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PubMed2002

Native valve endocarditis due to Streptococcus vestibularis and Streptococcus oralis.

Viridans streptococci are the commonest cause of native valve infective endocarditis (IE). The taxonomy of this group is evolving allowing new disease associations to be made. Streptococcus vestibularis is a recently described member of the viridans group, first isolated from the vestibular mucosa of the human oral cavity. It has rarely been associated with human disease. Streptococcus oralis, another member of the viridans group resident in the human oral cavity is a well known cause of IE and bacteraemia in neutropenic patients. We report the first case of native mitral valve endocarditis due to S. vestibularis in a patient with co-existing S. oralis endocarditis.

Aged↗
PubMed1989

Identification of a high-virulence clone of type III Streptococcus agalactiae (group B Streptococcus) causing invasive neonatal disease.

Chromosomal genotypes of 128 isolates of six serotypes (Ia, Ib, Ic, II, Ic/II, and III) of Streptococcus agalactiae (group B Streptococcus) recovered predominantly from human infants in the United States were characterized by an analysis of electrophoretically demonstrable allelic profiles at 11 metabolic enzyme loci. Nineteen distinctive electrophoretic types (ETs), representing multilocus clonal genotypes, were identified. Mean genetic diversity per locus among ETs of isolates of the same serotype was, on average, nearly equal to that in all 19 ETs. Cluster analysis of the ETs revealed two primary phylogenetic divisions at a genetic distance of 0.65. A single clone (ET 1) represented by 40 isolates expressing type III antigen formed division I. Division II was composed of 18 ETs in three major lineages diverging from one another at distances greater than 0.35 and included strains of all six antigenic classes. The type III organisms in division I produce more extracellular neuraminidase and apparently are more virulent than the type III strains in division II, which are related to strains of other serotypes that cause disease much less frequently. The existence of this unusually virulent clone accounts, in major part, for the high morbidity and mortality associated with infection by type III organisms.

Genotype↗
PubMed1992

Protein F, a fibronectin-binding protein, is an adhesin of the group A streptococcus Streptococcus pyogenes.

Binding to fibronectin has been suggested to play an important role in adherence of the group A streptococcus Streptococcus pyrogenes to host epithelial cells; however, the identity of the streptococcal fibronectin receptor has been elusive. Here we demonstrate that the fibronectin-binding property of S. pyogenes is mediated by protein F, a bacterial surface protein that binds fibronectin at high affinity. The gene encoding protein F (prtF) produced a functional fibronectin-binding protein in Escherichia coli. Insertional mutagenesis of the cloned gene generated a mutation that resulted in the loss of fibronectin-binding activity. When this mutation was introduced into the S. pyrogenes chromosome by homologous recombination with the wild-type allele, the resulting strains no longer produced protein F and lost their ability to bind fibronectin. The mutation could be complemented by prtF introduced on a plasmid. Mutants lacking protein F had a much lower capacity to adhere to respiratory epithelial cells. These results demonstrate that protein F is an important adhesin of S. pyogenes.

Animals↗
PubMed1982

Fatal Streptococcus MG-intermedius (Streptococcus milleri) meningitis in an adult.

A case of purulent meningitis in an adult caused by Streptococcus MG-intermedius, also known as Streptococcus milleri, is described. The intriguing taxonomical history of this organism and its association with mycoplasma pneumoniae pulmonary infections is reviewed. The incidence of central nervous system infections due to this organism is also discussed.

Cross Reactions↗
PubMed1979

Species-specific resistance to antimocrobial synergism in Streptococcus faecium and Streptococcus faecalis.

