Group A streptococcal infections and acute rheumatic fever

Genetic diversity and relationships among Streptococcus pyogenes strains expressing serotype M1 protein: recent intercontinental spread of a subclone causing episodes of invasive disease

Chromosomal diversity and relationships among 126 Streptococcus pyogenes strains expressing M1 protein from 13 countries on five continents were analyzed by multilocus enzyme electrophoresis and restriction fragment profiling by pulsed-field gel electrophoresis. All isolates were studied for the presence of the gene encoding streptococcal pyrogenic exotoxin A by PCR. Strain subsets were also examined by automated DNA sequencing for allelic polymorphism in genes encoding M protein (emm), streptococcal pyrogenic exotoxin A (speA), streptokinase (ska), pyrogenic exotoxin B (interleukin-1 beta convertase) (speB), and C5a peptidase (scp). Seven distinct emm1 alleles that encode M proteins differing at one or more amino acids in the N-terminal variable region were identified. Although substantial levels of genetic diversity exist among M1-expressing organisms, most invasive disease episodes are caused by two subclones marked by distinctive multilocus enzyme electrophoretic profiles and pulsed-field gel electrophoresis restriction fragment length polymorphism (RFLP) types. One of these subclones (ET 1/RFLP pattern 1a) has the speA gene and was recovered worldwide. Identity of speA, emm1, speB, and ska alleles in virtually all isolates of ET 1/RFLP type 1a means that these organisms share a common ancestor and that global dispersion of this M1-expressing subclone has occurred very recently. The occurrence of the same emm and ska alleles in strains that are well differentiated in overall chromosomal character demonstrates that horizontal transfer and recombination play a fundamental role in diversifying natural populations of S. pyogenes.

You can lead a horse to water--improving physicians' knowledge of probabilities may not affect their decisions

OBJECTIVES

To determine whether improving physicians' judgments of the probability of streptococcal pharyngitis for patients with sore throats would affect their use of antibiotics and affect the variation in such use.

DESIGN

Post-hoc retrospective analysis of data previously collected as part of a controlled trial.

SETTINGS

University student health services in Pennsylvania and Nebraska.

PATIENTS

Sequential patients with pharyngitis seen before and after the time clinicians received either an experimental educational intervention designed to improve probabilistic diagnostic judgments (at the Pennsylvania site) or a control intervention, a standard lecture (at the Nebraska site). The clinician-subjects were the primary case physicians practicing at either site.

MEASUREMENTS

Clinical variables prospectively recorded by the clinicians, probability assessments, and treatment decisions.

RESULTS

At the experimental site, despite marked decreases in clinicians' overestimations of disease probability after the intervention, the proportion of patients prescribed antibiotics showed a trend toward increasing: 100/290 (34.5%) pre-intervention, 90/225 (40%) post-intervention. The intervention did not decrease practice variation between individual doctors. Univariable and multivariable analyses showed no major change in the relationships between clinical variables and treatment decisions after the intervention. At the control site there was no major change in probability judgments or treatment decisions after the intervention.

CONCLUSIONS

Teaching physicians to make better judgments of disease probability may not alter their treatment decisions.

Clonal diversity of Streptococcus pyogenes within some M-types revealed by multilocus enzyme electrophoresis

Twenty-two reference isolates and 30 local isolates of group A Streptococci were classified into 36 electrophoretic types (ET) on the basis of allozyme variation at 27 enzyme loci. Local isolates were characterized by a high frequency of M-non typable strains. M-type and ET were more closely associated in local isolates from an endemically-infected population; nevertheless, amongst the local isolates there were also strains of the same ET type with different M-types. A possible explanation is that genetic exchange between strains may introduce different M-types into strains of defined ET when these are exposed to strong selection in the presence of heavy loads of infection. In contrast to the reported clustering of strains associated with toxic shock-like syndrome into two closely related ET clones, we found no relationship of ET phenotype to acute poststreptococcal glomerulonephritis or rheumatic fever.

Streptokinase alleles and disease association in group A streptococci

Allele-specific oligonucleotides were used for PCR-based typing of the streptokinase locus of group A streptococcal strains, including well characterized type strains, isolates from patients with acute poststreptococcal glomerulonephritis and strains from Aboriginal communities in the Northern Territory of Australia. The streptokinase SKN allele, previously thought to be associated with glomerulonephritis, was no more frequent in nephritogenic than in non-nephritogenic streptococcal strains in this collection.

Comparative study of cytokine release by human peripheral blood mononuclear cells stimulated with Streptococcus pyogenes superantigenic erythrogenic toxins, heat-killed streptococci, and lipopolysaccharide

The differences between toxic or septic shocks in humans during infections by streptococci and gram-negative bacteria remain to be fully characterized. For this purpose, a quantitative study of the cytokine-inducing capacity of Streptococcus pyogenes erythrogenic (pyrogenic) exotoxins (ETs) A and C, heat-killed S. pyogenes bacteria, and Neisseria meningitidis endotoxin (lipopolysaccharide [LPS]) on human peripheral blood mononuclear cells (PBMC) and monocytes has been undertaken. The levels of interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6, IL-8, tumor necrosis factor alpha (TNF-alpha), and TNF-beta induced by these bacterial products and bacteria were determined by using cell supernatants. The capacity of ETs to elicit the monocyte-derived cytokines IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha was found to depend on the presence of T lymphocytes, because of the failure of purified monocytes to produce significant amounts of these cytokines in response to ETs. PMBC elicited large amounts of these cytokines, as well as IL-8 and TNF-beta, with an optimal release after 48 to 96 h. The most abundant cytokine produced in response to ETA was IL-8. In contrast to the superantigens ETA and ETC, LPS and heat-killed streptococci stimulated the production of significant amounts of IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha, with optimal production after 24 to 48 h in monocytes, indicating no significant involvement of T cells in the process. ETs, but neither LPS nor streptococci, were potent inducers of TNF-beta in PBMC. This study outlines the differences in the pathophysiological features of shock evoked by endotoxins and superantigens during infection by gram-negative bacteria and group A streptococci, respectively. The production of TNF-alpha was a common pathway for LPS, streptococcal cells, and ETs, although cell requirements and kinetics of cytokine release were different.

