Aspects of pathogenesis of serious group A streptococcal infections in Sweden, 1988-1989

Serotypes of serious, sometimes fatal, streptococcal infections in Sweden during 1988-1989 were analyzed. The T1M1 type totally dominated, representing almost 70% of all group A streptococci from serious and uncomplicated infections at the peak of the outbreak. Immunoblots of isolates from various patient groups showed that all isolates produced high amounts of erythrogenic toxin (ET) B and high amounts of ET-C, whereas ET-A was released only in small amounts and from few isolates. ELISAs showed high antibody levels to these toxins and to the M1 antigen in patients with uncomplicated infections. Low antibody levels against M1 were seen in patients with bacteremia and in fatal cases; the latter also had low antibody levels against ET-B. It seems likely that a combination of production of large amounts of toxin and low antibody titers to it and to the M antigen of the infecting isolate are determining factors for the outcome of the infection. No signs of primary immune deficiency were noted.

Role of streptococcal IgG Fc receptor in tissue deposition of IgG in rabbits immunized with Streptococcus pyogenes

Induction of anti-IgG during hyperimmunization of rabbit with Streptococcus pyogenes (group A streptococci; GAS) was previously shown to require the presence of IgG Fc receptors (FcR) in the vaccine strain. In the present work, we examined whether streptococcal FcR activity might also be of importance for heart and kidney deposition of IgG, known to occur in poststreptococcal sequelae as well as during experimental immunization of animals. Each of three IgG-binding (GAS types M1, M12 and M22) and two non-binding (GAS type T27 and S. agalactiae (GBS) type Ia) streptococcal strains were used for intravenous immunization of rabbits during two periods of eight and six weeks, respectively, separated by an interval of one month. Before use, vaccine strains were treated with KSCN and carefully washed in order to remove any surface-bound immunoglobulins. No deaths occurred among injected rabbits. No tissue deposition was elicited by the GAS type T27 or the GBS strain. In contrast, the strains of types M1, M12 and M22 all induced deposits of IgG in kidney and heart tissue, beginning during the first immunization period. In two tested animals, receiving GAS of types M1 or M22, circulating immune complexes containing anti-IgG antibodies were also detected. Finally, serum autoantibodies reacting with preparations of heart and kidney, but not lung or liver, were demonstrated in each of six animals receiving M1 or M22, reaching maximum levels during reimmunization; such antibodies were not evoked by the two strains not binding IgG. Our results suggest that, in GAS with capacity for non-immune binding of IgG, triggering of anti-IgG acted to enhance tissue deposition of IgG or immune complexes in immunized rabbits. Furthermore tissue-specific antibodies were elicited only by the IgG-binding strains and occurred comparatively late during immunization, suggesting that those antibodies might have been triggered due to the exposition of hidden kidney and heart determinants.

Role of a streptococcal antigen in the pathogenesis of acute poststreptococcal glomerulonephritis. Characterization of the antigen and a proposed mechanism for the disease

We studied the significance of a streptococcal protein (preabsorbing Ag) (PA-Ag) in the pathogenesis of acute poststreptococcal glomerulonephritis (APSGN). This protein was isolated from nephritogenic streptococci. Purification of PA-Ag was achieved by chromatography, followed by Sephadex IEF. A single protein band at pH 4.7 was identified as PA-Ag. The m.w. was 43,000. Rabbit antisera against PA-Ag and sera of patients with APSGN showed identical precipitation lines by immunodiffusion. Antibodies to PA-Ag were found to be present in 30 of 31 patients with APSGN, in 1 of 36 patients with uncomplicated group A streptococcal upper respiratory tract infections, and in 1 of 36 normal adults. By using immunoelectrophoresis, it was found that PA-Ag activates the alternate pathway of C. Other water-soluble streptococcal fractions, used as controls, did not activate the C system. The demonstration that PA-Ag is present in the glomeruli in the early phase of APSGN and its ability to activate C3 and factor B suggest that PA-Ag may be involved in the pathogenesis of APSGN, via in situ C activation.

