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Mapping Antibiotic Resistance Determinants in Oral Streptococci
K S M Shawrob1, A S Sagen1, T M Lunde2
1Institute of Oral Biology, Faculty of Dentistry, University of Oslo (UiO), Oslo, Norway.
Journal of Dental Research
|July 25, 2026
Summary
Antibiotic resistance in oral streptococci is a major health concern. This study reveals high abundance of tetracycline and macrolide resistance genes, and significant genetic exchange with Streptococcus pneumoniae.
Area of Science:
- Microbiology
- Genomics
- Antimicrobial Resistance
Background:
- Antibiotic resistance is a critical global health challenge.
- Oral streptococci harbor resistance determinants that can transfer to pathogens.
- Understanding gene exchange is vital for combating resistance.
Purpose of the Study:
- To identify core antibiotic resistance determinants in oral streptococci.
- To assess the variability and patterns of gene exchange.
- To investigate the role of mobile genetic elements in resistance spread.
Main Methods:
- Analysis of 2,087 whole-genome sequences from 15 oral streptococci species.
- Identification of resistance genes using AMRFinderPlus and CARD.
- Detection of integrative and conjugative elements with ICEscreen.
- Assessment of penicillin-binding protein (PBP) sequence variability.
Main Results:
- Over 3,500 resistance gene hits (55 unique genes) across 11 antibiotic classes were identified.
- Tetracycline and macrolide resistance genes were highly abundant and linked to mobile genetic elements.
- Oral streptococci, particularly *S. mitis* and *S. oralis*, contribute significantly to PBP recombination in *S. pneumoniae*.
- Nearly 17% of mobile genetic elements carried antibiotic resistance genes.
Conclusions:
- Oral streptococci are reservoirs of diverse antibiotic resistance genes.
- Integrative and conjugative elements play a key role in the dissemination of resistance.
- Genetic exchange from oral streptococci to *S. pneumoniae* is a significant mechanism for spreading resistance.
- Targeting gene exchange dynamics is crucial for antimicrobial resistance mitigation strategies.
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