Comparative efficacy and safety of cefprozil versus penicillin, cefaclor and erythromycin in the treatment of streptococcal pharyngitis and tonsillitis

Cefprozil is a new oral cephalosporin with an enhanced in vitro spectrum of activity that includes group A beta-hemolytic streptococci (GABHS). Four multicenter randomized clinical trials were conducted to compare the clinical efficacy and safety of cefprozil administered once or twice a day for the treatment of mild to moderate GABHS tonsillitis and pharyngitis. A total of 1597 patients were enrolled in the trials. Patient demographics and severity of infection were similar for all treatment groups. In Study 1, cefprozil administered at 20 mg/kg once daily was clinically, in 68 of 76 patients (89%) and bacteriologically, in 66 of 74 patients (89%) superior to penicillin -51 of 69 (74%) and 46 of 69 (67%)--administered three times a day in patients of two to 12 years of age. In Study 2, the patients enrolled were 13 years of age and older, and cefprozil administered at 20 mg/kg once a day had similar clinical (93% vs. 90%) and bacteriological (95% vs. 94%) response rates as cefaclor administered three times a day. Study 3 demonstrated that cefprozil administered twice daily was similar to penicillin given three times a day, the clinical satisfactory response being 164 of 175 (94%) for cefprozil and 146 of 165 (88%) for penicillin. In Study 4, identical clinical and bacteriologic responses (95%) were observed for cefprozil administered once a day and erythromycin ethylsuccinate administered four times a day in children over two years of age. There were no significant differences in the incidence or severity of drug-related adverse events, which, when reported, were mild and transient.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid detection of hyaluronic acid capsules on group A streptococci by buoyant density centrifugation

One of the virulence factors of group A streptococci is the hyaluronic acid polysaccharide capsule. A rapid method for ascertaining the status of the capsule phenotype in Streptococcus pyogenes is described. Bacteria with a capsule have a lower buoyant density than acapsular or hyaluronidase-treated cells. Early log phase cultures were underlaid with 65% Percoll and centrifuged at 500-1000 g for 5 min. Upon visual examination, encapsulated cells were observed at the interface, whereas acapsular cells appeared in the pellet. Cultures that produced at least 7 micrograms/ml of hyaluronic acid per A600 unit of cells were detected at the interface; this level of polysaccharide is only about 0.5%-4% of that found for most mucoid strains. Therefore, this procedure can detect capsules around strains that do not appear to be encapsulated by light microscopy or do not possess mucoid colony morphology. Furthermore, this method reduces dependence on other expensive assays that use labile radioactive reagents to detect hyaluronic acid.

Production and partial characterization of monoclonal antibodies against erythrogenic toxins type A and C from Streptococcus pyogenes

Hybridoma cell lines producing monoclonal antibodies against streptococcal erythrogenic toxins type A and C were established from fusions of immunized BALB/c mice splenocytes with P3X63-Ag8.653 myeloma cells. Six MAbs recognize ETA and 11 MAbs bind to ETC. Two MAbs (designated ETA-2 and ETC-10) were produced in ascitic fluid and further characterized. ETA-2 (IgG2a) binds to ETA with an affinity constant of 1.8 x 10(10) M-1 and ETC-10 (IgG1) binds to ETC with an affinity constant of 3.5 x 10(9) M-1. The specificities of the MAbs were evaluated by ELISA and immunoblotting. Both MAbs ETA-2 and ETC-10 are useful in developing specific double-sandwich ELISAs, in which the MAbs were used as solid-phase capture antibodies for the quantitative determinations of ETA and ETC.

Invasive group A streptococcus carriage in a child care centre after a fatal case

After a fatal case of invasive group A streptococcal disease, serotype T-1, in a child care centre, group A streptococcal T-1 prevalence was measured and risk factors for carriage were determined. A total of 87% (224/258) had throat culture tests. Group A streptococcus was isolated from 57 (25%), and of the 50 isolates serotyped, 38 (76%) were T-1. Group A streptococcal T-1 prevalence was 18% (38/217) and six of nine rooms had children with group A streptococcal T-1 isolates. The risk of group A streptococcal T-1 carriage was increased for children who shared the index case's room (odds ratio (OR) = 2.7; 95% confidence interval (CI) = 0.8 to 9.4) and for each additional hour per week in child care (OR = 1.03; 95% CI = 1.001 to 1.061); and decreased in children taking antibiotics in the preceding four weeks (OR = 0.2; 95% CI = 0.1 to 0.9). Carriage of the invasive group A streptococcal strain could not be determined by identified risk factors alone.

Group A streptococcal antigens and superantigens in the pathogenesis of autoimmune arthritis

Evidence from repeated clinical observations and from a variety of experimental approaches implicates group A streptococci in the pathogenesis of the autoimmune arthritides. Several streptococcal antigens and superantigens have now been characterized and their properties suggest that they may be involved in the mechanisms which underlie these diseases, although other antigens and superantigens yet to be discovered may also be involved. The association between group A streptococcal infection and autoimmune arthritis offers a useful model for providing a long-elusive understanding of the role of bacterial infection in the pathogenesis of autoimmune disease.

