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A combination of metronidazole (MET) and amoxicillin (AMX) is commonly used as adjunct to mechanical therapy of periodontal disease. The use of broad spectrum antibiotics such as AMX may contribute to development of antibiotic resistance. The aim was to evaluate the in vitro effect of replacing AMX with penicillin V (PV) in combination with MET on a biofilm model. A biofilm model consisting of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Fusobacterium nucleatum was developed. The biofilms were exposed to AMX + MET and PV + MET in two different concentrations. Bacterial viability in biofilms following antibiotic exposure was assessed by viable counts and by confocal microscopy. No live colonies of P. gingivalis nor F. nucleatum were retrieved from biofilms exposed to AMX + MET or PV + MET. The amount of A. actinomycetemcomitans was 4–5 logs reduced following antibiotic treatment; no statistical significance was achieved between AMX + MET or PV + MET treated biofilms. Replacement of AMX with PV at the same concentration, in combination with MET, resulted in similar effect on bacterial viability in this in vitro model. The option of using PV + MET instead of AMX + MET deserves further investigation, as this may contribute to reduce the risk of antibiotic resistance development.

Objective The tongue microbiome has emerged as a non-invasive diagnostic and tracking prognostic tool in the detection of diseases mainly cancer. This scoping review aimed to identify the association between tongue microbiome and pre-cancer or cancer lesions. Design A comprehensive electronic database search including PubMed, Web of Science, and Scopus was undertaken up to March 2021, without language or date restrictions. This review was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guideline. All observational studies that compared microbial community on the dorsal surface of the tongue between cancer or precancerous cases and healthy controls using NGS techniques were included. Results Of 274 records identified, nine studies were eligible to be included. Despite the inconsistent observations in terms of diversity and richness, most studies reported alteration in bacterial communities between pre-cancer or cancer cases and control groups. The bacterial profile among cases was so far correlated at the phylum level with a noticeable diverse degree at the genus level. The majority of included studies reported a higher abundance of certain kinds of microorganisms as compared to healthy participants including Firmicutes, Fusobacteria and Actinobacteria at phyla level as well as Streptococcus, Actinomyces, Leptotrichia, Campylobacter, and Fusobacterium at the genus level. Conclusion The alteration of the tongue microbial community has been associated with several diseases mainly cancer. So, the tongue microbiome may serve as a promising diagnostic tool or as a long-term monitor in precancerous or cancer cases.

Background: Antibiotic resistance has become life-threatening. A combination of metronidazole and amoxicillin is commonly used as adjunct to periodontal therapy. The aim of this study was to utilize an in vitro biofilm model to test the effect of replacing the broad-spectrum amoxicillin with penicillin V in the combination with metronidazole. Methods: An in vitro biofilm model, consisting of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum was developed. Biofilms were exposed to chlorhexidine digluconate (CHX) 0.2%, as positive control, and either to metronidazole/amoxicillin or metronidazole/penicillin V in two different concentrations. Statistical significance was achieved if p < 0.05 with paired t-test. Results: There was no growth of any bacterial species after 2h exposure to 0.2% CHX. Together, the two combinations of antibiotics were effective against F. nucleatum and P. gingivalis, but less effective against A. actinomycetemcomitans. No significant difference was found between the two combinations of antibiotics to combat A. actinomycetemcomitans neither in high (p = 0.95) nor in low concentration (p = 0.17). Conclusion: A combination of metronidazole with penicillin V had similar inhibiting effect as metronidazole combined with amoxicillin on an in vitro three-species biofilm model. Use of a narrow spectrum antibiotic may be indicated in combination with metronidazole.