The effects of toothpastes on the residual microbial contamination of toothbrushes.

BACKGROUND: Contaminated toothbrushes have been shown to harbor and transmit viruses and bacteria. The authors conducted a study to evaluate the effect of a triclosan-containing toothpaste on the residual anaerobic microbial contamination of toothbrushes. METHODS: Twenty patients who had Type III or Type IV periodontitis participated in this study. One side of each of their mouths served as a control (no toothpaste). The teeth on the other side were brushed with a regular toothpaste or a triclosan-containing toothpaste. After the toothbrushes were allowed to dry in air for four hours, the authors placed the toothbrush heads in solution, dislodged the microbes from the brushes by vortexing and plated them in culture dishes. The authors anerobically incubated the culture dishes and determined the presence or absence of Prevotella species or Ps; Porphyromonas gingivalis, or Pg; and Actinobacillus actinomycetemcomitans, or Aa. RESULTS: The authors detected Aa and Pg on the control toothbrushes more frequently than they did Ps. This variation in isolation frequency was statistically significant by chi 2 analysis (P < .001). The authors compared the isolation frequency of the three test organisms between the control and regular-toothpaste groups, between the control and triclosan-containing--toothpaste groups, and between the triclosan-containing--toothpaste and regular-toothpaste groups. They found no significant intergroup differences in the isolation frequencies after using chi 2 analysis. CONCLUSIONS: Toothpaste use reduced the residual microbial contamination for two of three test organisms, but the lower isolation frequencies were not statistically significant. Further study in this area is indicated. CLINICAL IMPLICATIONS: Dental professionals should advise patients who have systemic, localized or oral inflammatory diseases to disinfect or frequently replace their toothbrushes.

Performance of composite finishing and polishing instruments after sterilization.

PURPOSE: To evaluate the performance before and after sterilization of Enhance and Min-Identoflex finishing and polishing systems on TPH and Z100 composites. MATERIALS AND METHODS: Finishing and polishing instruments consisted of a light-cured resin cup impregnated with an abrasive and a silicon dioxide impregnated rubber cup. Sterilization methods included microwaving and autoclaving. RESULTS: Performance of the finishing and polishing instruments were affected more by the composite being finished and polished than by autoclaving or microwaving.

Disinfection and sterilization of composite polishing instruments.

PURPOSE: To evaluate the efficacy of several methods of sterilization and disinfection on two different types of composite finishing and polishing instruments. MATERIALS AND METHODS: The instruments consisted of a proprietary light-cured resin cup impregnated with an abrasive and a silicon dioxide-impregnated rubber cup. Chemical and physical methods included treatment with iodophor, synthetic phenol, glutaraldehyde, microwaving, autoclaving, and chemiclaving. RESULTS: Glutaraldehyde (Vital Defense-S) was an effective disinfectant; however, other chemical (cold) disinfectants overall, were not reliable. Autoclaving, chemiclaving, and microwaving all provided to be effective means of sterilization.

The efficacy of antifungal agents incorporated into a facial prosthetic silicone elastomer.

Microbiologic isolation techniques and scanning electron microscopy were used to determine whether a fungus is associated with the black discoloration of some silicone nasal prostheses. Colonies of fungal growth were seen on scanning electron micrographs of the affected areas of a nasal prosthesis, and a fungus belonging to the genus Penicillium was isolated from similar areas. Disk diffusion tests determined that the antifungal agent clotrimazole, when incorporated into silicone samples, was effective in inhibiting in vitro growth of the fungus.

Reduced bactericidal activity in neutrophils from scorbutic animals and the effect of ascorbic acid on these target bacteria in vivo and in vitro.

