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Biomedical subjects

S A Syed

Publications and source records attributed to S A Syed.

At least 73 records · Page 4Linked to original sources
PubMed1982

Plasmid content of some oral microorganisms isolated from subgingival plaque.

Eighty-five strains of bacterial species selected from the predominant cultivable dental plaque flora of patients with different periodontal pathologies were examined for their plasmid content. Microorganisms studied included: Actinomyces viscosus, A. odontolyticus, Bacteroides asaccharolyticus (B. gingivalis), B. melaninogenicus subspecies intermedius, and subspecies melaninogenicus, Capnocytophaga ochracea (B. ochraceus), and Fusobacterium nucleatum. Three B. melaninogenicus isolates showed plasmids of approximately 2.7-2.9 Mdalton (mega-dalton) molecular size. Restriction enzyme digests of the plasmids demonstrated dissimilar patterns when electrophoresed on agarose gels. In other microorganisms, including the Actinomyces species, plasmids were not observed.

Actinomyces↗
PubMed1982

The bacteriology of acute necrotizing ulcerative gingivitis.

Plaque samples from 22 ulcerated sites in eight patients with ANUG were cultured using quantitative anaerobic procedures and were examined microscopically. The partial characterization of the predominant cultivable flora revealed a constant flora comprised of a limited number of bacterial types and a variable flora composed of a heterogeneous array of bacterial types. This constant flora would appear to be pathognomonic of acute necrotizing ulcerative gingivitis (ANUG) and included the various Treponema and Selenomonas sp., which comprised about 32 and 6%, respectively, of the microscopic count; B. melaninogenicus ssp. intermedius and Fusobacterium sp., which averaged 24 and 3%, respectively, of the viable count. One week of metronidazole treatment caused a prompt resolution of clinical symptoms, which coincided with a significant reduction in the plaque proportions of the Treponema sp., B. melaninogenicus ssp., intermedius and Fusobacterium sp. for at least 2 to 3 months following treatment. Thus, the same anaerobic species which were numerically associated with the ANUG lesion were also selectively reduced in the plaque flora following resolution of the infection. This supports a role for the above species in the ulcerative stage of the lesion but does not demonstrate that these specific anaerobes initiated the infection. although not confirmed by the data, it was proposed that these particular anaerobic species gained ascendency in the plaque as a result of being selected through the availability of host-derived nutrients in individuals who had undergone certain physiological and psychological stresses.

Bacteria↗
PubMed1981

Treatment of periodontal infections due to anaerobic bacteria with short-term treatment with metronidazole.

In the present report, five selected periodontal patients were treated for 1 week with metronidazole. Two of the patients had their teeth scales and root-planed the week they received metronidazole. Prior to treatment, B. asaccharolyticus accounted for 41% of the cultivable isolates and the spirochetes averaged 29% of the microscopic count in plaque removed from each of four pockets per patient. The presence of these elevated proportions of periodontopathic bacteria combined with the presence of periodontal pockets and attachment loss suggested that the patients were in a state of an active infectious process involving primarily anaerobic bacteria. If this be the case, then antimicrobial therapy directed against these anaerobes wih metronidazole was indicated. The 1-week treatment with metronidazole significantly reduced the proportions of these organisms for up to 6 months after treatment. Coincident with these findings was an improvement in the clinical parameters, especially in those sites that initially had greater than 5 mm pocket or attachment loss. These sites showed a 2 mm or more reduction in pocket depth and an almost 2 mm gain in apparent attachment that was evident 6 months after treatment. The results obtained were in only five patients. However, the magnitude of improvement suggests that antimicrobial therapy directed against anaerobic organisms may be a valuable adjunct to periodontal therapy.

Adolescent↗
PubMed1981

The predominant cultivable dental plaque flora of beagle dogs with periodontitis.

