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PubMed2003

Antimicrobial susceptibility and survey of macrolide resistance mechanisms among Streptococcus pyogenes isolated in Rio de Janeiro, Brazil.

A total of 357 clinical Streptococcus pyogenes isolates collected between 1994 and 1999 in Rio de Janeiro city were tested for susceptibility to 10 antimicrobial drugs by agar-diffusion tests. All isolates were susceptible to penicillin, cephems, and vancomycin. High resistance rates were observed for tetracycline (43.1%) and trimethoprim/sulfamethoxazole (77.9%). Three isolates (0.8%) were resistant to erythromycin, and three exhibited intermediate susceptibility. Determination of the erythromycin MICs by the agar dilution method, showed 1.6% of erythromycin resistant isolates (the three erythromycin-resistant and the three erythromycin-intermediate isolates found by agar-diffusion test). Of the erythromycin-resistant isolates subjected to the double-disc diffusion test for erythromycin and clindamycin, three isolates expressed the iMLSB and three the M phenotype. The resistance phenotypes were confirmed by comparing the clindamycin MICs determined under normal testing conditions and those determined after induction by pre-growth in 0.06 microg/ml of erythromycin. Three ermTR and three mefA-containing isolates were detected by PCR. In strains belonging to the iMLSB phenotype, two clones were identified by PFGE following restriction with SmaI. M phenotype isolates could not be restricted with SmaI. Our results indicate a low rate of erythromycin resistance among S. pyogenes isolated in Rio de Janeiro, Brazil, and pointed to the presence of both resistance mechanisms found in streptococci.

Anti-Bacterial Agents↗
PubMed1988

Septic scarlet fever due to Streptococcus pyogenes cellulitis.

We report three cases of septic scarlet fever due to Streptococcus pyogenes Group A (serotype M1/T1/OF-) cellulitis in healthy young adults. Despite prompt treatment two of the patients died. Such cases of cellulitis associated with scarlet fever, severe toxaemia and septicaemia have not been reported in the post-antibiotic era.

Adult↗
PubMed1995

Biological properties of a Streptococcus pyogenes mutant generated by Tn916 insertion in mga.

The mga regulon of Streptococcus pyogenes contains genes which contribute to the pathogenicity and virulence of this significant human pathogen. Transposon insertional inactivation of the regulatory mga gene in a S. pyogenes strain of the clinically important M1 serotype, blocked the expression of four genes located downstream of mga. These genes encode the M1 protein, the IgG-binding protein H, protein SIC which is an extracellular inhibitor of complement, and the C5a peptidase which interferes with granulocyte migration. The wild-type strain is resistant to phagocytosis and adheres to human skin tissue sections; properties that were lost in the transposon mutant. Moreover, the mutant was less virulent to mice but more cytolytic to human lymphocytes, the latter due to an increased activity of streptolysin S, whereas the production of streptolysin O, another toxin of S. pyogenes, was not affected. The mga mutation was complemented in trans with an intact mga gene which restored the phenotype of the wild-type strain.

Adhesins, Bacterial↗
PubMed2006

Characterization of erythromycin resistance of Streptococcus pyogenes isolated from pharyngitis patients in Korea.

Six hundred fifteen isolates of Streptococcus pyogenes were collected over a 6-year period from patients with pharyngitis in Korea. All isolates were characterized in terms of their antibiotic resistance, the phenotypes of erythromycin resistance, the frequencies of erm(B), erm(A), and mef(A) genes, and the emm genotype. The prevalent emm genotypes were emm12 and emm4. Moreover, the emm12 genotype was found to be the most resistant strain to erythromycin. Among the 126 strains demonstrating resistance to erythromycin, those with erm(B) were the most prevalent, accounting for 64.3% of the total. In summary, it is suggested that the S. pyogenes pathogen isolated from pharyngitis patients in Korea developed resistant gene acquisition, as well as a resistant phenotype, according to the annual prevailing emm type. It is also suggested that the emm genotype distribution of erythromycin-resistant strains is correlated to the acquisition of resistant genes.

Anti-Bacterial Agents↗
PubMed2002

Crystallization and preliminary crystallographic studies of Streptococcus pyogenes cysteine protease precursor.

Streptococcal protease precursor, secreted by the human pathogen Streptococcus pyogenes, becomes activated to a cysteine protease. The precursor and the mature enzyme appear to contribute to S. pyogenes virulence. The precursor protein was crystallized in the form of very thin flexible flakes. X-ray diffraction data were collected to 3.15 A resolution at 100 K using synchrotron radiation. The crystals are monoclinic, space group P2(1), with unit-cell parameters a = 41.6, b = 136.0, c = 156.7 A, beta = 95.7 degrees, and contain four copies of the protein in the asymmetric unit.