Typing of group A streptococci by random amplified polymorphic DNA analysis

Random amplified polymorphic DNA (RAPD) analysis was evaluated in comparison with restriction endonuclease analysis (REA) of genomic DNA and serotyping in the typing of 160 epidemiologically unrelated group A streptococci (GAS). Amplification of genomic DNA of GAS was performed with a single primer with an arbitrarily selected nucleotide sequence of 12 nucleotides. In total, 31 RAPD patterns and 15 REA patterns were observed among the isolates studied. The results of RAPD analysis were in accordance with the results of REA for 86% of the isolates, as both methods identified 15 different strains among 138 isolates. However, RAPD analysis differentiated 16 additional strains among 22 isolates. RAPD analysis was somewhat better than REA for differentiation of isolates of the same and different serotypes. However, not all of the serotypes were differentiated by RAPD analysis either. In conclusion, RAPD analysis provides a practical alternative for genomic typing of GAS. It can be recommended for the typing of GAS, especially if used in parallel with serotyping.

Acute rheumatic fever in children in the Ankara area in 1990-1992 and comparison with a previous study in 1980-1989

Two hundred and twenty-eight patients with acute rheumatic fever (ARF), who were admitted to Dr Sami Ulus Children's Hospital between January 1990 and November 1992, were evaluated. Compared with the 1980s, an increase in the frequency of the disease was observed. The majority of patients (56.5%) were between 9 and 12 years old and 36.8% were admitted in winter. One hundred patients had arthritis only, 59 carditis and 40 chorea; 5 had carditis and chorea and 24 had arthritis and carditis. Nineteen percent of patients had a history of a previous attack. Seven of 84 patients with carditis had congestive heart failure and 2 had pericarditis. Cardiomegaly was present in 36 patients. The mitral valve was affected in 77 patients, tricuspid valve in 1 patient and both miral and aortic valves in 6 patients. One patient died as a result of severe congestive cardiac failure. Twenty-one patients had a recurrent attack. We observed that ARF is still a significant cause of morbidity in our country. As the disease is preventable by the eradication of streptococcus, we conclude that more effort should be made in the early detection and treatment of streptococcal infections.

Nontropical pyomyositis in adults

Pyomyositis (PMS) is a primary infection of striated muscle. Recent scanty reports suggest that non-tropical PMS may differ from classical tropical PMS. To address this question, 12 cases of nontropical PMS seen at two hospitals between 1976 and 1992 were reviewed and an English-literature search of similar cases was conducted. Both the series and reported cases are pooled together and herein reported. The age distribution of the 97 patients showed 30-50 and 60-70-year peaks, with a 3:1 (male-female) ratio. Fever, high erythrocyte sedimentation rate, and muscle stiffness or inflammation were present in more than 75% of patients. Muscles of the thigh (54%), back (13%), buttock (11%), arm (9%), or chest wall (4%) were involved. Staphylococci (61%), gram-negative bacilli (16%), streptococci (12%), and fungi (2%) were isolated from muscle specimens. Human immunodeficiency virus infection, diabetes mellitus, hemopoietic disorders, and other conditions with defective neutrophil function were present in 64 patients (66%). Drainage of pus and antibiotic therapy were the standard treatments. The mortality rate reached 10%. Analysis of patients classified by the comorbid condition showed differences in age, causative microorganisms, clinical features, and death rate. It is concluded that several clinical presentations of nontropical PMS are at variance with that of tropical PMS.

Rapid typing of group A streptococci by the use of DNA amplification and non-radioactive allele-specific oligonucleotide probes

Because of the allelic variations within the M protein gene (emm gene) of group A streptococci, reliable typing of this important human pathogen can be accomplished by the use of emm gene-specific oligonucleotide probes. Two technical modifications (a reverse dot blot and a reverse line blot hybridization assay) of a novel approach for the type-specific identification of emm genes have been developed. Both procedures involved amplification of an emm gene by polymerase chain reaction. The non-radioactively labeled amplicon was subsequently hybridized to a membrane carrying an array of immobilized emm gene-specific oligonucleotide probes, thus allowing the simultaneous analysis of the gene polymorphism in a single hybridization reaction. The feasibility of these rapid and easy to perform methods was shown for the unequivocal identification of reference strains and clinical isolates belonging to 16 different M serotypes.

Comparison of Gen-Probe Group A streptococcus Direct Test with culture for diagnosing streptococcal pharyngitis

The Group A Streptococcus Direct Test (GP-ST test; Gen-Probe, Inc., San Diego, Calif.) was compared with culture for the detection of Streptococcus pyogenes from throat swabs of 767 patients with pharyngitis. Swabs were tested by the GP-ST test after inoculating a 5% sheep blood agar (SBA) plate. SBA plates were incubated at 35 degrees C in room air for 72 h. SBA plates with no evidence of beta-hemolytic colonies after 18 to 24 h of incubation were subcultured by taking a swipe across the primary inoculum from the SBA plate to an agar selective for Streptococcus spp. In a low-prevalence (11.9%) population and in comparison with the number of positive cultures detected by the 72-h single-culture method (SBA plate method), the GP-ST test had a sensitivity of 88.6%, a specificity of 97.8%, a positive predictive value of 83.9%, and a negative predictive value of 98.5%. In comparison with the growth of any colonies of S. pyogenes on the 72-h SBA plates plus a subculture onto selective blood agar, the sensitivities and specificities were as follows: 72-h SBA plate method, 96.7 and 100%, respectively; GP-ST test, 85.7 and 97.8%, respectively. The GP-ST test is an easy-to-perform, reliable test for batch screening of throat swabs for S. pyogenes.

Health insurance status and ambulatory care for children

BACKGROUND

Many children in the United States lack health insurance. We tested the hypothesis that these children are less likely than children with insurance to visit a physician when they have specific conditions for which care is considered to be indicated.

METHODS

We examined the association between whether children were covered by health insurance and whether they received medical attention from a physician for pharyngitis, acute earache, recurrent ear infections, or asthma. Data were obtained on the subsample of 7578 children and adolescents 1 through 17 years of age who were included in the 1987 National Medical Expenditures Survey, a national probability sample of the civilian, noninstitutionalized population.

