Discover the most talked about and latest scientific content & concepts.

Concept: Streptococcaceae


BACKGROUND: Tea has been suggested to promote oral health by inhibiting bacterial attachment to the oral cavity. Most studies have focused on prevention of bacterial attachment to hard surfaces such as enamel. FINDINGS: This study investigated the effect of five commercial tea (green, oolong, black, pu-erh and chrysanthemum) extracts and tea components (epigallocatechin gallate and gallic acid) on the attachment of five oral pathogens (Streptococcus mutans ATCC 25175, Streptococcus mutans ATCC 35668, Streptococcus mitis ATCC 49456, Streptococcus salivarius ATCC 13419 and Actinomyces naeslundii ATCC 51655) to the HGF-1 gingival cell line. Extracts of two of the teas (pu-erh and chrysanthemum) significantly (p < 0.05) reduced attachment of all the Streptococcus strains by up to 4 log CFU/well but effects of other teas and components were small. CONCLUSIONS: Pu-erh and chrysanthemum tea may have the potential to reduce attachment of oral pathogens to gingival tissue and improve the health of oral soft tissues.

Concepts: Bacteria, Streptococcus, Tea, Camellia sinensis, Gram positive bacteria, Streptococcaceae, Pu-erh tea, Oolong


Pseudomonas aeruginosa causes devastating chronic pulmonary infections in cystic fibrosis (CF) patients. Although the CF airway is inhabited by diverse species of microorganisms interlaced within a biofilm, many studies focus on the sole contribution of P. aeruginosa pathogenesis in CF morbidity. More recently, oral commensal streptococci have been identified as cohabitants of the CF lung, but few studies have explored the role these bacteria play within the CF biofilm. We examined the interaction between P. aeruginosa and oral commensal streptococci within a dual species biofilm. Here we report that the CF P. aeruginosa isolate, FRD1, enhances biofilm formation and colonization of Drosophila melanogaster by the oral commensal Streptococcus parasanguinis. Moreover, production of the P. aeruginosa exopolysaccharide, alginate, is required for the promotion of S. parasanguinis biofilm formation and colonization. However, P. aeruginosa is not promoted in the dual species biofilm. Furthermore, we show that the streptococcal adhesin, BapA1, mediates alginate-dependent enhancement of the S. parasanguinis biofilm in vitro, and BapA1 along with another adhesin, Fap1, are required for the in vivo colonization of S. parasanguinis in the presence of FRD1. Taken together, our study highlights a new association between streptococcal adhesins and P. aeruginosa alginate, and reveals a mechanism by which S. parasanguinis potentially colonizes the CF lung and interferes with the pathogenesis of P. aeruginosa.

Concepts: Immune system, Bacteria, Streptococcus, Pseudomonas aeruginosa, Cystic fibrosis, Polysaccharide, Biofilm, Streptococcaceae


Despite widespread use of intrapartum antibiotic prophylaxis, group B streptococcus remains a leading cause of morbidity and mortality in infants in Europe, the Americas, and Australia. However, estimates of disease burden in many countries outside of these regions is not available. We aimed to examine the current global burden of invasive disease and the serotype distribution of group B streptococcus isolates.

Concepts: Medicine, Death, Streptococcus, England, Islam, Streptococcus agalactiae, Streptococcaceae, Group A streptococcal infection


We conducted a randomized double-blind trial to evaluate the effects of fermented milk produced using only Lactococcus lactis strain H61 as a starter bacterium (H61-fermented milk) on the general health and various skin properties of young women. Healthy female volunteers (n = 23; age = 19-21 yr) received H61-fermented milk (10(10) cfu of strain H61/d) or conventional yogurt (10(10) cfu of both Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus per day), as a reference food, daily for 4 wk. Before and at the end of 4 wk, blood samples were taken, and skin hydration (inner forearms and cheek) and melanin content, elasticity, and sebum content (cheek only) were measured. Skin hydration at the inner forearm was higher at wk 4 than at wk 0 in both groups. Sebum content in cheek rose significantly after intervention in the H61-fermented milk group, but not the conventional yogurt group. Other skin parameters did not differ in either group. Serum analysis showed that total protein concentration and platelet count were elevated and reactive oxygen species decreased in both groups after the intervention. Although H61-fermented milk and conventional yogurt had similar effects on skin status and some blood characteristics of participants, an increase of sebum content in cheek is preferable to H61-fermented milk. As skin lipids contribute to maintaining the skin barrier, H61-fermented milk would provide beneficial effects on skin for young women.

