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PubMed1999

Streptococcus waius sp. nov., a thermophilic Streptococcus from a biofilm.

Thermophilic streptococci were isolated from biofilms on stainless steel samples exposed to pasteurized skimmed milk and from dairy products from a dairy manufacturing plant. The phenotypic characters of these isolates were distinct from those of other thermophilic streptococci of dairy origin (Streptococcus thermophilus and Streptococcus bovis). Genotypic data [restriction endonuclease analysis, ribotyping, random amplified polymorphic DNA (RAPD) profiles, DNA-DNA hybridization and G + C contents] support the classification of these isolates as a new species. The sequence of the 16S rRNA was compared with that of 29 species of streptococci and shown to be significantly different. The sequence of the 16S-23S rRNA intergenic spacer region also differed from published sequences of closely related species. A fluorescent in situ hybridization probe prepared to a specific part of the 16S rRNA gene sequence was able to distinguish the unknown isolates from reference isolates of S. thermophilus and S. bovis. It is proposed that these thermophilic streptococcal isolates from a dairy environment be classified in the genus Streptococcus as a new species, Streptococcus waius (from waiu, the New Zealand Maori word for milk). The type strain is 3/1T (= NZRCC 20100T).

Animals↗
PubMed1984

DNA base composition, DNA-DNA homology and long-chain fatty acid studies on streptococcus thermophilus and Streptococcus salivarius.

DNA base composition, DNA-DNA homology and long-chain fatty acid studies were performed on Streptococcus thermophilus and Streptococcus salivarius. These species possess similar mol % G + C values (about 37 to 41), long-chain fatty acid profiles and belong to a single DNA homology group. On the basis of the present and earlier studies it is proposed that Streptococcus thermophilus (Orla-Jensen) be reclassified as Streptococcus salivarius subsp. thermophilus comb. nov.

Base Composition↗
PubMed1996

Rapid species identification of "Streptococcus milleri" strains by line blot hybridization: identification of a distinct 16S rRNA population closely related to Streptococcus constellatus.

A collection of 399 "Streptococcus milleri" strains were identified to the species level by the use of a line blot assay. Their PCR-amplified partial 16S rRNA gene sequences were hybridized with species-specific 5'-biotinylated oligonucleotide probes homologous to the bp 213 to 231 regions of the 16S rRNA gene sequences of the type strains Streptococcus anginosus ATCC 33397, Streptococcus constellatus ATCC 27823, and Streptococcus intermedius ATCC 27335. The hybridization results were compared with the reference phenotypic identification method data (R. A. Whiley, H. Fraser, J. M. Hardie, and D. Beighton, J. Clin. Microbiol. 28:1497-1501, 1990). Most strains (357 of 399 [89.5%]) reacted unambiguously with only one probe. However, 42 of the 399 strains (10.5%) reacted with both the S. constellatus- and S. intermedius-specific probes; 41 of them were phenotypically identified as S. constellatus. These dually reactive strains hybridized with a 5'-biotinylated probe based on the bp 213 to 231 region of the 16S rRNA gene sequence of one of two species. Analysis of the 5' ends of the 16S rRNA gene sequences (487 bp) demonstrated that the dually reactive strains represent a distinct rRNA population sharing 98.1% sequence similarity with S. constellatus. Phenotypic consistency between the dually reactive strains and the S. constellatus strains was not demonstrated. Line blot hybridization proved to be a simple and inexpensive method to screen large numbers of strains for genetic relatedness, and it allowed the detection of a distinct 16S rRNA type within the "S. milleri" group.

Bacterial Typing Techniques↗
PubMed1991

[Cloning the gene of beta-galactosidase from the industrial strain of Streptococcus lactis 111 in E. coli cells and conjugated transfer of this gene to Streptococcus thermophilus cells].

