Mitis group streptococci (MGS) were classified based on the nucleotide sequences 16S rRNA gene (16S rDNA) and comprised 13 Streptococcus species. However, 16S rDNA homogeneity among MGS was too high to discriminate between clinical strains at the species level, notably between Streptococcus mitis, Streptococcus oralis, Streptococcus pneumoniae, and Streptococcus pseudopneumoniae. The purpose of this study was to discriminate between 37 strains of MGS isolated from Korean oral cavities using phylogenetic analysis of the DNA-dependant RNA polymerase beta-subunit gene (rpoB). 16S rDNA and rpoB from clinical strains of MGS were sequenced using the dideoxy chain termination method and analyzed using MEGA version 5 software. The resulting phylogenetic data showed that the rpoB sequences could delineate clinical strains of MGS at the species level. Phylogenetic analysis of rpoB is therefore a useful approach for identifying MGS at the species level.
Base Sequence ; Discrimination (Psychology) ; DNA, Ribosomal ; DNA-Directed RNA Polymerases ; Genes, rRNA ; Streptococcus ; Streptococcus mitis ; Streptococcus oralis ; Streptococcus pneumoniae

The authors observed the long term effects of chlorhexidine varnish treatment on microbial of dental plaque in orthodontic patients with fixed appliances. The initial sample was 100 patients who were arranged to be treated with fixed orthodontic appliances. The final sample consisted of 21 patients who could be traced for 32 weeks after application of fixed orthodontic appliances. They were classified into the experimental group (12 patients) and the control group (9 patients). The experimental group was treated with chlorhexidine varnish once a week for 4 weeks before application of fixed orthodontic appliance. The control group was not treated with chlorhexidine varnish before application of fixed orthodontic appliance. The experimental group was treated once more after 20 weeks. The microbial changes of dental plaque were analysed by indirect immunofluorescence technique at pre-treatment 4, 8, 20, and 32 weeks. The result were as follows. 1. In the experimental group, streptococcus mutans was significantly suppressed during experimental period. (p<0.01) But, in the control group, streptococcus mutans was significantly increased after placement of fixed orthodontic appliances during experiment period. (p<0.05) 2. Streptococcus sanguis, streptococcus mitis, Actinomyces viscosus, and Actinomyces naeslundii did not show significant change between the experimental and the control group during experiment period.
Actinomyces ; Actinomyces viscosus ; Chlorhexidine* ; Dental Plaque* ; Fluorescent Antibody Technique, Indirect ; Humans ; Orthodontic Appliances ; Paint* ; Streptococcus mitis ; Streptococcus mutans ; Streptococcus sanguis

BACKGROUND: Right-to-left vascular shunts are associated with brain abscess. CASE REPORT: We present a 47-year-old female with a cryptogenic left thalamic abscess on which Streptococcus mitis grew upon aspiration. Computed tomography of the chest with contrast agent revealed an anomalous connection between the left superior pulmonary and brachiocephalic veins. A right-to-left shunt was confirmed in a transthoracic echocardiogram study in which bubbles were injected into the left arm; this shunt had not previously been noted upon right-arm injection. CONCLUSIONS: We recommend aggressive evaluation for right-to-left shunts in patients who present with cryptogenic brain abscesses. In addition to imaging, this should include a bubble-based study with left-arm saline injection.
Abscess ; Arm ; Brachiocephalic Veins ; Brain Abscess* ; Brain* ; Female ; Humans ; Middle Aged ; Streptococcus mitis ; Thorax

Botryomycosis is an uncommon chronic suppurative bacterial infection of the skin and visceral organs seen primarily in immunocompromised patients. Here, we report a case of splenic botryomycosis caused by Streptococcus mitis in a 53-year-old immunocompetent woman with a history of distal gastrectomy for advanced gastric cancer.
Bacterial Infections ; Female ; Gastrectomy* ; Humans ; Immunocompromised Host ; Middle Aged ; Skin ; Spleen ; Stomach Neoplasms ; Streptococcus mitis*

