PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Streptococcus pyogenes”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,603 records · Page 89Linked to original sources
PubMed1985

Inhibition of complement-mediated opsonization and phagocytosis of Streptococcus pyogenes by D fragments of fibrinogen and fibrin bound to cell surface M protein.

The biological effects of the binding of fibrin(ogen) degradation products to M protein-bearing group A streptococci were investigated. Type 24 group A streptococci bind fibrinogen degradation products of the D family, but not fragment E. Binding appears to be mediated by M protein, since a large peptide of this molecule (pep M24) bound to fragments containing the terminal domains of the fibrinogen molecule (D, X, and Y), but not fragment E, and pep M24 inhibited the binding of digested fibrinogen to streptococcal cells. An M protein-binding site occurs on fragment D3 and, therefore, differs from several functional sites present on D1 but not D3, including the fibrin polymerization site, the two gamma chain crosslink sites, and the bindings sites for platelet fibrinogen receptor, staphylococcal clumping factor, and ionized calcium. Bound fibrinogen degradation products prevented deposition of C3 on the streptococcal cell surface, and, in consequence, prevented phagocytosis by neutrophils in nonimmune blood. The average affinity of D fragments for the streptococcal cell surface was approximately 30 times lower than that of native fibrinogen, and a terminal plasmic digest was approximately 50 times less potent in inhibiting opsonization by C3. However, physiologic concentrations of digested fibrinogen sufficed to inhibit opsonization and phagocytosis completely. Digests of crosslinked fibrin clot also inhibited opsonization, although slightly less effectively than did fibrinogen digests. The antiopsonic effect of fibrin(ogen) degradation products may be relevant to circumstances in which fibrin(ogen)olysis is occurring, e.g., exudation and suppuration.

Antigens, Bacterial↗
PubMed2004

Post-proteomic identification of a novel phage-encoded streptodornase, Sda1, in invasive M1T1 Streptococcus pyogenes.

The M1T1 strain remains the most frequently isolated strain from group A streptococcal (GAS) infection cases worldwide. We previously reported that M1T1 differs from the fully sequenced M1 SF370 strain. To better understand the reason for the persistence and increased virulence of M1T1, we analysed its secreted proteome and identified two virulence proteins that are not present in the sequenced M1 SF370 strain: streptococcal pyrogenic exotoxin A (SpeA) and a streptodornase D (SdaD) homologue. In the present study, we determined the nucleotide sequence of the M1T1 streptodornase and found that its deduced amino acid sequence is highly similar to other streptococcal streptodornases, and is most closely related to the SdaD of GAS strain M49. M1T1 Sda shares two highly conserved domains with several DNases and putative DNases in streptococci; however, it possesses a unique C-terminal amino acid sequence. Thus, we named the protein Sda1, and we detected the presence of the sda1 gene in 16 M1T1 clinical isolates. The cloned and expressed Sda1 degrades both streptococcal and mammalian DNA at physiological pH. Amino acid similarity analyses of known GAS deoxyribonucleases suggest that Sda1 may be a chimeric protein created through recombination events. Moreover, a natural mutation that resulted in longer Sda1 and SdaD as compared to other GAS DNases was found to confer increased activity on the protein. Analysis of the sequences flanking sda1 determined that it is carried by a prophage or a prophage-like element inserted in the tRNA-Ser gene of M1T1 GAS. Ongoing studies in our laboratory aim to determine the contribution of Sda1 to the virulence of this globally disseminated M1T1 strain.

Amino Acid Sequence↗
PubMed2003

Genomic location and variation of the gene for CRS, a complement binding protein in the M57 strains of Streptococcus pyogenes.

All isolates of serotype M1 of group A streptococci possess a gene for streptococcal inhibitor of complement (SIC) in the mga regulon, which harbors genes for other virulence factors, such as M and M-like proteins, C5a peptidase, and a regulator. In serotype M57 the gene for a protein that is closely related to SIC (crs57) is located outside the mga regulon. We mapped the location of the crs57 gene in six strains of emm57 (gene encoding the M57 protein) sequence types to an intergenic region between the ABC transporter gene (SPy0778) and the gene for a small ribosomal protein (rpsU). The noncoding sequences on both sides of crs57 exhibited high degrees of identity to the corresponding regions of sic from M1 strains. This included one of the inverted repeat sequences of IS1562 but not the insertion element itself. These observations suggest that crs57 was recently acquired by serotype M57 or its progenitor via horizontal acquisition from serotype M1. The six emm57 sequence type isolates analyzed in this study belong to two distinct molecular types (vir types VT8 and VT101). Although the crs57 sequences from VT8 strains had very few substitution mutations, the VT101 crs57 sequence had a large number of such mutations. The CRS57 proteins from these strains are secretory products and have the ability to bind to complement proteins. All these proteins contain several tryptophan-rich repeats designated DWS motifs and internal repeat sequences. In all of these structural and biochemical characteristics CRS57 resembles SIC from M1 strains. Hence, CRS57 has a functional role similar to that of SIC in an M1 strain.