Actinomycetes, involved in oral and periodontal diseases, cause serious infections in immunocompromised hosts. Severely scorbutic guinea pig leukocytes killed only 12% of phagocytosed actinomycetes, had distorted nuclear morphology, had 16 times less ascorbate, and had no chemotactic responses in vitro. Ascorbate reversed these indices and also prevented nitrosamine formation by oral organisms. Degranulating leukocytes release lactoferrin and ascorbate that chelate iron, essential for microorganisms. Ascorbic acid, 2,2'-bipyridine and 1,10-phenanthroline were bactericidal to several bacterial pathogens at millimolar concentrations. Iron alone reversed this effect. In in vivo experiments an Actinomyces viscosus monoflora was implanted in rhesus monkeys. Plaque and serum samples showed decreased (by six orders of magnitude) bacterial counts and decreased actinomycete antibody titers in animals given 1 g ascorbate/d. Removing ascorbate returned counts and titers to preascorbate concentrations. Fifteen marmosets, receiving twice daily topical applications of ascorbate or water, had comparatively lower gingival, calculus, and plaque indices and only slightly lowered actinomycete counts.

New aniline blue dye medium for rapid identification and isolation of Candida albicans.

Organic dyes have long been used in diagnostic microbiology to differentiate species by color reactions. We studied the ability of a new noninhibitory medium, YM agar containing 0.01% aniline blue WS dye, Colour Index 42780 (YMAB), to identify Candida albicans among 1,554 yeast specimens obtained from seven clinical laboratories. Appropriate American Type Culture Collection and other characterized strains served as controls. A total of 487 of the clinical strains were identified as C. albicans. The remainder were other Candida species and non-Candida yeasts. Clinical isolates and controls were grown on Sabouraud agar for 18 h at 30 degrees C and then transferred to YMAB. Plates were incubated for 12 to 18 h at 30 degrees C, and colonies were observed for yellow-green fluorescence under long-wave UV light (A365). All control strains of C. albicans and Candida stellatoidea fluoresced, as did 480 of the 490 isolates designated as C. albicans (which included 3 strains of C. stellatoidea). Cells of C. albicans grown on YMAB produced germ tubes in serum. Only five of the other 1,062 non-C. albicans yeasts fluoresced. The sensitivity and specificity were 98.0 and 99.5%, respectively, with a predictive value of 99.1%. A fluorescent metabolite was found in cell wall particulate fractions of C. albicans sonic extracts grown on YMAB but not in non-C. albicans yeasts. This metabolite showed the same spectral curve as those of metabolites from whole cells in a recording spectrofluorometer when it was excited at 400 nm and scanned from 420 to 550 nm. Thus, growth on YMAB generates the production of a fluorescent moiety that can be used to specifically identify C. albicans within 12 to 18 h.

The effect of ascorbic acid deficiency on leukocyte phagocytosis and killing of actinomyces viscosus.

The ascorbic acid content of guinea pig leukocytes is reduced by a factor of 16:1 between normal and scorbutic guinea pigs. Ascorbic acid deficiencies do not appear to affect phagocytic activity but do change leukocyte morphology. A deficiency of this vitamin appears to significantly interfere with the in vitro bactericidal effectiveness of circulating leukocytes against ingested, cell-associated, and extracellular bacterial cells of the oral pathogen, Actinomyces viscosus. Leukocytes from scorbutic guinea pigs killed 13% of ingested and cell-associated Actinomyces viscosus compared to 83% killed by normal leukocytes by both acridine orange staining and viable count. Degranulation resulted in extracellular killing in normal but not scorbutic leukocytes. This decreased bactericidal activity can be reversed by adding supplements of the vitamin to the diet of scorbutic animals. Chemotactic responses were much lower in vivo and absent in vitro in scorbutic leukocytes. The acridine orange staining technique is an excellent indicator of leukocyte health. This study supports the important role for ascorbic acid in leukocyte function and also discusses its probable protective and bactericidal activities related to oral pathogens.

Selecting a Miniaturized System for Identification of Enterobacteriaceae.

The most commonly used commercial diagnostic kits for identification of Enterobacteriaceae are API, Enteric-Tek, Enterotube II, Micro-ID, Minitek and Spectrum-10. The accuracy of identification by all systems does not vary significantly, and falls within the acceptable range. Therefore, a bacteriologist who is considering the use of these products should evaluate factors other than accuracy when making a choice. Twenty-three professional microbiologists who had previous experience with these systems listed advantages and disadvantages of each system, and evaluated the conventional procedure for identification. The comments were summarized and presented in tabular form. The current cost per isolate of each system and the cost of the identification manual, reagents and incidental costs were also determined. These data provide the potential user with comparative information on price, shelf-life, versatility, time required for inoculation, incubation and manipulation after incubation, possible difficulties in determining positive and negative reactions, and potential safety factors for laboratory personnel.

