T cell activation and cytokine release in streptococcal toxic shock-like syndrome

Superantigens and SARS-CoV-2

It has been posited SARS-CoV-2 contains at least one unique superantigen-like motif not found in any other SARS or endemic coronaviruses. Superantigens are potent antigens that can send the immune system into overdrive. SARS-CoV-2 causes many of the biological and clinical consequences of a superantigen, and, in the context of reinfection and waning immunity, it is important to better understand the impact of a widely circulating, airborne pathogen that may be a superantigen, superantigen-like or trigger a superantigenic host response. Urgent research is needed to better understand the long-term risks being taken by governments whose policies enable widespread transmission of a potential superantigenic pathogen, and to more clearly define the vaccination and public health policies needed to protect against the consequences of repeat exposure to the pathogen.

Refractory Toxic Shock-Like Syndrome from Streptococcus dysgalactiae ssp. equisimilis and Intravenous Immunoglobulin as Salvage Therapy: A Case Series

Infections from Streptococcus dysgalactiae ssp. equisimilis (SDSE) can cause a wide variety of infections, ranging from mild cellulitis to invasive disease, such as endocarditis and streptococcal toxic shock-like syndrome (TSLS). Despite prompt and appropriate antibiotics, mortality rates associated with shock have remained exceedingly high, prompting the need for adjunctive therapy. IVIG has been proposed as a possible adjunct, given its ability to neutralize a wide variety of superantigens and modulate a dysregulated inflammatory response. We present the first reported cases of successful IVIG therapy for reversing shock in the treatment of SDSE TSLS.

Intravenous immunoglobulin in children with streptococcal toxic shock syndrome

BACKGROUND

Streptococcal toxic shock syndrome (TSS) is a rare and severe manifestation of group A streptococcal infection. The role of intravenous immunoglobulin (IVIG) for streptococcal TSS in children is controversial. This study aims to describe the epidemiology of streptococcal TSS in children and to determine whether adjunctive therapy with IVIG is associated with improved outcomes.

METHODS

A multicenter, retrospective cohort study of children with streptococcal TSS from 1 January 2003 through 31 December 2007 was conducted. Propensity scores were used to determine each child's likelihood of receiving IVIG. Differences in the primary outcomes of death, hospital length of stay, and total hospital costs were compared after matching IVIG recipients and nonrecipients on propensity score.

RESULTS

The median patient age was 8.2 years. IVIG was administered to 84 (44%) of 192 patients. The overall mortality rate was 4.2% (95% confidence interval, 1.8%-8.0%). Differences in mortality between IVIG recipients (n = 3; 4.5%) and nonrecipients (n = 3; 4.5%) were not statistically significant (p > .99). Although patients receiving IVIG had higher total hospital and drug costs than nonrecipients, differences in hospital costs were not significant once drug costs were removed (median difference between matched patients, $6139; interquartile range, -$8316 to $25,993; P = .06). No differences were found in length of hospital stay between matched IVIG recipients and nonrecipients.

CONCLUSION

This multicenter study is, to our knowledge, the largest to describe the epidemiology and outcomes of children with streptococcal TSS and the first to explore the association between IVIG use and clinical outcomes. IVIG use was associated with increased costs of caring for children with streptococcal TSS but was not associated with improved outcomes.

Treatment options in the management of necrotising fasciitis caused by Group A Streptococcus

Invasive Group A Streptococcus (GAS) disease is a serious condition that has multiple manifestations. A particularly severe form of invasive GAS disease is necrotising fasciitis (NF). The case-fatality rate of GAS NF is approximately 20%. Penicillin remains the antibiotic of choice when treating invasive GAS infections. Epidemiological studies have shown that clindamycin is effective in the treatment of deep infections that are caused by GAS. Clinicians should consider adding clindamycin to the beta-lactam antibiotic regimen when NF or myositis is present. Intravenous immunoglobulin appears to be a promising adjunctive therapy in the management of GAS NF. Consultations with surgeons and infectious disease specialists are imperative.