The ability of the industrial strains of Streptococcus lactis to synthesize the enzyme beta-galactosidase was studied. Five strains among sixteen were found to produce high levels of the enzyme. The beta-galactosidase gene in the most active strain Streptococcus lactis 111 was shown to be located on the 50 kb conjugative plasmid. The plasmid was transferred by conjugation into Streptococcus thermophilus cells and subsequently the gene for beta-galactosidase was studied in transconjugants. The beta-galactosidase gene from Streptococcus lactis 111 was subcloned in Escherichia coli cells on the plasmid pBR322. The gene was localized on the 4.8 kb BgIII fragment of DNA. Following the restriction of DNA by the Sau3A the gene was subcloned on the birepliconed plasmid vector pCB20 capable of replication in the Gram-negative as well as Gram-positive microorganisms. The recombinant derivatives of pCB20 were isolated that carry the beta-galactosidase gene on the DNA fragments of different size.

Cloning, Molecular↗
PubMed1986

Susceptibility of enterococci. II. Inhibitory and bactericidal activity of drugs in combination against Streptococcus faecalis and Streptococcus faecium.

The microbiological utility of antibiotic combinations against Streptococcus faecalis and Streptococcus faecium strains was studied. The drugs used were netilmicin + amoxicillin (20 strains); netilmicin + piperacillin (20 strains); netilmicin- + vancomycin (20 strains); netilmicin + rifampicin (20 strains). Netilmicin used in combination with the penicillins was advantageous against Streptococcus faecalis, but not uniformly against Streptococcus faecium. The combinations of netilmicin with vancomycin or rifampicin were no more effective than the single drugs in most cases, although the response varied for the different strains of the two species.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Evaluation of phenotype characteristics of streptococci in the identification of the Streptococcus anginosus (Streptococcus milleri) group].

Microorganisms referred to as Streptococcus anginosus (Streptococcus milleri) group which consist of S. anginosus, S. intermedius and S. constellatus is very difficult to identify to the species level, because of their diversity of biochemical, hemolytic and serological characteristics and because of confusion surrounding their taxonomy. Identification procedures on three isolates from primary sterile sites of three different patients, using API 20A system are described. Streptococcus intermedius was established in two and Streptococcus anginosus in one case. The importance of these organisms as human pathogens should enhance efforts of clinical microbiologist towards their accurate identification.

Adolescent↗
PubMed1997

A global gene pool for high-level cephalosporin resistance in commensal Streptococcus species and Streptococcus pneumoniae.

Highly penicillin- and cephalosporin-resistant Streptococcus mitis and Streptococcus oralis were isolated in Spain, Hungary, and Berlin. With chromosomal DNA of these strains, resistant transformants of Streptococcus pneumoniae were obtained that expressed low-affinity variants of penicillin-binding proteins (PBPs) 2x, 1a, 2a, and 2b in different combinations, depending on the selective conditions. The transformants had cefotaxime MICs of up to 6 microg/mL, and those with a low-affinity PBP 2b were highly deficient in penicillin-induced lysis. Sequence analysis of the pbp2x genes confirmed the presence of a global gene pool of penicillin resistance determinants shared by commensal and pathogenic streptococci.

Amino Acid Sequence↗
PubMed1995

Acid production by human strains of Streptococcus mutans and Streptococcus sobrinus.

Acid production by washed suspensions of human strains of Streptococcus mutans (n = 18) and Streptococcus sobrinus (n = 12) was measured. The strains were isolated from infants and adolescents with varying caries experience. Some of these strains and two laboratory strains (1 S. mutans and 1 S. sobrinus) had been tested in an earlier study for their cariogenicity in hamsters. Further, 3 Streptococcus sanguis strains and 1 S. sobrinus laboratory strain were included. Acid production was determined in repeated titration experiments at a constant pH of 5.5. Higher mean acid production activities (p < 0.05) were obtained by S. sobrinus compared with both S. mutans and S. sanguis. However, large variations among the strains were found both between and within the species. No clear relationship was found between the glycolytic activity of strains and the caries prevalence of the children from whom the strains had been isolated or the caries scores in a hamster model. In conclusion, although both S. mutans and S. sobrinus have aciduric and acidogenic properties, it is difficult to relate the acid production activity of pure cultures in vitro to the caries process in vivo.