Concepts: Oxygen, Bacteria, Streptococcus, Melanin, Lactobacillus, Serum total protein, Streptococcaceae, Lactococcus lactis


Genomic, taxonomic and biochemical studies were performed on two strains of alpha-haemolytic streptococci that showed to be clustered with major members of the Streptococcus mitis group. These Gram-positive strains were isolated from tooth surfaces of caries-free humans and show the classical spherical-shape of streptococcal species growing in chains. Sequence analysis from concatenated 16S and 23S rDNA, and sodA genes showed that these strains belonged to the Mitis group, but both of them cluster into a new phylogenetic branch. The genomes of these two isolates were sequenced, and whole-genome Average Nucleotide Identity (ANI) demonstrated that these strains significantly differ from any streptococcal species, showing ANI values under 91% even when compared to their phylogenetically closest species such as Streptococcus oralis and Streptococcus mitis. Biochemically, the two isolates also showed distinct metabolic features relative to close species, like an α-galactosidase activity. From the results of the present study, the name Streptococcus dentisani sp. nov. is proposed for these new couple of strains deposited in open collection at the Spanish Type Culture Collection (CECT) and Leibniz Institute DSMZ-German Collection of Microorganism and Cell Cultures (DSMZ); being respectively identified as Streptococcus dentisani Str. 7746 (CECT 8313, DSM 27089) and Streptococcus dentisani Str. 7747 (CECT 8312T, DSM 27088T).

Concepts: Gene, Bacteria, Organism, Streptococcus, Gram positive bacteria, Streptococcaceae, Streptococcus oralis, Streptococcus mitis


Considerable human illness can be linked to the development of oral microbiota disequilibria. The predominant oral cavity commensal, Streptococcus salivarius has emerged as an important source of safe and efficacious probiotics, capable of fostering more balanced, health-associated oral microbiota. Strain K12, the prototype S. salivarius probiotic, originally introduced to counter Streptococcus pyogenes infections, now has an expanded repertoire of health-promoting applications. K12 and several more recently proposed S. salivarius probiotics are now being applied to control diverse bacterial consortia infections including otitis media, halitosis and dental caries. Other potential applications include upregulation of immunological defenses against respiratory viral infections and treatment of oral candidosis. An overview of the key steps required for probiotic development is also presented.

Concepts: Immune system, Bacteria, Gut flora, Streptococcus, Dental caries, Lactobacillus, Streptococcaceae, Streptococcus salivarius


The prevalence of dental caries continues to increase and novel strategies to reverse this trend appear necessary. The probiotic Streptococcus salivarius strain M18 offers potential to confer oral health benefits since it produces a) bacteriocins targeting the important cariogenic species Streptococcus mutans and b) the enzymes dextranase and urease, which could help reduce dental plaque accumulation and acidification respectively. In a randomised double-blind, placebo-controlled study of 100 dental caries- active children, treatment with strain M18 was administered for three months and the participants were assessed for changes to their plaque score, gingival and soft tissue health and to their salivary levels of S. salivarius, Streptococcus mutans, lactobacilli, beta haemolytic streptococci and Candida species. At treatment end, the plaque scores were significantly (P=0.05) lower for children in the M18-treated group especially in subjects having high initial plaque scores. The absence of any significant adverse events supported the safety of the probiotic treatment. Cell culture analyses of sequential saliva samples showed no differences between the probiotic and placebo groups in the counts of the specifically-enumerated oral microorganisms, with the exception of that subgroup of the M18-treated children who appeared to have colonised most effectively with M18. This subgroup exhibited reduced S. mutans counts, indicating that the anti-caries activity of M18 probiotic treatments may be enhanced if the efficiency of colonisation is increased. It is concluded that S. salivarius M18 can provide oral health benefits when taken regularly.

