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C B Walker

Publications and source records attributed to C B Walker.

At least 37 records · Page 2Linked to original sources
PubMed1992

Phenotypic characteristics and DNA relatedness in Prevotella intermedia and similar organisms.

We have recently isolated from the gingival pockets, periapical lesions and saliva some anaerobic gram-negative, black-pigmented rods. Many of these isolates exhibited phenotypic characteristics similar to Prevotella intermedia (Bacteroides intermedius). However, several of these isolates, although resembling P. intermedia in most of the phenotypic expressions, were capable of fermenting lactose, a biochemical characteristic atypical of P. intermedia. These atypical clinical isolates (strains capable of fermenting lactose) and isolates exhibiting more typical phenotypic characteristics (i.e., lactose nonfermenting) were definitively identified as P. intermedia by DNA-DNA hybridization using a photoprobe biotin method. Quantitative hybridization of clinical isolates with labeled DNA of P. intermedia-type strains (ATCC 25611 and ATCC 33563) showed that almost all the clinical strains isolated from disease sites of adults belonged to the ATCC 25611 group, whereas strains isolated from the saliva of children belonged to the ATCC 33563 group. These data, together with the phenotypic characterization of the isolates, suggested that P. intermedia is a heterogeneous species both phenotypically and genetically.

Bacteroides↗
PubMed1992

The effect of 3 mouthrinses on plaque and gingivitis development.

The aim of this study was to evaluate the effect of 3 mouthrinses, Listerine Antiseptic (thymol), Peridex (chlorhexidine), Perimed (povidone iodine and hydrogen peroxide), and a placebo (water) on the development of dental plaque and gingivitis, when used as the only oral hygiene procedure for 14 days. 71 subjects were entered into a randomized, double-blind study. At the baseline examination, papillary bleeding score (PBS), and plaque index (PI) were registered, after which subjects received supragingival prophylaxis and were assigned to 1 of 4 study cells. Subjects were asked to refrain from all oral hygiene procedures except for the supervised 14-day 2 x daily rinsing with the assigned preparation. At day 14, the same clinical parameters were again registered. Statistical analysis was performed by a one-way analysis of variance (ANOVA) to compare the 4 groups, followed by Duncan's multiple range test to determine specific group differences. At baseline, average PBS and PI scores were similar for all 4 groups. After 14 days, the average PBS for Peridex and Perimed was significantly lower than for Listerine Antiseptic and water. The frequency of interdental units with a PBS greater than 2 was significantly lower for Peridex and Perimed than for Listerine Antiseptic and water. We concluded that both Peridex and Perimed were effective in reducing plaque and gingivitis when used as a 2 x daily mouthrinse by subjects refraining from other oral hygiene procedures. In vitro, a synergistic effect was assumed when inhibition was achieved with Perimed at the same or greater dilution than was achieved with povidone-iodine alone.

Actinomyces viscosus↗
PubMed1992

Identification of a streptomycin resistance gene and a partial Tn3 transposon coding for a beta-lactamase in a periodontal strain of Eikenella corrodens.

The beta-lactamase gene from a periodontal strain of Eikenella corrodens, resistant to penicillins and streptomycin, was inserted into pBGS9 and transformed into Escherichia coli DH5 alpha. A 4.7-kb insert of pJML1, one of the transformants, was partially sequenced and found to contain the right section of transposon Tn3 from the middle of the TnpR resolvase gene to the right inverted repeat RI(R), including the TEM-1 gene. Sequences identical to RSF1010 were found on either side of the Tn3 sequence. pJML1 also contained a streptomycin resistance gene, probably identical to that of RSF1010. A portion of the pJML1 insert was not homologous to either Tn3 or RSF1010 but was homologous to the chromosomal DNA of E. corrodens ATCC 23834. It is assumed that the insert of pJML1 was derived from the chromosomal DNA of E. corrodens EC-38.

DNA Transposable Elements↗
PubMed1991

Clinical, microbiological and immunological characteristics of subjects with "refractory" periodontal disease.

