title: Phototargeting oral black-pigmented bacteria.
abstract: We have found that broadband light (380 to 520 nm) rapidly and selectively kills oral black-pigmented bacteria (BPB) in pure cultures and in dental plaque samples obtained from human subjects with chronic periodontitis. We hypothesize that this killing effect is a result of light excitation of their endogenous porphyrins. Cultures of Prevotella intermedia and P. nigrescens were killed by 4.2 J/cm2, whereas P. melaninogenica required 21 J/cm2. Exposure to light with a fluence of 42 J/cm2 produced 99% killing of P. gingivalis. High-performance liquid chromatography demonstrated the presence of various amounts of different porphyrin molecules in BPB. The amounts of endogenous porphyrin in BPB were 267 (P. intermedia), 47 (P. nigrescens), 41 (P. melaninogenica), and 2.2 (P. gingivalis) ng/mg. Analysis of bacteria in dental plaque samples by DNA-DNA hybridization for 40 taxa before and after phototherapy showed that the growth of the four BPB was decreased by 2 and 3 times after irradiation at energy fluences of 4.2 and 21 J/cm2, respectively, whereas the growth of the remaining 36 microorganisms was decreased by 1.5 times at both energy fluences. The present study suggests that intraoral light exposure may be used to control BPB growth and possibly benefit patients with periodontal disease.
authors.affiliation: Applied Molecular Photomedicine Laboratory, The Forsyth Institute, 140 The Fenway, Boston, Massachusetts 02115, USA. nsoukos@forsyth.org
authors.forename: Nikolaos S
authors.initials: NS
authors.lastname: Soukos
authors.forename: Sovanda
authors.initials: S
authors.lastname: Som
authors.forename: Abraham D
authors.initials: AD
authors.lastname: Abernethy
authors.forename: Karriann
authors.initials: K
authors.lastname: Ruggiero
authors.forename: Joshua
authors.initials: J
authors.lastname: Dunham
authors.forename: Chul
authors.initials: C
authors.lastname: Lee
authors.forename: Apostolos G
authors.initials: AG
authors.lastname: Doukas
authors.forename: J Max
authors.initials: JM
authors.lastname: Goodson
mesh_terms: D002908:Chronic Disease; D015169:Colony Count, Microbial; D003773:Dental Plaque / Q000382:microbiology*; D006801:Humans; D008027:Light; D009693:Nucleic Acid Hybridization; D010518:Periodontitis / Q000382:microbiology / Q000628:therapy; D010789:Phototherapy; D010860:Pigments, Biological / Q000378:metabolism; D011166:Porphyrins / Q000378:metabolism; D016966:Porphyromonas gingivalis / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D018720:Prevotella / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D018713:Prevotella intermedia / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D001443:Prevotella melaninogenica / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D034365:Streptococcus constellatus / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*
chemical_list: D010860:Pigments, Biological; D011166:Porphyrins