Concepts: Streptococcus, Dental caries, Lactobacillus, Dental plaque, Streptococcaceae, Streptococcus mutans, Oral microbiology, Streptococcus salivarius


The peptide LYS-[TRP(6)]-Hy-A1 (Lys-a1) is a synthetic derivative of the peptide Hy-A1, initially isolated from the frog species Hypsiboas albopunctatus. According to previous research, it is a molecule with broad antimicrobial activity. The objective of this study was to evaluate the antimicrobial activity of the synthetic peptide Lys-a1 (KIFGAIWPLALGALKNLIK-NH(2)) on the planktonic and biofilm growth of oral bacteria. The methods used to evaluate antimicrobial activity include the following: determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in microtiter plates for growth in suspension and quantification of biomass by crystal violet staining and counting of colony forming units for biofilm growth. The microorganisms Streptococcus oralis, Streptococcus sanguinis, Streptococcus. parasanguinis, Streptococcus salivarius, Streptococcus mutans and Streptococcus sobrinus were grown in Brain Heart Infusion broth at 37°C under atmospheric pressure with 10% CO(2). The peptide was solubilized in 0.1% acetic acid (v/v) at various concentrations (500 to 1.9μg.mL(-1)). Chlorhexidine gluconate 0.12% was used as the positive control, and BHI culture medium was used as the negative control. The tested peptide demonstrated a remarkable antimicrobial effect, inhibiting the planktonic and biofilm growth of all strains tested, even at low concentrations. Thus, the peptide Lys-a1 is an important source for potential antimicrobial agents, especially for the control and prevention of microbial biofilms, which is one of the most important factors in cariogenic processes.

Concepts: Archaea, Bacteria, Microbiology, Streptococcus, Biofilm, Gram positive bacteria, Streptococcaceae, Streptococcus mutans


Background: Streptococcus salivarius K12 has been shown to inhibit the growth of Streptococcus pyogenes due to bacteriocins release. Because of its ability to colonize the oral cavity, we have tested the strain K12 for its efficacy in preventing streptococcal pharyngitis and/or tonsillitis in adults. Methods: Forty adults with a diagnosis of recurrent oral streptococcal pharyngitis were enrolled in the study. Twenty of these subjects took for 90 days a tablet containing Streptococcus salivarius K12 (Bactoblis®). The other 20 subjects served as untreated controls. A 6-month follow-up was included to evaluate any persistent protective role. Results: The 20 adults who completed the 90-day course of Bactoblis® showed a reduction in their episodes of streptococcal pharyngeal infection (about 80%). The 90 days treatment was also associated with an approximately 60% reduction in the incidence of reported pharyngitis in the 6-month period following use of the product. The product was well tolerated by the subjects with no treatment-related side effects or drop-outs reported. Conclusion: Prophylactic administration of Streptococcus salivarius K12 to adults having a history of recurrent oral streptococcal pathology reduced the number of episodes of streptococcal pharyngeal infections and/or tonsillitis.

Concepts: Streptococcus pyogenes, Rheumatic fever, Streptococcus, Gram positive bacteria, Streptococcaceae, Group A streptococcal infection, Streptococcus thermophilus, Streptococcus salivarius


Viridans group streptococci (VGS) are a major cause of bacteraemia in neutropenic cancer patients, particularly those receiving fluoroquinolone prophylaxis. In this study, we sought to understand the molecular basis for fluoroquinolone resistance in VGS causing bacteraemia in cancer patients by assigning 115 VGS bloodstream isolates to specific species using multilocus sequence analysis (MLSA), by sequencing the quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC and parE, and by testing strain susceptibility to various fluoroquinolones. Non-susceptibility to one or more fluoroquinolones was observed for 78% of isolates, however only 68.7% of patients were receiving fluoroquinolone prophylaxis. All but one of the determinative QRDR polymorphisms occurred in GyrA or ParC, yet the pattern of determinative QRDR polymorphisms was significantly associated with the fluoroquinolone prophylaxis received. By combining MLSA and QRDR data, multiple patients infected with genetically indistinguishable fluoroquinolone-resistant Streptococcus mitis or Streptococcus oralis strains were discovered. Together these data delineate the molecular mechanisms of fluoroquinolone resistance in VGS isolates causing bacteraemia and suggest possible transmission of fluoroquinolone-resistant S. mitis and S. oralis isolates among cancer patients.

Concepts: Streptococcus, Gram positive bacteria, Streptococcaceae, Group A streptococcal infection, Quinolone, Streptococcus viridans, Streptococcus oralis, Streptococcus mitis