Toxic shock syndrome: a review

Disseminated Infections

The ability of microorganisms to cause infection is governed by multiple different factors – some linked to the microorganisms itself and others to the host or environment. In this chapter we explore some of these factors and provide an overview of disseminated infections examining some important manifestations such as toxic shock syndrome and sepsis as well as examining some of molecular aspects including host receptors and bacterial antigens. A brief discussion will also follow about disseminated infections in specific populations such as neonates and the immunosuppressed.

How T-cell-dependent and -independent challenges access the brain: vascular and neural responses to bacterial lipopolysaccharide and staphylococcal enterotoxin B

Bacterial lipopolysaccharide (LPS) is widely used to study immune influences on the CNS, and cerebrovascular prostaglandin (PG) synthesis is implicated in mediating LPS influences on some acute phase responses. Other bacterial products, such as staphylococcal enterotoxin B (SEB), impact target tissues differently in that their effects are T-lymphocyte-dependent, yet both LPS and SEB recruit a partially overlapping set of subcortical central autonomic cell groups. We sought to compare neurovascular responses to the two pathogens, and the mechanisms by which they may access the brain. Rats received iv injections of LPS (2 microg/kg), SEB (1mg/kg) or vehicle and were sacrificed 0.5-3h later. Both challenges engaged vascular cells as early 0.5h, as evidenced by induced expression of the vascular early response gene (Verge), and the immediate-early gene, NGFI-B. Cyclooxygenase-2 (COX-2) expression was detected in both endothelial and perivascular cells (PVCs) in response to LPS, but only in PVCs of SEB-challenged animals. The non-selective COX inhibitor, indomethacin (1mg/kg, iv), blocked LPS-induced activation in a subset of central autonomic structures, but failed to alter SEB-driven responses. Liposome mediated ablation of PVCs modulated the CNS response to LPS, did not affect the SEB-induced activational profile. By contrast, disruptions of interoceptive signaling by area postrema lesions or vagotomy (complete or hepatic) markedly attenuated SEB-, but not LPS-, stimulated central activational responses. Despite partial overlap in their neuronal and vascular response profiles, LPS and SEB appear to use distinct mechanisms to access the brain.

CNS activational responses to staphylococcal enterotoxin B: T-lymphocyte-dependent immune challenge effects on stress-related circuitry

Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that engages the immune system in a T-lymphocyte-dependent manner and induces a cytokine profile distinct from that elicited by the better-studied bacterial pathogen analog, lipopolysaccharide (LPS). Because of reports of SEB recruiting central nervous system (CNS) host defense mechanisms via pathways in common with LPS, we sought to further characterize central systems impacted by this agent. Rats were treated with SEB at doses of 50-5,000 mug/kg, and killed 0.5-6 hours thereafter. SEB injection produced a discrete pattern of Fos induction in brain that peaked at 2-3 hours postinjection and whose strength was dose-related. Induced Fos expression was predominantly subcortical and focused in a set of interconnected central autonomic structures, including aspects of the bed n. of the stria terminalis, central amygdala and lateral parabrachial nuclei; functionally related (and LPS-responsive) cell groups in the n. solitary tract, ventrolateral medulla, and paraventricular hypothalamic n. (PVH) were, by contrast, weakly responsive. SEB also activated cell groups in the limbic forebrain (lateral septal n, medial prefrontal cortex) and hypothalamic GABAergic neurons, which could account for its failure to elicit reliable increases in Fos-ir or corticotropin-releasing factor (CRF) mRNA in the PVH. SEB nevertheless did provoke reliable pituitary-adrenal secretory responses. The identification of subsets of central autonomic and limbic forebrain structures that are sensitive to SEB provides a basis for a systems-level understanding of the physiological and behavioral effects attributed to the superantigen. Core SEB-responsive cell groups exclude a medullary-PVH circuit implicated in pituitary-adrenal responses to LPS.

