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At least 829 records · Page 46Linked to original sources
PubMed1996

In situ localization of Streptococcus pyogenes during acute tonsillitis: an immunocytochemical study with gold markers.

Epithelial cells were harvested from the surface of the palatine tonsils of seven patients with current acute tonsillitis, proven culture-positive for Streptococcus pyogenes. The epithelial cells harboured attached bacteria, which expressed positive affinity to gold-labelled antiserum to S. pyogenes. The gold particles adhered selectively to the bacterial capsules. The microorganisms were held in place by projections protruding from the epithelial cells, which were in close contact with the pili of the bacteria. In some areas, positive immunogold-labelled bacteria intermingled with bacteria lacking such labelling. None of the culture-negative controls harboured epithelial cells with positive immunogold-labelled bacteria. Orally administered phenoxymethylpenicillin caused a significant reduction in both culture-positive S. pyogenes and bacteria displaying positive coating with specific gold-labelled antiserum to S. pyogenes.

Acute Disease↗
PubMed2001

Streptococcal pyrogenic exotoxin B enhances tissue damage initiated by other Streptococcus pyogenes products.

This study compared the pathology and infection pattern of streptococcal pyrogenic exotoxin B-positive (SpeB(+)) and SpeB-negative (SpeB(-)) isogenic variants of an M1 isolate of Streptococcus pyogenes in a mouse skin air sac model. SpeB(+) strains resulted in severe local tissue damage that extended from the epidermis through the subcutaneous layers, whereas isogenic SpeB(-) variants had reduced gross pathology. At the histologic level, differences in necrosis and host responses to each variant were apparent. Injection of purified SpeB alone into a skin air sac failed to induce any significant tissue damage; however, coinjection of the enzyme with either the wild-type or the speB mutant resulted in increased and accelerated tissue necrosis. Surprisingly, coinjection of the enzyme with the spleen-recovered SpeB(-) variant failed to induce a lesion.

Animals↗
PubMed1999

Streptococcus pyogenes isolated in Portugal: macrolide resistance phenotypes and correlation with T types. Portuguese Surveillance Group for the Study of Respiratory Pathogens.

From January 1998 to June 1999, 302 clinical isolates of Streptococcus pyogenes were collected from 10 microbiology laboratories in Portugal. All strains were highly sensitive to penicillin (MIC90 = 0.012 mg/liter). The prevalence of erythromycin resistance was 35.8% and of tetracycline resistance 41.4%. The majority (79.6 %) of erythromycin-resistant strains were of the MLSB constitutive resistance (CR) phenotype with high-level resistance to erythromycin (MIC90 >256 mg/liter) and to clindamycin (MIC90 >256 mg/liter), 16.7% showed the M phenotype with low-level erythromycin-resistance (MIC90 = 24 mg/liter) and susceptibility to clindamycin, and four isolates showed a phenotype characterized by low-level erythromycin resistance (MIC90 = 8 mg/liter) and high-level clindamycin resistance (MIC90 >256 mg/liter), not previously described. Erythromycin resistance was not associated with invasive strains. Only minor discrepancies between disk diffusion and E-test methods were observed. T serotyping was very useful for the epidemiological characterization of the strains. The most prevalent T types were T1, T4, T9, T12, T13, and T28. A statistically significant association with resistance patterns was found: T12 with erythromycin resistance MLS(B) CR phenotype (p< 0.001), T4 with erythromycin resistance M phenotype (p<0.001), and T13 with tetracycline resistance (p<0.01). Because of the high prevalence of resistance, careful surveillance of S. pyogenes isolates in Portugal is essential, routine antimicrobial susceptibility testing in clinical microbiology laboratories should be strongly encouraged, antibiotic prescription should be reviewed, and macrolides should no longer be used in the empirical therapy of acute pharyngitis.

Anti-Bacterial Agents↗
PubMed1997

Absorption of kininogen from human plasma by Streptococcus pyogenes is followed by the release of bradykinin.

H-kininogen (high-molecular-mass kininogen, HK) is the precursor of the vasoactive peptide hormone bradykinin (BK). Previous work has demonstrated that HK binds to Streptococcus pyogenes through M-proteins, fibrous surface proteins and important virulence factors of these bacteria. Here we find that M-protein-expressing bacteria absorb HK from human plasma. The HK bound to the bacteria was found to be cleaved, and analysis of the degradation pattern suggested that the cleavage of HK at the bacterial surface is associated with the release of BK. Moreover, addition of activated plasma prekallikrein to bacteria preincubated with human plasma, resulted in BK release. This mechanism, by which a potent vasoactive and proinflammatory peptide is generated at the site of infection, should influence the host-parasite relationship during S. pyogenes infections.