The effect of roxithromycin on the virulence of gram-positive cocci

Antibiotics whose recognized mode of action comprises inhibition of bacterial protein biosynthesis are also recognized to modulate the expression of bacterial virulence factors when incorporated into culture media at sub-MIC levels. In this respect, one of the new macrolides, roxithromycin, has been examined for its effect on toxin/enzyme production by strains of Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae. Biosynthesis of staphylococcal coagulase and DNase could be potentiated, whereas that of staphylococcal alpha-hemolysin, streptolysins O and S, and pneumolysin were unaltered. Expression of one structural virulence factor, pneumococcal polysaccharide, was repressed in the drug's presence, resulting in potentiation of phagocytic ingestion of the drug-exposed bacteria. The drug failed to have any effect on ingestion of Staph. aureus or Strep. pyogenes. These studies provide evidence that roxithromycin may exhibit "added value" as an antibiotic in its ability to potentiate the susceptibility of Strep. pneumoniae to host defenses such as phagocytosis.

Genetic control of streptococcus-induced hepatic granulomatous lesions in mice

Hepatic granulomatous lesions were induced in mice by a single intraperitoneal injection of 3 mg of disrupted Streptococcus pyogenes cell-wall material. Mice carrying the H-2b or H-2k haplotypes were highly susceptible to the induction and three weeks after the injection produced numerous granulomas. In contrast, mice of the H-2d haplotype were resistant and produced only a few hepatic granulomas. Resistance was inherited as a dominant trait and in the backcross generation segregated together with the H-2d phenotype. Testing of the H-2-recombinant mice indicated that the putative gene(s) determining resistance/susceptibility is located to the right of the S and to the left of the D region. This location corresponds to the recently described gene cluster consisting of tumor necrosis factor (TNF) and lymphotoxin genes and several BAT sequences. The known effect of TNF on granuloma formation in mice is consistent with a possible effect of TNF genes, and their variants, on S. pyogenes-inducibility of hepatic granulomas in mice.

Gut flora induces and maintains resistance against streptococcal cell wall-induced arthritis in F344 rats

Streptococcal cell wall (SCW)-induced arthritis is a chronic, erosive polyarthritis that can be induced in susceptible Lewis rats by one i.p. injection of an aqueous, sterile suspension of SCW. F344 rats are resistant to chronic joint inflammation. Our previous studies showed a correlation between susceptibility to SCW-induced arthritis and the ability to mount SCW-specific T cell responses, suggesting tolerance to SCW as a putative mechanism. Here we prevented the induction of tolerance to bacterial epitopes in F344 rats by using them germ-free and analysed susceptibility to arthritis subsequently. In addition, we conventionalized germ-free F344 rats at different times before induction of arthritis. Our results show that germ-free F344 rats are susceptible to SCW-induced arthritis with a similar severity, chronicity, incidence and onset as Lewis rats. Moreover, T cells isolated from germ-free F344 rats were able to respond to SCW. Conventionalization dramatically moderates arthritis and makes T cells unresponsive to SCW again. Thus, in normal rats (F344) a state of tolerance to arthritogenic epitopes is induced (neonatally) and maintained through life by the bacterial flora, resulting in resistance to bacterium-induced arthritides. In arthritis-prone (Lewis) rats, this tolerance is deficient and/or easily broken.

[Evaluation of a rapid technique for detecting the type A Streptococcus antigen (Test Pack Strep A)]

OBJECTIVE

To test a rapid technique of Antigen Detection (TAD) of Type A Betahemolitic Streptococci (BHSA) in Acute Tonsillitis (AT), comparing it with and using as a point of reference traditional Blood Agar Cultivation (BAC). Additionally, the use of Clinical Data as a method of supposed Diagnosis was studied.

DESIGN

Prospective observational study. SITE. Health Primary Care (Maspalomas Health Centre).

PATIENTS AND OTHER PARTICIPANTS

118 patients between the ages of 1 and 71 affected by AT.

