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Validation of antibiotic efficacy on in vitro subgingival biofilms


Belibasakis, Georgios N; Thurnheer, Thomas (2014). Validation of antibiotic efficacy on in vitro subgingival biofilms. Journal of Periodontology, 85(2):343-348.

Abstract

Background: Systemic antibiotics are often used as adjunctive treatment modalities for periodontal diseases. Testing of antimicrobial efficacy can be relevant only if the bacteria are in the form of biofilms rather than in planktonic state, and at concentrations of physiological relevance i.e. reachable in the periodontal pocket. The aim of the present study was to test on a multi-species in vitro biofilm model the antimicrobial efficacy of five different antibiotic schemes, at physiologically relevant concentrations. Methods: A 10-species in vitro "subgingival" biofilm model was exposed to metronidazole (15 µg/ml), amoxicillin (15 µg/ml), their combination, doxycycline (2 µg/ml) and azithromycin (10 µg/ml), over 24 h. Species-specific bacterial numbers were determined by culture on selective agar media, or by epifluorescence microscopy. Results: Metronidazole alone did not affect biofilm composition. Total bacterial counts were significantly reduced by doxycycline, azithromycin and amoxicillin, or its combination with metronidazole, albeit by less than 1-log. On the species-specific level, these regimens significantly reduced the numbers of Streptococcus anginosus, Porphyromonas gingivalis, Fusobacterium nucleactum and Campylobacter rectus (except from amoxicillin). The strongest effects were displayed by the combination of amoxicillin and metronidazole. Conclusions: Antibiotics at concentrations detectable in gingival crevicular fluid do not dramatically reduce total bacterial loads in this in vitro biofilm model, but cause species-specific reductions, which may disrupt the biofilm unity.

Abstract

Background: Systemic antibiotics are often used as adjunctive treatment modalities for periodontal diseases. Testing of antimicrobial efficacy can be relevant only if the bacteria are in the form of biofilms rather than in planktonic state, and at concentrations of physiological relevance i.e. reachable in the periodontal pocket. The aim of the present study was to test on a multi-species in vitro biofilm model the antimicrobial efficacy of five different antibiotic schemes, at physiologically relevant concentrations. Methods: A 10-species in vitro "subgingival" biofilm model was exposed to metronidazole (15 µg/ml), amoxicillin (15 µg/ml), their combination, doxycycline (2 µg/ml) and azithromycin (10 µg/ml), over 24 h. Species-specific bacterial numbers were determined by culture on selective agar media, or by epifluorescence microscopy. Results: Metronidazole alone did not affect biofilm composition. Total bacterial counts were significantly reduced by doxycycline, azithromycin and amoxicillin, or its combination with metronidazole, albeit by less than 1-log. On the species-specific level, these regimens significantly reduced the numbers of Streptococcus anginosus, Porphyromonas gingivalis, Fusobacterium nucleactum and Campylobacter rectus (except from amoxicillin). The strongest effects were displayed by the combination of amoxicillin and metronidazole. Conclusions: Antibiotics at concentrations detectable in gingival crevicular fluid do not dramatically reduce total bacterial loads in this in vitro biofilm model, but cause species-specific reductions, which may disrupt the biofilm unity.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Dental Medicine > Institute of Oral Biology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2014
Deposited On:21 Oct 2013 07:03
Last Modified:07 Dec 2017 22:56
Publisher:American Academy of Periodontology
ISSN:0022-3492
Publisher DOI:https://doi.org/10.1902/jop.2013.130167
PubMed ID:23659420

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