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PubMed1990

Molecular genetics of Streptococcus thermophilus.

The metabolism and genetics of Streptococcus thermophilus (presently Streptococcus salivarius ssp. thermophilus) have only been investigated recently despite its widespread use in milk fermentation processes. The development of recombinant DNA technology has allowed impressive progress to be made in the knowledge of thermophilic dairy streptococci. In particular, it has permitted a careful analysis of phenotypically altered variants which were derived from a mother strain by plasmid or chromosomal DNA reorganization. While natural phage defense mechanisms of S. thermophilus remain poorly documented, information on the bacteriophages responsible for fermentation failures has accumulated. The lysogenic state of two S. thermophilus strains has also been demonstrated for the first time. Gene transfer techniques for this species have been established and improved to the point that targeted manipulation of their chromosomal determinants is now feasible. Cloning and expression vectors have been constructed, and a few heterologous genes were successfully expressed in S. thermophilus. The first homologous genes, involved in carbohydrate utilization, have been cloned and sequenced, shedding some light on the molecular organization of key metabolic steps.

Bacteriophages↗
PubMed1992

Studies on a murine model for evaluation of virulence of Streptococcus suis capsular type 2 isolates.

Five different parameters, time of incubation of the culture, type of culture medium, inoculum, strain of inbred mice, and age of mice, were tested using the LD50 technique to standardize a murine model for the evaluation of the virulence of Streptococcus suis capsular type 2 isolates. A model using 28 day-old mice belonging to CF1 strain appeared to give the best results. The inoculum size was the parameter most influencing the 50% lethal dose obtained with mice. Inoculation with 1-ml volume of a bacterial suspension instead of 0.1 or 0.5 ml decreased the LD50. The standardized model was used to evaluate the virulence of some isolates of known pathogenicity for pigs. The minimum lethal dose was used in the model and it appeared that the virulence of Streptococcus suis capsular type 2 isolates can be measured from highly virulent to totally avirulent.

Animals↗
PubMed1992

De novo glucan synthesis by mutants streptococcal glucosyltransferases present in pellicle promotes firm binding of Streptococcus gordonii to tooth surfaces.

Adherence of 3H-labelled cells of Streptococcus gordonii and Streptococcus milleri to artificial pellicles prepared from saliva supplemented with glucosyltransferases from mutants streptococci was examined using a new assay for sucrose-dependent cell-to-pellicle attachment. Results indicate that S. gordonii, but not S. milleri, could attach tightly to hydroxylapatite surfaces through de novo glucan synthesis by mutants streptococcal glucosyltransferases present in the experimental salivary pellicles.

Bacterial Adhesion↗
PubMed1996

A host-vector system for heterologous gene expression in Streptococcus gordonii.

We have developed a host-vector system for heterologous expression in Streptococcus gordonii (Sg) Challis (formerly Streptococcus sanguis), a commensal bacterium of the human oral cavity. The system is based on (i) integration of plasmid insertion vectors into the chromosome of specially engineered recipient hosts, and (ii) the use of the M6-protein-encoding gene (emm6) as a partner for construction of translational gene fusions. M6 is a streptococcal surface protein already proven useful as a fusion partner for the delivery of foreign antigens to the surface of Sg [Pozzi et al., Infect. Immun. 60 (1992) 1902-1907]. Insertion vectors carry a drug-resistance marker, different portions of emm6 and a multiple cloning site to allow construction of a variety of emm6-based fusions. Upon transformation of a recipient host with an insertion vector, 100% of transformants acquire both the drug-resistance marker and the capacity of displaying the M6 molecule on the cell surface. Chromosomal integration occurred at high frequency in recipient host GP1221. Transformation with 1 microgram of insertion vector DNA yielded 8.1 X 10(5) transformants per ml of competent cells.

Base Sequence↗
PubMedDate not supplied

Septic arthritis of the knee due to Streptococcus anginosus.

A case of arthritis caused by Streptococcus anginosus was observed in which the only predisposing factor was osteoarthritis of the knee and an acute meniscal tear. We report here the fifth case of septic arthritis due to Streptococcus anginosus.

Aged↗
PubMed1994

Development of a polymerase chain reaction assay to detect the presence of Streptococcus pneumoniae DNA.