MEASUREMENTS AND MAIN RESULTS

There was a proportion of 13.56% BHSA in the AT of our sample, with a Confidence Interval (CI) of 95% (7.38-19.74) using the BAC; and 17.80% with a CI of 95% (10.90-24.70) using the TAD. The following values were obtained for the TAD: Sensitivity (S) of 93.75%, Specificity (Sp) of 94.12%, Positive Predictive Value (PPV) of 71.43% and Negative Predictive Value (NPV) of 98.9%. Of the clinical variables studied, only the presence/absence of Exudate and Adenopathies were linked to the presence of BHSA in the Cultivations (p less than 0.05 and p less than 0.01 respectively); with, however, inconclusive S, Sp, PPV and PNV values.

CONCLUSIONS

We found insufficient correlation between clinical findings and the presence of BHSA to consider it a valid method of supposed diagnosis. There was however a statistical link between the presence of Exudate and local Adenopathies, and a positive result in the cultivation. The TAD is shown to be a rapid method, easy to use, and highly reliable for the discovery of the presence of BHSA in AT.

[Common cold: diagnostic steps? Antibiotics?]

The common cold is caused by more than 100 virus types. However, the clinical manifestation is always similar with rhinorrhea, stuffiness, sneezing, pharyngitis, laryngitis and cough. The local inflammatory reactions are not due to the presence of virus but caused by locally produced inflammatory mediators. Bacterial superinfections may cause otitis or sinusitis. Bacterial nasopharyngitis has been described in children. This entity possibly exists also in adults. Traditional viral cultures are rarely positive and are not recommended in the daily routine. In children, antigen detection for adenovirus, respiratory syncytial virus, parainfluenza and influenza virus are recommended to confirm the viral etiology or for epidemiological surveillance. The presence of group-A streptococci must be proven by culture or antigen detection before treatment with penicillin. Antiviral treatment is limited to interferon or ribavirin. New antiviral substances are in development. Today, treatment of common cold is limited to symptomatic measures, and antibiotic treatment is not justified.

Gamma interferon and interleukin 2, but not interleukin 4, are detectable in gamma/delta T-cell cultures after activation with bacteria

Mycobacterium tuberculosis- or group A streptococcus-activated gamma/delta T cells from normal healthy individuals were negatively sorted and restimulated in vitro from 48 h. Significant amounts of gamma interferon were detected after restimulation with M. tuberculosis, group A streptococci, or Listeria monocytogenes. In contrast, interleukin 4 was undetectable in the culture supernatants. Our findings provide indirect evidence for the involvement of gamma/delta T cells in immunity against tubercle bacilli and probably other bacteria.

Epitopes of group A streptococcal M protein that evoke cross-protective local immune responses

The present studies were undertaken to identify conserved epitopes of group A streptococcal M proteins that evoke cross-protective mucosal immune responses. Two synthetic peptides copying conserved regions of type 5 M protein, designated SM5(235-264)C and SM5(265-291)C, were covalently linked to carrier molecules and their immunogenicity was tested in laboratory animals. Rabbit antisera against both peptides cross-reacted with multiple serotypes of group A streptococci, indicating that the peptides contained broadly cross-reactive, surface exposed M protein epitopes. Serum antipeptide antibodies adsorbed to the surface of heterologous type 24 streptococci passively protected mice against intranasal challenge infections. Mice that were actively immunized intranasally with each synthetic peptide covalently linked to the B subunit of cholera toxin were protected against colonization and death after intranasal challenge infections with type 24 streptococci in the absence of serum opsonic antibodies. These data confirm and extend previous observations that conserved M protein epitopes evoke cross-protective local immunity and may serve as the basis for broadly cross-protective M protein vaccines.

Arthritis by autoreactive T cell lines obtained from rats after injection of intestinal bacterial cell wall fragments