Intravenous immunoglobulin G therapy in streptococcal toxic shock syndrome: a European randomized, double-blind, placebo-controlled trial

The efficacy and safety of high-dose intravenous polyspecific immunoglobulin G (IVIG) as adjunctive therapy in streptococcal toxic shock syndrome (STSS) were evaluated in a multicenter, randomized, double-blind, placebo-controlled trial. The trial was prematurely terminated because of slow patient recruitment, and results were obtained from 21 enrolled patients (10 IVIG recipients and 11 placebo recipients). The primary end point was mortality at 28 days, and a 3.6-fold higher mortality rate was found in the placebo group. A significant decrease in the sepsis-related organ failure assessment score at days 2 (P=.02) and 3 (P=.04) was noted in the IVIG group. Furthermore, a significant increase in plasma neutralizing activity against superantigens expressed by autologous isolates was noted in the IVIG group after treatment (P=.03). Although statistical significance was not reached in the primary end point, the trial provides further support for IVIG as an efficacious adjunctive therapy in STSS.

Immunoglobulin therapy in non-menstrual streptococcal toxic shock syndrome

We describe a case of non-menstrual streptococcal toxic shock syndrome requiring high doses of noradrenaline. The intravenous administration of pooled immunoglobulin was associated with improved haemodynamics and weaning of vasoconstrictors.

Staphylococcal and streptococcal superantigens: molecular, biological and clinical aspects

Superantigens (SAgs) include a class of certain bacterial and viral proteins exhibiting highly potent lymphocyte-transforming (mitogenic) activity towards human and or other mammalian T lymphocytes. Unlike conventional antigens, SAgs bind to certain regions of major histocompatibility complex (MHC) class II molecules of antigen-presenting cells (APCs) outside the classical antigen-binding groove and concomitantly bind in their native form to T cells at specific motifs of the variable region of the beta chain (Vbeta) of the T cell receptor (TcR). This interaction triggers the activation (proliferation) of the targeted T lymphocytes and leads to the in vivo or in vitro release of high amounts of various cytokines and other effectors by immune cells. Each SAg interacts specifically with a characteristic set of Vbeta motifs. The review summarizes our current knowledge on S. aureus and S. pyogenes superantigen proteins. The repertoire of the staphylococcal and streptococcal SAgs comprises 24 and 8 proteins, respectively. The staphylococcal SAgs include (i) the classical enterotoxins A, B, C (and antigenic variants), D, E, and the recently discovered enterotoxins G to Q, (ii) toxic shock syndrome toxin-1, (iii) exfoliatins A and B. The streptococcal SAgs include the classical pyrogenic exotoxins A and C and the newly identified pyrogenic toxins, G, H, I, J, SMEZ, and SSA. The structural and genomic aspects of these toxins and their molecular relatedness are described as well as the available 3-D crystal structure of some of them and that of certain of their complexes with MHC class II molecules and the TcR, respectively. The pathophysiological properties and clinical disorders related to these SAgs are reviewed.

The Treatment of Severe Group A Streptococcal Infections

Group A streptococci can cause a variety of diseases ranging from uncomplicated superficial infections to severe systemic infections associated with high morbidity and mortality. Since the late 1980s a drastic resurgence of highly aggressive invasive streptococcal infections, including streptococcal toxic shock syndrome and necrotizing fasciitis, have been noted worldwide. This has prompted intense research in the field and important new information has been gained regarding the pathogenesis and treatment of life-threatening invasive group A streptococcal infections. Exotoxins with superantigenic activities have been identified as central mediators of the systemic effects seen in streptococcal toxic shock syndrome. Novel therapeutic strategies include agents that can inhibit these superantigens, and one promising candidate is intravenous polyspecific immunoglobulin that contains neutralizing antibodies against a wide spectrum of streptococcal superantigens. Intravenous immunoglobulin adjunctive therapy was shown in a case-control study to reduce mortality in patients with streptococcal toxic shock syndrome.

Group A streptococcal meningitis: report of a case and review of literature since 1976

Group A streptococcal (GAS) invasive disease has become increasingly common in recent years. However, acute bacterial meningitis caused by this pathogen is unusual. We report a case of GAS meningitis in a previously healthy 21/2-year-old child associated with a dramatically rapid course and fatal outcome. A literature review of previously reported cases is presented. This case serves as a reminder that GAS can cause severe meningitis in otherwise healthy hosts.