Combinations of penicillin with various aminoglycosidic aminocyclitols were tested against a collection of clinical isolates of Streptococcus faecium in vitro and were used to treat endocarditis caused by S. faecium in the rabbit model. S. faecium proved more resistant to penicillin than Streptococcus faecalis. Even more striking, however, was the resistance to in vitro synergism by combinations of penicillin and various aminoglycosides. At clinically achievable concentrations, penicillin-gentamicin was the only combination that was synergistic against all strains that were tested. Combinations of penicillin and streptomycin and penicillin and amikacin were synergistic only against those strains that were not highly resistant to streptomycin and kanamycin, respectively. Combinations of penicillin with kanamycin, tobramycin, sisomicin, or netilmicin failed to produce synergism against any of these strains. The possible clinical significance of these findings was verified by use of the rabbit model of endocarditis. Combinations of penicillin with gentamicin or streptomycin were synergistic in the therapy of endocarditis that was produced by a strain of S. faecium that did not have a high level of resistance to aminoglycosides. However, the combination of penicillin and netilmicin was no more effective than penicillin alone.

Aminoglycosides↗
PubMed1991

Intraspecies variations in nutritionally variant streptococci: rRNA gene restriction patterns of Streptococcus defectivus and Streptococcus adjacens.

The rRNA gene restriction patterns of two species of nutritionally variant streptococci, Streptococcus defectivus and Streptococcus adjacens, were determined, and the results were compared with the electrophoretic migration profiles of penicillin-binding proteins. Reference strains belonging to various streptococcal species were used as controls. Our results correlated with the results of DNA-DNA hybridization experiments and confirmed the delineation of these two species. Moreover, they demonstrated that intraspecies variations occur and suggested that there are two subspecies of S. defectivus.

Genetic Variation↗
PubMed1997

The tannin-degrading species Streptococcus gallolyticus and Streptococcus caprinus are subjective synonyms.

The tannin-degrading species Streptococcus gallolyticus and Streptococcus caprinus have been shown to be subjective synonyms on the basis of their levels of 16S rRNA sequence similarity (98.3%) and DNA-DNA homology (> 70%) and the phenotypes of their type strains. S. gallolyticus has nomenclatural priority according to Rule 24b(2) of the International Code of Nomenclature of Bacteria.

Animals↗
PubMed2000

A new species of oral Streptococcus isolated from Sprague-Dawley rats, Streptococcus orisratti sp. nov.

Taxonomic studies were performed on an unusual oral Streptococcus strain isolated from Sprague-Dawley rats. The isolates were alpha-haemolytic, bile-tolerant, aesculin-hydrolytic and unable to grow in 6.5% NaCl. They fermented lactose, sucrose and trehalose. They were distinguished from other recognized species of oral and viridans streptococci by several biochemical characteristics and by Lancefield's group antigen, as well as by unique DNA-DNA hybridization characteristics. 16S rDNA sequence studies confirmed the genealogical distinctiveness of the species. The results of the study demonstrated that the isolates represented a new species of the oral and viridans streptococci. The name Streptococcus orisratti sp. nov. is proposed for the new species. The type strain is A63T (= ATCC 700640T).

Animals↗
PubMed1993

Albumin-binding proteins on the surface of the Streptococcus milleri group and characterization of the albumin receptor of Streptococcus intermedius C5.

Members of the Streptococcus milleri group (SMG) that react with Lancefield group C antisera were shown to bind large amounts of albumin although there was no direct relation between these two properties as polyclonal antisera to Lancefield group C antigen did not prevent the binding of albumin. There was a specificity for albumin binding, with albumin from man, monkeys, cat, dog and mouse being bound to a greater degree than albumin from cow, horse, goat or rabbit. Gold-labelled albumin was shown to be located close to the surface of strains by transmission electron microscopy. A cell-surface protein of M(r) 24,000, which was liberated by lysozyme treatment of cells, was shown to be the cell-surface receptor on Streptococcus intermedius C5. The receptor was physically dissimilar from protein G, an albumin- and IgG-binding protein of 'large-colony' Lancefield group C and G streptococci.

Animals↗
PubMed2003

Towards a genotyping system for Streptococcus agalactiae (group B streptococcus): use of mobile genetic elements in Australasian invasive isolates.