RESULTS

Uninsured children were more likely than children with health insurance to receive no care from a physician for all four conditions (unadjusted odds ratios, 2.38 for pharyngitis; 2.04 for acute earache; 2.84 for recurrent ear infections; and 1.87 for asthma). Multiple logistic-regression analysis was subsequently used to control for age, sex, family size, race or ethnic group, region of the country, place of residence (rural vs. urban), and household income. After adjustment for these factors, uninsured children remained significantly more likely than insured children to go without a visit to a physician for pharyngitis (adjusted odds ratio, 1.72; 95 percent confidence interval, 1.11 to 2.68), acute earache (1.85; 95 percent confidence interval, 1.15 to 2.99), recurrent ear infections (2.12; 95 percent confidence interval, 1.28 to 3.51), and asthma (1.72; 95 percent confidence interval, 1.05 to 2.83).

CONCLUSIONS

As compared with children with health insurance, children who lack health insurance are less likely to receive medical care from a physician when it seems reasonably indicated and are therefore at risk for substantial avoidable morbidity.

Molecular characterization and phylogenetic distribution of the streptococcal superantigen gene (ssa) from Streptococcus pyogenes

A striking increase in the frequency and severity of invasive infections caused by Streptococcus pyogenes has occurred in recent years. Among these diseases is streptococcal toxic-shock-like syndrome (TSLS), a condition characterized by fulminant soft-tissue destruction and multiorgan failure. Streptococcal superantigen (SSA), a superantigen isolated from a TSLS-inducing, serotype M3 S. pyogenes strain, has recently been identified. We here describe the cloning, sequencing, and phylogenetic distribution of the SSA structural gene. The 783-bp open reading frame encodes a predicted 260-amino-acid protein that is similar in size to several other bacterial superantigens. The deduced sequence of the mature protein is 60.2% identical to that of staphylococcal enterotoxin B but only 49% identical to that of streptococcal pyrogenic exotoxin A. Southern blot and PCR analysis of 138 group A streptococcal strains representing 65 M protein serotypes and 15 nontypeable isolates identified ssa in 68 strains from 10 distinct clonal lineages. All ssa-positive clones expressed SSA. Of the two clones associated with TSLS, the ET 2-M3 lineage, but not the ET 1-M1 lineage, carried the SSA gene. Further analysis of the ET 2-M3 lineage found evidence for temporal variation in ssa association. Contemporary ET 2-M3 disease isolates had ssa, but two older isolates of this clone recovered in 1910 and 1920 lacked the gene. The clonal and temporal distribution patterns of ssa suggest a relatively recent acquisition of this superantigen-encoding gene by the ET 2-M3 lineage, perhaps by horizontal transfer and recombination.

Restricted association between biotypes and serotypes within group A streptococci

Investigating individual variations between different isolates of group A streptococci, we observed a close correlation between biotypes and serotypes in 46 strains from pharyngitis patients. Biotyping, carried out with a commercially available rapid identification gallery, delineated 10 different associations of characteristics, designated biotypes 1 to 10, observed both in the manufacturer's (127 strains) and our personal (98 strains) collections of group A strains. Only the most frequent biotypes (biotypes 1 to 6) were observed in the pharyngitis cohort, but the overall frequencies of the biotypes did not display striking differences compared with the control collections. Serotyping of the pharyngitis strains showed that each M type was restricted to a sole biotype. For example, M types 1, 4, and 28 were found only in biotype 1 and M type 6 was found only in biotype 6 strains. This association was not due to an epidemiologic bias, since it was also observed in a control series consisting of reference strains and isolates from distant countries (the United States and Czech Republic versus France). An exception was for M type 78, which exhibited biotype 3 or biotype 4. Investigation of the heterogeneity of the strains at the DNA level showed no significant variations of the ribotype patterns between strains of different biotypes, confirming that group A streptococci belong to a unique and homogeneous species. This previously undescribed association between serotypes and biotypes is of interest for a rapid and preliminary characterization of strains isolated in individual patients or during an outbreak. A possible pathogenic association of some biotypic characteristics with specific M proteins is envisaged.

Optical immunoassay for streptococcal pharyngitis: evaluation of accuracy with routine and mucoid strains associated with acute rheumatic fever outbreak in the intermountain area of the United States

The Strep A OIA (BioStar, Inc., Boulder, Colo.) rapid detection system is an intriguing technology that utilizes an immunoassay relying on changes in reflected light to directly detect group A streptococcal antigen from specimens. In this evaluation, 424 routine pediatric throat specimens and 20 simulated oropharyngeal specimens with added mucoid (M type 3, 18) strains were cultured and tested by the Strep A OIA. The respective sensitivities and specificities were as follows: Strep A OIA versus enhanced broth culturing, 84.2 and 95.7%; and streptococcus-SXT agar (BBL Microbiology Systems, Cockeysville, Md.) culturing versus enhanced broth culturing, 82.9 and 98.6%. The Strep A OIA is an 8-min, technologist-friendly, accurate technique with an 89.4% agreement with traditional culturing.

Streptococcal toxic shock-like syndrome: case report and review of the literature

Streptococcal toxic shock-like syndrome is a newly recognized complication of infections by group A beta-haemolytic streptococci (GABHS). Previous reports of this syndrome have originated from developed countries, predominantly North American and Europe. This report describes a 5-year-old Saudi child who developed this syndrome in association with streptococcal pharyngitis. It indicates that the recent resurgence of severe GABHS diseases is a global phenomenon.

Capturing host plasmin(ogen): a common mechanism for invasive pathogens?

Plasmin is a potent enzyme that can dissolve blood clots and degrade extracellular matrix proteins. A number of pathogenic bacteria produce plasminogen activators. Many of these organisms can also bind plasmin(ogen) to surface receptors and protect the active enzyme from physiological inhibition. Cell-surface localization of plasmin may be a common mechanism used by bacteria to facilitate movement through normal tissue barriers.

How does Helicobacter pylori cause duodenal ulcer disease: the bug, the host, or both?

