College of Engineering
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/27
The College of Engineering at Montana State University will serve the State of Montana and the nation by fostering lifelong learning, integrating learning and discovery, developing and sharing technical expertise, and empowering students to be tomorrow's leaders.
Browse
2 results
Search Results
Item Selective killing of Aggregatibacter actinomycetemcomitans by ciprofloxacin during development of a dual species biofilm with Streptococcus sanguinis(2011-10) Suci, Peter A.; Young, Mark J.Objectives: Periodontal disease is associated with a pathogen-induced transition to a chronic destructive inflammatory response. Since commensals may either passively or actively contribute to immune homeostasis, therapies aimed at selectively reducing the competitive advantage of pathogens may be effective supplements to traditional methods. We developed an in vitro system to grow biofilms composed of the pathogen (Aggregatibacter actinomycetemcomitans) and the commensal (Streptococcus sanguinis). We used the biofilm model to determine the feasibility of selectively killing the pathogen using the fluoroquinolone, ciprofloxacin.Design: Biofilms were exposed to relevant ciprofloxacin doses during the first 24 h of development, with subsequent removal of the ciprofloxacin for a 24 h period. Biofilm growth was assessed by confocal laser scanning microscopy, crystal violet staining and DNA abundance.Results: Exposure to 0.01 mg/L or 0.5 mg/L ciprofloxacin significantly reduced the microcolony size and cell surface density of A. actinomycetemcomitans in the dual species biofilm over a 24 h period whilst allowing uninhibited S. sanguinis biofilm formation. A. actinomycetemcomitans biofilm development was insignificant over a subsequent 24 h period after removal of the ciprofloxacin indicating that A. actinomycetemcomitans cells were killed.Conclusions: A. actinomycetemcomitans residing in a dual species biofilm with the commensal, S. sanguinis can be selectively killed, or at least rendered metabolically inactive, by treatment with ciprofloxacin. The dual species biofilm model will be a useful tool for designing in vivo studies to determine the efficacy of selective killing agents as an adjunct treatment of localized aggressive forms of periodontal disease.Item Aggregatibacter actinomycetemcomitans biofilm killing by a targeted ciprofloxacin prodrug(2013-09) Reeves, Benjamin D.; Young, Mark J.; Grieco, Paul A.; Suci, Peter A.A pH-sensitive ciprofloxacin prodrug was synthesized and targeted against biofilms of the periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa). The dose required to reduce the viability of a mature biofilm of Aa by ∼80% was in the range of ng cm−2 of colonized area (mean biofilm density 2.33 × 109 cells cm−2). A mathematical model was formulated that predicts the temporal change in the concentration of ciprofloxacin in the Aa biofilm as the drug is released and diffuses into the bulk medium. The predictions of the model were consistent with the extent of killing obtained. The results demonstrate the feasibility of the strategy to induce mortality, and together with the mathematical model, provide the basis for design of targeted antimicrobial prodrugs for the topical treatment of oral infections such as periodontitis. The targeted prodrug approach offers the possibility of optimizing the dose of available antimicrobials in order to kill a chosen pathogen while leaving the commensal microbiota relatively undisturbed.