Bradykinin↗
PubMed1996

[Evaluation of the Respiralex test for rapid isolation of Streptococcus pyogenes directly from throat swabs].

Results obtained by fast Respiraplex test were compared with findings of classical method of cultivation in order to assess possibilities of this test in isolation of Streptococcus pyogenes directly in the throat swab. The sensitivity of the fast test was 79.4%; specificity 100%. On the basis of gathered results, the following can be concluded: the fast test cannot completely substitute the classic method of cultivation although high specificity occurs, because of low sensitivity especially in patients with small number of colonies in the culture.

Antigens, Bacterial↗
PubMed2003

Role of RopB in growth phase expression of the SpeB cysteine protease of Streptococcus pyogenes.

The Rgg family of transcription regulators is widely distributed among gram-positive bacteria; however, how the members of this family control transcription is poorly understood. In the pathogen Streptococcus pyogenes, the Rgg family member RopB is required for transcription of the gene that encodes the secreted SpeB cysteine protease. Expression of the protease follows distinct kinetics that involves control of transcription in response to the growth phase. In this study, the contribution of RopB to growth phase control was examined. The gene encoding the protease (speB) and ropB are transcribed divergently from a 940-bp intergenic region. Primer extension analyses, in conjunction with reporter fusion studies, revealed that the major region controlling the transcription of both speB and ropB is adjacent to ropB and that the promoters for the two genes likely overlap. Furthermore, it was found that RopB is a DNA-binding protein that specifically binds to sequences in this control region. The interrelationship between ropB and speB expression was further reflected in the observation that transcription of ropB itself is subject to growth phase control. However, while expression of ropB from a promoter expressed during the early logarithmic phase of growth could complement a ropB deletion mutant, ectopic expression of ropB did not uncouple the expression of speB from its growth phase signal. These data implicate other factors in growth phase control and suggest that regulation of ropB expression itself is not the central mechanism of control.

Bacterial Proteins↗
PubMed2001

Bacteraemic Streptococcus pyogenes infection in the peri-partum period: now a rare disease and prior carriage by the patient may be important.

OBJECTIVES: To describe the features of invasive peri-partum Streptococcus pyogenes infection as it occurs in current day practice in North Yorkshire. METHODS: The case and laboratory records of all mothers and/or babies with detected S. pyogenes bacteraemia in the Harrogate and Northallerton districts of North Yorkshire (combined catchment population 260 000) were reviewed for the 20 years 1980-99. An additional bacteraemic case occurring recently in the York district was included. RESULTS: In six recorded episodes, both mother and baby were affected in three, mother only in two and baby only in one. The incidence of detected infection was one such episode per million population per year, one episode per 11 000 live births and one infected baby per 18 000 live births. Maternal features included endometritis, septicaemia, peritonitis, necrotising fasciitis and toxic shock syndrome while, in babies, infection was manifest by stillbirth or septicaemia, cyanosis, jaundice, lethargy and cellulitis. CONCLUSION: Peri-partum S. pyogenes infection is rare in North Yorkshire, with a local incidence revealed in this study of 1/million population/year, or 1:11 000 live births. Invasive neonatal infection with S. pyogenes appears to be six times less frequent in this locality than with group B streptococci. Mothers and/or their babies can be affected. Data suggests that some infection is autogenous from streptococci carried in the mother's genital tract. Although data in this setting are currently few, when a mother has suspected invasive group A streptococcal infection we recommend that the newborn child should also receive antibiotics without delay.

Adult↗
PubMed1991

Selective medium for isolation of Arcanobacterium haemolyticum and Streptococcus pyogenes.

Sheep blood agar using tryptic soy agar base and containing 3.5% sodium chloride was found to facilitate isolation of Arcanobacterium haemolyticum and improve isolation of Voges-Proskauer negative group A (Streptococcus pyogenes) and group C and G beta-haemolytic streptococci. Commensal oropharyngeal flora such as viridans streptococci, Neisseria species, non-haemolytic streptococci and beta-haemolytic streptococci not belonging to groups A, B, C or G were significantly inhibited.

Agar↗
PubMed2000

Necrotizing proctitis caused by Streptococcus pyogenes.

We report the case of a 65-year-old patient with peritonitis, septicaemia and toxic shock syndrome in whom the primary focus of infection was acute purulent proctitis with necrosis. Streptococcus pyogenes serotype T28R28 was isolated from blood culture and peritoneal pus. The patient recovered after a prolonged period of intensive therapy and four abdominal operations including anterior resection of the rectum. We believe this to be the first clinical description of streptococcal necrotizing proctitis.