The aim of the present study was to analyze the relationship between attachment loss and clinical, microbiological, and immunological parameters in a group of 21 human subjects exhibiting poor response to previous periodontal therapy. All had been treated with periodontal surgery, tetracycline, and subsequent maintenance recalls to periodontists who, upon detection of disease progression, referred the subjects to our clinic. In our clinic, each subject received oral hygiene instruction and a thorough subgingival scaling and root planing utilizing as many appointments as necessary. Clinical indices, including gingival index, bleeding on probing, suppuration, plaque index, pocket depth, and duplicate measurements of attachment level from an acrylic stent, were collected at monthly intervals. Probing measurements were performed using the Florida Probe. When significant attachment loss (0.8-1.2 mm) was detected in at least 1 site, a bacterial sample was taken from that site and from a comparably deep, but non-progressing, control site. Microbial samples were enumerated by darkfield microscopy, on selective and non-selective media, and by predominant cultivable technique. Blood samples were also collected to determine antibody levels against potential pathogens. There was no difference in the amount of plaque present in sites gaining or losing attachment, but losing sites exhibited more bleeding and suppuration. 20 of the 21 subjects were tested; of these, 17 exhibited elevated serum antibody against one or more of the following microorganisms: Actinobacillus actinomycetemcomitans, Bacteroides, gingivalis, and Eikenella corrodens. However, few, if any, of the "classical" pathogens were detected in the plaque samples obtained at the time progressive disease was diagnosed. The only exception was Streptococcus intermedius, which occurred in slightly higher numbers in active sites.

Actinobacillus↗
PubMed1990

Localization and identification of root canal bacteria in clinically asymptomatic periapical pathosis.

Twenty-one teeth with clinically asymptomatic periapical pathosis (class 3) were extracted and the isolation, identification, and localization of bacteria in the root apex were examined. Mixtures involving several bacteria were isolated from more than 60% of the cases. Scanning electron microscopy revealed bacterial masses to be associated with the apical part of the root canal, but not with the area of apical foramen or on the surface of root apex. Our results indicate that the bacteria in class 3 cases may be derived from organisms which colonized before or during endodontic treatment, but not from anachoresis. The bacteria-positive cases of asymptomatic periapical pathosis have the potential to progress to symptomatic periapical pathosis.

Actinomyces↗
PubMed1989

Surface appendages, hemagglutination, and adherence to human epithelial cells of Bacteroides intermedius.

Four types of morphologically distinct surface appendages were found on oral strains of Bacteroides intermedius. These appendages, designated as A, B, C, and D, were different in size, with diameters of 1-2 nm, 12 nm, 8 nm, and 5 nm, respectively. Twenty different strains were examined by electron microscopy and 5 strains, 5, 17, 27, 113, and 25611, were selected to be representative of the different appendages encountered. Type A appendages were thin filaments peritrichously arranged on the cell surface and were associated mainly with Strains 5, 113, and ATCC 25611. Type B appendages were present on all 5 strains but these structures were scarce (i.e., less than or equal to 3 per organism). Type C appendages were associated exclusively with Strain 17. Type D appendages were present mainly on Strain 27. Hemagglutination activity of these organisms and their ability to adhere to human buccal epithelial cells were also tested. Strain 17, which possessed Type C appendage (uncommon to the other strains), agglutinated strongly with 5 different species of erythrocytes and adhered avidly to human buccal epithelial cells. The other strains, possessing different types of appendages, showed considerable variation in hemagglutination activity and adherence properties. Correlation between these surface appendages and adherent functions was speculated.

Animals↗
PubMed1989

Efficacy of Perimed antibacterial system on established gingivitis. (I). Clinical results.