T cell lines (B13, B19) were isolated from the lymph nodes of Lewis rats 12 days after an arthritogenic injection of cell wall fragments of Eubacterium aerofaciens (ECW), a major resident of the human intestinal flora. These cell wall fragments consist of peptidoglycan polysaccharide complexes (PPC). The cell lines that bear the helper phenotype were arthritogenic in knee or ankle joints upon intravenous injection into irradiated Lewis recipients. B13 was, however, not arthritogenic in irradiated F344 recipients that are largely RT1 identical. The arthritis induced in the knee joints of the irradiated Lewis rats was clearly shown by a 99mtechnetium-pertechnetate scanning technique and was confirmed histologically. In vitro the cell lines showed a proliferative response after stimulation with syngeneic spleen cells alone. The proliferation was significantly higher when bacterial PPC, isolated in soluble form from normal feces or ileostomy fluid were added. Recognition by B13 appeared to be MHC class II restricted. These results show that autoreactive T cell lines can be isolated from rats after injection of bacterial cell wall antigens and that these cell lines can be arthritogenic. This suggests a role for autoreactive T cells in the induction of bacterial cell wall arthritis and might give a clue for the arthritogenic properties of the normal human intestinal flora.

[Detection of polymeric IgA antibody to herpes simplex virus by pretreatment of sera with Streptococcus pyogenes--its application to diagnosis of primary infection]

In 17 patients of genital herpes virus infections, herpes simplex virus (HSV)-specific IgA antibody responses were analyzed using an enzyme-linked immunosorbent assay (ELISA) and the absorption of sera with Streptococcus pyogenes, AW43 and AR1, which bind monomeric IgA (m-IgA) and IgG antibodies, respectively. The ratio of polymeric IgA (p-IgA) to total IgA was calculated from the formula, the p-IgA index = IgA activity after absorption/IgA activity before absorption. In early-convalescent-phase sera from primary cases, the p-IgA indices were 0.5-0.9, whereas in recurrent or provoked cases, they were lower than 0.2. There results indicate that the p-IgA index may be useful for rapid and simple differentiation of primary from non-primary HSV infections.

Outbreaks of group A beta-hemolytic streptococcal pharyngitis in children: correlation of serotype T4 with scarlet fever

We evaluated the clinical features of 121 children who had group A beta-hemolytic streptococcal (GABHS) pharyngitis during 2 outbreaks in the Chikuhou district, Fukuoka, Japan, with respect to T types. During the first outbreak (November 1989-February 1990), T12 (50%) and T22 (27%) were the dominant T types isolated. During the second outbreak (January-April 1991), 64% of the typable strains were T4. Pus on the tonsils was less common and strawberry tongue more common in patients with eruptions than in those without. Skin eruptions were much more common in the patients infected with T4 than with other T types (p < 0.001). Despite a 10-day regimen of amoxicillin, 12/69 patients (17.4%) had evidence of GABHS on repeat cultures. The results suggest that T4 may be associated with a high incidence of scarlet fever. Serotyping should be performed to identify disease carriers and patterns of GABHS infection.

The role of streptococcal infection in the initiation of guttate psoriasis

BACKGROUND AND DESIGN

Although the association between streptococcal infection and guttate psoriasis is well known, to date there has been little information on whether only limited groups and/or serotypes of beta-hemolytic streptococci are involved. One hundred eleven patients with a sudden onset or deterioration of psoriasis were investigated for evidence of streptococcal infection. Of these patients, 34 had acute guttate psoriasis, 30 had a guttate flare of chronic psoriasis, 37 had chronic plaque psoriasis, and 10 had other types of psoriasis.

RESULTS

Serologic evidence of recent streptococcal infection was present in 19 (58%) of 33 patients with acute guttate psoriasis compared with seven (26%) of 27 patients with guttate exacerbations of chronic psoriasis. Streptococcus pyogenes was isolated from 19 (17%) of all 111 patients (9 [26%] of 34 with acute guttate psoriasis, four [13%] of 30 with guttate exacerbations of chronic psoriasis, and five [14%] of 37 patients with chronic psoriasis) compared with seven (7%) of 101 of a control population of patients being seen for treatment of viral warts. Other beta-hemolytic streptococci were found with equal frequency in the study and control populations. Thirteen isolates of 10 different streptococcal serotypes were obtained from the 64 patients with guttate psoriasis. These serotypes were similar in distribution and prevalence to those present in the local community.

CONCLUSIONS

This study confirms the strong association between prior infection with S pyogenes and guttate psoriasis but suggests that the ability to trigger guttate psoriasis is not serotype specific.