This study forms part of the development of an integrated genotyping system for Streptococcus agalactiae (group B streptococcus, GBS) that can be used to study the population genetics of the organism and the pathogenesis and epidemiology of GBS disease. In recent previous studies, two sets of markers, the capsular polysaccharide synthesis (cps) gene cluster and surface protein antigen genes, have been used to assign molecular serotypes (MS) and protein-gene profiles (PGP) to more than 200 isolates. In the present study, five mobile genetic elements (MGE) have been used as a third set of markers, to characterize further 194 invasive isolates, recovered from blood or cerebrospinal fluid (CSF). Of these, 97 % contained one or more of the five MGE, the distribution of which was related to MS and PGP, as illustrated by MS III, which is divisible into four serosubtypes with different combinations of the MGE (or none). Fifty-six different genotypes and eight genetic clusters were identified, each with different combinations of the three sets of molecular markers. Five predominant genotypes (Ia-1, Ib-1, III-1, III-2 and V-1) contained 62 % of the isolates and five of the eight genetic clusters contained 92 % of the isolates. The 17 CSF isolates were relatively widely distributed between 10 genotypes and across seven of the eight clusters. Further study is needed to determine whether these genotypes or clusters share common markers of increased virulence. In future, comparison of invasive with colonizing strains of GBS may elucidate the significance of these findings.

Adolescent↗
PubMed1990

Molecular taxonomic studies on Streptococcus uberis types I and II. Description of Streptococcus parauberis sp. nov.

The nucleotide sequences of 16S ribosomal-RNA of Streptococcus uberis types I and II were determined by reverse transcriptase. Comparative analysis of the sequence data showed that the two types are phylogenetically distinct and worthy of separate species status. A new species Streptococcus parauberis is proposed for the type II strains. The type strain of Strep. parauberis is NCDO 2020.

Base Sequence↗
PubMed1990

Streptococcus cricetus and Streptococcus rattus bind to different segments of collagen molecules.

Strains of Streptococcus cricetus and Streptococcus rattus exhibited striking differences in their ability to bind to different types of collagen. For example, S. cricetus AHT bound in highest numbers to hydroxyapatite (HA) treated with human type V collagen, while rat type I collagen was ineffective. In contrast, human type V collagen was least effective in promoting attachment of S. rattus LB-1, while treatment with rat or human type I collagen was effective. Adsorption of both species to human type I collagen-treated HA showed a high correlation with a Langmuir model. Estimates of adsorption parameters indicated there were greater numbers of binding sites with higher affinity for S. rattus LB-1 than for S. cricetus AHT. Treatment of HA with either the alpha 1 (1) or alpha 2 (1) polypeptide chains of collagen was effective in promoting adhesion of S. rattus LB-1 cells. In contrast, the alpha 2 (1) chain was more effective than the alpha 1 (1), chain for S. cricetus AHT. These observations indicate that S. cricetus AHT and S. rattus LB-1 cells bind to different segments of collagen molecules. Adhesion of both species was also promoted by collagen-rich fractions of human dentin.

Bacterial Adhesion↗
PubMed2005

Evaluation of Group B Streptococcus Differential Agar for detection and isolation of Streptococcus agalactiae.

In total, 320 vaginal or rectal swabs were cultured on Granada medium (GM) or Group B Streptococcus Differential Agar (GBSDA), and were also inoculated into LIM broth (Todd-Hewitt broth supplemented with selective antibiotics), for detection of group B Streptococcus (GBS). Overall, GBS isolates were detected on 53 of the 320 swabs; 47 of these isolates grew on both GM and GBSDA, five only on GBSDA, and one only following subculture from LIM broth. GBSDA appears to be a valid alternative to GM for the growth of GBS isolates from pregnant women.

Agar↗
PubMed1990

Streptococcus parasanguis sp. nov., an atypical viridans Streptococcus from human clinical specimens.

