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1.  Contribution of the Interaction of Streptococcus mutans Serotype k Strains with Fibrinogen to the Pathogenicity of Infective Endocarditis 
Infection and Immunity  2014;82(12):5223-5234.
Streptococcus mutans, a pathogen responsible for dental caries, is occasionally isolated from the blood of patients with bacteremia and infective endocarditis (IE). Our previous study demonstrated that serotype k-specific bacterial DNA is frequently detected in S. mutans-positive heart valve specimens extirpated from IE patients. However, the reason for this frequent detection remains unknown. In the present study, we analyzed the virulence of IE from S. mutans strains, focusing on the characterization of serotype k strains, most of which are positive for the 120-kDa cell surface collagen-binding protein Cbm and negative for the 190-kDa protein antigen (PA) known as SpaP, P1, antigen I/II, and other designations. Fibrinogen-binding assays were performed with 85 clinical strains classified by Cbm and PA expression levels. The Cbm+/PA− group strains had significantly higher fibrinogen-binding rates than the other groups. Analysis of platelet aggregation revealed that SA31, a Cbm+/PA− strain, induced an increased level of aggregation in the presence of fibrinogen, while negligible aggregation was induced by the Cbm-defective isogenic mutant SA31CBD. A rat IE model with an artificial impairment of the aortic valve created using a catheter showed that extirpated heart valves in the SA31 group displayed a prominent vegetation mass not seen in those in the SA31CBD group. These findings could explain why Cbm+/PA− strains are highly virulent and are related to the development of IE, and the findings could also explain the frequent detection of serotype k DNA in S. mutans-positive heart valve clinical specimens.
PMCID: PMC4249299  PMID: 25287921
2.  Effect of Cryotherapy after Spine Surgery 
Asian Spine Journal  2014;8(6):753-758.
Study Design
Historical controlled trial.
To clarify the usefulness of cryotherapy after spine surgery.
Overview of Literature
Cryotherapy has generally been performed subsequent to surgery on joints and in this application its clinical effects are well understood. However, cryotherapy has yet to be used following spine surgery. Its clinical efficacy in this context is unknown.
Thirty six patients had undergone one level microendoscopic surgery. Sixteen were enrolled into the cooling group, with the remaining 20 making up the no postoperative cryotherapy control group. Cryotherapy was performed at 5℃ using an icing system. A silicone balloon catheter with a thermo sensor on the tip was placed in the surgical wound. The temperature in the wound was recorded every 30 minutes until the next morning. The relationship between the depth of the sensor and the temperature in the wound were investigated using simple linear regression analysis. Laboratory data, visual analogue scale (VAS) for wound pain and postoperative bleeding were investigated.
The mean temperature in the surgical wound was 37.0 in the control group and 35.0℃ in the cooling group (p<0.001). There was a positive correlation between the depth of the thermo sensor and the temperature in the wound in the cooling group (y=0.91x+30.2, r=0.67, p=0.004). There were no significant differences between the groups in terms of laboratory data, VAS or postoperative bleeding.
The temperature in the wound was decreased significantly by spinal surgery cryotherapy.
PMCID: PMC4278980  PMID: 25558317
Cryotherapy; Spine; Temperature
3.  Identification and Functional Analysis of an Ammonium Transporter in Streptococcus mutans 
PLoS ONE  2014;9(9):e107569.