In this study, we have developed a chemically sensitive and specific polymerase chain reaction (PCR) assay to detect the presence of Streptococcus pneumoniae genomic DNA. The target DNA sequence was a 322-base pair segment of the S. pneumoniae DNA polymerase I gene (pol I). PCR products of pure cultures of a set of pneumococcal serotypes commonly associated with human infection could be amplified in water and in blood cultures of clinical isolates containing S. pneumoniae. We were able to detect 2 fg of purified S. pneumoniae DNA. There were no false-positive reactions when the assay was performed on samples containing the following clinically encountered bacteria: Haemophilus influenzae type B, Neisseria meningitidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas spp. nontypeable H. influenzae, Staphylococcus aureus, coagulase-negative staphylococci, and Streptococcus pyogenes. The addition of EDTA and citrate-anticoagulated whole blood to the PCR reaction mixture inhibited the PCR assay, whereas the addition of lithium heparin, sodium heparin, and sodium polyanetholesulfonate-anticoagulated whole blood to PCR reaction mixture did not interfere with the ability to detect the presence of S. pneumoniae DNA.

Base Sequence↗
PubMed1996

Rapid antigen testing for group A Streptococcus by DNA probe.

The Gen-probe group A Streptococcus direct test (GASD), a nucleic acid probe assay for detecting GAS from throat swabs, has recently been developed. The test uses an acridium ester-labeled DNA probe which is complementary to the rRNA of Streptococcus pyogenes. In this study, 318 single culturette throat swabs were tested by this method using culture as a "gold standard." After plating onto trypticase soy agar plates with 5% sheep blood, swabs were stored at 4 degrees C for no more than 72 h before the probe assay was performed. Our patient population consisted of symptomatic outpatients seen in the Memorial Hospital Emergency Department and in the Family Care Center. After discrepancy testing, sensitivity, specificity, and positive and negative predictive values were 91.4%, 97%, 91.4%, and 97%. The GASD is a rapid, easy-to-perform method for batch screening for streptococcal pharyngitis.

Antigens, Bacterial↗
PubMed1996

Atypical Streptococcus pyogenes from an ear discharge.

An atypical variant of Streptococcus pyogenes was isolated from a discharge from a child's ear. Although this variant streptococcus grew aerobically on chocolate agar, the isolate would not grow on blood agar, the medium used to screen for S. pyogenes, unless it was incubated anaerobically or incubated in air with cocarboxylase.

Child, Preschool↗
PubMed1988

Purification and immunological characterization of neuraminidase produced by Streptococcus pneumoniae.

Previous workers have suggested that Streptococcus pneumoniae, the pneumococcus, produces multiple forms of the enzyme neuraminidase. By serial chromatography on DEAE-cellulose, Sephacryl S-200, Amicon Red-A gel and hydroxylapatite we have purified to electrophoretic homogeneity a pneumococcal neuraminidase with an apparent molecular weight of 86,000 (as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis). Mouse antiserum raised against the purified material reacted with a single species with molecular weight 107,000 (107K form) in crude pneumococcal cell lysate. During the purification procedure this species was progressively degraded to the molecular weight 86,000 (86K) form whilst retaining enzyme activity. Degradation of neuraminidase was inhibited by phenylmethylsulphonylfluoride (PMSF) and ethylenediaminetetraacetic acid (EDTA). Purification of the enzyme in the presence of these protease inhibitors permitted the isolation of the 107K species substantially undegraded and greater than 98% pure. Our findings on the degradation of neuraminidase during its purification account for previous reports of multiple neuraminidase isoenzymes in Streptococcus pneumoniae.

Antigens, Bacterial↗
PubMed1991

Identification of Streptococcus pyogenes proteins that bind to rabbit kidney in vitro and in vivo.

Proteins were extracted from the surface of a nephritogenic strain of Streptococcus pyogenes M12 and tested for binding to rabbit kidney using indirect immunofluorescence and enzyme-linked immunoassays. Streptococcal antigens bound in vitro in a fine linear pattern to basal laminae of glomeruli, Bowman's capsule, and tubules. Perfusion of rabbit kidney in vivo with streptococcal components resulted in focal and segmental fine granular staining of glomerular capillaries. Three streptococcal proteins (43, 31 and 9 kDa) were recovered from renal tissue that was pretreated in vitro with S. pyogenes extract. Streptococcal components bound in vitro to heparan sulfate, heparin, laminin and collagen IV but only weakly or not at all to fibronectin, bovine serum albumin or dextran sulfate. Affinity chromatography of bacterial extracts on heparin-agarose produced a 9 kDa streptococcal protein (pI 9.5) which bound to kidney basement membranes in vitro and in isolated perfused kidneys. Several additional strains of group A streptococci were found to contain the 9 kDa cationic protein. This bacterial protein, when released into the blood by the bacterium during infection, may contribute to the pathogenesis of streptococcus-associated nephritides in man.