Superantigen bacterial toxins: state of the art

Superantigens (SAgs) are viral and bacterial proteins exhibiting a highly potent polyclonal lymphocyte-proliferating activity for CD4(+), CD8(+) and sometimes gammadelta(+) T cells of human and (or) various animal species. Unlike conventional antigens, SAgs bind as unprocessed proteins to invariant regions of major histocompatibility complex (MHC) class II molecules on the surface of antigen-presenting cells (APCs) and to particular motifs of the variable region of the beta chain (Vbeta) of T-cell receptor (TcR) outside the antigen-binding groove. As a consequence, SAgs stimulate at nano-to picogram concentrations up to 10 to 30% of host T-cell repertoire while only one in 10(5)-10(6) T cells (0.01-0.0001%) are activated upon conventional antigenic peptide binding to TcR. SAg activation of an unusually high percentage of T lymphocytes initiates massive release of pro-inflammatory and other cytokines which play a pivotal role in the pathogenesis of the diseases provoked by SAg-producing microorganisms. We briefly describe in this review the molecular and biological properties of the bacterial superantigen toxins and mitogens identified in the past decade.

Antibiotic prophylaxis for group A streptococcal burn wound infection is not necessary

BACKGROUND

Historically, group A beta-hemolytic streptococci (GAS) burn wound infection has been a major source of morbidity and mortality in burn patients and has prompted the prophylactic administration of antibiotics to children with burns. Wound monitoring, surveillance cultures, and early excision of deep wounds may have changed this. Our objective in this project was to determine the efficacy of routine antibiotic prophylaxis in the era of early excision and closure of deep burn wounds.

METHODS

Two cohorts of burned children were compared: all children admitted during calendar years 1992 through 1994 (group 1) and during calendar years 1995 through 1997 (group 2). All group 1 children received routine GAS antibiotic prophylaxis. Only those group 2 children with documented positive admission or surveillance cultures for GAS were treated.

RESULTS

There were 511 children in group 1 and 406 children in group 2. They were well matched for age (4.7 +/- 0.21 years vs. 5.3 +/- 0.26 years, p = 0.06) and burn size (11.0% +/- 0.7% vs. 12.4% +/- 0.8%, p = 0.18). GAS species were recovered at admission or during hospitalization from 11 (2.6%) of group 1 children and 18 (4.4%) of group 2 children (p = 0.05), indicating a marginally higher rate of carriage in group 2. Nevertheless, in group 1 there were three (0.6%) who developed GAS wound infection and in group 2 there were four (0.98%, p = 0.71). The incidence of GAS infection in those patients with positive admission cultures was three (27%) of group 1 and four (22%) of group 2. No child developed fulminant GAS infection.

CONCLUSION

Routine antibiotic prophylaxis of burn wounds in children in not effective in further reducing a low baseline incidence of GAS wound infection if admission screening by culture is used to identify those children who carry the organism and early excision of deep burns is practiced.

Pyrogenicity and cytokine-inducing properties of Streptococcus pyogenes superantigens: comparative study of streptococcal mitogenic exotoxin Z and pyrogenic exotoxin A

Streptococcal mitogenic exotoxin Z (SMEZ), a superantigen derived from Streptococcus pyogenes, provoked expansion of human lymphocytes expressing the Vbeta 2, 4, 7 and 8 motifs of T-cell receptor. SMEZ was pyrogenic in rabbits and stimulated the expression of the T-cell activation markers CD69 and cutaneous lymphocyte-associated antigen. A variety of cytokines was released by human mononuclear leukocytes stimulated with SMEZ, which was 10-fold more active than streptococcal pyrogenic exotoxin A. Th2-derived cytokines were elicited only by superantigens and not by streptococcal cells.

Severe group A streptococcal infection and streptococcal toxic shock syndrome

PURPOSE

To review the literature on group A streptococcal toxic shock syndrome, (STSS).

DATA SOURCE

Medline and EMBASE searches were conducted using the key words group A streptococcal toxic shock syndrome, alone and in combination with anesthesia; and septic shock, combined with anesthesia. Medline was also searched using key words intravenous immunoglobulin, (IVIG) and group A streptococcus, (GAS); and group A streptococcus and antibiotic therapy. Other references were included in this review if they addressed the history, microbiology, pathophysiology, incidence, mortality, presentation and management of invasive GAS infections. Relevant references from the papers reviewed were also considered. Articles on the foregoing topics were included regardless of study design. Non-English language studies were excluded. Literature on the efficacy of IVIG and optimal antibiotic therapy was specifically searched.

