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Updated: May 15, 2026
12:16
Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells
Published on: December 17, 2015
Azithromycin kills invasive Aggregatibacter actinomycetemcomitans in gingival epithelial cells
Pin-Chuang Lai1, John D Walters
1Division of Oral Biology, The Ohio State University Health Sciences Center, Columbus, OH, USA.
Antimicrobial Agents and Chemotherapy
|January 1, 2013
Summary
Aggregatibacter actinomycetemcomitans invades gingival epithelium, making it hard to treat. Gingival epithelial cells accumulate azithromycin, enhancing its ability to kill these intracellular bacteria.
Area of Science:
- Microbiology
- Pharmacology
- Cell Biology
Background:
- Aggregatibacter actinomycetemcomitans is a key pathogen in periodontitis, residing within gingival epithelial cells.
- Standard periodontal treatments are less effective against intracellular bacteria.
- Azithromycin is known to be taken up by mammalian cells.
Purpose of the Study:
- To investigate the uptake of azithromycin by gingival epithelial cells.
- To determine if azithromycin accumulation enhances the killing of intracellular A. actinomycetemcomitans.
- To characterize the transport mechanism of azithromycin in oral epithelial cells.
Main Methods:
- Characterized [3H]azithromycin transport in Smulow-Glickman and SCC-25 oral epithelial cells.
- Infected cell monolayers with A. actinomycetemcomitans, treated with gentamicin, then incubated with azithromycin.
- Quantified viable intracellular bacteria after azithromycin treatment.
Main Results:
- Azithromycin transport followed Michaelis-Menten kinetics and was inhibited by organic cations like L-carnitine.
- High intracellular azithromycin concentrations were achieved (118-144 μg/ml).
- Azithromycin demonstrated dose- and time-dependent killing of intracellular A. actinomycetemcomitans, with significant reduction (≥82%) at 8 μg/ml.
Conclusions:
- Human gingival epithelial cells actively accumulate azithromycin via a shared organic cation transporter.
- This active accumulation enhances the elimination of intracellular A. actinomycetemcomitans.
- Azithromycin holds potential as a therapeutic agent against intracellular periodontal pathogens.
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