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Arch Oral Biol. 2017 Sep;81:7-14. doi: 10.1016/j.archoralbio.2017.04.018. Epub 2017 Apr 21.

Cariogenic properties of Streptococcus mutans clinical isolates with sortase defects.

Author information

1
Department of Oral Microbiology, Faculty of Dentistry, Mahidol University, Bangkok, 10400, Thailand. Electronic address: jinthana.lap@mahidol.ac.th.
2
Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8525, Japan.
3
Department of Oral Microbiology, Faculty of Dentistry, Mahidol University, Bangkok, 10400, Thailand.
4
Department of Pediatric Dentistry, Faculty of Dentistry, Mahidol University, Bangkok, 10400, Thailand.
5
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, 565-0871, Japan.

Abstract

OBJECTIVE:

In Streptococcus mutans, a Gram-positive pathogen of dental caries, several surface proteins are anchored by the activity of sortase enzyme. Although various reports have shown that constructed S. mutans mutants deficient of sortase as well as laboratory reference strains with a sortase gene mutation have low cariogenic potential, no known studies have investigated clinical isolates with sortase defects. Here, we examined the cariogenic properties of S. mutans clinical isolates with sortase defects as well as caries status in humans harboring such defective isolates.

DESIGN:

Sortase-defective clinical isolates were evaluated for biofilm formation, sucrose-dependent adhesion, stress-induced dextran-dependent aggregation, acid production, and acid tolerance. Additionally, caries indices of subjects possessing such defective isolates were determined.

RESULTS:

Our in vitro results indicated that biofilm with a lower quantity was formed by sortase-defective as compared to non-defective isolates. Moreover, impairments of sucrose-dependent adhesion and stress-induced dextran-dependent aggregation were found among the isolates with defects, whereas no alterations were seen in regard to acid production or tolerance. Furthermore, glucan-binding protein C, a surface protein anchored by sortase activity, was predominantly detected in culture supernatants of all sortase-defective S. mutans isolates. Although the sortase-defective isolates showed lower cariogenic potential because of a reduction in some cariogenic properties, deft/DMFT indices revealed that all subjects harboring those isolates had caries experience.

CONCLUSIONS:

Our findings suggest the impairment of cariogenic properties in S. mutans clinical isolates with sortase defects, though the detection of these defective isolates seemed not to imply low caries risk in the subjects harboring them.

KEYWORDS:

Cariogenicity; Clinical isolate; Defect; Sortase; Streptococcus mutans

[Indexed for MEDLINE]

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