Helicobacter pylori infection is the most common cause of duodenal ulcer disease, yet duodenal ulcer is an uncommon outcome of H. pylori infection. We reviewed the possible explanations such as differences in the host or in the strain of H. pylori. Host factors reviewed included genetic susceptibility to H. pylori infection and excess gastric acid secretion. The role of potential H. pylori virulence factors not present in all strains such as the cagA gene and the results of other molecular methods to identify disease-specific differences among isolates was also reviewed. Although cure of H. pylori infection resolves gastrin releasing peptide stimulated acid secretion there was no change in parietal cell mass. Twin studies have shown genetic differences in H. pylori susceptibility. There was no difference in the prevalence of the cagA gene between H. pylori infected asymptomatic volunteers and duodenal ulcer patients (P = 1.0). DNA-DNA hybridization of whole genomic DNA in solution and cluster analysis of rep-PCR genomic DNA fingerprints suggest that isolates from patients with duodenal ulcer disease are different from those obtained from individuals with asymptomatic gastritis. Cluster analysis of the rep-PCR DNA fingerprints revealed two major groups of the strains; one set consisted of strains from patients with duodenal ulcer disease and the second cluster consisted largely of strains from individuals with asymptomatic gastritis. Recent molecular studies suggest that disease-specific cell lineages or strains may exist among H. pylori isolates leading to the various outcomes observed in patients with H. pylori infection.

Persistence of acute rheumatic fever in the intermountain area of the United States

We report our 8-year experience with the resurgence of acute rheumatic fever during the years 1985 through 1992. The records of 274 confirmed cases referred to Primary Children's Medical Center were reviewed. The clinical features including the presence of the Jones criteria, demographic data, preceding streptococcal infection, and the use of echocardiographic studies were tabulated and assessed. Patients came predominantly (84%) from middle-class families with access to medical care. Only 46 patients (17%) sought medical attention for a preceding sore throat. Carditis evident by auscultation was the dominant major manifestation in 68% of the cases. Echocardiography demonstrated mitral regurgitation that was not audible in 15 (47%) of 32 patients who had only polyarthritis at onset and in 30 (57%) of the 53 who had pure chorea. The incidence of acute rheumatic fever has been declining since the peak of the outbreak in 1985 but is continuing in the intermountain area at rates comparable to those of the 1960s.

Rapid detection of Streptococcus pyogenes in pediatric patient specimens by DNA probe

A chemiluminescent DNA probe test (Group A Streptococcus Direct Test; Gen-Probe, Inc., San Diego, Calif.) for rapid, direct detection of cRNA of Streptococcus pyogenes in throat swabs was compared with conventional culture and identification techniques. Throat swabs from 277 patients suspected of having streptococcal pharyngitis were examined. By DNA probe alone, 10 specimens were positive, 51 were positive by both assays, and 8 were positive by culture alone. Thus, DNA probe sensitivity, specificity, and positive and negative predictive values were 86, 95, 84, and 96%, respectively. Including an indeterminate category, sensitivity, specificity, and positive and negative predictive values were 89, 96, 86, and 97%, respectively. After discrepancy testing, these values for the raw data improved to 90, 98, 93, and 97%, respectively. None of the 24 specimens that grew non-S. pyogenes beta-hemolytic streptococci in culture were positive by the DNA probe. Because mucoid S. pyogenes strains are more virulent than nonmucoid strains, 24 isolates were retrospectively tested with the DNA probe to ensure that both types would be detected equally well. Isolates were examined in pure cultures as well as mixed with representative normal oral flora. There was no statistical difference in detection of any of the four groups. Group A Streptococcus Direct Test is a rapid, sensitive, and specific test for S. pyogenes.

Comparison of the Gen-Probe Group A streptococcus Direct Test with culture and a rapid streptococcal antigen detection assay for diagnosis of streptococcal pharyngitis

The Gen-Probe Group A Streptococcus Direct Test (GP-ST) is a new assay which utilizes a nucleic acid probe to detect group A streptococci directly from pharyngeal swabs. In this study, 1,103 specimens were cultured and tested by GP-ST. The sensitivities and specificities were as follows: culture, 98.8 and 100%; GP-ST, 92.4 and 99.6%. Of the 1,103 specimens, 808 were also tested with the TestPack Strep A assay. For the specimens tested by all three methods, the sensitivities and specificities were as follows: culture, 99.5 and 100%; TestPack Strep A assay, 76.3 and 99.7%; GP-ST, 93.5 and 99.7%. The GP-ST is a very user-friendly assay which has the potential to replace culture for the diagnosis of streptococcal pharyngitis.

A novel superantigen isolated from pathogenic strains of Streptococcus pyogenes with aminoterminal homology to staphylococcal enterotoxins B and C

Streptococcus pyogenes (group A Streptococcus) has re-emerged in recent years as a cause of severe human disease. Because extracellular products are involved in streptococcal pathogenesis, we explored the possibility that a disease isolate expresses an uncharacterized superantigen. We screened culture supernatants for superantigen activity with a major histocompatibility complex class II-dependent T cell proliferation assay. Initial fractionation with red dye A chromatography indicated production of a class II-dependent T cell mitogen by a toxic shock-like syndrome (TSLS) strain. The amino terminus of the purified streptococcal superantigen was more homologous to the amino termini of staphylococcal enterotoxins B, C1, and C3 (SEB, SEC1, and SEC3), than to those of pyrogenic exotoxins A, B, C or other streptococcal toxins. The molecule, designated SSA, had the same pattern of class II isotype usage as SEB in T cell proliferation assays. However, it differed in its pattern of human T cell activation, as measured by quantitative polymerase chain reaction with V beta-specific primers. SSA activated human T cells that express V beta 1, 3, 15 with a minor increase of V beta 5.2-bearing cells, whereas SEB activated V beta 3, 12, 15, and 17-bearing T cells. Immunoblot analysis of 75 disease isolates from several localities detected SSA production only in group A streptococci, and found that SSA is apparently confined to only three clonal lineages as defined by multilocus enzyme electrophoresis typing. Isolates of one of these lineages, (electrophoretic type 2) are strongly associated with TSLS. The data identify SSA as a novel streptococcal superantigen that appears to be more related structurally to staphylococcal enterotoxins than to streptococcal exotoxins. Because abundant SSA production is apparently confined to only three streptococcal clonal lineages, the data also suggest that the SSA gene has only recently been acquired by S. pyogenes.