PRINCIPAL FINDINGS

Reports of invasive GAS infections have recently increased. Invasive GAS infection is associated with a toxic shock syndrome, (STSS), in 8-14% of cases. The STSS characteristically results in shock and multi-organ failure soon after the onset of symptoms, and is associated with a mortality of 33-81%. Many of these patients will require extensive soft tissue debridement or amputation in the operating room, on an emergency basis. The extent of tissue debridement required is often underestimated before skin incision.

CONCLUSIONS

Management of STSS requires volume resuscitation, vasopressor/inotrope infusion, antibiotic therapy and supportive care in an intensive care unit, usually including mechanical ventilation. Intravenous immunoglobulin infusion has been recommended. Further studies are needed to define the role of IVIG in STSS management and to determine optimal anesthetic management of patients with septic shock.

Relative neutralizing activity in polyspecific IgM, IgA, and IgG preparations against group A streptococcal superantigens

In this study we compared the ability of different immunoglobulin (Ig) preparations containing IgG, IgM, and/or IgA to neutralize the activity of streptococcal pyrogenic exotoxin A (SpeA) or culture supernatant from a clinical group A streptococcal isolate. All Ig preparations markedly inhibited the mitogenic and cytokine-inducing activity of SpeA and culture supernatant at concentrations of 0.05-0.5 mg/mL, and at 0.5 mg/mL, most caused 95-100% inhibition of both stimuli. A significantly higher (P< or =.05) inhibition of SpeA was achieved by Pentaglobin (IgG, IgM, and IgA) and IgAbulin (IgA and IgG), as compared with pure IgG preparations. IgM- and IgA-enriched preparations had significantly higher inhibitory activity against SpeA than against culture supernatant, whereas the reverse was true for the IgG preparations (P< or =.05). The data show that IgM and IgA are potent inhibitors of specific streptococcal superantigens. These findings may have implications for the optimization of immunotherapy in invasive streptococcal infections.

Improved outcome of clindamycin compared with beta-lactam antibiotic treatment for invasive Streptococcus pyogenes infection

CONTEXT

Animal model studies have demonstrated the failure of penicillin to cure Streptococcus pyogenes myositis and have suggested that clindamycin is a more effective treatment.

OBJECTIVE

To determine the most effective antibiotic treatment for invasive S. pyogenes infection in humans.

DESIGN AND SETTING

We conducted a retrospective review of the outcomes of all inpatients from 1983 to 1997 treated for invasive S. pyogenes infection at Children's Hospital.

PATIENTS

Fifty-six children were included, 37 with initially superficial disease and 19 with deep or multiple tissue infections.

MAIN OUTCOME MEASURE

Lack of progression of disease (or improvement) after at least 24 h of treatment.

RESULTS

The median number of antibiotic exposures was 3 per patient (range 1 to 6) with clindamycin predominating in 39 of 45 courses of protein synthesis-inhibiting antibiotics and beta-lactams predominating amongst the cell wall-inhibiting antibiotics in 123 of 126 of the remainder. Clindamycin was often used in combination with a beta-lactam antibiotic. Overall there was a 68% failure rate of cell wall-inhibiting antibiotics when used alone. Patients with deep infection were more likely to have a favorable outcome if initial treatment included a protein synthesis-inhibiting antibiotic as compared with exclusive treatment with cell wall-inhibiting antibiotics (83% vs. 14%, P = 0.006) with a similar trend in those with superficial disease (83% vs. 48%, P = 0.07). For those children initially treated with cell wall-inhibiting antibiotics alone, surgical drainage or debridement increased the probability of favorable outcome in patients with superficial disease (100% vs. 41%, P = 0.04) with a similar trend in a smaller number of deep infections (100% vs. 0%, P = 0.14).

CONCLUSIONS

This retrospective study suggests that clindamycin in combination with a beta-lactam antibiotic (with surgery if indicated) might be the most effective treatment for invasive S. pyogenes infection.

