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Building biofilms in vital host tissues: a survival strategy of Actinomyces radicidentis


Nair, P N R; Brundin, M; Sundqvist, G; Sjögren, U (2008). Building biofilms in vital host tissues: a survival strategy of Actinomyces radicidentis. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 106(4):595-603.

Abstract

OBJECTIVE: To investigate the ability of Actinomyces radicidentis to survive and establish in soft connective tissue that grew into subcutaneously implanted tissue cages in Sprague-Dawley rats. STUDY DESIGN: Known concentrations of A. radicidentis suspension, grown on blood agar and broth cultures, were inoculated into tissue cages in rats. The cage contents were retrieved after 7, 14, and 28 days for culturing and correlative light and transmission electron microscopy. RESULTS: Cell suspensions harvested from both types of cultures showed substantial decline in numbers in tissue cages during the observation period. However, correlative light and transmission electron microscopy revealed numerous aggregates of coccoid bacteria already by 7 days of observation compared with the formation of well established colonies with characteristic actinomycotic features by 14 days after inoculation. CONCLUSIONS: These results suggest that the pathogenicity of A. radicidentis is due to its ability to form large aggregates of cells held together by embedding themselves in an extracellular matrix in vital host tissues. Thus, A. radicidentis, like other pathogenic Actinomyces, existing in the protected biofilm-environment can collectively evade destruction and elimination by host defenses, including phagocytosis.

Abstract

OBJECTIVE: To investigate the ability of Actinomyces radicidentis to survive and establish in soft connective tissue that grew into subcutaneously implanted tissue cages in Sprague-Dawley rats. STUDY DESIGN: Known concentrations of A. radicidentis suspension, grown on blood agar and broth cultures, were inoculated into tissue cages in rats. The cage contents were retrieved after 7, 14, and 28 days for culturing and correlative light and transmission electron microscopy. RESULTS: Cell suspensions harvested from both types of cultures showed substantial decline in numbers in tissue cages during the observation period. However, correlative light and transmission electron microscopy revealed numerous aggregates of coccoid bacteria already by 7 days of observation compared with the formation of well established colonies with characteristic actinomycotic features by 14 days after inoculation. CONCLUSIONS: These results suggest that the pathogenicity of A. radicidentis is due to its ability to form large aggregates of cells held together by embedding themselves in an extracellular matrix in vital host tissues. Thus, A. radicidentis, like other pathogenic Actinomyces, existing in the protected biofilm-environment can collectively evade destruction and elimination by host defenses, including phagocytosis.

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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:October 2008
Deposited On:09 Jan 2009 10:56
Last Modified:05 Apr 2016 12:45
Publisher:Elsevier
ISSN:1079-2104
Publisher DOI:https://doi.org/10.1016/j.tripleo.2008.05.001
PubMed ID:18602301

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