Amino Acid Sequence↗
PubMed1983

Complex surveillance of streptococcus pyogenes. VI. Relationship between hypersensitivity to zymosan and indicators of immunity against group A streptococci.

A prospective study involving 20 volunteers was designed to test relationships between the sensitivity to zymosan and the indicators of nonspecific immunity against streptococci (inhibitory activity of blood and production of mediators). The immunization with Mannozym produced a conversion of zymosan-induced MIF with a subsequent improvement of immunity indicators in 4 out of 7 primovaccinated and 2 revaccinated subjects. This effect was detectable in some vaccines within 2-4 days after immunization and persisted for up to 5 months. Initially detected changes, their kinetics in the vaccinated subjects as well as time-related variations in the pattern of indicators during a one-year period of observation seem to suggest that there was a relationship between the natural and induced cellular sensitivity to zymosan and the inhibitory activity of blood. The inhibitory activity of blood was effectuated through enhanced mediator-induced phagocytic activity and nonspecific opsonin mechanisms. The mediators fluctuated in their values with time and were demonstrable in immunized subjects. There were observed interlinked reactions of cellular immunity with zymosan, peptidoglycan and streptococci. The mechanisms found are believed to constitute a fundamental, relatively easy-to-stimulate means of human immunity which may explain the experimental and epidemiological inconsistencies in the strictly type-specific interpretation of the M - anti-M system. Under in vitro conditions the effect of nonspecific immunization was bacteriostatic, but the role of these nonspecific mechanisms under conditions in vivo remains unclear. It is recommended that effectiveness of nonspecific immunization be verified under conditions of natural infection in man.

Blood Bactericidal Activity↗
PubMed1994

Gene organization of the Streptococcus pyogenes plasmid pDB101: sequence analysis of the orf eta-copS region.

The gene organization of the broad-host-range low-copy-number pSM19035-derived plasmid pDB101 is presented. Analysis of the 19,202-bp sequence revealed thirteen different open reading frames (orfs). Nine of these orfs (repS-orf-orf beta-orf gamma-orf delta-orf epsilon-orf zeta-erm2-erm1 have been previously identified [Cegłowski et al., Gene 136 (1993) 1-12]. The extraordinarily long inverted repeated sequence, which includes orf alpha-orf beta-orf gamma-orf delta-orf epsilon-orf zeta, comprises 76% of the pDB101 molecule. The gene order in pDB101 is repS-orf alpha-orf beta-orf gamma-orf delta-orf epsilon-orf zeta-erm2-erm1-orf zeta-orf epsilon-orf delta-orf gamma-orf beta-orf alpha-orf eta-orf theta-orf1-copS. The organization of genes of the orf eta-orf gamma region resembles the organization of genes in the orfA-orfI region of pAM beta 1. Except for Orf1, bands of radioactive proteins corresponding to the molecular mass of the deduced reading frames (26.7, 14.3 and 10.3 kDa) were detected using the T7 promoter-expression system. The orf1 encoded a product (deduced molecular mass 28.3 kDa) which shows anomalous electrophoretical mobility corresponding to 60 kDa. The copS- and orf1-encoded proteins share homology to plasmid copy number control systems and Gram+ cocci surface proteins, respectively. The orf eta and orf theta encode proteins with unknown activity.

Amino Acid Sequence↗
PubMed2004

Recognition of DNA by omega protein from the broad-host range Streptococcus pyogenes plasmid pSM19035: analysis of binding to operator DNA with one to four heptad repeats.