The predominant cultivable dental plaque flora was studied in 10 adult female beagle dogs with advanced periodontitis. Supragingival and subgingival plaque from a maxillary third premolar (P3) was removed and cultured anaerobically on various growth media and all colonies were subcultured and partially characterized. Histopathological specimens of the plaque sampling sites showed significant loss of connective tissue attachment. Spirochetes were found in all samples. Anaerobic gram-negative organisms were predominant in both types of plaque accounting for about 55% of the cultivable organisms in the supragingival plaque and almost 75% in the subgingival plaque. Bacteroides asaccharolyticus was the most predominant organism in the supragingival plaque, whereas Fusobacterium nucleatum predominated in the subgingival flora. Streptococcal and actinomycotic species were common in the supragingival plaque, but their proportions, especially those of the actinomycetes, were decreased in the subgingival flora. In many respects the bacterial profile associated with disease resembled that reported in human periodontal disease.

Actinomyces↗
PubMed1981

Comparison of Marion's anaerobic culture/set-A and the Baltimore Biological Laboratory Gaspak anaerobic system in the cultivation and recovery of bacteria from human dental plaque.

Marion's anerobic culture/set-A (Bio-Bag A) and the Baltimore Biological Laboratory (BBL) Gaspak anaerobic system were evaluated for their efficiency in the cultivation and recovery of anaerobes and capnophilic organisms from human dental plaque samples. Both culture systems were relatively efficient in supporting the growth of pure culture of various bacterial species recently isolated from the human dental plaques. When the dental plaque samples were cultured the organisms commonly found were cultivatable in both culture systems. However, the counts and proportions of Fusobacterium nucleatum from the samples were significantly higher in Marion's culture system, whereas the proportions of black-pigmented Bacteroides sp. were significantly higher in the BBL anaerobic system.

Actinomyces↗
PubMed1980

Characteristics of Bacteroides asaccharolyticus from dental plaques of beagle dogs.

Gram-negative, non-saccharolytic, brown- or black-pigment-forming, nonmotile anaerboic coccobacilli, capable of decomposing hydrogen peroxide and identified as Bacteroides asaccharolyticus (B. melaninogenicus subsp. asaccharolyticus), were isolated from the supra- and subgingival plaques of beagle dogs with gingivitis or periodontitis. The organisms remained viable for many hours in an aerobic atmosphere as evidenced by their ability to grow subsequently in an anaerobic environment. They also grew well on agar media that were not reduced before use. Although blood was required for pigmentation of colonies, organisms grew on media that lacked hemin, menadione, blood, or reducing compounds. Increased oxygen tolerance, catalase activity, and different nutritional requirements differentiate these organisms from strains of B. asaccharolyticus isolated from humans.

Animals↗
PubMed1978

Bacteriology of human experimental gingivitis: effect of plaque age.

Twenty-five subjects with previously excellent hygiene and healthy gingiva developed heavy plaque accumulations and bleeding or nonbleeding gingivitis about certain papilla after 21 days of no oral hygiene. Gingival marginal plaque about a single papilla was collected at 0, 1, 2, and 3 weeks of no oral hygiene in each subject. The plaque was dispersed, serially diluted, and plated on MM10 sucrose agar in an oxygen-free atmosphere. From 50 to 100 colonies from a single high-dilution plate were characterized for each sample. Over 8,500 isolates were partially characterized and placed into one of 29 taxonomic species or groups. The flora was predominantly gram-positive at all time periods. Streptococcal species dominated in the 0- and 1-week-old plaques, i.e. 62 and 43% of the colonyforming units (CFU), but dropped to 26 to 32% of the CFU in the 2- and 3-week-old plaques. Actinomyces species dominated in the older plaques, i.e., 40 to 50% of the CFU. Actinomyces israelii was the most prominent species in the older plaques. Veillonella accounted for 15 to 20% of the CFU at all time periods. Although the other gram-negative species increased with time, collectively they averaged less than 5% of the CFU at week 3. The shift from a Streptococcus-dominated plaque to an Actinomyces-dominated plaque was the most striking microbial change observed as the plaque aged.

Adult↗
PubMed1978

Bacteriology of human experimental gingivitis: effect of plaque and gingivitis score.

