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PubMed2005

Simultaneous detection and serotype identification of Streptococcus agalactiae using multiplex PCR and reverse line blot hybridization.

Streptococcus agalactiae (group B streptococcus, GBS) is an important cause of sepsis in neonates and their mothers, and the elderly and immunocompromised patients. Ongoing surveillance to monitor GBS serotype distribution is needed to guide the development and assess the feasibility of GBS conjugate vaccines. The authors previously developed a molecular serotype identification method based on serotype-specific PCR and partial sequencing of cps genes. In this study, a novel 10-primer pair multiplex PCR and reverse line blot (mPCR/RLB) hybridization assay was developed for simultaneous detection and serotype identification of all nine GBS serotypes. For all 316 GBS isolates tested the mPCR/RLB results corresponded with those of conventional serotyping and individual serotype-specific PCR, and the method was more convenient and practical than either alternative.

Base Sequence↗

PubMed2006

Streptococcus agalactiae Cbeta protein gene (bac) sequence types, based on the repeated region of the cell-wall-spanning domain: relationship to virulence and a proposed standardized nomenclature.

The Cbeta protein (Bac) of Streptococcus agalactiae (group B streptococcus; GBS) is an IgA binding protein encoded by bac, of which at least 39 sequence types have been described, based on polymorphisms in the repeated region of the cell-wall-spanning domain ('bac sequence types'). Cbeta is usually found in serotype Ib, less commonly in serotype II, and rarely in other serotypes. The aim of this study was to examine the prevalence, variety and distribution, among GBS serotypes and between invasive and superficial isolates, of bac sequence types. A total of 1101 GBS isolates were tested, from 10 countries, with a bac-specific PCR, and amplicons from all 255 (23 %) with positive results were sequenced. Ninety-seven percent (184/190) of serotype Ib and 37 % of serotype II isolates were bac positive. The Calpha protein gene (bca) was present in 98 % (251/255), and insertion sequences IS1381 and IS861 in 94 % (239/255), of bac-positive isolates. The authors identified 59 bac sequence types belonging to 19 groups, based on length, from 496 to 946 bp, with up to six sequence variants (a-f) in each group. The median bac sequence length of invasive isolates was significantly shorter than that of superficial isolates overall (640 versus 586 bp; P < 0.001) and specifically for serotype Ib (541 versus 676 bp; P < 0.001), and invasive isolates were significantly (P < 0.001) more likely to have one or more 18 bp deletions relative to the original published bac sequence (X59771). bac sequence typing is a useful addition to the previously described genotyping system, and will help to predict relative virulence among S. agalactiae serotype Ib strains.

Antigens, Bacterial↗

PubMed2025

Genomic and transcriptomic insights into the virulence and adaptation of shock syndrome-causing Streptococcus anginosus.

Streptococcus anginosus is a common isolate of the oral cavity and an opportunistic pathogen for systemic infections. Although the pyogenic infections caused by S. anginosus are similar to those caused by Streptococcus pyogenes, S. anginosus lacks most of the well-characterized virulence factors of S. pyogenes. To investigate the pathogenicity of S. anginosus, we analysed the genome of a newly identified S. anginosus strain, KH1, which was associated with toxic shock-like syndrome in an immunocompetent adolescent. The genome of KH1 contains nine genomic islands, two Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated systems and many phage-related proteins, indicating that the genome is influenced by prophages and horizontal gene transfer. Comparative genome analysis of 355 S. anginosus strains revealed a significant difference between the sizes of the pan genome and core genome, reflecting notable strain variations. We further analysed the transcriptomes of KH1 under conditions mimicking either the oral cavity or the bloodstream. We found that in an artificial saliva medium, the expression of a putative quorum quenching system and pyruvate oxidase for H2O2 production was upregulated, which could optimize the competitiveness of S. anginosus in the oral ecosystem. Conversely, in a modified serum medium, purine and glucan biosynthesis, competence and bacteriocin production were significantly upregulated, likely facilitating the survival of KH1 in the bloodstream. These findings indicate that S. anginosus can utilize diverse mechanisms to adapt to different environmental niches and establish infection, despite its lack of toxin production.