Streptococcus mutans, a Gram-positive bacterium, is considered to be a major etiologic agent of human dental caries and reported to form biofilms known as dental plaque on tooth surfaces. This organism is also known to possess a large number of transport proteins in the cell membrane for export and import of molecules. Nitrogen is an essential nutrient for Gram-positive bacteria, though alternative sources such as ammonium can also be utilized. In order to obtain nitrogen for macromolecular synthesis, nitrogen-containing compounds must be transported into the cell. However, the ammonium transporter in S. mutans remains to be characterized. The present study focused on characterizing the ammonium transporter gene of S. mutans and its operon, while related regulatory genes were also analyzed. The SMU.1658 gene corresponding to nrgA in S. mutans is homologous to the ammonium transporter gene in Bacillus subtilis and SMU.1657, located upstream of the nrgA gene and predicted to be glnB, is a member of the PII protein family. Using a nrgA-deficient mutant strain (NRGD), we examined bacterial growth in the presence of ammonium, calcium chloride, and manganese sulfate. Fluorescent efflux assays were also performed to reveal export molecules associated with the ammonium transporter. The growth rate of NRGD was lower, while its fluorescent intensity was much higher as compared to the parental strain. In addition, confocal laser scanning microscopy revealed that the structure of biofilms formed by NRGD was drastically different than that of the parental strain. Furthermore, transcriptional analysis showed that the nrgA gene was co-transcribed with the glnB gene. These results suggest that the nrgA gene in S. mutans is essential for export of molecules and biofilm formation.
PMCID: PMC4167856  PMID: 25229891
4.  External validation of risk classification in patients with docetaxel-treated castration-resistant prostate cancer 
BMC Urology  2014;14:31.
Castration-resistant prostate cancer (CRPC) patients have poor prognoses, and docetaxel (DTX) is among the few treatment options. An accurate risk classification to identify CRPC patient groups for which DTX would be effective is urgently warranted. The Armstrong risk classification (ARC), which classifies CRPC patients into 3 groups, is superior; however, its usefulness remains unclear, and further external validation is required before clinical use. This study aimed to examine the clinical significance of the ARC through external validation in DTX-treated Japanese CRPC patients.
CRPC patients who received 2 or more DTX cycles were selected for this study. Patients were classified into good-, intermediate-, and poor-risk groups according to the ARC. Prostate-specific antigen (PSA) responses and overall survival (OS) were calculated and compared between the risk groups. A multivariate analysis was performed to clarify the relationship between the ARC and major patient characteristics.
Seventy-eight CRPC patients met the inclusion criteria. Median PSA levels at DTX initiation was 20 ng/mL. Good-, intermediate-, and poor-risk groups comprised 51 (65%), 17 (22%), and 10 (13%) patients, respectively. PSA response rates ≥30% and ≥50% were 33%, 41%, and 30%, and 18%, 41%, and 20% in the good-, intermediate-, and poor-risk groups, respectivcixely, with no significant differences (p = 0.133 and 0.797, respectively). The median OS in the good-, intermediate-, and poor-risk groups were statistically significant (p < 0.001) at 30.1, 14.2, and 5.7 months, respectively. A multivariate analysis revealed that the ARC and PSA doubling time were independent prognostic factors.
Most of CRPC patients were classified into good-risk group according to the ARC and the ARC could predict prognosis in DTX-treated CRPC patients.
Trial registration
University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) number, UMIN000011969.
PMCID: PMC3997751  PMID: 24742323
Castration-resistant prostate cancer; Docetaxel; Risk classification; Validation study
5.  Porphyromonas gingivalis fimbriae 
Journal of Oral Microbiology  2013;5:10.3402/jom.v5i0.20265.
Marginal periodontitis is not a homogeneous disease but is rather influenced by an intricate set of host susceptibility differences as well as diversities in virulence among the harbored organisms. It is likely that clonal heterogeneity of subpopulations with both high and low levels of pathogenicity exists among organisms harbored by individuals with negligible, slight, or even severe periodontal destruction. Therefore, specific virulent clones of periodontal pathogens may cause advanced and/or aggressive periodontitis. Porphyromonas gingivalis is a predominant periodontal pathogen that expresses a number of potential virulence factors involved in the pathogenesis of periodontitis, and accumulated evidence shows that its expression of heterogenic virulence properties is dependent on clonal diversity. Fimbriae are considered to be critical factors that mediate bacterial interactions with and invasion of host tissues, with P. gingivalis shown to express two distinct fimbria-molecules, long and short fimbriae, on the cell surface, both of which seem to be involved in development of periodontitis. Long fimbriae are classified into six types (I to V and Ib) based on the diversity of fimA genes encoding FimA (a subunit of long fimbriae). Studies of clones with type II fimA have revealed their significantly greater adhesive and invasive capabilities as compared to other fimA type clones. Long and short fimbriae induce various cytokine expressions such as IL-1α, IL-β, IL-6, and TNF-α, which result in alveolar bone resorption. Although the clonal diversity of short fimbriae is unclear, distinct short fimbria-molecules have been found in different strains. These fimbriae variations likely influence the development of periodontal disease.