Animals↗
PubMedDate not supplied

Introduction of the emm6 gene into an emm-deleted strain of Streptococcus pyogenes restores its ability to resist phagocytosis.

To complete the formal proof that the M protein functions to protect the group A streptococcus from phagocytosis and to lay the groundwork for the molecular genetic dissection of this major virulence factor, we have reintroduced a wild-type allele of the M protein gene (emm) into the chromosome of a strain from which it had previously been deleted. For this purpose, we used homologous recombination with an engineered plasmid that was introduced into the Streptococcus pyogenes chromosome by an electroporation technique that we developed. The plasmid pJRS120E was constructed in Escherichia coli and contains the structural gene for the antiphagocytic M6 protein (emm6) of S. pyogenes JRS4 and a selectable marker (ermAM) between the chromosomal regions that flank emm6 in S. pyogenes. This plasmid was introduced into S. pyogenes strain JRS75, a strain that is not resistant to phagocytosis as a result of the allelic replacement of the emm6 gene by a kanamycin resistance gene (aphA3). DNA hybridization analysis indicated that in erythromycin-resistant strain JRS115, homologous recombination resulted in the replacement of the aphA3 gene of JRS75 with the introduced emm6 allele. Strain JRS115 produces approximately the same amount of M6 as does the parental emm6+ strain JRS4, as assayed by Western blot analysis, and is resistant to phagocytosis.

Alleles↗
PubMed2026

Gene Contribution of Streptococcus dysgalactiae Subspecies equisimilis, an Emerging Pathogen, to Experimental Primate Necrotizing Myositis.

Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an emerging human pathogen closely related to group A Streptococcus. However, its genetic requirements for survival and growth in different conditions and for causing invasive infections remain poorly understood. To address this gap, transposon-directed insertion-site sequencing was used to identify genes contributing to fitness in experimental necrotizing myositis in nonhuman primates. Using two SDSE stG62647 human clinical isolates, MGCS36044 and MGCS36089, highly saturated transposon mutant libraries were generated and analyzed following in vitro growth and in vivo infection in eight nonhuman primates. A total of 398 essential genes were identified to be shared by both strains during growth in vitro and in vivo, and 17 and 7 conditionally essential genes required only in vitro or only in vivo, respectively. Additionally, 117 and 110 genes in MGCS36044 and MGCS36089, respectively, were found to be associated with fitness during necrotizing myositis. Transposon insertions in 34 MGCS36044 genes conferred increased fitness, whereas mutation of 83 genes conferred decreased fitness. Similarly, in MGCS36089, mutations in 38 and 72 genes conferred increased or decreased fitness, respectively. Importantly, both strains shared 46 fitness-associated genes, including an enrichment of transporter genes, highlighting nutrient acquisition as a dominant requirement during infection. The results provide critical information for guiding future translational efforts to develop preventive and therapeutic strategies against human SDSE infections.

Animals↗
PubMed2006

Use of leukocytes as treatment for endometritis in mares experimentally infected with Streptococcus equi subsp. zooepidemicus.

This study compared four treatments for bacterial endometritis in mares experimentally infected with Streptococcus zooepidemicus. Twenty-five mares were used, 20 resistant and five susceptible to endometritis. Mares would be in estrus when infected. Twenty-four hours after inoculation, clinical, bacteriological and cytological examinations were performed and repeated until the first occurrence: negative cytology and no Streptococcus growth or the seventh day post-infection. All mares showed clinical signs of endometritis and were assigned to one of the following treatments: (1) intrauterine infusion of fresh leukocytes; (2) intrauterine infusion of frozen-thawed leukocytes; (3) intrauterine infusion of lysed leukocytes; (4) intrauterine infusion of recombinant human interleukin-8 (rhIL-8); (5) control. Mares were submitted to all treatments, with at least a 14-day interval between treatments in a Latin square design. Treatment did not affect (P=0.121) time needed for resistant mares to eliminate bacteria. Time needed for elimination of bacteria was similar in susceptible mares treated with fresh and frozen leukocytes (P=0.333). Susceptible mares treated with frozen leukocytes also did not differ from those treated with lysed leukocytes (P=0.227) for time to eliminate bacteria, but were significantly different (P>0.02) from those treated with rhIL-8 and control. In resistant mares, physical clearance ability was probably the responsible for bacterial elimination. Intrauterine infusions in susceptible mares with viable or lysed leukocytes associated or not to opsonizing factors, reduced the time to elimination of bacteria. Infusions with bactericidal effect (functional neutrophils and granules) was likely effective and responsible for the more rapid elimination of bacteria in susceptible mares.