Streptococcus anginosus↗

PubMed2004

A novel glucan-binding protein with lipase activity from the oral pathogen Streptococcus mutans.

Streptococcus mutans produces extracellular glucosyltransferases (GTFs) that synthesize glucans from sucrose. These glucans are important in determining the permeability properties and adhesiveness of dental plaque. GTFs and the GbpA glucan-binding protein are characterized by a binding domain containing a series of 33-amino-acid repeats, called 'A' repeats. The S. mutans genome sequence was searched for ORFs containing 'A' repeats, and one novel gene, gbpD, which appears to be unique to the mutans group of streptococci, was identified. The GbpD sequence revealed the presence of three 'A' repeats, in the middle of the protein, and a novel glucan-binding assay showed that GbpD binds to dextran with a K(D) of 2-3 nM. Construction of truncated derivatives of GbpD confirmed that the 'A' repeat region was essential for binding. Furthermore, a gbpD knockout mutant was modified in the extent of aggregation induced by polymers derived from sucrose. The N-terminus of GbpD has a signal sequence, followed by a region with no homologues in the public databases, while the C-terminus has homology to the alpha/beta hydrolase family (including lipases and carboxylesterases). GbpD contains the two regions typical of these enzymes: a GxSxG active site 'lipase box' and an 'oxyanion hole'. GbpD released free fatty acids (FFAs) from a range of triglycerides in the presence of calcium, indicating a lipase activity. The glucan binding/lipase bifunctionality suggested the natural substrate for the enzyme may be a surface macromolecule consisting of carbohydrate linked to lipid. The gbpD mutant was less hydrophobic than wild-type and pure recombinant GbpD reduced the hydrophobicity of S. mutans and another plaque bacterium, Streptococcus sanguinis. GbpD bound to and released FFA from lipoteichoic acid (LTA) of S. sanguinis, but had no effect on LTA from S. mutans. These results raise the intriguing possibility that GbpD may be involved in direct interspecies competition within the plaque biofilm.

Amino Acid Sequence↗

PubMed2005

The putative autolysin regulator LytR in Streptococcus mutans plays a role in cell division and is growth-phase regulated.

Streptococcus mutans is the primary odontopathogen present in supragingival plaque and causes the oral disease known as dental caries. Colonization of the oral cavity by S. mutans requires the bacteria to adhere to the tooth surface and occurs by both sucrose-dependent and -independent mechanisms. Sucrose-independent adhesion of S. mutans in vitro has been shown to involve an ORF (ORF0317) encoding a homologue (39 %) to LytR, a regulator of autolysin activity in Bacillus subtilis. The protein encoded by ORF0317, LytR, belongs to the LytR/CpsA/Psr protein family. This family has a putative role in cell-wall structural maintenance, possibly through autolysin regulation. Autolysins have also been shown to be important in surface adhesion in Lactococcus lactis and in the pathogenic properties of Streptococcus pneumoniae. To investigate the role of autolysins in the adhesion and pathogenesis of S. mutans, a LytR mutant was constructed. The mutant grows in long chains, which may indicate a defect in cell division. Further experiments with the mutant strain show increased autolytic activity, indicating that LytR attenuates S. mutans autolytic activity, possibly through regulation of the expression of autolytic enzymes. No defect in cell-to-surface adherence or biofilm growth was seen in the LytR mutant. However, a connection between cell growth phase and transcription of lytR was found.

Amino Acid Sequence↗

PubMed2006

Dysgalacticin: a novel, plasmid-encoded antimicrobial protein (bacteriocin) produced by Streptococcus dysgalactiae subsp. equisimilis.