PMCID: PMC3647041  PMID: 23667717
P. gingivalis; long fimbriae; short fimbriae; FimA; genotype; mfa1
6.  Complete Genome Sequence of the Serotype k Streptococcus mutans Strain LJ23 
Journal of Bacteriology  2012;194(10):2754-2755.
Streptococcus mutans is the major pathogen of dental caries and occasionally causes infective endocarditis. Here we report the complete genome sequence of serotype k S. mutans strain LJ23, which was recently isolated from the oral cavity of a Japanese patient.
PMCID: PMC3347197  PMID: 22535936
7.  Infection of specific strains of Streptococcus mutans, oral bacteria, confers a risk of ulcerative colitis 
Scientific Reports  2012;2:332.
Although oral bacteria-associated systemic diseases have been reported, association between Streptococcus mutans, pathogen of dental caries, and ulcerative colitis (UC) has not been reported. We investigated the effect of various S. mutans strains on dextran sodium sulfate (DSS)-induced mouse colitis. Administration of TW295, the specific strain of S. mutans, caused aggravation of colitis; the standard strain, MT8148 did not. Localization of TW295 in hepatocytes in liver was observed. Increased expression of interferon-γ in liver was also noted, indicating that the liver is target organ for the specific strain of S. mutans-mediated aggravation of colitis. The detection frequency of the specific strains in UC patients was significantly higher than in healthy subjects. Administration of the specific strains of S. mutans isolated from patients caused aggravation of colitis. Infection with highly-virulent specific types of S. mutans might be a potential risk factor in the aggravation of UC.
PMCID: PMC3312205  PMID: 22451861
8.  Docetaxel with or without estramustine for estramustine refractory castration-resistant prostate cancer: a single institution experience 
BMC Urology  2012;12:3.
The significance of combination of docetaxel (DTX) with estramustine phosphate (EMP) in castration-resistant prostate cancer (CRPC) patients remains unclear. In this study, we aimed to retrospectively evaluate the efficacy and toxicity of DTX with or without EMP and to elucidate the significance of DTX and EMP combination therapy in Japanese EMP-refractory CRPC patients.
To compare the efficacy and toxicity of DTX and EMP, we divided CRPC patients, who were confirmed to be resistant to EMP, into the following two groups: group D (n = 28), which included patients treated with DTX (60 mg/m2, once in every four weeks) alone, and group DE (n = 33), which included patients treated with a combination of DTX (60 mg/m2, once in every four weeks) and EMP (twice daily oral administration at 280 mg).
Prostate specific antigen (PSA) response (> 50% decline in PSA) was observed in six patients (21%) in group D and eight patients (24%) in group DE. The median time to progression (TTP) was 12.0 months and 6.2 months and the median overall survival (OS) was 26.4 months and 24.3 months in group D and DE, respectively. There was no statistical difference between the two groups in terms of PSA response, TTP, and OS. The incidence of adverse events of grade 3/4 was low in both the groups, and there was no statistical difference between the two groups.
Although treatment with DTX at 60 mg/m2 was effective and highly tolerated in EMP-refractory Japanese CRPC patients, the DTX and EMP combination therapy might not exhibit any survival benefit for CRPC patients.
PMCID: PMC3305626  PMID: 22353627
9.  Life-threatening acute acalculous cholecystitis in a patient with renal cell carcinoma treated by sunitinib: a case report 
Sunitinib, an oral multitargeted tyrosine kinase inhibitor, is widely used in the treatment of renal cell carcinoma and gastrointestinal stromal tumor and has had a variety of adverse events. However, sunitinib-related acute cholecystitis has been reported in only two patients with gastrointestinal stromal tumor and renal cell carcinoma (clear cell subtype).