Animals↗
PubMed2006

Streptococcus gordonii soluble inorganic pyrophosphatase: an important role for the interdomain region in enzyme activity.

Streptococcus gordonii DL1(Challis) soluble inorganic pyrophosphatase was shown to be a homo dimer with a subunit molecular mass of 33407. In solution, in the presence of Mn(2+), the protein is ellipsoidal with an axial ratio of 3.37 and molecular mass of 67000. In the absence of the divalent cation, the molecular mass is unchanged but the axial ratio increases to 3.94. The enzyme, in the presence of 5 mM Mg(2+), at 25 degrees Celsius and pH 9.0, has K(m) and k(cat) values of 62 microM and 6290 s(-1), respectively. The free N- and C-terminal domains of Streptococcus gordonii PPase did not interact productively when mixed together. Replacing the interdomain region with that from Bacillus subtilis decreased the catalytic efficiency of the enzyme whereas inserting the same region from the Archaeglobus fulgidus thermophilic enzyme yielded an inactive protein. Substitution, deletion and insertion of amino acid residues in the interdomain region were found to affect the monomer dimer equilibrium in the absence of Mn(2+) ions. In the presence of these ions however the variant proteins were dimers. Proteins with altered interdomain regions also displayed a 2- to 625-fold decrease in catalytic efficiency. These data together with that of computer analysis show that the interdomain region has characteristics of a mechanical hinge. Modelling mutant proteins onto the wild type shows that the active site regions are not significantly perturbed. These results show that, although distant from the active site, the interdomain region plays a role in enzyme activity and both its length and composition are important. This supports the hypothesis that catalytic activity requires the N- and C terminal domains of the enzyme to open and close using the interdomain region as a hinge.

Amino Acid Sequence↗
PubMed2004

Characterisation of a novel homodimeric N-acetyl-beta-D-glucosaminidase from Streptococcus gordonii.

An N-acetyl-beta-D-glucosaminidase (GcnA) from Streptococcus gordonii FSS2 was cloned and sequenced. GcnA had a deduced molecular mass of 72,120 Da. The molecular weight after gel-filtration chromatography was 140,000 Da and by SDS-PAGE was 70,000 Da, indicating that the native protein was a homodimer. The deduced amino acid sequence had significant homology to a glycosyl hydrolase from Streptococcus pneumoniae and the conserved catalytic domain of the Family 20 glycosyl hydrolases. GcnA catalysed the hydrolysis of the synthetic substrates, 4-methylumbelliferyl (4MU)-N-acetyl-beta-D-glucosaminide, 4MU-N-acetyl-beta-D-galactosaminide, 4-MU-beta-D-N,N'-diacetylchitobioside, and 4-MU-beta-D-N,N',N''-chitotrioside as well as the respective chito-oligosaccharides. GcnA was optimally active at pH 6.6 and 42 degrees C. The Km for 4-MU-beta-D-N,N',N''-chitotrioside, 45 microM, was the lowest for all the substrates tested. Hg2+, Cu2+, Fe2+, and Zn2+ completely inhibited while Co2+, Mn2+, and Ni2+ partially inhibited activity. S. gordonii FSS2 and a GcnA negative mutant grew equally well on chito-oligosaccharides as substrates. The S. gordonii sequencing projects indicate two further N-acetyl-beta-D-glucosaminidase activities.

Acetylglucosaminidase↗
PubMed2006

Relationship of movements and behaviors to Group A Streptococcus infections in elementary school children.