Crystallization↗
PubMed2003

Assessment of Streptococcus pyogenes microcolony formation in infected skin by confocal laser scanning microscopy.

BACKGROUND: Streptococcus pyogenes and Staphylococcus aureus are often simultaneously detected from many cases of non-bullous impetigo with atopic dermatitis. OBJECTIVES: Using confocal laser scanning microscopy (CLSM), to investigate formation of S. pyogenes microcolonies in skin lesions. METHODS: The S. pyogenes cells in the stationary growth phase alone were strongly stained with fluorescein isothiocyanate-concanavalin A (FITC-ConA), and this staining was reduced by pretreatment with amylase. Although the components of sugars in glycocalyx produced by S. pyogenes cells are unknown, we suggested that the materials stained by FITC-ConA were consistent with the presence of ConA-reactive sugars in glycocalyx produced by S. pyogenes cells. RESULTS: S. pyogenes cells associated with streptococcal impetigo skin and croton-oil inflamed mouse skin formed microcolonies encircled by materials (glycocalyx) that stained strongly with FITC-ConA, and these findings were consistent with those in biofilms. In croton-oil inflamed mouse skin, polymorphonuclear leukocytes (PMNs) infiltrated to just below the epidermis in the cefdinir-treated group but only to the middle dermis in the cefdinir-non-treated group. In this case S. pyogenes and S. aureus cells formed separate microcolonies and existed independently in the outer walls of pustule lesions of streptococcal impetigo. CONCLUSION: In skin infections, S. pyogenes and S. aureus formed aggregates of microcolonies (similar to that in biofilms) encircled by glycocalyx, which can make the infection hard to eradicate using an antimicrobial agent alone. The effect of conventional antimicrobial agents against biofilm is mainly due to the increase of the invasion of PMNs into the biofilm.

Adolescent↗
PubMed2002

The bacterial superantigen streptococcal mitogenic exotoxin Z is the major immunoactive agent of Streptococcus pyogenes.

The gene encoding streptococcal mitogenic exotoxin Z (SMEZ) was disrupted in Streptococcus pyogenes. Despite the presence of other superantigen genes, mitogenic responses in human and murine HLA-DQ transgenic cells were abrogated when cells were stimulated with supernatant from the smez(-) mutant compared with the parent strain. Remarkably, disruption of smez led to a complete inability to elicit cytokine production (TNF-alpha, lymphotoxin-alpha, IFN-gamma, IL-1 and -8) from human cells, when cocultured with streptococcal supernatants. The potent effects of SMEZ were apparent even though transcription and expression of SMEZ were barely detectable. Human Vbeta8(+) T cell proliferation in response to S. pyogenes was SMEZ-dependent. Cells from HLA-DQ8 transgenic mice were 3 logs more sensitive to SMEZ-13 than cells from HLA-DR1 transgenic or wild-type mice. In the mouse, SMEZ targeted the human Vbeta8(+) TCR homologue, murine Vbeta11, at the expense of other TCR T cell subsets. Expression of SMEZ did not affect bacterial clearance or survival from peritoneal streptococcal infection in HLA-DQ8 mice, though effects of SMEZ on pharyngeal infection are unknown. Infection did lead to a rise in Vbeta11(+) T cells in the spleen which was partly reversed by disruption of the smez gene. Most strikingly, a clear rise in murine Vbeta4(+) cells was seen in mice infected with the smez(-) mutant S. pyogenes strain, indicating a potential role for SMEZ as a repressor of cognate anti-streptococcal responses.

Acute Disease↗
PubMed2004

Emergence of macrolide-resistant Streptococcus pyogenes strains in French children.

We studied the antimicrobial susceptibility of 322 Streptococcus pyogenes throat isolates from French children and their serotype and genomic diversity. A total of 22.4% were erythromycin resistant, and 69.4, 4.2, and 26.4% of these isolates harbored ermB, ermA, and mefA, respectively. Increasing resistance in France is mainly associated with a few emm type 28 clones.

Adolescent↗
PubMed2006

Fibrinogen fragment D is necessary and sufficient to anchor a surface plasminogen-activating complex in Streptococcus pyogenes.