Case presentation
A 75-year-old Japanese woman with a right sided abdominal swelling was referred to our hospital. Computed tomography (CT) showed a hypervascular bulky tumor in her right kidney, suggesting right renal cell carcinoma in clinical T4N0M0. Although sunitinib therapy was started as neoadjuvant chemotherapy, during the fourth week of the first cycle, she developed acute acalculous cholecystitis and disseminated intravascular coagulation associated with sunitinib. Sunitinib therapy was discontinued immediately and she recovered after subsequent treatment with antibiotics and gabexate mesilate followed by percutaneous cholecystostomy. Cholecystectomy and right radical nephrectomy were performed and pathological examination showed that her renal tumor was a chromophobe renal cell carcinoma (pT2) with necrosis. Inflammation and ischemia were observed in the gallbladder wall, which was compatible with acute acalculous cholecystitis. There has been no evidence of disease recurrence for more than six months.
We described the third case of sunitinib-related acute cholecystitis in a patient with chromophobe renal cell carcinoma. Attention is required to sunitinib-related acute cholecystitis which, while uncommon, could be life-threatening.
PMCID: PMC3307430  PMID: 22348690
10.  Involvement of a periodontal pathogen, Porphyromonas gingivalis on the pathogenesis of non-alcoholic fatty liver disease 
BMC Gastroenterology  2012;12:16.
Non-alcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome that is closely associated with multiple factors such as obesity, hyperlipidemia and type 2 diabetes mellitus. However, other risk factors for the development of NAFLD are unclear. With the association between periodontal disease and the development of systemic diseases receiving increasing attention recently, we conducted this study to investigate the relationship between NAFLD and infection with Porphyromonas gingivalis (P. gingivalis), a major causative agent of periodontitis.
The detection frequencies of periodontal bacteria in oral samples collected from 150 biopsy-proven NAFLD patients (102 with non-alcoholic steatohepatitis (NASH) and 48 with non-alcoholic fatty liver (NAFL) patients) and 60 non-NAFLD control subjects were determined. Detection of P. gingivalis and other periodontopathic bacteria were detected by PCR assay. In addition, effect of P. gingivalis-infection on mouse NAFLD model was investigated. To clarify the exact contribution of P. gingivalis-induced periodontitis, non-surgical periodontal treatments were also undertaken for 3 months in 10 NAFLD patients with periodontitis.
The detection frequency of P. gingivalis in NAFLD patients was significantly higher than that in the non-NAFLD control subjects (46.7% vs. 21.7%, odds ratio: 3.16). In addition, the detection frequency of P. gingivalis in NASH patients was markedly higher than that in the non-NAFLD subjects (52.0%, odds ratio: 3.91). Most of the P. gingivalis fimbria detected in the NAFLD patients was of invasive genotypes, especially type II (50.0%). Infection of type II P. gingivalis on NAFLD model of mice accelerated the NAFLD progression. The non-surgical periodontal treatments on NAFLD patients carried out for 3 months ameliorated the liver function parameters, such as the serum levels of AST and ALT.
Infection with high-virulence P. gingivalis might be an additional risk factor for the development/progression of NAFLD/NASH.
PMCID: PMC3305584  PMID: 22340817
Non-alcoholic fatty liver disease (NAFLD); Non-alcoholic steatohepatitis (NASH); P. gingivalis; Oral bacteria; Insulin resistance
11.  Distribution of periodontopathic bacterial species in Japanese children with developmental disabilities 
BMC Oral Health  2009;9:24.
Recent developments in molecular biological techniques have enabled rapid detection of periodontopathic bacterial species in clinical specimens. Accumulated evidence suggests that detection of specific bacterial species enables identification of subjects at high risk for the onset of periodontitis. We investigated the distribution of 10 selected periodontopathic bacterial species in dental plaque specimens obtained from children with disabilities who were attending daycare centers.