pSM19035-encoded omega protein forms a dimer (omega2) that binds to a set of 7-bp repeats with sequence 5'-NATCACN-3'. Upon binding to its cognate sites, omega2 regulates transcription of genes required for copy number control and stable inheritance of plasmids, and promotes accurate plasmid segregation. Protein omega2 binds poorly to one heptad but the affinity to DNA increases with two and more unspaced heptads in direct or inverted orientation. DNA titration of increasing numbers of heptads with omega2, monitored by circular dichroism measurements, indicates the binding of one omega2 to one heptad (omega2:heptad stoichiometry of 1:1). Spacing of two directly or inversely oriented heptads by 1 to 7 bp reduces the affinity of the protein for its cognate target site. The binding affinity of omega2 for two directly repeated heptads was severely reduced if one of the base pairs of the core 5'-ATCAC-3' sequence of one of the heptads was individually substituted by any other base pair. Hydroxyl radical footprinting shows a protection pattern at the 5'-ATCAC-3' core. These data suggest that each heptad defines an operator half-site and that tight binding of the symmetric omega2 to the central 5'-TCA-3' core of symmetric or asymmetric targets (differently oriented heptads) is probably achieved by structural changes of DNA and/or protein or both.

Bacterial Proteins↗
PubMed2006

Development of serum IgM antibodies against superantigens of Staphylococcus aureus and Streptococcus pyogenes in Kawasaki disease.

To serologically determine the association of microbial superantigens and the pathogenesis of Kawasaki disease (KD), we conducted a case-control study. Serum IgG and IgM antibodies against staphylococcal enterotoxin A (SEA), SEB, SEC, toxic shock syndrome toxin-1 (TSST-1), and streptococcal pyrogenic exotoxin A (SPEA) were measured by an enzyme-linked immunosorbent assay in 293 serum samples from 65 KD patients on clinical days 1-28 and 120 control samples. The administration of immunoglobulin products, which contain high concentrations of IgG antibodies against all the superantigens, directly elevated antitoxin IgG antibodies in KD patients. In contrast, antitoxin IgM antibodies were not detected in immunoglobulin products. Actually, we found a significant elevation of IgM antibodies against SEA in KD patients in the first (median titre: 0.020, P < 0.01 versus control), second (0.024, P < 0.001), third (0.030, P < 0.001) and fourth (0.038, P < 0.001) weeks, compared to the controls (0.015). Significant differences of IgM antibodies were also true for SEB, TSST-1, and SPEA throughout the first to fourth weeks, and for SEC throughout the second to fourth weeks. The prevalence of KD patients having high IgM titres (> mean + 2SD of control values) to the 5 superantigens was increased with the clinical weeks, and reached 29-43% of KD subjects at the fourth week. This is the first study that describes kinetics of IgM antibodies against superantigens and clarifies the serological significance throughout the clinical course of KD. Our results suggest that multiple superantigens involve in the pathogenesis of KD.

Antibodies, Bacterial↗
PubMed2003

Genome sequence of an M3 strain of Streptococcus pyogenes reveals a large-scale genomic rearrangement in invasive strains and new insights into phage evolution.

Group Astreptococcus (GAS) is a gram-positive bacterial pathogen that causes various suppurative infections and nonsuppurative sequelae. Since the late 1980s, streptococcal toxic-shock like syndrome (STSS) and severe invasive GAS infections have been reported globally. Here we sequenced the genome of serotype M3 strain SSI-1, isolated from an STSS patient in Japan, and compared it with those of other GAS strains. The SSI-1 genome is composed of 1,884,275 bp, and 1.7 Mb of the sequence is highly conserved relative to strain SF370 (serotype M1) and MGAS8232 (serotype M18), and almost completely conserved relative to strain MGAS315 (serotype M3). However, a large genomic rearrangement has been shown to occur across the replication axis between the homologous rrn-comX1 regions and between two prophage-coding regions across the replication axis. Atotal of 1 Mb of chromosomal DNA is inverted across the replication axis. Interestingly, the recombinations between the prophage regions are within the phage genes, and the genes encoding superantigens and mitogenic factors are interchanged between two prophages. This genomic rearrangement occurs in 65% of clinical isolates (64/94) collected after 1990, whereas it is found in only 25% of clinical isolates (7/28) collected before 1985. These observations indicate that streptococcal phages represent important plasticity regions in the GAS chromosome where recombination between homologous phage genes can occur and result not only in new phage derivatives, but also in large chromosomal rearrangements.

Attachment Sites, Microbiological↗
PubMed2003

Combined contributions of streptolysin O and streptolysin S to virulence of serotype M5 Streptococcus pyogenes strain Manfredo.