In this study, the importance of different domains of the fibrinogen molecule in the binding and assembly of a surface plasminogen (plgn) activator has been analyzed. This was achieved using SELDI technology that enabled dissociation of bound fragments from intact bacteria and accurate distinction between fibrinogen fragments based on their molecular mass. These studies indicate that Streptococcus pyogenes binds directly to human fibrinogen fragment D but not fragment E. The predominant surface proteins binding to fragment D were associated with the mrp gene product. Surface-associated fibrinogen fragment D was capable of anchoring a functional surface plgn activator complex. Taken together, these data indicated that fragment D of fibrinogen is necessary and sufficient to anchor a plgn activator complex on the surface of Streptococcus pyogenes.

Fibrin Fibrinogen Degradation Products↗
PubMed1999

Protein H, an antiphagocytic surface protein in Streptococcus pyogenes.

Surface-associated M protein is a major virulence factor in Streptococcus pyogenes which confers bacterial resistance to phagocytosis. However, many S. pyogenes strains also express additional structurally related so-called M-like proteins. The strain studied here is of the clinically important M1 serotype and expresses two structurally related surface proteins, the M1 protein and protein H. Mutants were generated that expressed only one or none of these proteins at the bacterial surface. For survival in human blood either protein H or M1 protein was sufficient, whereas the double mutant was rapidly killed. The protein-binding properties of protein H, M1 protein, and the mutants suggest that bacterial binding of immunoglobulin G and factor H or factor H-like protein 1, which are regulatory proteins in the complement system, contribute to the antiphagocytic property.

Antigens, Bacterial↗
PubMed1984

[Isolation and characterization of erythrogenic toxins. VII. Study of the erythrogenic toxin type C produced by Streptococcus pyogenes].

Erythrogenic toxin (ET) type C was purified from culture filtrates of Streptococcus pyogenes strains NY 5, T 18, and AT 13. Methods used included ammonium sulfate precipitation, phosphate precipitation, column chromatography on CM-Sepharose and Sephadex G 100, and isoelectric focusing in Sephadex gel. The molecular weight was determined by SDS gel electrophoresis as 25,500. The preparation reacted only with homologous antiserum (anti-C), but not with antitoxins types A or B in double diffusion tests. The isoelectric point was determined to be 6.8 by analytical isoelectric focusing. Also the amino acid composition was determined. The toxin was found to be mitogenic (as well as pyrogenic and toxic for rabbits). The ET type C is digested by trypsin, pepsin, chymotrypsin and Pronase E, but is rather stable when treated with papain or streptococcal proteinase.

Amino Acids↗
PubMed2000

The NAD-glycohydrolase (nga) gene of Streptococcus pyogenes.

The gene for NAD-glycohydrolase (nga) of group A streptococci (Streptococcus pyogenes) was identified and shown to be located immediately adjacent to the gene for streptolysin O (slo). The nga gene contains 1341 base pairs and encodes a protein of 447 amino acids, including an N-terminal signal peptide. Results from analysis with the polymerase chain reaction indicated that the nga gene is present in all of the strains tested. Functional extracellular NAD-glycohydrolase, also known as NADase, was detected among a wide variety of clinical isolates and known laboratory strains and shown to be present in 72% of 100 strains examined. In contrast, 92% of strains isolated from patients with invasive streptococcal infections were positive for NADase production.

ADP-ribosyl Cyclase↗
PubMed2006

Characterisation of the main clones of Streptococcus pyogenes carrying the ermA (subclass TR) gene in Spain.

Seventy-four Streptococcus pyogenes isolates showing the macrolide-lincosamide-streptogramin B (MLS(B)) resistance phenotype carrying the ermA gene (72 of which showed the inducible resistance phenotype) were obtained between 1999 and 2004. Seven different sequence types (STs) and emm types were detected: emm22/ST46 (n=33); emm77/ST63 (n=22); emm73/ST331 (n=10); emm94/ST89 (n=6); and one isolate each of emm28/ST52, emm11/ST403 and emm4/ST38. All ST46 isolates were susceptible to tetracycline and almost all reacted against the T12 type (all agglutinated into the T-pattern 3/12/13/B3264). Resistance to tetracycline was observed in all ST63 (tetO+) and ST89 (tetM+) isolates. Most of the ST63 isolates reacted against the T28 type (all agglutinated into the T-pattern 9/13/28). The 74 isolates were grouped into eight pulsed-field gel electrophoresis pulsotypes (one cluster for each emm/ST type, except for emm77/ST63).

Anti-Bacterial Agents↗
PubMed2001

Complete genome sequence of an M1 strain of Streptococcus pyogenes.