Polyclonal activation of human lymphocytes and induction of cytotoxic lymphocytes by streptococcal preparations

Polyclonal activation of human peripheral blood lymphocytes (PBLs) in vitro by preparations of Streptococcus pyogenes Su strain (OK-432) and other heat-killed strains was investigated. The streptococcal preparations tested induce a proliferative response of PBLs via interleukin-2 (IL-2)-independent pathways. The proliferative response is accompanied by the generation of lymphoblastic cells (LBCs), which consist of heterologous lymphocyte populations: CD4+ helper type of T cells, and CD4-CD8- double-negative (DN) lymphocytes, including both CD3+ TcR gamma + T cells and CD2+CD3- immature type of T or non-T cell type of lymphocytes. Almost all the LBCs express Leu19, TfR (transferrin receptor), LFA-1 and CD38 (OKT10) antigens, which are expressed on activated T cells, NK cells and some other lymphocytes. The proliferative response of human PBLs is also accompanied by the generation of potent cytotoxic activity against NK-sensitive and -resistant targets. C-dependent cytolysis and cell sorting experiments of OK-432-activated LBCs revealed that both CD3+ and CD3- types of CD4-CD8- DN lymphocytes, but not CD4+ helper T cells, may be major populations responsible for the cytotoxicity induced. On the other hand, CD4-CD8- T cells may be required for the proliferation of PBLs and generation of cytotoxic effector cells. These results suggest that the OK-432 and other streptococcal preparations stimulate the human PBLs in vitro to induce the proliferation/activation of CD4+ T cells, mediating the following generation of DN cytotoxic effector lymphocytes.

[Level of antibodies to different determinants of Streptococcus group A polysaccharide and autoantibodies to basal layer of the skin epithelium in rheumatism]

Direct dependence was established between the presence of autoantibodies reacting with the basal layer of the skin epithelium (BLSE) and the high level of antibodies to the streptococcal group A polysaccharide (APS). By the primary active rheumatic fever (PARF) autoantibodies to the BLSE are revealed. By the recurrent active rheumatic fever (RARF) and in the control sera, autoantibodies reacting with the BLES, apparently, are directed to the rhamnose determinants of APS. These data confirm: different level of antibodies to the GS and to the rhamnose determinants of APS by PARF, RARF and in the control sera; the experiments of the autoantibody inhibition, reacting with the BLSE by the APS or the polysaccharide of streptococci A-variant, containing only the rhamnose determinants.

Mapping T-cell epitopes in group A streptococcal type 5 M protein

Group A streptococcal cell surface M proteins elicit highly protective, serotype-specific opsonic antibodies and many serotypes also elicit host cross-reactive antibodies, which may contribute to the pathogenesis of poststreptococcal autoimmune disease. To date, studies aimed at designing safe (non-host-cross-reactive, defined-epitope) M vaccines have focused almost exclusively on antibody epitopes. Here we identify T-cell epitopes recognized by T cells from BALB/c, C57BL/6, and CBA/Ca mice immunized with purified, recombinant serotype 5 M protein (rM5). The responses of rM5-specific, major histocompatibility complex class II-restricted, T-cell clones to synthetic peptides representing most of the M5 sequence identified at least 13 distinct T-cell recognition sites, including sites recognized by more than one major histocompatibility complex haplotype of mice. Although none of these sites appeared to be strongly immunodominant, an N-terminal peptide, sM5[1-35], was recognized by lymph node T cells of rM5-immunized mice and by a larger proportion of rM5-specific T-cell clones than any other individual peptide. The fine specificity of these clones was mapped with subpeptides to a single site at or overlapping the sequence ELENHDL at residues 21 to 27, which is in close proximity to previously mapped protective antibody epitopes. Other T-cell recognition sites are distributed throughout the M protein and include several in the highly conserved C-terminal region of the molecule. One of these C-terminal sites, located within residues 300 to 319, was recognized by a significant proportion of T-cell clones from two strains of mice. Helper T-cell epitopes located in the C-terminal region of M5 are likely to be widely conserved between different M serotypes and could be particularly useful in designing multivalent, defined-epitope M vaccines.