A Case Report of the Effect of Plasma Exchange on Reactive Hemophagocytic Syndrome Associated with Toxic Shock Syndrome

We report here the case of a patient suffering from hemophagocytic syndrome (HPS) associated with toxic shock syndrome (TSS). A 50-year-old man was admitted because of fever, watery diarrhea and shortness of breath. Clinical analysis revealed systemic cyanosis, sunburn-like erythema and septic shock. Staphylococcus aureus was identified from both blood and sputum culture and the serum enterotoxin A antibody test was positive, suggesting that this was a case of TSS. Though the respiratory and hemodynamic status improved by the mechanical ventilation, fluid resuscitation with catecholamine and antibiotic therapy, the platelet count decreased rapidly. Bone marrow aspiration revealed a large quantity of hemophagocytosis by macrophages. This reactive HPS was treated not with immunosuppressive drugs but with therapeutic plasma exchange in order to prevent worsening of S. aureus infection. After plasma exchange, the circulating macrophage colony-stimulating factor (M-CSF) level was reduced and the platelet count increased rapidly. Bacteria associated HPS remains a difficult diagnosis with high mortality and there is a crucial question of whether this should be treated with immunosuppressive drugs. The patient's clinical course would suggest that the therapeutic plasma exchange should be considered as a therapeutic tool for the bacteria associated HPS instead of immunosuppressive drugs.

Murine lethal toxic shock caused by intranasal administration of staphylococcal enterotoxin B

Currently available murine staphylococcal enterotoxin B (SEB) shock models require pretreatment with various agents to increase mouse sensitivity to SEB. This study was performed to show that C3H/HeJ mice are highly susceptible to intranasal SEB inoculation, which caused toxic shock without using pretreatment agents. For this purpose, mice were injected intranasally with different doses of SEB and observed for up to 1 month. The median lethal dose of SEB was determined using the probit procedure. Tissue samples were taken at different time points for histopathological examination. The LD(50) was found at 1.6 microg/g (95% fiducial limit (f.l.) 0.7 to 2.2), the LD(80) at 2.7 microg/g (95% f.l. 1.9 to 4.0) and the LD(90) at 3.6 microg/g (95% f.l. 2.7 to 6.4). Histopathologic examination revealed pulmonary edema and bronchopneumonia. Mucosal-associated lymphoid tissue first became activated, followed by increasing lymphocyte apoptosis and depletion. In the liver there were intralobular and portal inflammatory foci with increasing lymphocyte apoptosis and degenerative necrosis. The splenic white pulp was characterized by early activation and subsequent depletion of lymphoid follicle germinal centers. The thymus initially was activated, followed by increasing apoptosis and migration of lymphoid cells from the cortex to the medulla. The pathological features detected in the mice were similar to those of rhesus monkeys treated with SEB aerosol challenge.

Toxicity of the staphylococcal enterotoxin B mutants with histidine-to-tyrosine substitutions

In this study we made a series of site-directed mutants of staphylococcal enterotoxin B (SEB), in which histidine residues in the molecule were replaced by tyrosine. The mutant genes were cloned and expressed, and the corresponding proteins were purified. These mutant proteins were tested for binding to human HLA-DR4 and for mitogenetic activity in mouse splenocyte culture. Toxicity of the proteins in vivo was evaluated in the actinomycin D-primed C3H/HeJ mouse model. We found that SEB mutant proteins with fewer than four histidine-to-tyrosine (his-to-tyr) substitutions retained toxic properties similar to wild-type SEB. However, studies showed that his-to-tyr substitution of four consecutive histidine residues eliminated SEB toxicity. Our results clearly show that this genetically modified SEB protein is non-toxic and justifies its further development as a component of a new, safer vaccine to prevent SEB intoxication.

Cutaneous (non-HIV) infections

Cutaneous infections continue to represent a large proportion of inpatient dermatology. Though most infectious skin diseases do not warrant hospitalization, some do and can rapidly become fatal if not treated promptly. A selected group of infections are reviewed--primary cutaneous infections, exotoxin-mediated syndromes, and systemic infections--that warrant hospitalization. Dermatologists play a critical role in the synthesis of patient history and appreciation of morphologic skin disease, which, when coupled with appropriate lab tests, may help to establish a diagnosis allowing for the timely implementation of effective and targeted therapy.

