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Tips from the journals of the American Society for Microbiology

American Society for Microbiology

Ulcer Drug Inhibits Gum Disease in Rabbits

Researchers from Boston University School of Medicine have discovered that topical application of an ulcer drug to teeth may help prevent gum disease. Their findings appear in the April 2006 issue of the journal Infection and Immunity.

Periodontitis (gum disease) occurs when the bacterium Porphyromonas gingivalis accumulates on the tooth's surface causing inflammatory disease which leads to loss of connective tissue and bone. This disease affects tens of millions of people in the U.S. alone, emphasizing the importance of effective preventative care and treatment method.

Cimetidine is a powerful H2 receptor antagonist originally designed to treat ulcers by blocking the acid producing cells in the stomach. In the study three groups of rabbits were simultaneously induced with experimental periodontitis using P. gingivalis and treated with varying levels of topically applied cimetidine three times a week over a six-week period. Results showed that topical application of cimetidine at all concentrations inhibited inflammation and bone loss by approximately 90%.

"The findings of this study provide morphological and histological evidence that topically active cimetidine is a potent inhibitor of P. gingivalis-elicited periodontal inflammation, arresting and/or preventing tissue destruction and influencing cell populations present in the inflammatory cell infiltrate," say the researchers.

(H. Hasturk, A. Kantarci, N. Ebrahimi, C. Andry, M. Holick, V.L. Jones, T.E. Van Dyke. 2006. Topical H2 antagonist prevents periodontitis in a rabbit model. Infection and Immunity, 74. 4: 2402-2414.)

Artificial Illumination Using White or Green Light May Prevent Biofilm Formation on Artwork

Using white or green light to artificially illuminate artwork may prevent biofilm formation and surface deterioration, say researchers from Spain. They report their findings in the April 2006 issue of the journal Applied and Environmental Microbiology.

Inappropriate artificial illumination of archeological remains and interior works of art can result in the development of uncontrolled photosynthetic microorganisms which form biofilms and contribute to surface biodeterioration. Biofilms are best described as a cluster of microorganisms attached to either an inert or living surface. Current control efforts include cleaning damaged surfaces and chemical treatments, both of which have had little success at biofilm prevention.

Spectral ambient light can cause variations in pigment distribution enabling an abundance of cyanobacteria and microalgae. Researchers selected green light for testing as it has previously shown to slow growth and affect pigment composition. It also represents the maximum absorbance of human vision. In the study researchers exposed artificial biofilms formed by Gloeothece membranacea and Chlorella sorokiniana to green and white light and evaluated their potential for preventing biofilm growth. Observations made suggest that green light could prevent the growth of biofilms with the exception of those capable of modifying accessory pigments.

"Although laboratory data cannot be extrapolated to natural environments, our results have prompted studies of the application of green light to artificially illuminated works of art," say the researchers.

(M. Roldan, F. Oliva, M.A. Gonzalez del Valle, C. Saiz-Jimenez, M. Hernandez-Marine. 2006. Does green light influence the fluorescence properties and structure of phototrophic biofilms? Applied and Environmental Microbiology, 72. 4: 3026-3031.)

Archaea Identified As Possible Human Pathogen

For the first time German researchers have linked Archaea to infectious diseases in humans by identifying it as a possible cause of endodontic infections. They report their findings in the April 2006 issue of the Journal of Clinical Microbiology.

Archaea, one of the three domains of life, has previously been recognized as a component of human microbiota, but not as a cause of human disease. High numbers of methane-producing archaea (methanogens) have been found in the gastrointestinal tract, vagina, and oral cavity but are often ignored in routine laboratory diagnostics despite the diversity of pathogens identified in the other two domains, Bacteria and Eukarya.

In attempt to gather more evidence for the existence of pathogenic methanogens researchers focused on their possible role in primary endodontic infections. A tooth's root canal is devoid of microbes in a healthy state, emphasizing that endodontic microbes must gain access while evading host defense mechanisms, both of which are features displayed by pathogens. In the study researchers analyzed samples from 20 different endodontic patients that had not undergone prior treatment, but had been previously screened for bacteria. Of those 20 samples, five returned positive results for the presence of methanogenic archaea.

"Here we report for the first time the detection, identification, and quantification of a defined phylotype of archaea in infected root canals," say the researchers. "This finding may contribute to an emerging view of archaea as potential human pathogens."

(M.E. Vianna, G. Conrads, B.P.F.A. Gomes, H.P. Horz. 2006. Identification and quantification of Archaea involved in primary endodontic infections. Journal of Clinical Microbiology, 44. 4: 1274-1282.)


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