Aged↗
PubMed2001

Enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR); its ability to differentiate Streptococcus pyogenes strains and applicability to the study of outbreaks of streptococcal infection.

We evaluated the ability of enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR) to differentiate 95 Streptococcus pyogenes strains with M or T serotypes isolated from sporadic streptococcal infections as compared with M or T serotypings and pulsed-field gel electrophoresis (PFGE). Although the ERIC-PCR had less discriminatory power, defined as the ability to divide the strains with the same serotypes into the different sub-types, than PFGE, it consistently classified the strains into 16 patterns with a high correlation with M or T serotyping. The PCR method further discriminated 4 M or T serotypes into sub-types. The application of ERIC-PCR to 5 outbreaks of streptococcal infection produced the results that agreed closely with those of T serotyping and PFGE. ERIC-PCR has sufficient discriminatory power and is a quick and relatively easy technique, making it useful for routine epidemiological investigations.

Bacterial Typing Techniques↗
PubMed1980

Mutational loss of sensitivity to mutacin GS-5 in Streptococcus pyogenes: characterization of a mutant deficient in receptor protein.

By means of a stepwise selection procedure, mutants capable of growing in the presence of relatively high multiplicities of a bacteriocin from Streptococcus mutans GS-5 were obtained from a sensitivie strain of Streptococcus pyogenes. Mutacin-neutralizing activity of cell extracts containing receptor protein was examined in one variant that adsorbed 1/6 the amount of bacteriocin adsorbed by the parent strain under conditions equivalent to "saturation." Partially purified receptor protein from both parent and mutant cells neutralized an equivalent amount of bacteriocin on a weight-to-weight basis, indicating that in vitro there was no significant difference in affinity for the mutacin between the respective receptor fractions. Cell extracts from the mutant, solubilized by treatment with trichloroacetic acid, neither neutralized mutacin activity nor interfered with receptor protein-mediated mutacin neutralization in vitro. The mutant phenotype may thus represent a cell surface density of receptor protein which results in the adsorption of sublethal amounts of mutacin. The mutant retained its sensitivity to other mutacins, e.g., those produced by strains LM-7 and BHT of S. mutans, and did not differ from wild-type cells with respect to either detergent sensitivity (sodium lauryl sulfate and Triton X-100) or to inhibition by penicillin, rifampin, bacitracin, erythromycin, and tetracycline.

Bacterial Proteins↗
PubMed2005

Clonal spread of fluoroquinolone non-susceptible Streptococcus pyogenes.

BACKGROUND: Fluoroquinolones are an important group of antibiotics widely used in adults, and, despite the absence of official approval, these drugs are also used in children. So far, resistance to fluoroquinolones in Streptococcus pyogenes is very rare. METHODS: During a national surveillance programme in Belgium from 1999 to 2002, 2793 non-duplicate S. pyogenes recovered from tonsillopharyngitis patients were screened for fluoroquinolone resistance. Mutations in topoisomerase genes and the presence of any efflux pump activity were investigated to elucidate the fluoroquinolone resistance mechanisms. Clonality was assessed by pulsed-field gel electrophoresis (PFGE) and emm typing. RESULTS: Non-susceptibility to fluoroquinolones, defined as ciprofloxacin MIC > or = 2 mg/L, was identified in 152 (5.4%) of 2793 S. pyogenes. Fifty-five (36%) fluoroquinolone non-susceptible isolates were investigated for known resistance mechanisms; all showed mutations in parC, and 29 (19%) isolates also in parE; antibiotic efflux was not noted. Two major PFGE types comprised 88% of fluoroquinolone non-susceptible S. pyogenes and belonged to serotypes emm6 and emm75. Overall, emm6 and emm75 constituted >90% of all fluoroquinolone non-susceptible isolates and showed a significant temporal and geographical shift within Belgian provinces. Although fluoroquinolone-susceptible S. pyogenes also showed fluctuations in the predominant S. pyogenes serotypes, emm6 or emm75 were under-represented in this population. Approx. 55% of the fluoroquinolone non-susceptible isolates were recovered from children ( < or =16 years). CONCLUSIONS: We show here, for the first time, a multi-clonal spread of fluoroquinolone non-susceptible S. pyogenes exhibiting a known resistance mechanism. Non-susceptibility to fluoroquinolones in paediatric isolates is of concern.

Adolescent↗