A total of 187 children (136 boys, 51 girls) aged 1-6 years old and diagnosed with such disabilities as mental retardation, cerebral palsy, and autism, participated in the study. Subgingival dental plaque specimens were collected from the buccal side of the maxillary left second primary molar after a clinical examination. Bacterial DNA was extracted from the specimens and PCR analyses were carried out to detect 10 selected periodontopathic species using specific primers for each. In addition, statistical analyses were performed to analyze the correlations among clinical parameters and the detected species.
The most frequently detected species was Capnocytophaga sputigena (28.3%), followed by Aggregatibacter actinomycetemcomitans (20.9%) and Campylobacter rectus (18.2%). Eikenella corrodens, Capnocytophaga ochracea, and Prevotella nigrescence were detected in approximately 10% of the specimens, whereas Treponema denticola, Tannerella forsythia, and Prevotella intermedia were rarely found, and Porphyromonas gingivalis was not detected in any of the subjects. The total numbers of detected species were positively correlated with the age of the subjects. There were 10 subjects with positive reactions for T. denticola and/or T. forsythia, in whom the total number of bacterial species was significantly higher as compared to the other subjects. Furthermore, subjects possessing C. rectus showed significantly greater values for periodontal pocket depth, gingival index, and total number of species.
We found that approximately one-fourth of the present subjects with disabilities who possessed at least one of T. denticola, T. forsythia, and C. rectus were at possible risk for periodontitis. Follow-up examinations as well as preventive approaches should be utilized for such individuals.
PMCID: PMC2758840  PMID: 19772671
12.  Comparative genomic analyses of Streptococcus mutans provide insights into chromosomal shuffling and species-specific content 
BMC Genomics  2009;10:358.
Streptococcus mutans is the major pathogen of dental caries, and it occasionally causes infective endocarditis. While the pathogenicity of this species is distinct from other human pathogenic streptococci, the species-specific evolution of the genus Streptococcus and its genomic diversity are poorly understood.
We have sequenced the complete genome of S. mutans serotype c strain NN2025, and compared it with the genome of UA159. The NN2025 genome is composed of 2,013,587 bp, and the two strains show highly conserved core-genome. However, comparison of the two S. mutans strains showed a large genomic inversion across the replication axis producing an X-shaped symmetrical DNA dot plot. This phenomenon was also observed between other streptococcal species, indicating that streptococcal genetic rearrangements across the replication axis play an important role in Streptococcus genetic shuffling. We further confirmed the genomic diversity among 95 clinical isolates using long-PCR analysis. Genomic diversity in S. mutans appears to occur frequently between insertion sequence (IS) elements and transposons, and these diversity regions consist of restriction/modification systems, antimicrobial peptide synthesis systems, and transporters. S. mutans may preferentially reject the phage infection by clustered regularly interspaced short palindromic repeats (CRISPRs). In particular, the CRISPR-2 region, which is highly divergent between strains, in NN2025 has long repeated spacer sequences corresponding to the streptococcal phage genome.
These observations suggest that S. mutans strains evolve through chromosomal shuffling and that phage infection is not needed for gene acquisition. In contrast, S. pyogenes tolerates phage infection for acquisition of virulence determinants for niche adaptation.
PMCID: PMC2907686  PMID: 19656368
13.  Different responses to two types of 5-fluorouracil prodrugs in combination with interferon-alpha in pulmonary metastases of renal cell carcinoma: a case report 
Cases Journal  2009;2:6567.
A 66-year-old Japanese man with pulmonary metastases of renal cell carcinoma found 8 months after radical nephrectomy was treated with interferon-alpha and tegafur-uracil. Since it failed to achieve tumor responses resulting in progression, he was given interferon-alpha and capecitabine. After 2 courses of combination therapy with IFN-alpha and capecitabine, significant tumor responses were obtained; two out of four pulmonary metastatic sites disappeared completely, one site showed over 50% decrease in size, and the remaining one site did no change in size. The regimen was well tolerated and toxicity observed was World Health Organization grade 1 anorexia. His disease status was maintained as stable disease by the repeated treatment with interferon-alpha and capecitabine for 17 months after tumor responses were obtained. However, tumor progression was observed thereafter. He is at present under treatment with sorafenib. This is the first case report of metastatic renal cell carcinoma, which showed different responses to two types of 5-fluorouracil prodrugs in combination with interferon-alpha, suggesting the biochemical modulation of capecitabine by interferon-alpha as a possible mechanism underlying the antitumor effect of the combination of interferon-alpha and capecitabine at the clinical setting. Present case also suggests that a combination of tumor-selective capecitabine with interferon-alpha is a potentially useful therapeutic option in metastatic renal cell carcinoma.