Streptolysin O (SLO) and streptolysin S (SLS) are potent cytolytic toxins produced by almost all clinical isolates of group A streptococci (GAS). Allele-replacement mutagenesis was used to construct nonpolar (in-frame) deletion mutations in the slo and sagB genes of the serotype M5 GAS strain Manfredo, producing isogenic single and double SLO- and SLS-defective mutants. In contrast to recent reports on SLS-defective insertion mutants (I. Biswas, P. Germon, K. McDade, and J. Scott, Infect. Immun. 69:7029-7038, 2001; Z. Li, D. Sledjeski, B. Kreikemeyer, A.Podbielski, and M. Boyle, J. Bacteriol. 181:6019-6027, 1999), none of the mutants described here had notable pleiotropic effects on the expression of other virulence factors examined. Comparison of isogenic parent and mutant strains in various virulence models revealed no differences in their abilities to multiply in human blood or in their 50% lethal doses (LD(50)s) upon intraperitoneal infection of BALB/c mice. A single log unit difference in the LD(50)s of the parent and SLS-defective mutant strains was observed upon infection by the subcutaneous (s.c.) route. Comparisons over a range of infective doses showed that both SLO and SLS contributed to the early stages of infection and to the induction of necrotic lesions in the murine s.c. model. Individually, each toxin made an incremental contribution to virulence that was not apparent at higher infective doses, although the absence of both toxins reduced virulence over the entire dose range examined. Interestingly, in some cases, the contribution of SLO to virulence was clear only from an analysis of the double-mutant strain, highlighting the value of not confining virulence studies to mutant strains defective in the expression of only single virulence factors.

Animals↗
PubMed2006

Characterization of group A streptococci (Streptococcus pyogenes): correlation of M-protein and emm-gene type with T-protein agglutination pattern and serum opacity factor.

Strain characterization of group A streptococci (GAS) has traditionally been based on serological identification of M protein. Additional tests to determine T-protein serotype and production of streptococcal serum opacity factor (SOF) provide important information both to aid in and to supplement M-protein serotyping. Advances in DNA-sequencing technology in the late twentieth century resulted in the development of a method for determining the M type of GAS from the sequence of the gene encoding M protein, the emm gene. Although emm-sequence typing has largely replaced M typing in many laboratories, information provided by T typing and SOF determination continues to provide valuable supplementary information for strain characterization. A comprehensive summary of the correlation of T pattern and SOF production with M type was last published in 1993, several years before emm typing became widely available. Since then, the ease of M-type identification afforded by emm typing has resulted in an increase in the number of confirmed M/emm types of more than 50 %. However, comprehensive information about T-protein serotype and the correlation of SOF production with these new M/emm types is not widely available. This report presents a comprehensive summary of this information, not only for newly described types, but also updated information for previously described types. This information was extracted from combined records from streptococcal reference laboratories at the University of Minnesota and at the Centers for Disease Control and Prevention in Atlanta. Data from more than 40,000 strains (representing uncomplicated GAS infections, systemic invasive infections and strains associated with non-suppurative sequelae, collected from the US and diverse locations worldwide) were analysed.

Agglutination↗
PubMed1998

Binding of complement subcomponent C1q to Streptococcus pyogenes: evidence for interactions with the M5 and FcRA76 proteins.

Binding of C1q, the first component of the complement system, to some human pathogens has been earlier reported. In the present study, direct binding of C1q to group A streptococci (GAS) of various serotypes as well as some other Gram-positive and Gram-negative species was demonstrated. The interaction between C1q and GAS was investigated more in detail. In hot neutral extracts of a number of GAS strains two components of 64 and 52 kDa, respectively, bound C1q; alkaline and SDS extracts yielded the 52 kDa component as the main C1q-binding substance. Trypsin treatment of the SDS extracts of two GAS strains suggested the C1q-binding component(s) to be of protein nature. C1q-binding material purified from the SDS extract of an avirulent strain, type T27, was separated in 12% SDS-PAGE and probed in Western blot with human C1q and fibrinogen, conjugated to horse radish peroxidase (HRP) as well as rabbit IgG antibodies complexed to HRP (PAP system). The 52 kDa component was non-reactive with fibrinogen or rabbit IgG. However, C1q-binding components purified from the alkaline extracts of two M-positive strains revealed strong binding of either fibrinogen (type M5) or both fibrinogen and rabbit IgG (type M76); the molecular mass of these components. 55 kDa and 43-40 kDa, respectively, was in agreement with the reported molecular mass of the M5 and FcRA76 proteins. Our findings suggest that C1q may interact with GAS through certain M-family proteins as well as by a so far unidentified surface factor of protein nature occurring in most GAS strains. The involvement of M-family proteins, regarded as virulence factors of these organisms, may suggest the interaction of GAS with C1q as biologically important.