BACKGROUND: Viridans group streptococci (VGS) are being increasingly reported as pathogens causing septicemia in neutropenic and other immunocompromised patients since 1980s. In the past, VGS were nearly uniformly susceptible to beta-lactam antimicrobial agents, aminoglycosides, tetracyclines, and macrolides. Several recent published studies, however, indicate that antimicrobial resistance may be emerging as a problem with VGS. The purpose of this study was to determine the antimicrobial susceptibility of VGS strains isolated from blood cultures in recent period. METHODS: A total of 45 consecutive strains of VGS isolated from blood cultures between May 2001 and March 2002 at Wonju Christian Hospital were tested for antimicrobial susceptibility. Identification of VGS were performed by API Strep 32(bioMerieux sa, Marcy-l'Etoile, France) commercial kit. Antimicrobial susceptibility tests were done by NCCLS recommended disk diffusion method and penicillin MICs were determined by E test. RESULTS: Among the 45 VGS strains, frequently isolated organisms were Streptococcus mitis (31.1%), Streptococcus oralis (17.8%), Streptococcus constellatus (11.1%), and Streptococcus anginosus (8.9%). Overall intermediate-and resistant rates to antimicrobial agents of VGS were as follows: penicillin; 26.7% and 8.9%, erythromycin; 4.4% and 28.9%, clindamycin 2.2% and 22.2%, and ceftriaxone; 4.4% and 6.7%, respectively. Resistant rates of Streptococcus mitis and Streptococcus oralis were as follows: penicillin; 50% vs 50%, erythromycin 43% vs 37%, clindamycin 21% vs 37%, and ceftriaxone 7% vs 25%, respectively. CONCLUSIONS: These results indicate the species-related variability of susceptibility among VGS isolated from blood in recent period. In addition to S. mitis, S. oralis also displayed high rates of resistance to penicillin, macrolides, and ceftriaxone. The difference in susceptibilities between species of VGS indicates the importance of accurate identification and the need for continuing monitoring of antimicrobial resistance.
Aminoglycosides ; Anti-Infective Agents ; Ceftriaxone ; Clindamycin ; Diffusion ; Erythromycin ; Gangwon-do ; Immunocompromised Host ; Macrolides ; Penicillin Resistance ; Penicillins ; Sepsis ; Streptococcus anginosus ; Streptococcus constellatus ; Streptococcus mitis ; Streptococcus oralis ; Tetracyclines ; Viridans Streptococci*

This study aimed to evaluate the antimicrobial effects of Acanthopanax sessiliflorum fruit (ASF; Ogaza) extracts on Streptococcus mutans and Streptococcus sobrinus, which are agents that cause dental caries, and on Streptococcus mitis and Streptococcus salivarius, the microbial flora of the oral cavity. The ASF extracts obtained using 70% ethanol were fractionated in the order of ethyl acetate and n-Butanol, concentrated under reduced pressure, and lyophilized to give powdery solvent extracts. The antimicrobial activity of ASF extracts from each solvent was examined using the disk diffusion method. As a result, only those extracts obtained using an ethyl acetate solvent showed antimicrobial activity. These extracts were selected, and the minimum inhibitory concentration was measured by disk diffusion method at various extract concentrations. Results showed a minimum inhibitory concentration of 32 mg/ml. The viable cell count was measured to confirm the minimum bactericidal concentration. Results showed a minimum bactericidal concentration of 64 mg/ml. In the cytotoxicity test using normal human dermal fibroblast cells, the absorbance value of the test group was similar to that of the control group at 0.64, 1.28, and 6.4 mg/ml. The bacteria and their colonies were examined using a scanning electron microscope. Boundaries between the antimicrobial activity region and non-antimicrobial activity region were observed around the paper disk, which was immersed in the extract with 32 mg/ml concentration. Bacterial colonization was not observed in the area with antimicrobial activity. This finding suggests that ASF extracts can inhibit the growth of some microorganisms in the oral cavity, in addition to the effects of these extracts known to date. In particular, ASF extracts may be used as a preparation for preventing dental caries by adding the extract to the toothpaste or oral mouthwash.
1-Butanol ; Bacteria* ; Cell Count ; Colon ; Dental Caries ; Diffusion ; Eleutherococcus* ; Ethanol ; Fibroblasts ; Fruit* ; Humans ; Methods ; Microbial Sensitivity Tests ; Mouth ; Streptococcus ; Streptococcus mitis ; Streptococcus mutans ; Streptococcus sobrinus ; Toothpastes

BACKGROUND: Cases of infective endocarditis (IE) require prompt etiological diagnosis for effective treatment. Molecular methods can aid in rapid and reliable diagnosis of culture-negative IE cases. We evaluated the utility of 16S rDNA PCR and sequencing in determining the causative agents of IE in valve tissues, especially when specimens were obtained after initiation of antimicrobial therapy. METHODS: We performed 16S rDNA PCR and sequencing in heart valve specimens and medical records review of 80 patients who underwent protocol-based cardiac surgery from 2013 to 2015. One patient did not meet the criteria for IE. Sixty-five (81.3%) and 14 pa-tients (17.5%) were diagnosed as having definite IE and possible IE, respectively. Blood and heart valve biopsy tissue were examined by using routine microbiological methods. RESULTS: Blood cultures in our hospital were IE-positive for 33 patients (41.8%), whereas 49 patients (62.0%) showed positive blood cultures when initial blood cultures performed at the referring hospital were included. Eighteen (22.8%) and 40 patients (50.6%) were IE-positive in valve tissue cultures and 16S rDNA PCR, respectively. Bacteria in the Streptococcus mitis group (n=26) were the most common etiological agents of IE. Eight (10.1%) culture-negative specimens tested positive by 16S rDNA PCR. In five of eight PCR-positive and culture-negative cases, fastidious or anaerobic organisms were the cause of IE. CONCLUSIONS: Direct 16S rDNA PCR and sequencing can be used as a supplementary method to conventional blood and biopsy culture testing, especially in culture-negative IE cases that are negative for IE by culture.
Bacteria ; Biopsy ; Diagnosis* ; DNA, Ribosomal* ; Endocarditis* ; Heart Valves ; Humans ; Medical Records ; Methods ; Polymerase Chain Reaction* ; Streptococcus mitis ; Thoracic Surgery

