Biomedical subjects
Publications and source records attributed to M G Newman.
A better understanding of the etiology and pathogenesis of periodontal diseases provides clinicians and researchers with a number of new diagnostic techniques and treatment alternatives. These new developments may also offer the clinician additional information for treatment planning.
In the early 1950s the randomized control trial (RCT) was introduced and became widely accepted as the definitive proof of efficacy of a specific medical treatment. In fact, the acceptance and application of this methodology were instrumental in converting medicine from an unpredictable art to a science. At present no other methodologies exist that allow the evaluation of therapeutic efficacy with confidence comparable to that achieved with randomized controlled trials. In recent years researchers have applied new experimental designs and data analysis techniques to clinical trials conducted in a field trial environment to facilitate the understanding of proper use of new therapeutic agents and procedures. Since many of the new methodologies are still evolving or have only recently been introduced, this review considers some of the major trends and developments, as well as experiences of the authors, in field trial methodology. This manuscript addresses the following questions: 1) are there current clinical trial needs that are not met by RCT? 2) If so, what considerations are necessary for new approaches to have scientific usefulness? and 3) What are the strengths and weaknesses of the field trial's setting relative to an institutional environment?
The purpose of the study was to validate the Epsilometer test (E-test) method for antimicrobial susceptibility testing of selected periodontopathic microorganisms using the agar dilution method as a standard. The E-test has been developed to provide a direct quantification of antimicrobial susceptibility of microorganisms. The device consists of a predefined, continuous, and exponential gradient of antibiotic concentrations immobilized along a rectangular plastic test strip. After 48 hours incubation a drop-shaped inhibition zone intersects the graded test strip at the inhibitory concentration (IC) of the antibiotic. Twenty-two subgingival plaque samples from periodontitis sites were plated on trypticase soy agar supplemented with 5% rabbit blood or 5% sheep blood and trypticase soy agar supplemented with vancomycin and bacitracin. A total of 60 strains of key periodontal pathogens (Prevotella intermedia, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Eikenella corrodens, Campylobacter rectus, and Capnocytophaga) isolated from 22 sites of 12 patients were studied. The antibiotics tested were clindamycin, metronidazole, tetracycline, ciprofloxacin, cefoxitin, and ampicillin at concentrations above and below the achieved blood or gingival crevicular fluid levels. As a standard reference the minimal inhibitory concentrations (MICs) were determined using the agar dilution method. MICs were compared with ICs determined using the E-test method. The results showed an agreement ranging from 67% to 100%; sensitivity ranging from 75% to 100%; predictability ranging from 56% to 100% and specificity ranging from 33% to 96%. The E-test ICs for ampicillin, cefoxitin, and metronidazole against the Gram-negative capnophilic and microaerophilic rods and the black-pigmented anaerobic rods ICs for ampicillin, clindamycin, metronidazole, and tetracycline showed a high percentage of agreement with the agar dilution MICS.(ABSTRACT TRUNCATED AT 250 WORDS)
Working independently, three laboratories had recognized considerable similarity among certain strains of dysgonic, fermentative, capnophilic, surface translocating, gram-negative bacilli referred to as Capnocytophaga, Bacteroides ochraceus, and Center for Disease Control biogroup DF-1. To determine the relationship among these groups, 21 strains were exchanged and independently characterized by the three laboratories. Additionally, a fourth laboratory examined the deoxyribonucleic acid homologies of the same strains. Using methods common to dental microbiology, eight of the strains had been isolated from the gingival sulcus and periodontal lesions and identified as Capnocytophaga. Three strains isolated from blood and transtracheal aspirate had been characterized by conventional anaerobic methods and recorded as B. ochraceus. Ten strains isolated from sputum, blood, throat, spinal fluid, and tracheal aspirate had been identified as DF-1 with the methods of E. O. King and a buffered single-substrate technique. All strains were similar in respect to colonial and microscopic morphology, surface translocation, biochemical features, gas-liquid chromatograms of metabolic end products, and deoxyribonucleic acid composition. We conclude that these biogroups should be termed Capnocytophaga species.
A simplified method for processing dental plaque samples was devised and compared to previously used methods. Analysis of 36 nonstandardized subgingival plaque samples from various states of periodontal health and disease and 12 standardized supragingival plaque samples demonstrated that there was no significant difference between the recovery offered by the two techniques. Comparable recovery, increased convenience, and adaptation to the clinical setting suggests that implementation of this simplified technique may be of great value.
Selected anaerobic, capnophilic and facultative bacteria isolated from patients with various forms of periodontal health and disease were tested for their susceptibility to antibiotics and antimicrobial agents. Specific bactericidal and minimum inhibitory concentrations were compared to disc zone diameters, thereby generating new standards for the potential selection of antimicrobial agents.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Recent taxonomic and anatomical studies of dental plaque associated with periodontal health and disease have demonstrated that differences in the microbial populations in plaque may be responsible for the initiation and progression of disease. The consistent isolation of large numbers of anaerobic and capnophilic bacteria from the depths of periodontal lesions has suggested an important role for these organisms. Bacteria that have been isolated include Capnocytophaga (Bacteroides ochraceus), other species of Bacteroides, Fusobacterium, Selenomonas, spirochetes, Campylobacter, Veillonella, Actinomyces, Propionibacterium, Peptococcus, and other genera. The periodontopathic potential of oral strains of Bacteroides melaninogenicus has been explored in a number of investigations because these organisms are consistently isolated from periodontal lesions. Studies of B. melaninogenicus have included purification of a capsular substance, characterization of the lipopolysaccharide and a variety of toxic substances and lytic enzymes, and ecologic aspects of its colonization. Understanding of the nature and pathogenic mechanisms of the oral microbiota may lead to control of this pandemic infection.