The 1,852,442-bp sequence of an M1 strain of Streptococcus pyogenes, a Gram-positive pathogen, has been determined and contains 1,752 predicted protein-encoding genes. Approximately one-third of these genes have no identifiable function, with the remainder falling into previously characterized categories of known microbial function. Consistent with the observation that S. pyogenes is responsible for a wider variety of human disease than any other bacterial species, more than 40 putative virulence-associated genes have been identified. Additional genes have been identified that encode proteins likely associated with microbial "molecular mimicry" of host characteristics and involved in rheumatic fever or acute glomerulonephritis. The complete or partial sequence of four different bacteriophage genomes is also present, with each containing genes for one or more previously undiscovered superantigen-like proteins. These prophage-associated genes encode at least six potential virulence factors, emphasizing the importance of bacteriophages in horizontal gene transfer and a possible mechanism for generating new strains with increased pathogenic potential.

Bacteriophages↗
PubMed1989

Effects of benzylpenicillin on Streptococcus pyogenes during the postantibiotic phase in vitro.

A postantibiotic effect (PAE) for Streptococcus pyogenes M12, P1800 was induced by 10 x MIC of benzylpenicillin for 2 h in vitro. The PAE was found to be 2.4 h (range 1.75-3.0 h). No incorporation of 3H-thymidine by the streptococci occurred during the first hours of the postantibiotic phase (PA-phase), indicating that bacterial cell division was inhibited during this period. However, these bacteria showed the same killing rate as previously unexposed control cultures when 10 x MIC of benzylpenicillin was added during the PA-phase. When bacteria in PA-phase were re-exposed to penicillin at a concentration of 0.2 x MIC multiplication of the bacteria was inhibited for 6-7 h, while at a concentration of 0.3 x MIC slow killing was induced. In contrast, previously untreated controls exposed to 0.2 x MIC and 0.3 x MIC showed a growth rate corresponding to that of bacteria grown in the absence of penicillin. The effects of subinhibitory concentrations on streptococci previously exposed to penicillin may therefore be a more important factor in determining dosage intervals than the PAE.

Kinetics↗
PubMed2004

Hydrogen peroxide production in Streptococcus pyogenes: involvement of lactate oxidase and coupling with aerobic utilization of lactate.

Streptococcus pyogenes strains can be divided into two classes, one capable and the other incapable of producing H2O2 (M. Saito, S. Ohga, M. Endoh, H. Nakayama, Y. Mizunoe, T. Hara, and S. Yoshida, Microbiology 147:2469-2477, 2001). In the present study, this dichotomy was shown to parallel the presence or absence of H2O2-producing lactate oxidase activity in permeabilized cells. Both lactate oxidase activity and H2O2 production under aerobic conditions were detectable only after glucose in the medium was exhausted. Thus, the glucose-repressible lactate oxidase is likely responsible for H2O2 production in S. pyogenes. Of the other two potential H2O2-producing enzymes of this bacterium, NADH and alpha-glycerophosphate oxidase, only the former exhibited low but significant activity in either class of strains. This activity was independent of the growth phase, suggesting that the protein may serve in vivo as a subunit of the H2O2-scavenging enzyme NAD(P)H-linked alkylhydroperoxide reductase. The activity of lactate oxidase was associated with the membrane while that of NADH oxidase was in the soluble fraction, findings consistent with their respective physiological roles, i.e., the production and scavenging of H2O2. Analyses of fermentation end products revealed that the concentration of lactate initially increased with time and decreased on glucose exhaustion, while that of acetate increased during the culture. These results suggest that the lactate oxidase activity of H2O2-producing cells oxidizes lactate to pyruvate, which is in turn converted to acetate. This latter process proceeds presumably via acetyl coenzyme A and acetyl phosphate with formation of extra ATP.

Aerobiosis↗
PubMed1990

A secreted receptor related to M1 protein of Streptococcus pyogenes binds to fibrinogen, IgG, and albumin.

An extracellular protein (eMP) of Streptococcus pyogenes M type 1 was isolated by affinity chromatography on albumin- and IgG-Sepharose. The protein was found to bind to the human plasma proteins, fibrinogen, IgG, and albumin. Analysis of eMP by Western blotting demonstrated a major band with a molecular weight of 49 kD which was responsible for binding of the three plasma proteins. The purified protein was found to bind selectively to human and primate polyclonal IgG, human and mouse albumin, as well as human fibrinogen which has been the only fibrinogen tested. Serological investigations revealed a close relation of eMP to streptococcal M1 protein. It showed a reaction of identity with cell-extracted M1 protein in immunodiffusion. Moreover, the 49 kD peptide responsible for binding, was recognized with an antiserum directed against the 20 amino acids comprising synthetic peptide (42VAL-61GLU) of the N-terminal part of the M1 protein sequence. The affinity of M protein to plasma proteins other than fibrinogen opens new approaches to its purification by affinity chromatography.

Animals↗