In Vivo Effects of a Bacterial Superantigen on Macaque TCR Repertoires

A macaque model was employed to explore staphylococcal enterotoxin B (SEB) superantigen-driven T lymphocyte responses. The SEB-reactive Vβ+ cell subpopulations demonstrated a striking tri-phase response in rhesus monkeys following an SEB challenge in vivo. The hyperacute down-regulation, seen as early as 2 h through 2 days after SEB injection, was characterized by a disappearance of the reactive Vβ-restricted PBL subpopulations from the circulation and decreased expression of these cell subpopulations in lymphoid tissues. Following this, a dominant expansion of reactive Vβ-expressing CD4+ cell subpopulations occurred in lymph nodes and spleens, whereas in the peripheral blood a preferential expansion of reactive Vβ-expressing CD8+ cell subpopulations was seen. An exhaustion of this response was then seen, with a prolonged decrease in the number of the reactive Vβ+ CD4+ lymphocyte subpopulations. Interestingly, monoclonal or oligoclonal dominance was seen in the reactive Vβ+ cell subpopulations in the period of the transition from the polyclonal cellular expansion to the exhaustion of the response, suggesting that some Vβ+ cell clones may be more resistant than others to superantigen-mediated depletion. These results indicate that in vivo SEB superantigen-mediated effect on lymphocyte subpopulations in macaques is complex, suggesting that profound dynamics in the TCR repertoires may in part account for the susceptibility of higher primates to SEB-induced diseases.

Immunogenicity and efficacy against lethal aerosol staphylococcal enterotoxin B challenge in monkeys by intramuscular and respiratory delivery of proteosome-toxoid vaccines

Staphylococcal enterotoxin B (SEB), a primary cause of food poisoning, is also a superantigen that can cause toxic shock after traumatic or surgical staphylococcal wound [correction of would] infections or viral influenza-associated staphylococcal superinfections or when aerosolized for use as a potential biologic warfare threat agent. Intranasal or intramuscular (i.m.) immunization with formalinized SEB toxoid formulated with meningococcal outer membrane protein proteosomes has previously been shown to be immunogenic and protective against lethal respiratory or parenteral SEB challenge in murine models of SEB intoxication. Here, it is demonstrated that immunization of nonhuman primates with the proteosome-SEB toxoid vaccine is safe, immunogenic, and protective against lethal aerosol challenge with 15 50% lethal doses of SEB. Monkeys (10 per group) were primed i.m. and given booster injections by either the i.m. or intratracheal route without adverse side effects. Anamnestic anti-SEB serum immunoglobulin G (IgG) responses were elicited in all monkeys, but strong IgA responses in sera and bronchial secretions were elicited both pre- and post-SEB challenge only in monkeys given booster injections intratracheally. The proteosome-SEB toxoid vaccine was efficacious by both routes in protecting 100% of monkeys against severe symptomatology and death from aerosolized-SEB intoxication. These data confirm the safety, immunogenicity, and efficacy in monkeys of parenteral and respiratory vaccination with the proteosome-SEB toxoid, thereby supporting clinical trials of this vaccine in humans. The safety and enhancement of both bronchial and systemic IgA and IgG responses by the proteosome vaccine delivered by a respiratory route are also encouraging for the development of mucosally delivered proteosome vaccines to protect against SEB and other toxic or infectious respiratory pathogens.

Humoral immunity to aerosolized staphylococcal enterotoxin B (SEB), a superantigen, in monkeys vaccinated with SEB toxoid-containing microspheres

Staphylococcal enterotoxin B (SEB) toxoid-containing microspheres were tested for efficacy in rhesus monkeys as a vaccine candidate for respiratory SEB toxicosis and toxic shock. Forty monkeys were randomly separated into 10 groups of four monkeys each: 9 groups were vaccinated with the microspheres via combinations of mucosal and nonmucosal routes, and 1 group served as nonvaccinated controls. Both vaccinated and nonvaccinated monkeys were then challenged with a high lethal dose of SEB aerosol. Monkeys primed with an intramuscular dose of the microspheres followed by an intratracheal booster all survived the SEB challenge. Overall, monkeys with an intratracheal booster generally had the highest antibody levels, which is consistent with their high survival rate and lower rate of illness. Protective immunity was correlated with antibody levels in both the circulation and the respiratory tract. The protection was not due to the depletion or anergy of SEB-reactive T cells, since SEB-induced proliferation in cultures of circulating lymphocytes was not significantly reduced after the microsphere vaccination. It is evident that the nonsurvivors did not die of systemic anaphylaxis or hypersensitivity because the monkeys did not die immediately after SEB challenge and there were no significant differences in histamine levels between the vaccinated and control monkeys before and after SEB challenge. The antibodies seemed to neutralize the SEB that got into the airway and the circulation.