Calcifiability comparison among selected microorganisms.

Seven ATCC strains of bacteria were examined for apatite formation in a chemically-defined calcification-supporting medium and also in a metastable calcium phosphate solution. One, E. coli, calcified in both. One, S. aureus, calcified in the solution, but not in the medium. The other five did not calcify in either. The results substantiate the belief that calcification is restricted to certain microorganisms. However, they do not rule out the possibility that a noncalcifiable microorganism has the potential to calcify, and the activity is prevented by a cell component. Additionally, the findings emphasize that determining microbiologic calcifiability only in a calcification-supporting culture medium is inadequate. In culture, an efficient calcium pump might preclude calcification by establishing a cytoplasmic calcium level too low for nucleation activation. Calcifiability assays should be done by incubating minimally-metabolizing freeze-dried cells in metastable calcium phosphate solution.

Enteropathogenic Escherichia coli: lack of correlation of serotype with pathogenicity.

Forty-eight strains of Escherichia coli isolated from children with diarrhea were classified according to nine enteropathogenic serotypes. The strains were examined for production of enterotoxin and for invasiveness by study of bacteria or bacteria-free filtrates in conventional animal and tissue culture models. Filtrates of only three strains (6%) consistently dilated rabbit ileal loops, while all 48 strains yielded negative results in suckling mice, adrenal cells, and guinea pig eyes. When filtrates of the three strains that dilated the rabbit ileum were heated at 60 C for 30 min, the reaction in rabbit ileal loops was negative; this finding indicated the production of a heat-labile enterotoxin. This study shows the lack of correlation between classical enteropathogenic serotypes of E. coli and presently known virulence properties in animal models. The results raise doubts about the value of serotyping E. coli isolates from sporadic cases of diarrhea. When it is suspected that an E. coli isolate is enteropathogenic, it may be important to perform more than one laboratory assay.

Antimicrobial susceptibilities of shigellae isolated in Houston, Texas, in 1974.

One hundred seventy-three strains of shigellae (113 Shigella sonnei, 56 S. flexneri, and four others) isolated in Houston during 1974 were tested for susceptibility to commonly used and newer antimicrobial agents. Forty-five percent of S. sonnei strains were susceptible to ampicillin, whereas 93% of S. flexneri strains were susceptible to that agent. S. sonnei and S. flexneri strains were equally susceptible to tetracycline (35 and 33%, respectively). All 173 strains were uniformly susceptible to quinoline drugs (cinoxacin, oxolinic acid, and nalidixic acid) and to trimethoprim-sulfamethoxazole. This study supports recent suggestions that the initial therapy of bacillary dysentery no longer should be ampicillin or tetracycline. It remains for field testing to determine whether quinoline agents or trimethoprim-sulfamethoxazole will be the treatment of choice.

Determination of bacterial cell concentrations by electrical measurements.

An instrument was developed to measure the concentration of bacterial suspensions by their electrical characteristics. It employed a square-wave signal generator, a tetra-polar electrode probe, and a voltage detector in the form of an oscilloscope. When electrical measurements were made on washed bacteria obtained from cultures or urine specimens, there was a direct relationship between the concentration of the cells and the electrical characteristics of the system as reflected by voltage changes. As little as 10(3) organisms per ml could be detected. The resolution between readings taken on samples containing 10(3) to 10(9) cells per ml was found to be a function of the input frequency. The maximal resolution between concentration readings was obtained at a input frequency of 10 Hz. Thus, with relatively simple instrumentation, bacterial concentrations could be determined within a few minutes. This technique, therefore, eliminates the more lengthy laboratory procedures as plate counts or the accumulation of measurable metabolic changes (such as the utilization of radioactive or other substrates). This method can efficiently monitor clinical urine specimens when a bacteriuria is suspected.

Effect of chemotherapeutic agents upon microorganisms isolated from cancer patients.