Antigens, Bacterial↗
PubMed2005

Mosaic prophages with horizontally acquired genes account for the emergence and diversification of the globally disseminated M1T1 clone of Streptococcus pyogenes.

The recrudescence of severe invasive group A streptococcal (GAS) diseases has been associated with relatively few strains, including the M1T1 subclone that has shown an unprecedented global spread and prevalence and high virulence in susceptible hosts. To understand its unusual epidemiology, we aimed to identify unique genomic features that differentiate it from the fully sequenced M1 SF370 strain. We constructed DNA microarrays from an M1T1 shotgun library and, using differential hybridization, we found that both M1 strains are 95% identical and that the 5% unique M1T1 clone sequences more closely resemble sequences found in the M3 strain, which is also associated with severe disease. Careful analysis of these unique sequences revealed three unique prophages that we named M1T1.X, M1T1.Y, and M1T1.Z. While M1T1.Y is similar to phage 370.3 of the M1-SF370 strain, M1T1.X and M1T1.Z are novel and encode the toxins SpeA2 and Sda1, respectively. The genomes of these prophages are highly mosaic, with different segments being related to distinct streptococcal phages, suggesting that GAS phages continue to exchange genetic material. Bioinformatic and phylogenetic analyses revealed a highly conserved open reading frame (ORF) adjacent to the toxins in 18 of the 21 toxin-carrying GAS prophages. We named this ORF paratox, determined its allelic distribution among different phages, and found linkage disequilibrium between particular paratox alleles and specific toxin genes, suggesting that they may move as a single cassette. Based on the conservation of paratox and other genes flanking the toxins, we propose a recombination-based model for toxin dissemination among prophages. We also provide evidence that a minor population of the M1T1 clonal isolates have exchanged their virulence module on phage M1T1.Y, replacing it with a different module identical to that found on a related M3 phage. Taken together, the data demonstrate that mosaicism of the GAS prophages has contributed to the emergence and diversification of the M1T1 subclone.

Amino Acid Sequence↗
PubMed1997

Streptococcal pyrogenic exotoxin A, streptolysin O, exoenzymes, serotype and biotype profiles of Streptococcus pyogenes isolates from patients with toxic shock syndrome and other severe infections.

The determination of protein M and T serotypes, biotypes and pyrogenic (erythrogenic) exotoxin A (SPE A), streptolysin O (SLO), streptokinase (SK), hyaluronidase (HA) and cysteine proteinase release by 212 S. pyogenes isolates from patients with severe invasive group A streptococcal (GAS) infections, among them 74 cases of streptococcal toxic shock syndrome (STSS) has been investigated. M1 or M3 serotypes were expressed by 25% of the isolates (53/212), whereas 59% (125/212) belonged to 15 other different serotypes and 16% (34/212) were untypeable. Of the 74 isolates from STSS patients, 42% (31/74) expressed M1 and to a lesser extent M3 serotypes versus 19% of the non STSS isolates (26/138). Among the ten different biotypes known, biotypes 1 and 3 were prevalent, particularly the former in the case of STSS isolates. SPE A was detectably produced by about 25% (54/212) of the strains. However, as high as 40.5% of the STSS isolates (30/74) versus 17.4% of non STSS isolates (24/138) released SPE A. Moreover, 67% of the SPE A producing strains were of serotype M1 or M3. SK and HA were released by 71% and 10% of the isolates respectively. All strains released SLO (4 to 256 HU/ml) and 85% cysteine proteinase. No relationship between toxin or enzyme titer and the type of disease or clinical origin of the strains was found. Culture supernatants of all isolates showed moderate to high lymphocyte transforming activity with index values ranging from 14.5 to 50.3 including those strains which did not release detectable amounts of SPE A suggesting that SPE C and other mitogenic factor(s) are released by the isolates investigated.

Adolescent↗
PubMed1992

Cytokine production by murine cells activated by erythrogenic toxin type A superantigen of Streptococcus pyogenes.