Dysgalacticin is a novel bacteriocin produced by Streptococcus dysgalactiae subsp. equisimilis strain W2580 that has a narrow spectrum of antimicrobial activity directed primarily against the principal human streptococcal pathogen Streptococcus pyogenes. Unlike many previously described bacteriocins of Gram-positive bacteria, dysgalacticin is a heat-labile 21.5 kDa anionic protein that kills its target without inducing lysis. The N-terminal amino acid sequence of dysgalacticin [Asn-Glu-Thr-Asn-Asn-Phe-Ala-Glu-Thr-Gln-Lys-Glu-Ile-Thr-Thr-Asn-(Asn)-Glu-Ala] has no known homologue in publicly available sequence databases. The dysgalacticin structural gene, dysA, is located on the indigenous plasmid pW2580 of strain W2580 and encodes a 220 aa preprotein which is probably exported via a Sec-dependent transport system. Natural dysA variants containing conservative amino acid substitutions were also detected by sequence analyses of dysA elements from S. dysgalactiae strains displaying W2580-like inhibitory profiles. Production of recombinant dysgalacticin by Escherichia coli confirmed that this protein is solely responsible for the inhibitory activity exhibited by strain W2580. A combination of in silico secondary structure prediction and reductive alkylation was employed to demonstrate that dysgalacticin has a novel structure containing a disulphide bond essential for its biological activity. Moreover, dysgalacticin displays similarity in predicted secondary structure (but not primary amino acid sequence or inhibitory spectrum) with another plasmid-encoded streptococcal bacteriocin, streptococcin A-M57 from S. pyogenes, indicating that dysgalacticin represents a prototype of a new class of antimicrobial proteins.

Amino Acid Sequence↗

PubMed2004

Distribution and characterization of hemolytic activity by an oral anaerobe from the Streptococcus milleri group.

Some oral anaerobes from the Streptococcus milleri strain group were found to secrete human specific hemolytic toxin, which was detected when bacteria were cultured in Todd-Hewitt broth and Brain Heart Infusion broth. The toxin elicited by the Streptococcus intermedius strain was partially fractionated by ammonium sulfate precipitation. Preincubation with glutathione or cysteine showed significant inhibiting effects; however, no effects were seen with dithiothreitol or beta-mercaptoethanol, and cholesterol was a weak inhibitor. Five kinds of protease inhibitor had no effect on the hemolytic activity, and rabbit preimmune and immune sera against the bacterial cells showed weak inhibition at a similar level. Digestion with trypsin, chymotrypsin, proteinase-K, subtilisin and pronase-P brought about a rise in activity, followed by a decrease during long-term incubation. Other enzymes tested showed no effects. Further, the presence of the intermedilysin gene in the portion with hemolytic activity was not identified by polymerase chain reaction.

Adult↗

PubMed1995

Effect of Porphyromonas gingivalis ATCC 33277 vesicle on adherence of Streptococcus mutans OMZ 70 to the experimental pellicle.

The vesicles of Porphyromonas gingivalis ATCC 33277 strongly aggregated Streptococcus cricetus, S. rattus, and S. mutans, but poorly aggregated S. sobrinus. The adherence of S. mutans OMZ 70 to hydroxyapatite (HA) coated with whole saliva was increased in parallel with the quantity of the vesicles. The significant increase of adherence of S. mutans OMZ 70 by the vesicles was also observed on the HA coated with parotid saliva, submandibular saliva, serum, and type I collagen. These findings suggest that the vesicles may act as a bridge between mutans streptococcus and the tooth surface.

Animals↗

PubMed1995

Sequence analysis of the Streptococcus mutans Ingbritt dexA gene encoding extracellular dextranase.