Molecular taxonomic studies were performed on ten strains of an unusual 'viridans streptococcus' that were originally isolated from human throats, blood and urine. On the basis of DNA-DNA hybridization studies the strains formed a single homology group distinct from all recognized species of oral and viridans streptococci. 16S ribosomal RNA reverse transcriptase sequence studies confirmed the genealogical distinctiveness of the human strains. The results of the present study clearly demonstrate that the human strains represent a new species of the viridans group for which the name Streptococcus parasanguis sp. nov. is proposed. The type strain is ATCC 15912.

Base Sequence↗
PubMed1998

Determination of 23S rRNA sequences from members of the genus Streptococcus and characterization of genetically distinct organisms previously identified as members of the Streptococcus anginosus group.

The 23S rRNA gene sequences of eight type strains of the genus Streptococcus were determined. Three species-specific probes for the three members of the Streptococcus anginosus group and one group-specific probe for these three species were designed. The PCR-amplified 23S rRNA gene sequences of 28 clinical strains were examined by hybridization with the four oligonucleotide probes. They were suspected to be members of the S. anginosus group by biochemical tests; however, only 21 strains (75%) hybridized to one of the three species probes. Seven biochemically atypical strains did not hybridize to these species-specific probes. Of the seven strains, three hybridized to the group-specific probe. The 23S ribosomal RNA sequences of these three strains differed by three bases within the 20-base probe area of S. anginosus. The phylogenetic tree of the 16S rRNA of these three strains located them within the branch of S. anginosus. The remaining four strains, which did not hybridize to group- or species-specific probes, had a raffinose-positive and VP-negative phenotype. The probe hybridization results showed that these four strains did not belong to the S. anginosus group and were closely related to S. parasanguis according to partial sequences of their 16S rRNA genes.

Base Sequence↗
PubMed1998

Detection of new and persistent Streptococcus uberis and Streptococcus dysgalactiae intramammary infections by polymerase chain reaction-based DNA fingerprinting.

Polymerase chain reaction-based DNA fingerprinting was used as a tool to differentiate new and persistent Streptococcus uberis and Streptococcus dysgalactiae intramammary infections (IMI) in dairy cows. The same subtype of S. uberis or S. dysgalactiae was detected from some infected mammary glands from one lactation to the next documenting the persistence of these infections. Conversely, some streptococci isolated from mammary glands during a lactation or from one lactation to the next were different subtypes suggesting that a new IMI occurred. These new streptococcal IMI would never have been detected using phenotypic methods of streptococcal identification. Results of this study indicate that PCR-based DNA fingerprinting can be used as an effective procedure to differentiate new and persistent S. uberis and S. dysgalactiae IMI in dairy cows. This technique will be useful in epidemiological investigations, and drug and vaccine efficacy studies when attempting to delineate new and persistent IMI.

Animals↗
PubMed2006

Streptococcus mutans glucan-binding protein-A affects Streptococcus gordonii biofilm architecture.

The glucan-binding protein-A (GbpA) of Streptococcus mutans has been shown to contribute to the architecture of glucan-dependent biofilms formed by this species and influence virulence in a rat model. As S. mutans synthesizes multiple glucosyltransferases and nonglucosyltransferase glucan-binding proteins (GBPs), it is possible that there is functional redundancy that overshadows the full extent of GbpA contributions to S. mutans biology. Glucan-associated properties such as adhesion, aggregation, and biofilm formation were examined independently of other S. mutans GBPs by cloning the gbpA gene into a heterologous host, Streptococcus gordonii, and derivatives with altered or diminished glucosyltransferase activity. The presence of GbpA did not alter dextran-dependent aggregation nor the initial sucrose-dependent adhesion of S. gordonii. However, expression of GbpA altered the biofilm formed by wild-type S. gordonii as well as the biofilm formed by strain CH107 that produced primarily alpha-1,6-linked glucan. Expression of gbpA did not alter the biofilm formed by strain DS512, which produced significantly lower quantities of parental glucan. These data are consistent with a role for GbpA in facilitating the development of biofilms that harbor taller microcolonies via binding to alpha-1,6-linkages within glucan. The magnitude of the GbpA effect appears to be dependent on the quantity and linkage of available glucan.

Bacterial Adhesion↗