The mode of pathogenic action of the Steptococcus pyogenes superantigen erythrogenic toxin type A (ETA) in causing toxic shock-like syndrome in humans is thought to be mediated by massive release of cytokines by patients immune cells. The cytokine-inducing capacity of ETA as an extracellular protein was compared with that of lipopolysaccharide (LPS), a component of cell wall of gram-negative bacteria. Peritoneal macrophages and splenocytes of BALB/c and C3H/HeJ mice were stimulated by ETA and LPS. Tumor necrosis factor (TNF), interleukin 3 (IL-3) and interleukin 6 (IL-6) activities in the supernatants of stimulated cells were evaluated. In contrast to LPS, ETA induced only low amounts of IL-6 and no detectable TNF activities in peritoneal macrophage supernatants. ETA-triggered BALB/c and C3H/HeJ splenocytes produced great amounts of IL-6. ETA triggered the production of IL-3 by both mice strains splenocytes in a dose dependent manner. The amounts of IL-3 in supernatants were comparable to those induced by concanavalin A. The simultaneous presence of ETA and LPS in macrophage and splenocyte cultures induced a slight enhancement above an additive value after 72-96 h. Challenge of BALB/c mice with ETA 6 h before the harvest of peritoneal macrophages led to an enhanced production of IL-6 upon stimulation with ETA as well as with LPS. Splenocytes of nude BALB/c mice did not produce IL-6 upon stimulation with ETA, whereas LPS-induced IL-6 production was similar in these mice and in their littermates. The pathogenic effect of ETA on host's immune cells could most likely be explained as a consequence of T cell activation. The results confirm also that LPS- and ETA-induced shock is mediated by different cell types.

Animals↗
PubMed1991

Inverse correlation in nutritionally variant streptococci between the production of bacteriolytic activity and sensitivity to a Streptococcus pyogenes bacteriocinlike inhibitory substance.

Nineteen strains of nutritionally variant streptococci (NVS) were tested for bacteriolytic activity and for their production of and sensitivity to streptococcal bacteriocinlike inhibitory substances (BLIS). None appeared to produce BLIS. An inverse relationship was found between the sensitivity to BLIS and the production of bacteriolytic activity against Micrococcus luteus. All but one of the 14 Streptococcus defectivus isolates were sensitive to the BLIS of S. pyogenes P5, and these isolates were nonlytic. The five S. adjacens isolates were not sensitive to any BLIS tested, and all of these isolates displayed bacteriolytic activity. Sensitivity to the BLIS of S. agalactiae P3 separated the nonlytic S. defectivus strains into two categories.

Bacteriocins↗
PubMed2000

Haemolysin-deficient variants of Streptococcus pyogenes and S. dysgalactiae subsp. equisimilis may be overlooked as aetiological agents of pharyngitis.

Variants of large colony beta-haemolytic Lancefield group A, C and G streptococci that are non-haemolytic or alpha-haemolytic on sheep blood agar have been detected in clinical specimens due to their enhanced haemolytic activity when grown on a new selective and differential blood agar medium containing colistin, nalidixic acid and pH 7.5-adjusted PIPES buffer (CNA-P). The large colony Lancefield group C and G isolates were identified as Streptococcus dysgalactiae subsp. equisimilis by API 20 Strep classification and 16S rDNA profiling. The haemolytic activity of these variants on various blood agar media, including CNA-P, was closely similar to that of known streptolysin S-defective mutants of S. pyogenes and was blocked by addition of cholesterol, a specific inhibitor of the streptolysin O family of haemolysins. As haemolysin variants could be detected in large numbers in cultures from patients with clinical symptoms of pharyngitis it is suggested that they may function as primary pathogens in such infections. The high frequency with which haemolysin variants were isolated from clinical specimens during a 3-month trial (3%, 13% and 10%, respectively, of group A, C and G streptococcal isolates) indicated that a substantial proportion of streptococcal infections may go undetected if only conventional sheep blood agar media are used in clinical laboratories for the detection of beta-haemolytic streptococci. As haemolysin variants have been implicated in the development of serious streptococcal sequelae, further investigation of the full extent of their contribution to streptococcal disease is indicated.

Antigens, Bacterial↗
PubMed2000

[In vitro susceptibility of different erythromycin-resistant phenotypes of Streptococcus pyogenes to moxifloxacin and other fluoroquinolones]

The aim of the present study was to evaluate the in vitro activity of moxifloxacin (BAY 12-8039) compared with ciprofloxacin, ofloxacin and sparfloxacin against 156 Group A beta-haemolytic Streptococcus (GABHS) strains. Sixty strains were macrolide- lincosamide- and streptogramin B susceptible; 16 strains exhibited a constitutive resistance phenotype; 32 strains exhibited an inducible phenotype; and 48 strains were characterized by the M-type efflux-dependent phenotype. The MICs were determined by an agar dilution method according to NCCLS-approved guidelines. Moxifloxacin showed an enhanced activity compared with the other fluoroquinolones against all the different macrolide-resistant phenotypes.

Journal Article↗