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*

LIVE/DEAD(R) BacLight(TM) and alamarBlue(R) are fluorescent materials used for the enumeration of live and dead bacteria. LIVE/DEAD(R) BacLight(TM) is generally used for confocal microscopy applications to differentiate live from dead bacteria in a biofilm or planktonic state. AlamarBlue(R) has also been used widely to assay live and dead bacteria in a planktonic state. Whilst these materials are successfully utilized in experiments to discriminate live from dead bacteria for several species of bacteria, the application of these techniques to oral bacteria is limited to the use of LIVE/DEAD(R) BacLight(TM) in biofilm studies. In our present study, we assessed whether these two methods could enumerate live and dead oral bacterial species in a planktonic state. We tested the reagents on Streptococcus mutans, Streptococcus sobrinus, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans and Enterococcus faecalis and found that only LIVE/DEAD(R) BacLight(TM) could differentiate live from dead cells for all five of these oral strains. AlamarBlue(R) was not effective in this regard for P. gingivalis or A. actinomycetemcomitans. In addition, the differentiation of live and dead bacterial cells by alamarBlue(R) could not be performed for concentrations lower than 2 x 10(6) cells/ml. Our data thus indicate that LIVE/DEAD(R) BacLight(TM) is a more effective reagent for this analysis.
Bacteria ; Biofilms ; Enterococcus faecalis ; Fluorescence ; Indicators and Reagents ; Microbial Viability ; Microscopy, Confocal ; Oxazines ; Plankton ; Porphyromonas gingivalis ; Streptococcus mutans ; Streptococcus sobrinus ; Viridans Streptococci ; Xanthenes

OBJECTIVETo evaluate the effects of Yili dark bee propolis on the main cariogenic biofilm and mechanisms.

METHODSSusceptibilities to the ethanolic extract of propolis against Streptococcus mutans (S. mutans), Streptococcus sobrinus (S. sobrinus), Streptococcus sanguis (S. sanguis), Actinomyces viscosus (A. viscosus), and Actinomyces naeslundii (A. naeslundii) were analyzed by crystal violet stain method to determine the minimum biofilm eradication concentration (MBEC). The biofilm was initially cultivated for 24 h. Subsequently, the propolis groups with different concentration MBEC and initial pH 7.0 were cultured for 24 h. Moreover, the pH value was measured to evaluate the acid-producing ability of the tested plaque biofilm. The effects of propolis on the insoluble extracellular polysaccharide synthesis of S. mutans biofilm were evaluated by anthrone method.

RESULTSThe MBEC of Yili propolis on S. mutans, S. sobrinus, S. sanguis, A. viscosus, and A. naeslundii were 6.25, 1.56, 3.13, 0.78, and 0.78 mg.mL-1, respectively. Propolis could decrease the ΔpH of the tested plaque biofilm, and the differences between the control and propolis groups were statistically significant (P<0.05). At MBEC, propolis could reduce the ability of S. mutans in synthesizing insoluble extracellular polysaccharides.

CONCLUSIONYili propolis demonstrate remarkable eradicative effects on the cariogenic plaque biofilm, showing inhibition of the synthesis of biofilm-produced acids and insoluble extracellular polysaccharides.

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

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

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

Two matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS)-based methods were compared for their ability to identify viridans streptococci. One approach employed a reference database and software developed in-house. All inhouse measurements were performed using an Autoflex II Instrument (Bruker Daltonics GmbH, Germany). The other system, a VITEK-MS (BioMérieux, France) was operated on the commercially available V2.0 Knowledge Base for Clinical Use database. Clinical isolates of viridans streptococci (n=184) were examined. Discrepant results were resolved by 16S rDNA sequencing. Species-level identification percentages were compared by a chi-square test. The in-house method correctly identified 179 (97%) and 175 (95%) isolates to the group and species level respectively. In comparison, the VITEK-MS system correctly identified 145 (79%) isolates to the group and species level. The difference between the two methods was statistically significant at both group and species levels. Using the Autoflex II instrument combined with an extraction method instead of whole cell analysis resulted in more reliable viridans streptococci identification. Our results suggest that combining extraction with powerful analysis software and the careful choice of well-identified strains included into the database was useful for identifying viridans streptococci species.
DNA, Ribosomal ; Knowledge Bases ; Mass Spectrometry* ; Methods* ; Viridans Streptococci*

Oral viridans streptococci are recognized as one of the etiological agents of a variety of infectious diseases such as dental caries and infective endocarditis. Although antimicrobial susceptibility tests for these fastidious bacterial species are now established and standardized, a comparison between the broth microdilution and broth macrodilution tests has not previously been performed. This comparison was performed in the present study using the tests adopted by the Clinical and Laboratory Standards Institute (CLSI) and seven clinical isolates of oral viridans streptococcal strains. A modified broth macrodilution susceptibility test method was also included in this analysis, in which the media was not supplemented with horse blood. The susceptibility interpretation category agreements were measured at 83% (broth microdilution versus broth macrodilution) and 71% (broth microdilution versus modified broth macrodilution). The interpretation category agreement between the broth macrodilution and modified broth macrodilution tests was also 83%. These data indicate that the interpretation of antibiotic susceptibility test results for oral viridans streptococci are influenced by the methods used.
Communicable Diseases ; Dental Caries ; Endocarditis ; Horses ; Viridans Streptococci

No abstract available.
Erythrosine ; Light ; Photochemotherapy ; Streptococcus ; Streptococcus mutans ; Streptococcus sobrinus

Anginosus group streptococci (AGS) were classified based on the nucleotide sequences of the 16S rRNA gene (16S rDNA) and comprised Streptococcus anginosus, Streptococcus intermedius, and Streptococcus constellatus. It is known that AGS is a causative factor of oral and systematic diseases. The purpose of this study was to discriminate the 56 clinical strains of AGS isolated from Korean oral cavities using phylogenetic analysis of 16S rDNA and species-specific PCR at the species-level. The 16S rDNA of clinical strains of AGS was sequenced using the dideoxy chain termination method and analyzed using MEGA version 5 software. PCR was performed to identify the clinical strains using species-specific primers described in previous studies and S. intermedius-specific PCR primers developed in our laboratory. The resulting phylogenetic data showed that the 16S rDNA sequences can delineate the S. anginosus, S. intermedius, and S. constellatus strains even though the 16S rDNA sequence similarity between S. intermedius and S. constellatus is above 98%. The PCR data showed that each species-specific PCR primer pair could discriminate between clinical strains at the species-level through phylogenetic analysis of 16S rDNA nucleotide sequences. These results suggest that phylogenetic analysis of 16S rDNA and PCR are useful tools for discriminating between AGS strains at the species-level.
Base Sequence ; DNA, Ribosomal ; Genes, rRNA ; Mouth ; Polymerase Chain Reaction ; Streptococcus anginosus ; Streptococcus constellatus ; Streptococcus intermedius