Molecular and clinical analyses of the gene encoding the collagen-binding adhesin of Streptococcus mutans.
Streptococcus mutans is a known pathogen of dental caries and its major cell surface antigens have been widely investigated. Recently, an approximately 120 kDa Cnm protein with binding properties to type I collagen was identified, and its encoding gene (cnm) cloned and sequenced. In the present study, we sequenced cnm from 47 different clinical S. mutans strains and found that the nucleotide alignment of the collagen-binding domain was well conserved. We devised a PCR method for identifying the cnm gene, examined the prevalence of cnm-positive S. mutans strains in various mother-child groups, and assessed the significance of such strains for transmission and dental caries. The detection rate of cnm-positive strains was significantly lower in strains isolated from Japanese children in the 2000s (8.0 %) as compared to those isolated in the 1980s (15.8 %) (P<0.05). Furthermore, the presence of S. mutans possessing cnm in salivary specimens collected from 55 S. mutans-positive mother-child pairs was 40 and 32.7 % in the mothers and children, respectively. The frequency of cnm-positive children whose mothers were also positive was 72 %, which was significantly higher than that of cnm-positive children with negative mothers (P<0.0001, odds ratio 17.5). In addition, clinical parameters indicating dental caries were significantly increased in children with cnm-positive S. mutans in saliva (n=13), as compared to those with cnm-negative S. mutans (n=15) and S. mutans-negative children (n=20) (P<0.01). These results indicate that cnm-positive S. mutans strains are closely correlated with dental caries, while vertical transmission in cnm-positive mother-child pairs was also demonstrated.
Nomura
Ryota
R
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
Nakano
Kazuhiko
K
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
Taniguchi
Naho
N
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
Lapirattanakul
Jinthana
J
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
Nemoto
Hirotoshi
H
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
Grönroos
Lisa
L
Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, Helsinki, Finland.
Alaluusua
Satu
S
Department of Pediatric and Preventive Dentistry, Institute of Dentistry, University of Helsinki, Helsinki, Finland.|Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, Helsinki, Finland.
Ooshima
Takashi
T
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
D018829:Adhesins, Bacterial / Q000235:genetics*; D000328:Adult; D002352:Carrier Proteins / Q000235:genetics*; D002648:Child; D003094:Collagen / Q000378:metabolism*; D003731:Dental Caries / Q000382:microbiology; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006801:Humans; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D011485:Protein Binding; D012463:Saliva / Q000382:microbiology; D013290:Streptococcal Infections / Q000382:microbiology / Q000635:transmission; D013295:Streptococcus mutans / Q000235:genetics* / Q000378:metabolism
D018829:Adhesins, Bacterial; D002352:Carrier Proteins; C488758:Cnm protein, Streptococcus mutans; D003094:Collagen