Human infection caused by Shewanella algae is rare, which usually occurred after direct contact with seawater or ingestion of raw seafood in the immunocompromised host. There have been anecdotal reports about Shewanella infections in human, but their pathogenic role and microbiologic data are limited. Here, we report a fatal case of spontaneous bacterial peritonitis with bacteremia due to S. algae in a 57-year-old male with liver cirrhosis who had no history of exposure to seawater or raw seafood. Polymicrobial infection with Streptococcus mitis and Escherichia coli was combined and the patient died in spite of early appropriate antimicrobial therapy and early goal-directed therapy for sepsis.
Bacteremia* ; Coinfection ; Eating ; Escherichia coli ; Humans ; Immunocompromised Host ; Liver Cirrhosis ; Male ; Middle Aged ; Peritonitis* ; Seafood ; Seawater ; Sepsis ; Shewanella* ; Streptococcus mitis

PURPOSE: Streptococcus mitis, one of the Viridans streptococci, is a normal female genital tract flora. It is known as a common cause of chorioamnionitis and subsequent abortions in perinatal period. Although it has been suggested to be less virulent they can cause severe neonatal infections. In this study, we focused on the clinical presentations of neonatal septicemia and the antibiotic susceptibilities of Streptococcus mitis. METHODS: Nine newborns for whom Streptococcus mitis was isolated from normally sterile sites were seen in the NICU of Eulji University Hospital from Jan. 1 to Dec. 31 2005. Medical records were reviewed for the perinatal risk factors, maternal clinical manifestations, obstetric complications and the placental pathologic findings. We also observed the neonatal clinical courses and antibiotic susceptibilities of Streptococcus mitis. RESULTS: All nine infants were high-risk newborns because of prematurity, low birth weight and/or co-morbid diseases. Clinical manifestations varied from asymptomatic to severe neonatal sepsis. Six cases resistant to ampicillin were all sensitive to vancomycin. Five among them had clinical sepsis, and one infant was asymptomatic. Three cases were sensitive to ampicillin, two of them were asymptomatic and one infant with sepsis was successfully treated with ampicillin and aminoglycoside. CONCLUSION: Streptococci mitis should not be overlooked as a contaminant when isolated from normally sterile sites. If Streptococci mitis or Viridans streptococci are recovered from a high-risk newborn showing no clinical response to penicillin, it would be better to switch antibiotics to vancomycin until the susceptibility results available.
Ampicillin ; Anti-Bacterial Agents ; Chorioamnionitis ; Female ; Humans ; Infant ; Infant, Low Birth Weight ; Infant, Newborn ; Medical Records ; Penicillins ; Pregnancy ; Risk Factors ; Sepsis* ; Streptococcus mitis* ; Streptococcus* ; Vancomycin ; Viridans Streptococci

Dental professionals are repeatedly exposed to many microorganisms present in both blood and saliva. Thus, dental professionals are at a greater risk of acquiring and spreading infections, and the implementation of infections control guidelines is necessary. Cellular phones have become a necessary device for communicating in hospitals. Cellular phones contaminated with bacteria may serve as a fomite in the transmission of pathogens by the hands of medical personnel. Nevertheless, studies about rate and levels of bacterial contamination of cellular phones have been extremely limited with regards to dental personnel. The purpose of this study was to identify bacterial flora on the cellular phones of dentists by a molecular biological method using the 16S rRNA cloning and sequencing method. We acquired total 200 clones from dentists' cell phones and identified the bacterial species. Pseudomonas (34.6%), Lactobacillus (18.5%), Azomonas (11.5%), and Janthinobacterium (6%) were the dominant genera on dentists' cell phones. The oral bacteria identified were Anaerococcus lactolyticus, Gibbsiella dentisursi, Lactobacills leiae, Streptococcus mitis, Streptococcus oligofermentans, and Streptococcus sanguinis. Pathogenic bacteria and opportunistic pathogens such as Carnobacterium funditum, Raoultella planticola, Shigella flexneri, Lactobacillus iners, Staphylococcus aureus, and Staphylococcus epidermidis were also identified.
Bacteria ; Carnobacterium ; Cellular Phone* ; Clone Cells ; Cloning, Organism ; Dentists* ; Fomites ; Hand ; Humans ; Lactobacillus ; Pseudomonadaceae ; Pseudomonas ; Saliva ; Shigella flexneri ; Staphylococcus aureus ; Staphylococcus epidermidis ; Streptococcus ; Streptococcus mitis