Influence of IgG1 and IgG2 antibodies to streptococcal group A carbohydrate on neutrophil chemiluminescence

IgG antibodies to streptococcal group A carbohydrate (A-CHO) were isolated from normal human serum and from pooled Cohn fraction II using N-acetyl-D-glucosamine affinity chromatography columns. They consisted of the subclasses IgG1 and IgG2 in variable proportions depending on the pH of the elution buffer and on the subclass composition of anti-A-CHO in the starting material. Streptococcal group A particles exposing the antigen A-CHO were opsonized with various concentrations of these antibodies and incubated with normal human polymorphonuclear leukocytes (PMN). The luminol-enhanced chemiluminescence (CL) elicited with these particles was recorded over a 60-min period. With 12 of the 14 antibody preparations tested, the observed CL signal was dose-dependent. When used at comparable concentrations for opsonization, the antibodies enriched in IgG1 induced markedly stronger CL signals than those consisting predominantly of IgG2. It was concluded that the observed CL differences reflect mainly the preferential recognition of IgG1 molecules by Fc gamma receptors of PMN.

[The enhancement of the immunogenicity of streptococcal group-A M protein by conjugation with a synthetic polyelectrolyte]

Immunization with the polypeptide fragment of group A streptococcal protein M conjugated with the copolymer of acrylic acid and N-vinylpyrrolidone in complete Freund's adjuvant has been found to lead to a sharp increase in the level of antibodies to the type-specific determinants of protein M, detected in the enzyme immunoassay (EIA). The possibility of the application of such sera to preliminary typing of streptococci in EIA with the use of whole microbial cells as antigens has been shown. The data on high activity of the sera thus obtained in the bactericidal test with streptococci of the homologous type are presented. Recommendations on the use of sera obtained by the above method for highly precise typing of the virulent cultures of group A streptococci in the bactericidal test are given.

Human heart sarcolemmal sheath antibodies in children with non-suppurative sequelae of group A streptococcal infections: a follow up study

The kinetics of the human heart sarcolemmal sheath antibody were studied in children with acute rheumatic fever who had no carditis, children with acute rheumatic fever who had carditis and developed rheumatic heart disease, and in children with acute poststreptococcal glomerulonephritis. The children with rheumatic fever and those who developed valvular heart disease were given continuous secondary antistreptococcal prophylaxis. The titre of antibody at onset was significantly higher than that of the controls in children with acute rheumatic fever and carditis and in children with acute poststreptococcal nephritis. The difference in the antibody titre between children with rheumatic fever who had no carditis and controls was not statistically significant. After a mean follow up of three years, however, a high titre was only maintained in children with rheumatic fever who developed valvular heart disease.

Group A streptococcal antigens and vaccine potential

Attempts over the past seventy years to produce an effective vaccine to protect humans against group A streptococcal infections and their immunologically mediated sequelae (acute rheumatic fever and post-streptococcal glomerulonephritis) have been frustrated by two basic problems, first, the ability of the highly protective cell-surface M proteins to elicit potentially harmful host reactions and second, the existence of a large number of distinct serovars of M proteins and the fact that human immunity to group A streptococcal infections is predominantly M serovar-specific. In recent years, progress towards overcoming these problems has been greatly facilitated by an increased understanding of the structural and immunological properties of protective group A streptococcal antigens, which has emerged from molecular biology studies. This article reviews these studies and discusses the potential for developing an effective group A streptococcal vaccine.

Rheumatogenic streptococci and autoimmunity

The uniqueness of the group A streptococcus in initiating a cardiodestructive disease in a limited segment of the human species, regardless of race or ethnic group, makes the quest for a unique host response to a specific streptococcal antigen an intriguing and persisting challenge for clinical investigators, particularly for those investigators interested in autoimmunity. New methodology is making possible more incisive research approaches. The defined streptococcal antigens that turn out to be epitopes identical with host tissues, such as the M protein/cardiac myosin model or the hyaluronate in the capsule of mucoid rheumatogenic strains, offer the opportunity for more incisive clinical investigations. The isolation and cultivation of cardiotoxic T cell clones directed against such epitopes shared by host and parasite may eventually be possible. We may then learn more about whether autoimmunity is indeed a factor in the pathogenesis of rheumatic heart disease.