Attempting to explain the predominance of Pseudomonas in leukemic patients, five of the most common gram-negative organisms isolated from sites of infection in cancer patients were exposed to several of the chemotherapeutic agents used in the treatment of this disease (methotrexate, cytosine arabinoside, cyclophosphamide, and 6-mercaptopurine). At concentrations of 125 mug/ml or higher, methotrexate inhibited all organisms except Pseudomonas. Cytosine arabinoside inhibited Escherichia and Klebsiella but appeared to stimulate the growth of Pseudomonas slightly at the higher concentrations. Thus, significant differences existed in individual susceptibilities to these agents. Clinical isolates were more resistant than the corresponding laboratory strains not previously exposed to these compounds. The resistance of Escherichia coli to cyclophosphamide was decreased 26% when it was grown in mixed culture with Pseudomonas. Only Pseudomonas was resistant to all of these compounds whether in pure or mixed culture. These observations may help to explain, in part, the predominant role that Pseudomonas plays as an infectious agent in leukemic patients.

Rapid methods for determining decarboxylase activity: ornithine and lysine decarboxylases.

A rapid biochemical method for the determination of ornithine and lysine decarboxylase (EC 4.1.1.18) activity has been developed for use in the routine clinical laboratory. It is based on the detection of the amine end product produced in response to the single key amino acid added to a synthetic medium. A modified ninhydrin reagent is used to detect the amine after a chloroform extraction. This procedure can be used with a 1- to 4-hr incubation period (utilizing an initial concentrated inoculum) or with an overnight culture. Thus, measurements based on the alkalinization of the medium after a lengthy incubation period are avoided. Optimal parameters for enzyme activity are discussed.

Rapid methods for determining decarboxylase activity: arginine decarboxylase.

A rapid biochemical method for the determination of arginine decarboxylase (EC 4.1.1.19) activity has been developed for use in the routine clinical microbiology laboratory and correlated with similar procedures for ornithine and lysine decarboxylase (EC 4.1.1.18) systems. It is based on the detection of agmatine, the amine end product formed during growth on a synthetic medium containing arginine as the key amino acid. A modified diacetyl reagent is used to detect this amine after a differential butanol extraction of the cultures. This procedure can be used to detect this amine after a 1- to 4-hr incubation period (with the use of an initial concentrated inoculum) or with an overnight culture. Thus, both an indirect measurement based on the alkalinization of the medium and a lengthy incubation period were avoided. Parameters for optimal enzyme activity and the pertinent enzyme systems involved in arginine and agmatine catabolism are discussed in detail.

Thiamine-induced formation of the monopyrrole moiety of prodigiosin.

Thiamine stimulates the production of a red pigment, which is chromatographically and spectrophotometrically identical to prodigiosin, by growing cultures of Serratia marcescens mutant 9-3-3. This mutant is blocked in the formation of 2-methyl-3-amylpyrrole (MAP), the monopyrrole moiety of prodigiosin, but accumulates 4-methoxy-2,2,'-bipyrrole-5-carboxaldehyde (MBC) and can couple this compound with MAP to form prodigiosin. Addition of thiamine caused production of MAP, and as little as 0.02 mg of thiamine per ml in a peptone-glycerol medium stimulated production of measurable amounts of prodigiosin. Phosphate salts and another type of peptone decreased the thiamine-induced formation of prodigiosin; yeast extract and glycerol enhanced the formation of this substance. Thiamine also enhanced production of prodigiosin by wild-type strain Nima of S. marcescens. The thiamine antagonists, oxythiamine and pyrithiamine, inhibited thiamine-induced production of MAP and of prodigiosin by the mutant strain 9-3-3, formation of prodigiosin by the wild-type strain Nima, and production of MAP by another mutant, strain WF. The pyrimidine moiety of thiamine was only 10% as effective as the vitamin; the thiazole moiety, only 4%; and the two moieties together, 25%. Various other vitamins tested did not stimulate formation of prodigiosin by strain 9-3-3. Thiamine did not stimulate production of prodigiosin by a single-step mutant that showed the same phenotypic block in prodigiosin biosynthesis as strain 9-3-3. This is not surprising since strain 9-3-3 originated as a result of two mutational events. One event may involve thiamine directly, and the other may involve the biosynthesis of MAP. Thiamine is probably involved in the regulation of the biosynthesis of MAP, because the vitamin or inhibitory antagonists must be added during the early phases of growth in order to be effective.