J Korean Acad Oral Health.  2020 Mar;44(1):34-40. 10.11149/jkaoh.2020.44.1.34.

Molecular epidemiology and characterization of Streptococcus mutans strains in Korea

  • 1Department of Preventive and Community Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea. jbomkim@pusan.ac.kr
  • 2Department of Dental Hygiene, College of Health and Welfare, Silla University, Busan, Korea.
  • 3Department of Laboratory Medicine, Inje University College of Medicine, Busan, Korea.


We investigated the characteristics of Streptococcus mutans in the national culture collection from Korea. Twenty-nine (dental plaque, n=27; endodontic infections, n=1; blood, n=1) isolates were included in this study.
Antimicrobial susceptibilities were tested using the disk diffusion test. Multilocus sequence typing (MLST), serotyping, and collagen-binding genes were used for polymerase chain reaction (PCR) and direct sequencing. A collagen-binding (to assess the adhesion properties) assay was performed. S. mutans demonstrated high susceptibility to antimicrobial agents. Differences in collagen-binding abilities of the cnm-positive and -negative groups were compared using the Mann-Whitney U test (P<0.05).
MLST analyses revealed 25 sequence types (STs), 17 of which (ST213-ST229) contained new alleles. The strains were classified into four serotypes with the c type encompassing 79.3% of all strains, while the e, f, and k types representing 6.9% each. Analysis of the cnm and cbm genes, which encode the two surface adhesin components of S. mutans, revealed three cnm-positive strains, each displaying greater adhesion ability than those of the cnm-negative strains.
This study highlights the presence of a wide variety of S. mutans genotypes in Korea. These findings may provide useful information regarding the pathogenesis of infectious diseases, such as dental caries.


Adhesion; Bacteremia; Collagen binding; MLST; Infection; Inflammation; Streptococcus mutans
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