insensitive to a variety of inhibitors of energy production or protonmotive force uncouplers. Therefore the respiratory chain-associated functions are not prerequisites for initiation of germination but these functions may be necessary to drive energy-dependent transport systems and other biosynthetic reactions during outgrowth.