Acids↗
PubMed1992

Expression of M6 protein gene of Streptococcus pyogenes in Streptococcus gordonii after chromosomal integration and transcriptional fusion.

The M6 protein of Streptococcus pyogenes was expressed on the cell surface and secreted in Streptococcus gordonii Challis (formerly Streptococcus sanguis) after chromosomal integration of a promoterless M6 protein gene (emm-6.1). The ermC gene, conferring resistance to erythromycin, was cloned downstream of emm-6.1, within the same ClaI fragment. The initiation codon of emm-6.1 was 19 bp downstream of a ClaI site, so that ClaI cleavage would leave the gene promoterless. The ClaI fragment containing the promoterless emm-6.1 and ermC was ligated in vitro with a ClaI digest of S. gordonii chromosomal DNA. Random chromosomal integration of the heterologous DNA was obtained by using the ligation mixture to transform the naturally competent S. gordonii Challis. Twenty-eight percent of transformants selected for erythromycin resistance also expressed M6. Among the best M6 producers, 10 clones were selected for the stability of their phenotype. Nine of the 10 clones were shown to harbour one intact copy of the emm-6.1/ermC ClaI fragment integrated into the chromosome. These strains both expressed M6 protein on the surface and secreted different amounts of the molecule, since in each case the protein was produced after a transcriptional fusion of emm-6.1 with a different chromosomal promoter. A S. gordonii strain expressing large amounts of surface M6 protein, as judged by immunofluorescence and Western blot, was compared to the M- parental strain in a standard opsonophagocytosis assay. Of the isogenic pair, M6+ S. gordonii survived better in human blood and was phagocytosed at a slower rate.

Bacterial Outer Membrane Proteins↗
PubMed2006

In vitro activity of sitafloxacin compared with several fluoroquinolones against Streptococcus anginosus and Streptococcus constellatus.

The in vitro activities of sitafloxacin and seven other fluoroquinolones a (ciprofloxacin, tosufloxacin, sparfloxacin, levofloxacin, T-3811ME, moxifloxacin and trovafloxacin) were examined by the microdilution method against 79 clinically isolated 'Streptococcus milleri' group (SMG) microorganisms. No statistically significant differences were found between the minimum inhibitory concentrations (MIC(50) and MIC(90)) against Streptococcus anginosus and Streptococcus constellatus. Sitafloxacin was the most active agent of the eight fluoroquinolones tested against SMG, with a MIC(90) of 0.06 microg/mL, which was 8 times more active than ciprofloxacin and 16 times more active than levofloxacin. Although none of the SMG strains showed high resistance to any of the fluoroquinolones tested, three agents (trovafloxacin, sitafloxacin and T-3811ME) had low MICs against 23 SMG strains against which levofloxacin had a MIC> 1 microg/mL. In conclusion, several fluoroquinolones have low MICs against SMG, but sitafloxacin has the lowest.

Anti-Bacterial Agents↗
PubMed2005

Biochemical analysis, cpn60 and 16S rDNA sequence data indicate that Streptococcus suis serotypes 32 and 34, isolated from pigs, are Streptococcus orisratti.

Streptococcus suis serotypes have traditionally been identified by morphology, biochemical profiling and serotyping. Analysis of the sequences of 16S rRNA and cpn60 genes of the 35 characterized serotypes of S. suis led to the observation that two serotypes 32 and 34, are significantly distinct from other S. suis serotypes and may represent a distinct species. Here we present DNA sequence data and biochemical profiles which indicate that S. suis serotypes 32 and 34, isolated from pigs, are clustered with Streptococcus orisratti, a Voges-Proskauer negative, alpha-haemolytic, aesculin-hydrolytic, Lancefield group A streptococcus isolated from the teeth of rats.

Animals↗
PubMed2006

Understanding the bacterial polysaccharide antigenicity of Streptococcus agalactiae versus Streptococcus pneumoniae.