A 6-month, double-blind controlled study was conducted on 101 subjects to determine the effect of Perimed antibacterial system, containing povidone-iodine (PVP-I) and hydrogen peroxide (H2O2), on established gingivitis. Subjects were randomly assigned to one of 4 treatment groups: PVP-I/H2O2, PVP-I/H2O, H2O2/H2O or H2O. Gingivitis was assessed by the papillary bleeding score (PBS) and plaque by a modified Quigley-Hein plaque index (PI) at baseline, 3, 12 and 24 weeks. The average baseline PBS and PI for the 4 groups ranged from 2.16-2.31 and 2.87-2.90, respectively. After baseline evaluation, subjects received a supra-gingival scaling and a subgingival irrigation with their respective rinse. Daily rinses were supervised and subgingival irrigation was repeated every 3 weeks. Duncan's multiple range test determined which groups differed from each other. The mean PI at 24 weeks was lower than at baseline in all groups. PVP-I had the lowest PI at all time points. The mean PBS at 24 weeks was 1.48 for PVP-I, 1.62 for H2O2, 1.88 for H2O and 1.34 for PVP-I/H2O2, a reduction from baseline of 31%, 27%, 18%, and 38% respectively. The difference between the PBS for PVP-I/H2O2 and H2O control was significant at each evaluation. There was a 70% reduction in sites with PBS greater than or equal to 3 for PVP-I/H2O2 between baseline and 24 weeks compared to a 34% decrease in the H2O group. It was concluded that the use of Perimed could be a beneficial adjunctive treatment for the prevention and control of gingivitis when used with routine oral hygiene procedures.

Adolescent↗
PubMed1989

Effect of non-surgical periodontal therapy combined with adjunctive antibiotics in subjects with "refractory" periodontal disease. (I). Clinical results.

The aim of the present study was to evaluate the clinical effect of non-surgical periodontal therapy with the adjunct of a selected antibiotic in subjects with refractory periodontitis. 10 subjects were selected for the study; all had a history of periodontal surgery, tetracycline therapy, and regular maintenance by a periodontist. Clinical registrations including gingival index, plaque index, presence of bleeding and suppuration, pocket depth, and duplicate measurements of attachment level were performed at baseline and at monthly intervals. When disease activity was detected based on the tolerance method, a bacterial sample was taken from the active site and its susceptibilities to a number of antibiotics were determined. For the selected 10 subjects, Augmentin was the antibiotic of choice. Each subject received 750 mg/day for 2 weeks, during which time a full-month scaling and root planing was performed under local anesthesia. Clinical re-evaluation was performed after 3, 6, 9 and 12 months. At the time disease activity was detected, the average loss of attachment at all active sites was 2.2 mm, and the increase in pocket depth 1.5 mm. At 3 months post-therapy, these sites had regained 2 mm of attachment which remained stable through the 12-month examination. Pocket depths decreased 2.5 mm over the first 6 months and then stabilized. The frequency of all sites that gained 1 mm or more of attachment increased by approximately 10% over the first 9 months following therapy. The frequency of all sites that decreased 1 mm or more in pocket depth increased approximately 15% over the same period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Microbiological effects of mouthrinses containing antimicrobials.

A number of mouthrinse formulations containing antimicrobials have been evaluated to determine their effectiveness as antiplaque and/or antigingivitis agents. These have included the bis-biguanides, phenols, quaternary ammonium compounds, oxygenating compounds, plant extracts, fluorides, antibiotics and antimicrobial combinations. These mouthrinses have often been tested as adjuncts to normal oral hygiene procedures as well as in the experimental gingivitis model. 2 agents in particularly, chlorhexidine gluconate and listerine, have been shown to both inhibit or reduce plaque accumulation and the severity of gingivitis. Chlorhexidine has been reported to reduce the accumulation of plaque by approximately 60% and the severity of gingivitis by 50-80% as determined by improvements in clinical indices. A 0.12% chlorhexidine gluconate rinse resulted in significant reductions after both 3 and 6 months use in the numbers of total anaerobes, total aerobes, streptococci, and actinomyces recovered from supragingival plaque. Listerine has been reported to retard the development of plaque by 45 to 56% and to reduce existing plaque by 39 to 48%. Gingivitis scores were reduced as much as 59%. Microbial studies have shown that the effect of listerine is exerted against the total microbial mass and results in an overall decrease in both the biomass and the activity. Long-term use of neither mouthrinse, chlorhexidine or listerine, resulted in the emergence of opportunistic or oral pathogens. Preliminary data obtained following the use of a novel mouthrinse consisting of a combination of povidone-iodine and hydrogen peroxide appears promising. This combination was more effective than was more effective than either single component alone in reducing gingivitis scores.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Infective Agents, Local↗
PubMed1986

Incidence of conjunctival colonization by bacteria capable of causing postoperative endophthalmitis.

Increased awareness of the range of pathogens capable of causing postoperative endophthalmitis prompted a study of the conjunctival flora in 100 patients admitted for intraocular surgery. Bacteria capable of causing endophthalmitis were present in 74% of these patients, a much higher proportion than previously documented. No correlation was found with blockage of the nasolacrimal duct.