Intravenous immunoglobulin as adjunctive treatment for streptococcal toxic shock syndrome associated with necrotizing fasciitis: case report and review

Streptococcal toxic shock syndrome (STSS) is caused by infection with a toxicogenic strain of Streptococcus pyogenes. Clinical manifestations may be those of a mild illness, characterized by malaise, fever, and muscle pain, to severe sepsis and multisystem organ failure. The syndrome may be associated with several invasive infections including necrotizing fasciitis. Treatment is primarily surgical debridement of infected tissue with supportive care, antibiotics, and hemodynamic monitoring. Intravenous immunoglobulin (IVIG) is reported to have beneficial effects in the management of STSS associated with necrotizing fasciitis. The agent was successful in conjunction with surgical excision and antibiotics in a patient with necrotizing fasciitis, toxic shock, and multisystem organ failure. On the basis of this experience and a thorough literature review, we concur that IVIG may be a useful adjunct in the treatment of STSS associated with necrotizing fasciitis.

Therapeutic Approaches to Streptococcal Toxic Shock Syndrome

The streptococcal toxic shock syndrome (STSS) is a severe, life-threatening condition characterized by hypotension and multiorgan system dysfunction associated with infection by the group A Streptococcus (GAS) or rarely by streptococci of other Lancefield serogroups. It is associated with a soft tissue infection, such as necrotizing fasciitis, in about half of the cases; the remainder are secondary to a variety of other invasive and noninvasive GAS infections. Although the pathophysiology of STSS is not yet fully understood, there are compelling reasons to believe that the syndrome results at least in part from the action of the streptococcal pyrogenic exotoxins, which act as superantigens. Patients with STSS should be admitted to an intensive care unit for support of cardiovascular, respiratory, and renal function as required. In experimental models of overwhelming GAS infection, clindamycin has greater efficacy than penicillin, and therapy with this agent is recommended. Penicillin, to which GAS are uniformly susceptible, may be used in addition to clindamycin. Limited clinical experience, most of which is anecdotal, suggests marked improvement in some STSS patients after administration of intravenous immunoglobulin. Even in the absence of conclusive data, the potential benefits of intravenous immunoglobulin in this highly lethal disease make its use reasonable in life-threatening cases. Other experimental approaches are also discussed, such as the use of anti-tumor necrosis factor monoclonal antibodies and plasmapheresis.

Necrotising fasciitis and group A streptococcus toxic shock-like syndrome in pregnancy: treatment with plasmapheresis and immunoglobulin

A 30-year-old woman at 25 weeks gestation presented to the labour ward complaining of abdominal pain and a painful bruise in her right groin. Over the course of several hours, she developed rapidly spreading necrotising fasciitis of the right thigh. She required emergency radical debridement of the thigh and caesarean delivery of a dead fetus. She was admitted to the intensive care unit (ICU) with septic shock, where she received ventilatory and inotropic support. Streptococcus pyogenes was isolated from the infected tissue and a diagnosis of group A streptococcal toxic shock-like syndrome (GAS TS-LS) was confirmed. Following acute and rapid haemodynamic deterioration, plasmapheresis was given for 6 days, after which the patient's general condition improved and vasoconstrictor requirement was significantly reduced. Subsequently, immunoglobulin was given intravenously for thrombocytopenia, following which the platelet count steadily improved. Despite the development of acute renal failure, acute respiratory distress syndrome and a left hemiplegia, the patient made a remarkable recovery. She was later transferred to a plastic surgical unit for split skin-grafting. The importance of early diagnosis and aggressive treatment of GAS TS-LS is emphasized and the place of plasmapheresis and intravenous immunoglobulin therapy in this condition is discussed.

Toxic shock syndrome: case report of a postpartum female and a literature review

Toxic shock syndrome is one of the best understood of the systemic inflammatory response syndromes. The mechanisms of disease have been extensively studied; however, no therapies have been developed that can effectively reverse the syndrome once the inflammatory response has begun. Although toxic shock syndrome classically has been associated with tampon use, multiple other etiologies exist including postpartum toxic shock, which usually affects patients in the immediate weeks following delivery. We present a case of toxic shock in a woman 10 weeks postpartum and review the literature regarding both menstrual-related and nonmenstrual-related toxic shock.