Bacterial surface capsular polysaccharides (CPS) that are similar in carbohydrate sequence may differ markedly in immunogenicity and antigenicity. The structural origin of these phenomena is poorly understood. Such a case is presented by the Gram-positive bacteria Streptococcus agalactiae (Group B Streptococcus; GBS) type III (GBSIII) and Streptococcus pneumoniae (Pn) type 14 (Pn14), which share closely related CPS sequences. Nevertheless, antibodies (Abs) against GBSIII rarely cross-react with the CPS from Pn14. To establish the origin for the variation in CPS antigenicity, models for the immune complexes of CPS fragments from GBSIII and Pn14, with the variable fragment (Fv) of a GBS-specific mAb (mAb 1B1), are presented. The complexes are generated through a combination of comparative Ab modeling and automated ligand docking, followed by explicitly solvated 10-ns molecular dynamics simulations. The relationship between carbohydrate sequence and antigenicity is further quantified through the computation of interaction energies using the Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) method, augmented by conformational entropy estimates. Despite the electrostatic differences between Pn14 and GBSIII CPS, analysis indicates that entropic penalties are primarily responsible for the loss of affinity of the highly flexible Pn14 CPS for mAb 1B1. The similarity of the solution conformation of the relatively rigid GBSIII CPS with that in the immune complex characterizes the previously undescribed 3D structure of the conformational epitope. The analysis provides a comprehensive interpretation for a large body of biochemical and immunological data related to Ab recognition of bacterial polysaccharides and should be applicable to other Ab-carbohydrate interactions.

Amino Acid Sequence↗
PubMed1997

Streptococcus difficile is a nonhemolytic group B, type Ib Streptococcus.

Whole-cell protein electrophoretic analysis of the type strain of Streptococcus difficile (LMG 15799) revealed that this organism was indistinguishable from Streptococcus agalactiae strains. Although LMG 15799T (T = type strain) was originally described as serologically untypeable, we found that this strain was a group B streptococcus belonging to the capsular polysaccharide antigen type Ib group. The biochemical reactivity of S. difficile, which differed from the biochemical reactivity of typical S. agalactiae strains mainly by being less versatile, is similar to the biochemical reactivity of other group B, type Ib streptococci isolated from poikilothermic animals, such as fish and frogs.

Aerobiosis↗
PubMed2005

High genetic similarity of Streptococcus agalactiae and Streptococcus difficilis: S. difficilis Eldar et al. 1995 is a later synonym of S. agalactiae Lehmann and Neumann 1896 (Approved Lists 1980).

The genetic relationship between Streptococcus agalactiae and Streptococcus difficilis was studied. S. difficilis was originally described as serologically non-typable but was later reported to be a group B, type Ib streptococcus. Upon comparative analysis of five gene sequences, it was found that S. agalactiae and S. difficilis are closely related. Sequence similarity values between these two species were 100.0 % for 16S rRNA, 99.6 % for gyrB, 98.6 % for sodA, 99.5 % for gyrA and 99.8 % for parC genes. These data strongly suggest that S. agalactiae and S. difficilis are synonyms. The biochemical characteristics of S. difficilis, which differ slightly from those of typical S. agalactiae, are similar to those of other group B, type Ib streptococci isolated from fish and frogs. Whole genome DNA-DNA hybridization values between the type strains of both species were greater than 78.6 %. On the basis of these data, it is proposed that S. difficilis is a later synonym of S. agalactiae.

Animals↗
PubMed1994

Mosaic pbpX genes of major clones of penicillin-resistant Streptococcus pneumoniae have evolved from pbpX genes of a penicillin-sensitive Streptococcus oralis.

Penicillin-resistant clinical isolates of Streptococcus pneumoniae contain mosaic penicillin-binding protein (PBP) genes that encode PBPs with decreased affinity for beta-lactam antibiotics. The mosaic blocks are believed to be the result of gene transfer of homologous PBP genes from related penicillin-resistant species. We have now identified a gene homologous to the pneumococcal PBP2x gene (pbpX) in a penicillin-sensitive Streptococcus oralis isolate M3 from South Africa that diverged by almost 20% from pbpX of penicillin-sensitive pneumococci, and a central sequence block of a mosaic pbpX gene of Streptococcus mitis strain NCTC 10712. In contrast, it differed by only 2-4% of the 1 to 1.5 kb mosaic block in pbpX genes of three genetically unrelated penicillin-resistant S. pneumoniae isolates, two of them representing clones of serotype 6B and 23F, which are prevalent in Spain and are also already found in other countries. With low concentrations of cefotaxime, transformants of the sensitive S. pneumoniae R6 strain could be selected containing pbpX genes from either S. mitis NCTC 10712 or S. oralis M3, demonstrating that genetic exchange can already occur between beta-lactam-sensitive species. These data are in agreement with the assumption that PBPs as penicillin-resistance determinants have evolved by the accumulation of point mutations in genes of sensitive commensal species.