The complete nucleotide sequence (3,747 bp) of the dextranase gene (dexA) and flanking regions of the chromosome of Streptococcus mutans Ingbritt (serotype c) were determined. The open reading frame for dexA was 2,550 bp, ending with a stop codon TGA. A putative ribosome-binding site, promoter preceding the start codon, and potential stem-loop structure were identified. The presumed dextranase protein (DexA) consisting of 850 amino acids was estimated to have a molecular size of 94,536 Da and a pI of 4.79. The nucleotide sequence and the deduced amino acid sequences of S. mutans dexA exhibited homologies of 57.8% and 47.0%, respectively, to those of Streptococcus sobrinus dex. The homologous region of dex of S. sobrinus was in the N-terminal half. The C terminus of DexA consisted of a hexapeptide LPQTGD, followed by 7 charged amino acids, 21 amino acids with a strongly hydrophobic character, and a charged hexapeptide tail, which have been reported as a common structure of C termini of not only the surface-associated proteins of Gram-positive cocci but also the extracellular enzymes such as beta-fructosidase of S. mutans and dextranase of S. sobrinus. The DexA protein had no significant homology with the glucosyltransferases, the glucan-binding protein, or the dextranase inhibitor of mutans streptococci.

Amino Acid Sequence↗

PubMed2005

Intermedilysin is essential for the invasion of hepatoma HepG2 cells by Streptococcus intermedius.

Streptococcus intermedius causes endogenous infections leading to abscesses. This species produces intermedilysin (ILY), a human-specific cytolysin. Because of the significant correlation between higher ILY production levels by S. intermedius and deep-seated abscesses, we constructed ily knockout mutant UNS38 B3 and complementation strain UNS38 B3R1 in order to investigate the role of ILY in deep-seated infections. Strain UNS38 reduced the viability of human liver cell line HepG2 at infection but not of rat liver cell line BRL3A. Isogenic mutant strain UNS38 B3 was not cytotoxic in either cell line. Quantification of S. intermedius revealed that in infected HepG2 cells UNS38 but not UNS38 B3 increased intracellularly concomitantly with increasing cell damage. This difference between UNS38 and UNS38 B3 was not observed with UNS38 B3R1. Invasion and proliferation in BRL3A cells was not observed. Masking UNS38 or UNS38 B3R1 with ILY antibody drastically decreased adherence and invasion of HepG2. Moreover, coating strain UNS38 B3 with ILY partially restored adherence to HepG2 but without subsequent bacterial growth. At 1 day post-infection, many intact UNS38 were detected in the damaged phagosomes of HepG2 with bacterial proliferation observed in the cytoplasm of dead HepG2 after an additional 2 day incubation. These results indicate that surface-bound ILY on S. intermedius is an important factor for invasion of human cells by this bacterium and that secretion of ILY within host cells is essential for subsequent host cell death. These data strongly implicate ILY as an important factor in the pathogenesis of abscesses in vivo by this streptococcus.

Animals↗

PubMed1984

The enrichment and early detection of Streptococcus pyogenes in skin lesions, using colistin, oxolinic acid, Todd Hewitt broth and latex agglutination.

An improved selective broth, colistin, oxolinic acid, Todd Hewitt broth (COTHB) for the isolation of Streptococcus pyogenes and other streptococci from swabs is described. Staphylococci, coryneforms and Gram negative organisms are inhibited in COTHB inoculated with swabs from skin lesions. Streptococcus pyogenes could be detected by a fluorescent antibody method and by the Streptex and Phadebact streptococcal grouping methods after 6 and 24 h incubation. Other streptococci of groups B, C and G, were also detected. Streptex was the most sensitive and specific method for the detection of streptococci of groups A, B, C, and G in this broth. The method detected 78% of these streptococci in COTHB after 6 h incubation and 93% after 24 h incubation. Of the Strep. pyogenes isolated, 82% were detected in the broth by the Streptex method.

Colistin↗

PubMed1989

A comparison of the adhesive properties and surface ultrastructure of the fibrillar Streptococcus sanguis 12 and an adhesion deficient non-fibrillar mutant 12 na.