Adult↗
PubMed1985

Antibiotic susceptibilities of periodontal bacteria. In vitro susceptibilities to eight antimicrobial agents.

In vitro susceptibilities of 369 to 966 bacterial isolates from periodontal lesions to eight antibiotics were determined by agar dilution technique as a means of determining which antimicrobial agents were inhibitory for bacteria frequently associated with destructive periodontal diseases. Although most bacteria were relatively susceptible to the penicillins, greater activity was generally noted with amoxicillin than with either penicillin or ampicillin with the exception of Selenomonas sputigena and Peptostreptococcus. Antibacterial activities obtained with minocycline were significantly higher than with tetracycline for Actinobacillus actinomycetemcomitans and Streptococcus but comparable for most other taxa. Clindamycin and metronidazole both demonstrated excellent activity against the anaerobic Gram-negative rods but were less effective against some of the capnophilic and facultative organisms. Eikenella corrodens was exceptionally resistant to both of these drugs; and A. actinomycetemcomitans was generally resistant to clindamycin but relatively susceptible to metronidazole. Erythromycin was considerably less active than the other antibiotics against the majority of the periodontal bacteria. No single antibiotic, at concentrations equivalent to those achieved in body fluids, was uniformly effective in inhibiting all bacteria currently implicated or suspected as etiologic agents of periodontal diseases.

Actinobacillus↗
PubMed1983

Antibiotic susceptibility testing of subgingival plaque samples.

The in vitro inhibitory effect of several antimicrobial agents was determined against dispensed dental plaque samples taken from periodontally diseased sites as an aid in the selection of antibiotics for adjunctive use in periodontal therapy. 2 groups of patients were sampled. 1 group of 10 patients with severely advanced disease had received periodontal treatment which included the frequent adjunctive use of an antibiotic. The second group consisted of 15 individuals with less severe periodontal disease; only 4 individuals had been previously treated with antibiotics for their periodontal disease. Bacterial samples of subgingival plaque were taken from each patient and tested against a battery of antibiotics to determine which agent was the most effective in suppressing bacterial growth. Each antibiotic was incorporated into Trypticase-soy blood agar at a concentration equivalent to that achieved in either gingival fluid or blood following recommended oral dosages. The inhibitory effect was determined by comparing the number of bacterial recovered on the antibiotic-containing medium to the total number of bacteria recovered on the basal medium. Penicillins, with the exception of cloxacillin, were the most effective in inhibiting bacterial growth. Benzylpenicillin consistently inhibited the growth of 90% of the isolates recovered on media free of antibiotics while ampicillin and amoxicillin frequently inhibited 99% or more of the bacteria recovered. Tetracycline was generally inhibitory for at least 90% of the isolates if the patients had not been previously treated with this agent. However, resistance to this drug was common in samples taken from patients previously treated with tetracycline. Doxycycline, a tetracycline derivative, did not inhibit significantly more isolates than tetracycline. Clindamycin was inhibitory for 90% or more of the organisms in most of the samples; and, was usually effective in inhibiting isolates in samples which exhibited large numbers of isolates resistant to tetracycline. Erythromycin was relatively ineffective against the isolates recovered from samples from the severely diseased group but was inhibitory to isolates in some samples taken from the more moderately diseased group. Metronidazole, at the concentration tested, was largely ineffective against the isolates in bacterial samples from both groups. No single antimicrobial agent was found to be inhibitory for greater than 90% of the bacteria recovered from all of the subgingival plaque samples with the possible exception of some penicillins.

Adolescent↗
PubMed1982

An approach to the definition of periodontal disease syndromes by cluster analysis.