The plaque flora isolated from discrete dentogingival sites during a human gingivitis experiment was analyzed as a function of the plaque score and of the gingivitis score. When the gingivitis score was plotted as a function of the plaque score, a nonbleeding gingivitis was associated with a proportional increase in the Actinomyces sp. at the expense of the Streptococcus sp. In particular, the percentage of Actinomyces israelii increased significantly, while the percent Streptococcus sanguis decreased significantly. A. israelii also increased significantly when a bleeding gingivitis developed. When the plaque score was plotted as a function of the gingivitis score, A. israelii increased significantly as the nonbleeding gingivitis developed, but A. viscosus and Bacteroides melaninogenicus increased significantly when the bleeding gingivitis developed. The availability of a sufficient number of plaques with a plaque score of 2.0 permitted the examination of the interrelationship of gingivitis and flora minus the effect of plaque biomass. The bacteriological profile showed that when bleeding occurred, the levels and proportions of A. viscosus and B. melaninogenicus increased significantly. These findings raise the possibility that proportional changes in the gingival plaque flora may uniquely contribute to the development of gingival inflammation in this experimental model.

Adult↗
PubMed1978

The viability of microorganisms in carious lesions five years after covering with a fissure sealant.

Carious lesions that were covered with a pit and fissure sealant for five years yielded bacterial cultures that were predominantly negative. Sixteen of 18 test sites judged to have active caries in 1972 were found inactive in 1977; ten of 12 sites suspected to have caries in 1972 were deemed to have inactive caries in 1977. Sealant treatment resulted in an apparent 89% reversal from a caries-active to a caries-inactive state. These data confirm and extend previous observations that a limited number of cultivable organisms persist in some lesions but their numbers are few, and they do not appear capable of continuing the destruction of tooth structure.

Acid Etching, Dental↗
PubMed1975

Predominant cultivable flora isolated from human root surface caries plaque.

Plaque samples were obtained from tooth surfaces exhibiting typical lesions of root surface caries and were immediately cultured by a continuous anaerobic procedure. The bacterial composition of root caries flora was determined on individual samples. Representative isolates from each specimen were characterized by morphological and physiological criteria. In addition, fluorescent antibody reagents were used to confirm the identification of Streptococcus mutans and Actinomyces viscosus. The plaque samples could be divided into two groups on the basis of the presence or absence of S. mutans in the plaque. In group I plaques, S. mutans comprised 30 percent of the total cultivable flora. S. sanguis was either not found or was present in very low number. In group II plaques, S. mutans was not detected, and S. sanguis formed 48 percent of the total plaque flora. A. viscosus was the dominant organism in all plaque samples, accounting for 47 percent of the group I isolates and 41 percent of the group II isolates.

Actinomyces↗
PubMed1973

Efficiency of various growth media in recovering oral bacterial flora from human dental plaque.

MM10 sucrose blood agar (MM10 SB agar), N(2)C agar, Schaedler agar (SH agar), and mitis salivarius agar (MS agar) were tested for their ability to recover human dental plaque flora by a continuous anaerobic procedure and by a conventional anaerobic method. MM10 SB agar yielded higher recovery of bacteria from plaque samples as determined by the enumeration of colony-forming units (CFU). The CFU on N(2)C agar, SH agar, and MS agar were lower than MM10 SB agar when the continuous anaerobic procedure was used. The superior performance of MM10 SB agar was much more apparent when used for the cultivation of dental plaque by the conventional anaerobic method. Under these conditions the counts were consistently higher on MM10 SB agar as compared to the other media tested. However, the differential counts of Streptococcus sanguis and S. mutans from carious plaque samples were in general comparable on all culture media. Deletion of blood from MM10 SB agar did not lower counts. The elimination of dithiothreitol from this medium resulted in a significantly lower recovery of bacteria from the plaque samples when cultured by the conventional anaerobic method. The storage of MM10 SB agar for varying periods of time aerobic conditions did not seem to affect its performance. These findings suggest that MM10 SB agar is an ideal culture medium for the isolation, nonselective enumeration, and differential counts of bacteria present in normal and disease-associated plaques.

Anaerobiosis↗