Comparison of direct specimen testing utilizing TestPack strep A with testing of specimens following a two-hour broth enrichment

In a previous study, we demonstrated that a 2-h enrichment of throat swabs in broth followed by a direct fluorescent antibody test was significantly more sensitive than the Abbott TestPack Strep A for the detection of group-A streptococci. In this study, in an effort to simplify the technique, we utilized broth enrichment with an enzyme immunoassay detection method. A total of 1017 pharyngeal specimens were tested with TestPack Strep A (DTP), culture on a selective streptococcal agar, and a 2-h broth enrichment in Todd-Hewitt broth (THB) followed by TestPack Strep A (ETP). Subculture of the THB was used to arbitrate discordant test results. The sensitivities and specificities respectively were as follows: DTP (69% and 99%), ETP (90% and 98%), and SSA (97% and 100%). This enrichment method offers significantly greater sensitivity than direct testing for antigen yet still allows the potential for finalized same-day reporting of results.

Association of phenotypic and genotypic characteristics of invasive Streptococcus pyogenes isolates with clinical components of streptococcal toxic shock syndrome

Sixty-two invasive Streptococcus pyogenes strains, including 32 strains isolated from patients with streptococcal toxic shock syndrome (STSS), were analyzed for the following phenotypic and genotypic characteristics: M-protein type, serum opacity factor production, protease production, the presence of streptococcal pyrogenic exotoxin (Spe) genes A, B, and C, and in vitro production of SpeA and SpeB. These characteristics were analyzed for possible associations with each other as well as with clinical components of STSS. M-type 1, the most commonly isolated M-type, was significantly associated with protease production. Protease activity was significantly associated with the clinical sign of soft tissue necrosis. M-type 1 and 3 strains from STSS patients were significantly associated with the clinical signs of shock and organ involvement as well as with SpeA production in vitro. Finally, the production of SpeA was significantly associated with the clinical component of shock and organ involvement as well as with rash. These data suggest that STSS does not make up a single syndrome but, rather, that the multiple STSS clinical criteria probably reflect different phenotypic characteristics of individual S. pyogenes isolates.

Various rheumatic syndromes in adult patients associated with high antistreptolysin O titres and their differential diagnosis with rheumatic fever

OBJECTIVES

The purpose of this study was to analyse retrospectively adult patients with acute joint or muscle symptoms and a high antistreptolysin O (ASO) titre to find out which syndromes of clinical arthritis are associated with serological evidence of streptococcal infection.

METHODS

Seventy six adult patients with an acute arthritis syndrome or an exacerbation in their chronic rheumatic disease and simultaneously a high ASO titre (> or = 500 Todd units) were examined in two time periods in the 1980s.

RESULTS

Twenty six patients had arthritis associated with a known rheumatic disease, 25 had non-specific arthralgia/myalgia, 20 had reactive arthritis, and five had septic arthritis. No case of classic rheumatic fever classified by two major criteria was found. Six patients fulfilled one major and at least two minor criteria. The frequency of HLA-B27 was significantly higher in the whole patient group than in the healthy Finnish population (30 v 14%).

CONCLUSIONS

It is concluded that classic rheumatic fever is now rare, even in patients with arthritis with a high ASO titre. These results support the suggestion that beta haemolytic streptococci may trigger reactive arthritis as well as rheumatic fever.

Beta haemolytic streptococci and musculoskeletal sepsis in adults

Lancefield group A streptococci (GAS) account for 3-17% cases of septic arthritis, but other beta haemolytic streptococci (BHS) (groups B, C, and G) are being increasingly implicated. Epidemiological evidence suggests that the increase of BHS sepsis in adults is a true increase and not simply a reflection of better reporting. While underlying predisposing disease and old age are common concomitants of BHS sepsis, some subjects with devastating disease have been young and healthy. This is particularly the case for highly virulent M1 serotypes of GAS, where a toxic shock-like syndrome has led to a number of deaths in young adults in the United Kingdom and elsewhere. Musculoskeletal features, such as myalgias, painful swollen limbs, myositis, and fasciitis, are important features of this condition, so that rheumatologists may be involved in management. Group C and G musculoskeletal sepsis remains uncommon, with a high prevalence of underlying predisposing disease, or pre-existing arthritis in the septic joint. Group B BHS septic disease appears to be increasing in incidence. Musculoskeletal sepsis with these organisms usually takes place in subjects with other diseases, but healthy subjects have not been spared. Multiple septic foci and a rapidly destructive arthritis are not uncommon, and a recently described extra-articular feature is potentially blinding metastatic endophthalmitis. Clinicians need to be aware of an apparently increasing incidence of BHS musculoskeletal sepsis in adults so that early identification can lead to aggressive management in these potentially fatal infections.