Clinical syndromes of 22 untreated patients with advanced destructive periodontal disease were analyzed using cluster analysis. Clinical characteristics coded for each patient included age, sex, measures of gingival inflammation, plaque, suppuration, pocket depth, attachment level, extent and pattern of bone loss, rate of change in pocket depth, and correlation coefficients between certain clinical measurements. Microbiologic features included darkfield enumeration of 10 morphologically distinct forms of organisms which were removed from the three sites showing the most advanced destruction in each patient, as well as viable counts of specific microbial groups from the same teeth using elective and selective media. Serum antibody levels were determined by the ELISA technique to 13 species of subgingival microorganisms. The Gower coefficient was used to estimate similarity between patients and clusters were formed using an average unweighted linkage sort. Three distinct patient clusters were observed with greater than 70% average intra-cluster similarity. One subject did not fall into any of the patient clusters. The features which defined and differentiated the clusters were found to include age of subject, extent and patterns of bone loss, percent of sites showing change in pocket depth and attachment level, percent of small motile rods, intermediate spirochetes and fusiforms and serum IgG levels against Bacteroides gingivalis, Selenomonas sputigena and a Wolinella strain.

Adolescent↗
PubMed1981

Concentration of tetracycline in human gingival fluid after single doses.

The concentration of tetracycline in gingival fluid was measured following the oral administration of single doses of 250 or 500 mg. Six volunteers received a single dose of either 250 mg or 500 mg of tetracycline and gingival fluid was sampled at 15-min intervals during the first 2 h, 30-min intervals for the following 2 h and at hours 5, 6 and 7. Four volunteers were given a single dose of either 250 mg or 500 mg and were sampled every hour for 24 h. Gingival fluid was sampled using an intracrevicular technique from four gingival sites and blood was obtained by finger puncture. The concentration of tetracycline in gingival fluid peaked at 3 1/2-7 h achieving average levels typically in the range of 5-12 micrograms/ml. Blood levels peaked at 3-4 h and reached values between 1.0 to 2.6 micrograms/ml. Tetracycline was detectable in gingival fluid at least 19 h after a single dose but rarely was detectable at 24 h. The results demonstrated that tetracycline in the gingival fluid was typically 2-10 times blood levels after a single dose.

Gingival Crevicular Fluid↗
PubMed1981

Gingival crevicular fluid levels of clindamycin compared with its minimal inhibitory concentrations for periodontal bacteria.

Clindamycin concentrations in gingival crevicular fluid and in blood were determined over a 7-h period and were related to the minimal inhibitory concentrations of this agent for 340 bacterial strains isolated from diseased periodontal sites. The clindamycin levels after administration of single 300-mg oral doses were measured in gingival crevicular fluids by using an agar diffusion bioassay. Minimal inhibitory concentrations were determined by agar dilution techniques for 30 species of periodontal bacteria. With the exception of Eikenella corrodens and Actinobacillus actinomycetemcomitans, most of the bacteria were inhibited by a concentration of 1.0 microgram of clindamycin per ml or less. The peak concentrations in crevicular fluid (2.0 +/- 0.3 microgram/ml) and in blood (1.9 +/- 0.3 micrograms/ml) were approximately the same. However, crevicular fluid levels of 1.0 micrograms/ml and above were present for up to 6 h, whereas blood concentrations dropped below 1.0 micrograms/ml within 2 h after administration. Based on its minimal inhibitory concentrations, clindamycin at crevicular fluid levels of 1.0 micrograms/ml or above should inhibit most bacteria associated with diseased periodontal sites.

Bacteria↗
PubMed1981

Tetracycline: levels achievable in gingival crevice fluid and in vitro effect on subgingival organisms. Part I. Concentrations in crevicular fluid after repeated doses.

The concentration of tetracycline in gingival crevice fluid and blood was determined using a sensitive bioassay after oral administration of repeated doses of tetracycline. Crevicular fluid was sampled by an intracrevicular technique from four gingival sites in each individual and blood was obtained by finger puncture. Four volunteers received doses of 250 mg of tetracycline-HCl either every 6 hours or every 12 hours and were sampled at hours 0 to 15, 21 to 36, 48 to 60 and 96 to 102. Volunteers given 250 mg every 6 hours had average crevicular fluid concentrations between 4 to 8 micrograms/ml and blood concentrations between 2 to 2.5 micrograms/ml after 48 hours. The levels in crevicular fluid and blood of volunteers who received 250 mg every 12 hours were 2 to 4 micrograms/ml and 0.3 to 1.4 micrograms/ml respectively after 48 hours. The results demonstrated that after repeated doses of tetracycline the crevicular fluid levels were typically 2 to 4 times the blood levels.

Administration, Oral↗