Opsonic antibodies to the surface M protein of group A streptococci in pooled normal immunoglobulins (IVIG): potential impact on the clinical efficacy of IVIG therapy for severe invasive group A streptococcal infections

The surface M protein of group A streptococci (GAS) is one of the major virulence factors for this pathogen. Antibodies to the M protein can facilitate opsonophagocytosis by phagocytic cells present in human blood. We investigated whether pooled normal immunoglobulin G (IVIG) contains antibodies that can opsonize and enhance the phagocytosis of type M1 strains of GAS and whether the levels of these antibodies vary for different IVIG preparations. We focused on the presence of anti-M1 antibodies because the M1T1 serotype accounts for the majority of recent invasive GAS clinical isolates in our surveillance studies. The level of anti-M1 antibodies in three commercial IVIG preparations was determined by enzyme-linked immunosorbent assay (ELISA), and the opsonic activity of these antibodies was determined by neutrophil-mediated opsonophagocytosis of a representative M1T1 isolate. High levels of opsonic anti-M1 antibodies were found in all IVIG preparations tested, and there was a good correlation between ELISA titers and opsonophagocytic activity. However, there was no significant difference in the levels of opsonic anti-M1 antibodies among the various IVIG preparations or lots tested. Adsorption of IVIG with M1T1 bacteria removed the anti-M1 opsonic activity, while the level of anti-M3 opsonophagocytosis was unchanged. Plasma was obtained from seven patients with streptococcal toxic shock syndrome who received IVIG therapy, and the level of anti-M1 antibodies was assessed before and after IVIG administration. A significant increase in the level of type M1-specific antibodies was found in the plasma of all patients who received IVIG therapy (P < 0.006). The results reveal another potential mechanism by which IVIG can ameliorate severe invasive group A streptococcal infections.

Posttranscriptional regulation of T-cell IL-2 production by human pooled immunoglobin

We evaluated the mechanism by which human pooled gamma-globulin for intravenous use (hIVIG) inhibits interleukin-2 (IL-2) production by human T cells. hIVIG reduced by 70-95% the amount of IL-2 in culture supernatants from mitogen-stimulated peripheral blood T cells or Jurkat cells. This reduction was not apparent at the transcriptional level: hIVIG had no effect on the levels of IL-2 mRNA or on the accumulation of firefly luciferase when its gene was linked to the IL-2 promoters. In contrast, hIVIG inhibited IL-2 protein synthesis, and the intracellular IL-2 was not restored by monensin. Our results indicate that the inhibition of IL-2 production by hIVIG occurred post-transcriptionally, and also suggest that secretion was unaffected, and that this effect of hIVIG was specific for IL-2 (and possibly other related cytokines). The data identify a previously uncharacterized regulatory mechanism of IL-2 production and predict that this immunomodulatory effect of hIVIG may be significant for its therapeutic actions in immune-mediated diseases.

Intravenous immunoglobulin inhibits staphylococcal toxin-induced human mononuclear phagocyte tumor necrosis factor alpha production

Intravenous gamma immunoglobulin (IVIG) is used as therapy in superantigen-mediated disease, yet its mode of action is not clear. Pooled immunoglobulin G contains high concentrations of staphylococcal exotoxin (SE)-specific antibodies which inhibit the in vitro activation of T cells. However, SE and streptococcal exotoxins are potent stimulators of monocytes as well. Monocytes exposed to SE in vitro release large amounts of tumor necrosis factor alpha (TNF-alpha). The purpose of the present study was to determine if SE-specific antibodies in IVIG can inhibit the activation of monocytes by SE. We examined the in vitro effect of IVIG on the ability of staphylococcal exotoxin A (SEA) and staphylococcal exotoxin B (SEB) to stimulate release of TNF-alpha from human mononuclear phagocytes (MO). Pretreatment of SEA with 0.1 mg of IVIG per ml resulted in a slight decrease of SEA-induced TNF-alpha secretion by MO. In contrast, pretreatment of SEB with 0.1 mg of IVIG per ml resulted in significant (greater than 50%) inhibition of SEB-induced TNF-alpha secretion at 24, 48, 72, and 96 h (P < 0.05 for TNF-alpha levels induced by SEB alone versus SEB pretreated with IVIG at all time points). Enzyme-linked immunosorbent assay and Western immunoblotting assays of the IVIG revealed high concentrations of antibodies against SEB and lower concentrations of antibodies to SEA. These data indicate that IVIG can act in a toxin-specific manner to decrease the MO TNF-alpha response to superantigens. Such inhibition may be one mechanism by which IVIG exerts an immunoregulatory role in superantigen-mediated disease.