Streptococcus sanguis 12 and a naturally occurring mutant, 12 na, were screened for their ultrastructure and adhesive properties in vitro. Negative staining showed that Strep. sanguis 12 carried three types of surface structure. The majority of cells carried long fibrils that in different batches ranged in length from 80 to 207 nm, and shorter fibrils which were 51.0 +/- 15.7 nm long. Both types of fibrils were primarily located at the poles of the cells. Occasionally cells were seen that carried fimbriae, which are structurally distinct from fibrils, and were 3-4 nm wide and less than 1.0 micron long. Strain 12 na carried no detectable surface structures. Ruthenium red staining revealed that both strains carried a loose, amorphous, extracellular polysaccharide layer attached to the cell wall. Streptococcus sanguis 12 na was 83% less adhesive than strain 12 in a saliva-coated hydroxyapatite assay, and 50% less adhesive in a buccal epithelial cell adhesion assay. In contrast, strain 12 na was more sensitive to aggregation by parotid saliva than strain 12, and both strains were equally aggregated by whole saliva. The cell surface hydrophobicity of the two strains was similar. Extraction of surface proteins by sodium lauroyl-sarcosinate followed by sodium dodecylsulphate polyacrylamide gel electrophoresis demonstrated that Strep. sanguis 12 expressed more high mol.wt proteins on its surface than strain 12 na. Using immunogold labelling, the fibrils of strain 12 labelled well with antiserum directed against the long fibrils, but so did the cell surfaces of both Strep. sanguis 12 and 12 na. High molecular weight proteins and cell surface fibrils may be associated with adhesion in this strain.

Bacterial Adhesion↗

PubMed1990

The survival of streptococci and enterococci in animal feed and on straw with particular reference to Streptococcus uberis.

The survival of Streptococcus uberis, Strep. bovis, Enterococcus faecalis spp. faecalis and Ent. faecium in animal feed and on wheat straw was studied for one month. Streptococcus bovis survived the best in feed and Strep. uberis the worst while on straw Ent. faecium was the most resilient species and there was little to choose between the other three. The recovery of all species, excepting Strep. bovis, on selective and non-selective agar was comparable. The growth of Strep. bovis, on the other hand, was inhibited on both Edward's medium and inulin agar.

Animal Feed↗

PubMed1991

Enumeration by a miniaturized method of Escherichia coli, Streptococcus bovis and enterococci as indicators of the origin of faecal pollution of waters.

Counts of Escherichia coli, faecal streptococci and enterococci were made on faecal specimens from human and animal origin and urban raw sewage waters, with microtiter plates containing selective substances. Escherichia coli was more numerous than faecal streptococci and enterococci in 80% of the samples regardless of the origin. Consequently the use of the ratio E. coli/faecal streptococci to distinguish human from animal origin of faecal pollution is questionable. Enterococcus faecalis was predominant in human and poultry faeces, Streptococcus bovis was typical of the bovine faeces and to a lesser extent also of pig faeces whereas Enterococcus durans, Ent. hirae and Ent. faecium did not characterize any faecal source. Streptococcus bovis could be distinguished in the microtiter plate by its inability to reduce triphenyl tetrazolium chloride (TTC) in the medium.

Animals↗

PubMed2006

Factors affecting the activity of bovicin HC5, a bacteriocin from Streptococcus bovis HC5: release, stability and binding to target bacteria.

AIMS: To determine the factors affecting the release, stability and binding of bovicin HC5 to sensitive bacteria. METHODS AND RESULTS: Stationary phase Streptococcus bovis HC5 cultures had little cell-free bovicin HC5 activity until the final pH was <5.0, and even more bacteriocin was released by treatment with acidic NaCl (pH 2.0, 100 mmol l(-1)). Cultures grown with Tween 80 had more cell-free bovicin HC5 than untreated controls, but this nonionic detergent enhanced activity rather than release. Bovicin HC5 binding to S. bovis JB1 (a susceptible strain) was greater at pH values <6.0. Bovicin HC5 bound other sensitive Gram-positive bacteria, but not Gram-negative species. Cultures retained most of their activity for 35 days, but only if the final pH was <5.6. If the final pH was >5.6, peptidases destroyed much of the activity. CONCLUSIONS: Bovicin HC5 remains cell associated until the culture pH is <5.0, but it can be easily dissociated from the cell surface by acidic NaCl. It is highly stable in acidic environments and only binds sensitive bacteria at pH values <6.0. SIGNIFICANCE AND IMPACT OF THE STUDY: Streptococcus bovis HC5 does not have generally regarded as safe status. However, bovicin HC5 has a broad spectrum of activity and sensitive bacteria do not become resistant. Based on these results, bovicin HC5 may be a useful bacteriocin model.

