Effects of azithromycin, metronidazole, amoxicillin, and metronidazole plus amoxicillin on an in vitro polymicrobial subgingival biofilm model.
Chronic periodontitis is one of the most prevalent human diseases and is caused by dysbiosis of the subgingival microbiota. Treatment involves primarily mechanical disruption of subgingival biofilms and, in certain cases, adjunctive use of systemic antibiotic therapy. In vitro biofilm models have been developed to study antimicrobial agents targeting subgingival species. However, these models accommodate a limited number of taxa, lack reproducibility, and have low throughput. We aimed to develop an in vitro multispecies biofilm model that mimics subgingival plaque, to test antimicrobial agents. Biofilms were cultivated using the Calgary Biofilm Device and were exposed to amoxicillin (AMX), metronidazole (MTZ), azithromycin (AZM), and AMX-MTZ at four different concentrations for 12, 24, or 36 h. Chlorhexidine (CHX) (0.12%) was used as the positive control. The compositions of the biofilms were analyzed by checkerboard DNA-DNA hybridization, and the percent reduction in biofilm metabolic activity was determined using 2,3,5-triphenyltetrazolium chloride and spectrophotometry. Thirty-five of the 40 species used in the inoculum were consistently recovered from the resulting in vitro biofilms. After 36 h of exposure at the 1:27 dilution, AMX-MTZ reduced metabolic activity 11% less than CHX (q = 0.0207) but 54% more than AMX (q = 0.0031), 72% more than MTZ (q = 0.0031), and 67% more than AZM (q = 0.0008). Preliminary evidence of a synergistic interaction between AMX and MTZ was also observed. In summary, we developed reproducible biofilms with 35 subgingival bacterial species, and our results suggested that the combination of AMX and MTZ had greater antimicrobial effects on these in vitro multispecies biofilms than expected on the basis of the independent effects of the drugs.
Dental Research Division, Department of Periodontology, Guarulhos University, Guarulhos, São Paulo, Brazil Department of Applied Oral Science, Forsyth Institute, Cambridge, Massachusetts, USA geislamary@gmail.com rteles@email.unc.edu.
Geisla M S
GM
Soares
Department of Periodontology, University of North Carolina School of Dentistry, Chapel Hill, North Carolina, USA.
Flavia
F
Teles
Department of Applied Oral Science, Forsyth Institute, Cambridge, Massachusetts, USA Department of Oral Health Policy and Epidemiology, Harvard School of Dental Medicine, Harvard University, Boston, Massachusetts, USA.
Jacqueline R
JR
Starr
Dental Research Division, Department of Periodontology, Guarulhos University, Guarulhos, São Paulo, Brazil.
Magda
M
Feres
Department of Applied Oral Science, Forsyth Institute, Cambridge, Massachusetts, USA.
Michele
M
Patel
Department of Applied Oral Science, Forsyth Institute, Cambridge, Massachusetts, USA.
Lynn
L
Martin
Department of Periodontology, University of North Carolina School of Dentistry, Chapel Hill, North Carolina, USA geislamary@gmail.com rteles@email.unc.edu.
Ricardo
R
Teles
D000190:Actinomyces; D000658:Amoxicillin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017963:Azithromycin / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D008795:Metronidazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D013291:Streptococcus / Q000187:drug effects; D014678:Veillonella / Q000187:drug effects
D000900:Anti-Bacterial Agents; D008795:Metronidazole; D000658:Amoxicillin; D017963:Azithromycin