Evidence for the presence of streptococcal-superantigen-neutralizing antibodies in normal polyspecific immunoglobulin G

Recently we demonstrated that normal polyspecific immunoglobulin given intravenously (IVIG) and plasma samples from patients treated with IVIG neutralize the mitogenic and cytokine-inducing activities of group A streptococcal (GAS) superantigens. Here we investigated whether this neutralizing activity is mediated by antibodies to these superantigens. IVIG and plasma samples collected from a patient with GAS necrotizing fasciitis post-IVIG infusions markedly inhibited the mitogenic activity elicited by the streptococcal pyrogenic exotoxins SpeB and SpeC, as well as by GAS culture supernatant. Immunoblot analysis showed marked increases in the levels of antibodies to SpeC and proteins in the GAS culture supernatant in post-IVIG over those of pre-IVIG plasma samples. Removal of antisuperantigen antibodies in IVIG by adsorption to SpeC- and GAS culture supernatant-coupled Sepharose markedly reduced the neutralizing ability of IVIG against respective stimuli. The neutralizing activity was totally recovered in the eluted antibodies. By contrast, although pre- and post-IVIG plasma samples contained antibodies to SpeA, these antibodies did not block the activity of this superantigen. Nonspecific immunomodulatory activity of IVIG was ruled out because neither the IVIG nor the affinity-purified antibodies significantly inhibited the response to the polyclonal T-cell mitogen phytohemagglutinin A. These data provide direct evidence that the neutralizing activity in IVIG, and in patient plasma samples following IVIG treatment is mediated by antibodies to superantigens and indicate that the quality rather than the quantity of these antibodies may be more clinically relevant.

Toxic shock syndrome due to group C streptococci. A case report

BACKGROUND

Streptococcal toxic shock-like syndrome is a life-threatening illness which is on the increase. In early reports, only group A beta-hemolytic streptococcus was associated with the disease, but recent evidence indicates non-A streptococci groups are also involved.

OBSERVATIONS

We describe the first reported case of streptococcal toxic shock-like syndrome caused by a group C strain in Italy. Prior to the disease, the patient, a 46-year-old man, had been in good health and had only a 3-day history of sore throat, low grade fever, vomiting, diarrhea, and myalgia before admission. Initially, diagnosis was based only on clinical evidence: shock, multiorgan failure, profound hypothermia, and no apparent signs of infection. Toxic cardiomyopathy was also present.

RESULTS

Positive throat swab and blood culture confirmed a "definite case" following established criteria. Anamnesis showed a diagnosis of monoclonal gammopathy. Antibiotic treatment was begun immediately on admission of the patient, who was discharged 20 days later in good health.

CONCLUSIONS

This case illustrates how an early diagnosis and prompt antibiotic therapy can determine a more favorable outcome.

Orthopaedic manifestations of invasive group A streptococcal infections complicating primary varicella

The incidence of invasive group A streptococcal (GAS) infections in primary varicella appears to be increasing. GAS infections complicating varicella range from cellulitis, abscess, and septic arthritis to life-threatening necrotizing fasciitis and pyomyositis in association with GAS toxic shock syndrome (TSS). Four patients admitted in 1 year to the Children's Hospital and Medical Center in Seattle, whose care included evaluation and treatment by the Orthopaedic service, are presented to illustrate this spectrum. Three had a delay in diagnosis, including discharge from previous emergency department visits. One patient with polyarticular septic arthritis was treated with diagnostic aspiration and intravenous antibiotics. The remainder required urgent surgical debridement for treatment of deep infection. Patients with necrotizing fasciitis or pyomyositis had life-threatening complications of TSS, including hypotension, adult respiratory distress syndrome (ARDS), coagulopathy, and acute renal failure. These patients required aggressive fluid resuscitation and prolonged intensive care unit support. Diagnostic imaging studies were obtained in one patient with necrotizing pyomyositis but may have served only to delay definitive treatment. Recognition of the potential for secondary GAS infections and a high index of suspicion for the presence of necrotizing soft-tissue infection are essential in the evaluation of any child with fever and localized extremity pain with varicella.