BACKGROUND: Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus (PANDAS) research is based on the hypothesis that infections trigger changes in behavior and movement in children. METHODS: We enrolled 693 children (ages 3 to 12 years) into a systematic, longitudinal study. Data were collected monthly for 8 months (October-May) to determine point prevalence of Group A Streptococcal (GAS) infections, tics, behavior, and choreiform movements. Simultaneous throat cultures were obtained, and relational analyses were made between GAS and movement/observation ratings. RESULTS: Combined behavior/GAS associations (concurrent with or 3 subsequent months to GAS) revealed a strong relationship, relative risk (RR) of 1.71 (p < .0001). Detailed analysis revealed that balance/swaying and non-tic grimacing were responsible for a significant proportion of this association (RR = 2.92, p < .0001). A strong seasonal pattern was found, with fall being more significant for GAS infections and observation ratings (p < .0001) compared with winter/spring. Children with repeated streptococcus (n = 64) showed higher rates of behavior and distal choreiform observations (p = .005). CONCLUSIONS: Motor/behavior changes were noted to occur in relationship to positive GAS culture with support that repeated GAS increases risk.

Adolescent↗
PubMed2006

Application of a unique server-based oligonucleotide probe selection tool toward a novel biosensor for the detection of Streptococcus pyogenes.

We developed a software program for the rapid selection of detection probes to be used in nucleic acid-based assays. In comparison to commercially available software packages, our program allows the addition of oligotags as required by nucleic acid sequence-based amplification (NASBA) as well as automatic BLAST searches for all probe/primer pairs. We then demonstrated the usefulness of the program by designing a novel lateral flow biosensor for Streptococcus pyogenes that does not rely on amplification methods such as the polymerase chain reaction (PCR) or NASBA to obtain low limits of detection, but instead uses multiple reporter and capture probes per target sequence and an instantaneous amplification via dye-encapsulating liposomes. These assays will decrease the detection time to just a 20 min hybridization reaction and avoid costly enzymatic gene amplification reactions. The lateral flow assay was developed quantifying the 16S rRNA from S. pyogenes by designing reporter and capture probes that specifically hybridize with the RNA and form a sandwich. DNA reporter probes were tagged with dye-encapsulating liposomes, biotinylated DNA oligonucleotides were used as capture probes. From the initial number of capture and reporter probes chosen, a combination of two capture and three reporter probes were found to provide optimal signal generation and significant enhancement over single capture/reporter probe combinations. The selectivity of the biosensor was proven by analyzing organisms closely related to S. pyogenes, such as other Streptococcus and Enterococcus species. All probes had been selected by the software program within minutes and no iterative optimization and re-design of the oligonucleotides was required which enabled a very rapid biosensor prototyping. While the sensitivity obtained with the biosensor was only 135 ng, future experiments will decrease this significantly by the addition of more reporter and capture probes for either the same rRNA or a different nucleic acid target molecule. This will lead to the possibility of detecting S. pyogenes with a rugged assay that does not require a cell culturing or gene amplification step and will therefore enable rapid, specific and sensitive onsite testing.

Biosensing Techniques↗
PubMed2004

Complementary exploration of the action pattern of hyaluronate lyase from Streptococcus agalactiae using capillary electrophoresis, gel-permeation chromatography and viscosimetric measurements.

Hyaluronic acid (HA) was treated with hyaluronate lyase (GBS HA lyase, E.C. 4.2.2.1, from Streptococcus agalactiae strain 4755), and the products have been analyzed by capillary electrophoresis (CE-UV and online CE-ESIMS), gel-permeation chromatography (GPC) and viscosimetric measurements. The resulting electropherograms showed that the enzyme produced a mixture of oligosaccharides with a 4,5-unsaturated uronic acid nonreducing terminus. More exhaustive degradation of HA led to increasing amounts of di-, tetra-, hexa-, octa- and decasaccharides. Using CE, linear relationships were found between peak area of the observed oligosaccharides and reaction time. Determination of viscosity at different stages of reaction yielded an initial rapid decrease following Michaelis-Menten theory. A reaction time-dependent change in the elution position of the HA peak due to partial digestion of HA with GBS hyaluronate lyase has been observed by GPC. These results indicated that the HA lyase under investigation is an eliminase that acts in a nonprocessive endolytic manner, as at all stages of digestion a mixture of oligosaccharides of different size were found. For GBS HA lyase from Streptococcus agalactiae strain 3502, previously published findings reported an action pattern that involves an initial random endolytic cleavage followed by rapid exolytic and processive release of unsaturated disaccharides. Our results suggest that differences between the two enzymes from distinct S. agalactiae strains (GBS strains 4755 and 3502) have to be considered.

Chromatography, Gel↗