Long-term impact of oral surgery with or without amoxicillin on the oral microbiome-A prospective cohort study

R. K. Menon, A. Gomez, B. W. Brandt, Y. Y. Leung, D. Gopinath, R. M. Watt, W. Crielaard, K. E. Nelson, M. G. Botelho

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Routine postoperative antibiotic prophylaxis is not recommended for third molar extractions. However, amoxicillin still continues to be used customarily in several clinical practices worldwide to prevent infections. A prospective cohort study was conducted in cohorts who underwent third molar extractions with (group EA, n = 20) or without (group E, n = 20) amoxicillin (250 mg three times daily for 5 days). Further, a control group without amoxicillin and extractions (group C, n = 17) was included. Salivary samples were collected at baseline, 1-, 2-, 3-, 4-weeks and 3 months to assess the bacterial shift and antibiotic resistance gene changes employing 16S rRNA gene sequencing (Illumina-Miseq) and quantitative polymerase chain reaction. A further 6-month follow-up was performed for groups E and EA. Seven operational taxonomic units reported a significant change from baseline to 3 months for group EA (adjusted p < 0.05). No significant change in relative abundance of bacteria and β-lactamase resistance genes (TEM-1) was observed over 6 months for any group (adjusted p > 0.05). In conclusion, the salivary microbiome is resilient to an antibiotic challenge by a low-dose regimen of amoxicillin. Further studies evaluating the effect of routinely used higher dose regimens of amoxicillin on gram-negative bacteria and antibiotic resistance genes are warranted.

Original languageEnglish (US)
Article number18761
JournalScientific reports
Issue number1
StatePublished - Dec 1 2019

Bibliographical note

Funding Information:
RMW acknowledges financial support from the Infection and Immunology Strategic Research Theme (SRT) of the University of Hong Kong. RKM acknowledges financial support from the J. Craig Venter Institute, Ho King Chun Leadership fund and Pilot grant for Rpg students – University of Hong Kong.

PubMed: MeSH publication types

  • Comparative Study
  • Journal Article
  • Research Support, Non-U.S. Gov't

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