Human pro- and anti-inflammatory cytokine patterns induced by Streptococcus pyogenes erythrogenic (pyrogenic) exotoxin A and C superantigens

The superantigenic streptococcal erythrogenic toxins A and C (ETA/SPEA and ETC/SPEC) elicit the production by human peripheral blood mononuclear cells of substantial amounts of Th1-derived cytokines (interleukin-2 [IL-2] and gamma interferon) as well as anti-inflammatory cytokines (IL-10 and IL-1 receptor antagonist). In contrast, very low levels of IL-4 and no alpha interferon were induced. The production of these cytokines after stimulation with Streptococcus pyogenes heat-killed bacteria and lipopolysaccharide from gram negative bacteria differed qualitatively and quantitatively from that elicited by the superantigens.

Fatal group A streptococcal infection with toxic shock syndrome: complicating minor orthopedic trauma

Since 1987, reports have appeared of a streptococcal toxic shock syndrome in various clinical settings. None have appeared in the orthopaedic literature. Between 1989 and 1991 at our institution three patients with relatively minor orthopaedic injuries or procedures died of group A streptococcal infections complicated by toxic shock syndrome. The manifestations of this syndrome included rapid progression of systemic sepsis, necrotizing soft-tissue infections, acute renal failure, adult respiratory distress syndrome, and coagulopathy. All three patients died despite aggressive resuscitative measures and surgical debridement. Optimal treatment of this life-threatening process requires early recognition, aggressive surgical debridement, appropriate antibiotic management, and intensive care unit support.

Streptococcal toxic shock syndrome in a postpartum woman. Case report and review of the literature

A case of streptococcal toxic shock syndrome in a 29-year-old postpartum woman is described. The patient presented with hypotension, coagulation defects, adult respiratory distress syndrome and scarlet exanthema as a complication of hemolytic group A streptococcal endometritis. One hundred and twenty-two other cases of streptococcal toxic shock syndrome in the literature are reviewed and the criteria of the syndrome discussed. Streptococcal toxic shock syndrome seems to be increasing along with more frequent invasive streptococcal infections in several countries. It is therefore important to recognize and treat the infection as early as possible to minimize the risk of mortality.

The reemergence of serious group A streptococcal infections and acute rheumatic fever

Acute rheumatic fever and life-threatening group A streptococcal infections have reemerged during the past 15 years to once again become a serious health threat in the developed countries of the world. Reports of outbreaks of acute rheumatic fever in many parts of this country and others have shattered the complacency that the health-care community had acquired related to this devastating sequela of streptococcal pharyngitis. Invasive streptococcal infections, often associated with loss of limbs of life despite optimal antibiotic therapy, have underscored the potential virulence of these organisms. A new clinical entity, streptococcal toxic shock syndrome, has emerged as a consequence of the new invasive strains of group A streptococci. In this article, the authors summarize the recent changes in the epidemiology of group A streptococcal infections and rheumatic fever and review the potential reasons for the increased virulence of these organisms. In addition, they discuss prospects for a streptococcal M protein vaccine designed to control these infections and their sequelae.

Congenital streptococcal toxic shock syndrome with absence of antibodies against streptococcal pyrogenic exotoxins

Congenital infection with group A beta-hemolytic streptococcus was complicated by toxic shock syndrome in a neonate. We hypothesize that the severity of the clinical syndrome was related to the streptococcal pyrogenic exotoxin in the absence of corresponding antibodies. The outcome may have been favorably influenced by the antibodies to streptococcal pyrogenic exotoxin present in the immunoglobulins given as treatment.

Bacterial pyrogenic exotoxins as superantigens

The recent discovery of the mode of interaction between a group of microbial proteins known as superantigens and the immune system has opened a wide area of investigation into the possible role of these molecules in human diseases. Superantigens produced by certain viruses and bacteria, including Mycoplasma species, are either secreted or membrane-bound proteins. A unique feature of these proteins is that they can interact simultaneously with distinct receptors on different types of cells, resulting in enhanced cell-cell interaction and triggering a series of biochemical reactions that can lead to excessive cell proliferation and the release of inflammatory cytokines. However, although superantigens share many features, they can have very different biological effects that are potentiated by host genetic and environmental factors. This review focuses on a group of secreted pyrogenic toxins that belong to the superantigen family and highlights some of their structural-functional features and their roles in diseases such as toxic shock and autoimmunity. Deciphering the biological activities of the various superantigens and understanding their role in the pathogenesis of microbial infections and their sequelae will enable us to devise means by which we can intervene with their activity and/or manipulate them to our advantage.

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.