Erythrogenic toxin type A (ETA): epidemiological analysis of gene distribution and protein formation in clinical Streptococcus pyogenes strains causing scarlet fever and the streptococcal toxic shock-like syndrome (TSLS)

Erythrogenic toxin type A (ETA) is assumed to play a causative role in both scarlet fever and the streptococcal toxic shock-like syndrome (TSLS). For a molecular epidemiological analysis of the gene of erythrogenic toxin type A (speA) we used altogether 497 clinical isolates of Streptococcus pyogenes belonging to three groups: a) isolates from patients with scarlet fever, b) isolates from cases with TSLS, c) isolates from patients with other streptococcal infections (like otitis media, tonsillitis, impetigo) (general group). We found that less than 50% of the scarlet fever-associated strains possessed the speA gene as compared to 25% of the general group. Only 5 to 30% of these strains secreted the toxin under experimental conditions in very low quantities. Among strains isolated from TSLS, 67% appeared to contain the speA gene. The amount of ETA secreted into the medium was also extremely low. Southern hybridization patterns proved to be the same with an speA-specific probe in all three groups of streptococcal isolates (HaeIII, HindIII). Increased occurrence of the speA gene among scarlet fever and TSLS-associated strains does not seem to be sufficient to support the hypothesis that ETA may have a causative role in both diseases since a considerable number of strains in these groups did not possess the speA gene.

Beta haemolytic streptococci and reactive arthritis in adults

There is an increasing occurrence of reactive group A beta haemolytic streptococci (BHS) phenomena. This review makes a case for considering BHS in the differential diagnosis of adult reactive arthritis. This is based on (a) published reports over the past 45 years describing first attacks of rheumatic fever in adults; (b) the longstanding observation that polyarthritis is the most commonly expressed Jones major criterion in adults; (c) the broad spectrum of clinical expression of disease following streptococcal infection, with the re-emergence of the term 'poststreptococcal reactive arthritis'. The arthritis in adult rheumatic fever is characterised by sequential involvement of large weightbearing joints. Recurrent, severe, prolonged arthritis has been a prominent feature of adult poststreptococcal reactive arthritis. Carditis has been reported in 33% of adult patients with rheumatic fever. Consequently long term antibiotic prophylaxis for adults with reactive BHS phenomena should be strongly considered, and guidelines are suggested for this in individual patients. Further areas for research are discussed, particularly the interrelations between bacteria and host in disease expression, and the possibility that BHS might play a part in chronic arthritides and vasculitides.

Association between expression of immunoglobulin G-binding proteins by group A streptococci and virulence in a mouse skin infection model

In this study, we developed a mouse model of skin infection to test the association between expression of immunoglobulin-binding proteins by and infectivity of group A streptococci. Group A streptococci capable of crossing tissue barriers and establishing a lethal systemic infection in mice showed a higher level of immunoglobulin-binding protein expression. The group A streptococci recovered from the spleen of a mouse that died following a skin infection were found to be more virulent when injected into the skin of naive mice. Together, these results suggest that immunoglobulin-binding protein expression by group A streptococci correlates with their ability to establish invasive skin infections.

Temporal relationship of cytokine release by peripheral blood mononuclear cells stimulated by the streptococcal superantigen pep M5

We undertook this study to determine the quality, quantity, and temporal relationship of pep M5-induced cytokine release. The ability of pep M5 to stimulate interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) production by a T-cell-depleted, monocyte- and B-cell-enriched cell population was dependent on the presence of T cells. The requirement for T cells could be met by addition of exogenous gamma interferon (IFN-gamma). In the presence of IFN-gamma, pep M5 induced the release of TNF-alpha, IL-1, and IL-6, TNF-alpha levels peaked at 24 h, while IL-1 and IL-6 levels peaked at 48 h. pep M5 induced T cells to produce IFN-gamma, which may have accounted for the ability of the super antigen to induce the production of IL-1, IL-6, TNF-alpha, and TNF-beta by peripheral blood mononuclear cells (PBMC). The addition of excess IFN-gamma to cultures of pep M5 and PBMC did not further increase the release of these cytokines at 24 and 48 h but resulted in sustained higher levels at 72 h. Interestingly, TNF-beta production occurred only in the presence of pep M5 and exogenous IFN-gamma. The ability of pep M5 to induce cytokine production was compared with that of a potent super antigen, staphylococcal enterotoxin B (SEB). SEB was a 2- to 14-fold-more-potent inducer of IFN-gamma production. Furthermore, the profile of cytokine released by PBMC in response to this super antigen mimicked that seen with pep M5 in the presence of exogenous IFN-gamma. In conclusion, pep M5 induces the production of cytokines that are involved in immune regulation and inflammation. These cytokines also play a major role in human T-cell responses to this super antigen.

Characterization of a conserved helper-T-cell epitope from group A Streptococcal M proteins

We have previously defined major histocompatibility complex (MHC) class II-restricted T-cell epitopes from the carboxy-terminal region of group A streptococcal type 5 M protein. In this report, T-cell responses to one of these epitopes have been characterized in detail. T-cell clones from recombinant M5-immunized mice and popliteal lymph node cells from peptide-immunized mice were used to show that sM5[300-319] is recognized in the context of I-A alleles of four of nine independent MHC class II haplotypes: I-Ad, I-Af, I-Ak, and I-As. This epitope was also recognized by both helper (Th2) and inflammatory (Th1) subsets of murine T cells. The I-Ad-restricted epitope recognized by BALB/c mice was mapped to the 12-amino-acid peptide sM5[308-319] and was shown to provide helper function for an immunoglobulin G anti-peptide antibody response in BALB/c mice. Anti-peptide antibody was shown to be specific for M5[304-315] but failed to recognize intact rM5, suggesting that the conformation of the epitope differed between peptide and protein. However, the results demonstrate that overlapping epitopes can be the focus for both immunoglobulin G antibodies and the T cells which augment their production. Comparison of the available sequences for M proteins indicated that the T-cell epitope within M5[300-319] was highly conserved between M types and hence may elicit helper function for protective antibody responses to a wide range of M types. T-cell epitopes from conserved regions of M proteins which are recognized in the context of multiple MHC haplotypes have potential for the design of multivalent streptococcal vaccines.

Bacterial and viral superantigens: roles in autoimmunity?