PMCID: PMC2740210  PMID: 19829827
14.  Streptococcus mutans Clonal Variation Revealed by Multilocus Sequence Typing▿  
Journal of Clinical Microbiology  2007;45(8):2616-2625.
Streptococcus mutans is the major pathogen of dental caries, a biofilm-dependent infectious disease, and occasionally causes infective endocarditis. S. mutans strains have been classified into four serotypes (c, e, f, and k). However, little is known about the S. mutans population, including the clonal relationships among strains of S. mutans, in relation to the particular clones that cause systemic diseases. To address this issue, we have developed a multilocus sequence typing (MLST) scheme for S. mutans. Eight housekeeping gene fragments were sequenced from each of 102 S. mutans isolates collected from the four serotypes in Japan and Finland. Between 14 and 23 alleles per locus were identified, allowing us theoretically to distinguish more than 1.2 × 1010 sequence types. We identified 92 sequence types in these 102 isolates, indicating that S. mutans contains a diverse population. Whereas serotype c strains were widely distributed in the dendrogram, serotype e, f, and k strains were differentiated into clonal complexes. Therefore, we conclude that the ancestral strain of S. mutans was serotype c. No geographic specificity was identified. However, the distribution of the collagen-binding protein gene (cnm) and direct evidence of mother-to-child transmission were clearly evident. In conclusion, the superior discriminatory capacity of this MLST scheme for S. mutans may have important practical implications.
PMCID: PMC1951271  PMID: 17567784
15.  Detection of Cariogenic Streptococcus mutans in Extirpated Heart Valve and Atheromatous Plaque Specimens 
Journal of Clinical Microbiology  2006;44(9):3313-3317.
The involvement of oral bacteria in the pathogenesis of cardiovascular diseases has been the focus of attention in many studies, and several periodontal pathogens have been detected in diseased cardiovascular lesions, suggesting relationships between oral microorganisms and cardiovascular diseases. However, no information is available regarding the involvement of cariogenic pathogens such as Streptococcus mutans. The presence of oral streptococcal species and periodontitis-related bacteria in 35 heart valve and 27 atheromatous plaque clinical specimens, as well as 32 dental plaque specimens from the same subjects, was analyzed using a PCR method. Furthermore, broad-range PCR with DNA sequencing analysis was employed to identify the bacterial species in those samples. Streptococcus mutans was frequently detected in the heart valve (69%) and atheromatous plaque (74%) specimens, while other bacterial species, including those related to periodontitis, were detected with much lower frequencies. The bacterial composition in cardiovascular tissues was found to be markedly distinct from that in dental plaque, with only a limited number of species, including S. mutans, in the cardiovascular regions shown to have possibly originated from the oral cavity. Semiquantitative assay results revealed that S. mutans was detected in significant quantities in the heart valve (40%) and atheromatous plaque (48%) specimens, whereas the quantities of all other tested bacterial species, including several related to periodontitis, were negligible in the cardiovascular samples. These results indicate that S. mutans is a possible causative agent of cardiovascular disease.
PMCID: PMC1594668  PMID: 16954266
16.  Development of a PCR Method for Rapid Identification of New Streptococcus mutans Serotype k Strains 
Journal of Clinical Microbiology  2004;42(11):4925-4930.