Bacteriocins↗

PubMed2006

Introduction of air in the anaerobic culture of Streptococcus pneumoniae serotype 23F induces the release of capsular polysaccharide from bacterial surface into the cultivation medium.

AIM: An approach to increase Streptococcus pneumoniae capsular polysaccharide (CPS) in the culture medium during fed-batch cultivation in bioreactor. METHODS AND RESULTS: Streptococcus pneumoniae serotype 23F was cultivated in a 5-l bioreactor with nitrogen-sparging and followed by addition of air in the stationary phase. The amount of CPS released in the supernatant progressively increased under air sparging. The profile of cellular viability and optical density was similar in both cultures. Immunoelectron microscopy showed that the amount of tightly cell-bound CPS was higher in bacteria cultivated under nitrogen than under air. CONCLUSIONS: The stress caused by the addition of air at the stationary phase promoted a large increase of free CPS into the medium, as a consequence of the morphologic change in the capsule. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of air in the stationary phase of the culture would greatly simplify the subsequent downstream process, allowing CPS purification from the supernatant. The direct consequence of this process improvement is the reduction of vaccine production costs.

Air↗

PubMed2004

Lancefield group C Streptococcus dysgalactiae infection responsible for fish mortalities in Japan.

A Lancefield serological group C Streptococcus sp. was isolated from cultured amberjack, Seriola dumerili Risso, and yellowtail, Seriola quinqueradiata Temminck and Schlegel, immunized with Lactococcus garvieae commercial vaccines in Japan. The isolated bacteria were Gram-positive cocci, auto-aggregating in saline, morphologically long chains in growth medium, catalase negative and alpha-haemolytic on blood agar. An almost complete gene sequence of the 16S rDNA of two isolates was determined and compared with that of bacterial strains in the database. The isolates were identified as Streptococcus dysgalactiae based on the results of the 16S rDNA sequence, the bacteriological properties and the Lancefield serological grouping. Oligonucleotide primers specifically designed for the 16S-23S rDNA intergenic spacer region of S. dysgalactiae amplified a gene from all the fish isolates, as well as the type strains alpha-haemolytic S. dysgalactiae subsp. dysgalactiae ATCC430738 and beta-haemolytic S. dysgalactiae subsp. equisimilis ATCC35666, but not those of S. equi ATCC33398, Lactococcus garvieae ATCC43921 and L. garvieae KG9408. The severe necrotic lesions of the caudal peduncle seen in experimentally infected fish were similar to those seen in naturally infected fish.

Animals↗

PubMed1990

Effects of experimentally induced Streptococcus suis infection on the pharmacokinetics of penicillin G in pigs.

The pharmacokinetics of potassium penicillin G were studied in both healthy (n = 8) and experimentally Streptococcus-suis-infected (n = 6) pigs following intramuscular administration (15,000 iu/kg). Streptococcus-suis infection was induced artificially in young cross-bred pigs by subcutaneous inoculation with 9 x 10(8) to 10(9) colony-forming units of S. suis. The rectal temperature of infected pigs was significantly increased (P less than 0.01) before penicillin G injection and this was maintained for 8 h after the drug was given. Other clinical symptoms were also present. The serum concentration-time data for penicillin were found to fit a one-compartment open model with first-order absorption in the two groups of pigs. Significant changes were not observed between healthy and diseased pigs in following parameters: A, Ka, Ke and Tmax. However, in diseased pigs, significant increases (P less than 0.01) were found in Vd and ClB, and significant decreases (P less than 0.01) in Cmax and AUC occurred. The increased body clearance (ClB) and greater apparent volume of distribution (Vd) of penicillin G could partly explain why the serum values of the drug were much lower in diseased pigs than in healthy pigs.

Animals↗