Superantigens are bacterial, viral, or retroviral proteins which can activate specifically a large proportion of T cells. In contrast with classical peptide antigen recognition, superantigens do not require processing to small peptides but act as complete or partially processed proteins. They can bind to major histocompatibility complex class II molecules and stimulate T cells expressing particular T cell receptor V beta chains. The other polymorphic parts of the T cell receptor, which are crucial for classical antigen recognition, are not important for this interaction. When this strategy is used a large proportion of the host immune system can be activated shortly after infection. The activated cells have a wide variety of antigen specificities. The ability to stimulate polyclonal B (IgG) as well as T cell responses raises possibilities of a role for superantigens in the induction of autoimmune diseases. Superantigens have been a great tool in the hands of immunologists in unravelling some of the basic mechanisms of tolerance and immunity.

Role of antigen-presenting cells in activation of human T cells by the streptococcal M protein superantigen: requirement for secreted and membrane-associated costimulatory factors

The requirements for T-cell activation by the streptococcal superantigen (SAg), pepsin-extracted M protein from type 5 streptococci (pep M5), were studied by monitoring Ca2+ influx and cell proliferation. Cells from a pep M5-specific T-cell line showed no change in intracellular Ca2+ levels in response to pep M5 when added alone or with freshly isolated autologous antigen-presenting cells (APC). However, after being incubated with pep M5 overnight, the APC secreted soluble factors that together with pep M5 induced a marked increase in intracellular Ca2+ levels in pep M5-specific T cells or freshly isolated, purified T cells. Removal of the SAg from the overnight APC-derived supernatants resulted in loss of the Ca(2+)-mobilizing activity, which was restored within seconds of addition of SAg, suggesting that both the SAg and the soluble factors synergize to induce the Ca2+ influx. Induction of cell proliferation required additional signals inasmuch as the activated APC-derived supernatant failed to synergize with pep M5 to induce the proliferation of purified T cells and required the presence of phorbol myristate acetate for this activity. Metabolically inactive, fixed APC were impaired in their ability to present pep M5 to T cells. Presentation of pep M5 by fixed APC was, however, restored when the APC-derived soluble costimulatory factors were added to the culture. Our data suggest that pep M5-induced activation of T cells is dependent on APC-derived soluble factors and an APC membrane-associated costimulatory molecule(s). These interactions may be important in regulating the in vivo responses to M proteins, could contribute to the severity or progression of infections with Streptococcus pyogenes, and may influence the susceptibility of individuals to its associated nonsuppurative autoimmune sequelae.

Streptococcal toxic shock-like syndrome. The importance of surgical intervention

Pyrogenic exotoxins A, B, and C produced by group A beta-hemolytic streptococci (Streptococcus pyogenes) may cause a syndrome characterized by fever, rash, desquamation, hypotension, and multi-organ-system dysfunction. This syndrome, the streptococcal toxic shock-like syndrome (TSLS), has a rapid and fulminant course closely resembling the staphylococcal toxic shock syndrome (TSS) caused by the staphylococcal toxic shock syndrome toxin-1 (TSST-1). The recent recognition of this syndrome is thought to stem from the appearance of more virulent strains of streptococci that have a greater tendency to produce potent exotoxins than prior strains. During the past 6 years, the authors have treated six patients with TSLS; three of these patients have presented recently. The sites of streptococcal infection associated with the development of the syndrome are frequently in soft tissue and skin. Early diagnosis, treatment with penicillin, and radical operative debridement are required.

Group A beta-haemolytic streptococcus septicaemia: the toxic strep syndrome. Report of our cases developing septic shock and multiple organ failure

During the last two decades, severe group A beta-haemolytic streptococcal infections have been defined as the "toxic strep syndrome", and have been reported not only in immunocompromised or elderly people, but also occasionally in previously healthy patients. We describe 4 patients presenting with the toxic strep syndrome, requiring surgery and intensive care, and briefly review the related literature. Fatigue, localized pain and other nonspecific symptoms were associated with the onset of the disease, followed by septic shock with multiple organ failure. Early diagnosis and surgical intervention, if necessary, are mandatory. Subsequently, appropriate supportive treatment of vital organ dysfunction and penicillin as the antibiotic of choice represent the cornerstones of the management of this syndrome.

Erythrogenic toxins A, B and C: occurrence of the genes and exotoxin formation from clinical Streptococcus pyogenes strains associated with streptococcal toxic shock-like syndrome

We report the study of 53 clinical isolates of group A streptococci, all from patients with streptococcal toxic shock-like syndrome. The strains were analysed for the occurrence of the genes of erythrogenic toxins (pyrogenic exotoxins) types A, B and C and in vitro production of these toxins. In contrast to reports indicating that 85% of the toxic shock-like syndrome-associated isolates contained the erythrogenic toxin A gene, only 58.5% of our strains harboured this gene. The erythrogenic toxin C gene was detected in 22.6% of the isolates. Erythrogenic toxin A and erythrogenic toxin B were produced by 68.7% and 58.3% of the strains containing either gene. For all group A streptococci, irrespective of clinical association, the erythrogenic toxin B gene was detected in all the isolates tested. Thus, it is difficult to define a specific role for erythrogenic toxin B in toxic shock-like syndrome as there was no clear correlation between this disease and the presence of toxin genes. Our results suggest the existence of other pathogenic factor(s) produced by group A streptococci which may stimulate human peripheral T lymphocytes in a manner similar to that of erythrogenic toxins, thus explaining different observations in previous epidemiological genetic studies.

An international comparison of the prevalence of streptococcal infections and rheumatic fever in children

Differences in the socioeconomic standards of living remain an important and feasible partial explanation for the difference in incidence of rheumatic fever following GABHS infection in Egyptian compared with American children. However, past and ongoing studies of the epidemiology, diagnosis, and treatment of GABHS infections in Egypt, the United States, and elsewhere suggest other significant factors are relevant. Additional knowledge about the rheumatogenic GABHS serotypes that are most prevalent in all countries is an important area where additional research is needed. Streptococcal research will help not only in improving the quality of primary prevention of rheumatic fever, but also in developing streptococcal vaccines.