In a previous study, we isolated and characterized a new serotype k of Streptococcus mutans from human blood and oral cavities. Analysis of the genes involved in biosynthesis of the serotype-specific polysaccharide of serotype k strains revealed that the serotype k-specific nucleotide alignment was commonly present in the 5′ region of the rgpF gene (350 bp from the initial sequence) compared to the reference strains, and then a method for rapid identification of serotype k strains was developed by use of PCR with primers designed on the basis of the sequence of the variable region. PCR assays with primers specific for amplification of serotype k strains showed a negative reaction with serotype c, e, and f strains and a positive reaction with serotype k strains, with the sensitivity for identification of the serotype k strains shown to range from 5 to 50 cells. Next, the frequency of positive reactions for serotype k-specific primers was surveyed with DNA taken from saliva samples from 200 subjects (2 to 18 years of age), and 10 of those showed a positive reaction, which was higher than the frequency in our previous survey with a serological method. In addition, all saliva samples from subjects with serotype k strains in our previous study were shown to be positive with the serotype k-specific primers. These results indicate that this new PCR method is effective for identification of subjects with S. mutans serotype k.
PMCID: PMC525190  PMID: 15528675
17.  Demonstration of Streptococcus mutans with a Cell Wall Polysaccharide Specific to a New Serotype, k, in the Human Oral Cavity 
Journal of Clinical Microbiology  2004;42(1):198-202.
Streptococcus mutans organisms are occasionally isolated from the blood of patients with infective endocarditis, though the mechanisms of invasion and survival remain to be elucidated. Two of four blood isolates from patients with bacteremia or infective endocarditis (strains TW295 and TW871) were serologically untypeable by immunodiffusion testing, which was due to a lack of the glucose side chain of the serotype-specific polysaccharide antigen of S. mutans. Immunodiffusion analyses using antisera against these strains demonstrated that 2 of 100 isolates from 100 subjects showed a positive reaction, while further analysis of 2,500 isolates from 50 subjects revealed that all 50 isolates from a single subject were not reactive with anti-c, -e, and -f antisera, though they were reactive with anti-TW295 and -TW871 antisera. The oral isolates showed biological properties similar to those of the reference S. mutans strain MT8148, including high levels of sucrose-dependent adhesion and cellular hydrophobicity, along with expression of glucosyltransferases and a protein antigen, PA. We designated these organisms serotype k. A glucose side chain-defective mutant strain was then constructed by insertional inactivation of the gluA gene of strain MT8148, which showed biological properties similar to those of serotype k of S. mutans. Serotype k oral isolates were less susceptible to phagocytosis, as were the gluA-inactivated mutant of strain MT8148 and blood isolates. These results indicate that S. mutans serotype k strains are present in the oral cavity in humans and may be able to survive longer in blood owing to their low susceptibility to phagocytosis.
PMCID: PMC321689  PMID: 14715753
18.  The collagen-binding protein of Streptococcus mutans is involved in haemorrhagic stroke 
Nature Communications  2011;2:485-.
Although several risk factors for stroke have been identified, one-third remain unexplained. Here we show that infection with Streptococcus mutans expressing collagen-binding protein (CBP) is a potential risk factor for haemorrhagic stroke. Infection with serotype k S. mutans, but not a standard strain, aggravates cerebral haemorrhage in mice. Serotype k S. mutans accumulates in the damaged, but not the contralateral hemisphere, indicating an interaction of bacteria with injured blood vessels. The most important factor for high-virulence is expression of CBP, which is a common property of most serotype k strains. The detection frequency of CBP-expressing S. mutans in haemorrhagic stroke patients is significantly higher than in control subjects. Strains isolated from haemorrhagic stroke patients aggravate haemorrhage in a mouse model, indicating that they are haemorrhagic stroke-associated. Administration of recombinant CBP causes aggravation of haemorrhage. Our data suggest that CBP of S. mutans is directly involved in haemorrhagic stroke.
The risk factors associated with both ischemic and haemorrhagic stroke are not fully understood. Here a certain strain of the bacteria, Streptococcus mutans, which expresses a collagen-binding protein, is shown to be associated with haemorrhagic stroke in both animal models and human patients.
PMCID: PMC3220351  PMID: 21952219

Results 1-18 (18)