Amino Acid Sequence↗
PubMed1989

Characterisation of monoclonal antibodies to common protein epitopes on the cell surface of Streptococcus mutans and Streptococcus sobrinus.

Three monoclonal antibodies (MAb) were prepared against a cell surface antigen which cross-react between Streptococcus mutans (serotypes c, e and f) and Streptococcus sobrinus (serotypes d and g). Two of the MAb also recognise a determinant on the surface of Streptococcus cricetus (serotype a). The common antigen shared between S. mutans and S. sobrinus was demonstrated by Western blotting to be about 200 kD in size. This antigen is shared not only by the cell surfaces of serotypes a, c, d, e, f and g, but also by the major cell surface antigen of S. mutans of 185 kD and another of 150 kD. These MAb identify all but one mutans type of streptococci and can be utilised as analytical reagents.

Antibodies, Monoclonal↗
PubMed1994

Immunochemical study of polysaccharide antigen in Streptococcus sobrinus and Streptococcus downei with a cross-reactive monoclonal antibody.

A monoclonal antibody (mAb h-448) was prepared after cell fusion of mouse myeloma cells (SP2/0-Ag-14) to the spleen cells of mice immunised with serotype h strain (MF25) of Streptococcus downei. The antibody (IgM class) reacted in enzyme immunoassay only with whole cells as well as purified polysaccharide (PS) antigen of Streptococcus sobrinus (types d and g) and Streptococcus downei (serotype h), but not with cells or purified PS antigen from any other serotypes of the mutans group of streptococci. mAb h-448 also quantitatively precipitated in solution with the purified antigens. Competitive hapten inhibition tests demonstrated that beta-methylgalactopyranoside inhibited the reaction most strongly. Although rhamnose also showed a substantial inhibitory effect, the results of this study indicate that the antigenic determinant of the PS antigen has a structure similar to the beta-methylgalactopyranoside molecule.

Antibodies, Bacterial↗
PubMed1980

Genetic transformation of Streptococcus sanguis (Challis) with cryptic plasmids from Streptococcus ferus.

By using the basic methodology initially published by Kretschmer et al. (J. Bacteriol. 124:225-231, 1975), we have been able to introduce phenotypically cryptic plasmids from Streptococcus ferus (formerly Streptococcus mutans subsp. ferus) into Streptococcus sanguis by genetic transformation. In this system, the entry of the cryptic plasmids is selected indirectly. This is effected with transforming deoxyribonucleic acid mixtures in which the cryptic plasmid deoxyribonucleic acid is present in an approximate 10-fold molar excess with respect to a plasmid (pVA1) known to confer erythromycin resistance. Under such conditions, 5 to 10% of the pVA1-containing erythromycin-resistant transformants were cotransformed with cryptic plasmid deoxyribonucleic acid. pVA1 may be selectively eliminated by growth of its S. sanguis host strain at 42 degrees C, enabling the construction of isogenic strains with and without S. ferus cryptic plasmids. Comparative physiological studies of such strains have failed to reveal any plasmid-conferred phenotypes in S. sanguis. With this procedure, we have been able to physically separate two small cryptic plasmids (2.4 x 10(6) and 2.8 x 10(6) daltons) of S. ferus. Although these plasmids were found naturally to exist in a single S. ferus host, they were able to replicate independently of one another in S. sanguis. Restriction enzyme fingerprinting indicated that these plasmids did not share a common ancestry.

Bacteriocins↗