Toxic shock and Down syndromes in a dental patient: a case report and review of the literature

A literature review of Toxic Shock Syndrome is presented, including epidemiology, etiology, signs, symptoms and management, and its relationship to infection susceptibility in the Down Syndrome patient. A case of a Down Syndrome patient with Toxic Shock Syndrome is described, and the role of odontogenic infection is discussed.

Increased susceptibility to staphylococcal enterotoxin B intoxication in mice primed with actinomycin D

Mice (BALB/cJ, C3H/HeN, and C3H/HeJ) primed with actinomycin D became highly susceptible to lethal intoxication with staphylococcal enterotoxin B (SEB). The mice underwent toxicosis and toxic shock and died. Actinomycin D-primed C3H/HeN and C3H/HeJ mice showed equal sensitivity to SEB, suggesting that bacterial lipopolysaccharide derived from gram-negative bacteria in the gut may not be an important cofactor in intoxication. In a time course study of the illness, prominent pathological changes characterized by blood congestion and thickening of alveolar septa were seen in the lung, while blood congestion, inflammation, epithelial cell flattening, and villous blunting were seen in the small intestine. In lymphoid tissues, such as the spleen, congestion, inflammation, and lymphoid cell depletion were the major reactions. The pathological features of the mice had many similarities to those of rhesus monkeys intoxicated with intravenous SEB. The actinomycin D-primed C3H/HeJ mice are thus an ideal mouse model for studying SEB toxicosis and toxic shock.

A 33-year-old white female with abdominal pain, nausea, vomiting and hypotension

A thirty-three year old female presented to our emergency department complaining of severe abdominal pain, nausea, and vomiting. On physical examination she was hypotensive with a firm, tender abdomen, cervical motion tenderness and a diffuse erythematous rash. A surgical diagnosis of Acute Pelvic Inflammatory Disease was made during laparoscopy. Coagulant studies, liver function tests, culture results, and the desquamation of the patient's palms led to the additional diagnosis of Toxic Shock Syndrome. A literature search failed to reveal any similar cases of Pelvic Inflammatory Disease (PID) and Toxic Shock Syndrome (TSS) occurring concomitantly. Patients may present severely ill with either of these disease entities but potential for serious illness is greater when both of these syndromes occur in the same patient. We conclude that in patients with a similar presentation, the symptoms should not be attributed completely to PID without further investigation and consideration of a concomitant disease process including TSS.

Immunity and responses of circulating leukocytes and lymphocytes in monkeys to aerosolized staphylococcal enterotoxin B

Rhesus monkeys immunized intramuscularly or orally with staphylococcal enterotoxin B (SEB) toxoid or SEB toxoid incorporated in microspheres made of poly(DL-lactide-co-glycolide) were challenged with a lethal dose of aerosolized SEB to study their immunity and cellular responses in the circulation. It was found that circulating antibodies play a critical role in preventing SEB from triggering toxicosis. Monkeys with high levels of antibodies survived, while those with low levels underwent 2 to 3 days of toxicosis and died. Intramuscular immunization induced high levels and oral immunization induced low levels of antibodies. The circulating antibodies in surviving monkeys decreased dramatically within 20 min and started to rebound at 90 min after SEB challenge. At 90 min, the dying monkeys showed in the circulation a dramatic increase of polymorphonuclear leukocytes and decreases of NK cells and monocytes (CD16 and CD56 markers) as well as of lymphocytes with HLA-DR, CD2, CD8, and IL2R alpha (CD25) markers. The number of polymorphonuclear leukocytes showed an inverse correlation with the numbers of monocytes and various lymphocyte subpopulations which, except for IL-2R, CD16, and CD56(+) cells, showed a direct correlation with one another. The changes in the populations of leukocytes, monocytes, NK cells, and lymphocytes seem to be an indication of initial toxicosis; however, the roles of these cells in toxicosis and death remain to be defined.

Toxic shock syndrome in three adolescent males

Toxic shock syndrome (TSS) is associated with a spectrum of Staphylococcus aureus infections and is not just a disease of menstruating females. We report three cases of TSS in adolescent males. In one case the origin of infection was a cauterized wart that did not appear clinically infected. Two cases were associated with bacteremia and had demonstrable acute phase antibody to toxic shock syndrome toxin-1 (TSST-1). One of these patients died. The S. aureus strain from this patient did not produce TSST-1 but did produce enterotoxin D. The historical and clinical features of TSS are reviewed.