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

Soluble M1 protein of Streptococcus pyogenes triggers potent T cell activation

Streptococcus pyogenes of the M1 serotype is commonly associated with large outbreaks of invasive streptococcal infections and development of streptococcal toxic shock syndrome (STSS). The pathogenesis behind these infections is believed to involve bacterial superantigens that induce potent inflammatory responses, but the reason why strains of the M1 serotype are over-represented in STSS is still not understood. In the present investigation, we show that a highly purified soluble form of the M1 protein from S. pyogenes, which lacks the membrane-spanning region, is a potent inducer of T cell proliferation and release of Th1 type cytokines. M1 protein-evoked T cell proliferation was HLA class II-dependent but not MHC-restricted, did not require intracellular processing and was Vbeta-restricted. Extensive mass spectrometry studies indicated that there were no other detectable proteins in the preparation. Taken together, our data demonstrate that soluble M1 protein is a novel streptococcal superantigen, which likely contributes to the excessive T cell activation and hyperinflammatory response seen in severe invasive streptococcal infections.

[Toxic shock syndrome: experience in a pediatric intensive care unit]

OBJECTIVES

To review patients with toxic shock syndrome (TSS) in a pediatric intensive care unit.

METHODS

We performed a retrospective study of patients with TSS admitted to the intensive care unit in the previous 15 years. The patients included were those that met the clinical and microbiological criteria for TSS proposed by the Centers for Disease Control and Prevention.

RESULTS

There were nine patients (four boys). The mean age was 7 years. The most frequent findings were fever (100 %), hypotension (100 %), erythroderma (100 %), multisystem organ failure [coagulopathy (100 %), lethargy (89 %), hypertransaminasemia (89 %), increased creatine phosphokinase levels (78 %), renal failure (66 %)] and cutaneous desquamation (100 %). Laboratory studies showed changes in the leukocyte count and C-reactive protein value in all patients. The etiology was as follows: Staphylococcus was detected in six patients (S. epidermidis in three and S. aureus in three) and Streptococcus was detected in two patients (S. pyogenes in one and S. pneumoniae in one); no microorganisms were detected in only one patient. The origin of the infection was identified in seven patients (cutaneous in six patients and tonsillar in one). All patients received life support and antibiotic treatment. Six patients received corticosteroid treatment and one received intravenous immunoglobulins. Patients with TSS secondary to Streptococcus showed the greatest severity, exhibiting renal failure and requiring greater respiratory and circulatory support. All patients recovered well from the infection, without serious long-term sequelae. CONCLUSION. TSS should be included in the differential diagnosis of patients with fever, exanthema and shock, since early diagnosis has been shown to improve outcomes. S. pneumoniae should be included among the microorganisms that cause TSS. Treatment is based on life support measures and antibiotic therapy.

Epidemiology and outcome of necrotizing fasciitis in children: an active surveillance study of the Canadian Paediatric Surveillance Program

OBJECTIVE

To describe the epidemiology, management, and outcome of pediatric necrotizing fasciitis (NF) in Canada before full implementation of varicella immunization programs.

STUDY DESIGN

This was a prospective cohort study of all children under age 16 years identified by the Canadian Paediatric Surveillance Program (CPSP).

RESULTS

Between November 1, 2001 and October 31, 2003, 36 NF cases were identified (mean age, 5.9 +/- 5 years). Group A streptococcus (GAS)-related and non-GAS-related NF accounted for 2.12 and 0.81 cases per million children, respectively. The annual incidence was substantially higher in children under age 5 years (5.9 vs 1.8 per million; P = .0002). Males over age 1 year had the highest disease burden, with 12 cases per million, versus 3.2 cases per million for females under age 1 year (P < .0001). Most (15/26; 58%) GAS-related cases were associated with varicella. Complications occurred in 29 children (78%), and 2 children (5.4%) died.

CONCLUSION

In the prevaccine era, NF occurred most commonly in Canadian children under age 5 years, with a peak incidence in males under age 1 year. There is substantial associated morbidity and about 5% mortality. The data provide baseline incidence of disease and a surveillance mechanism for NF after the implementation of publicly funded varicella immunization programs in Canada.

Sepsis in 2003: are we still in the middle of nowhere?

PURPOSE OF REVIEW

Although enthusiasm of intensivists has been raised during the last 2-3 years due to several successful clinical trials, severe sepsis and septic shock still have an increasing incidence with more or less unchanged mortality. Within the last 12 months, the progress in sepsis research covering definitions, epidemiology, pathophysiology, diagnosis, standard and adjunctive therapy, as well as experimental approaches is encouraging. In this review, state-of-the-art publications of 2003 are presented to elucidate the possible impact on clinical routine.

RECENT FINDINGS

The rationale for using a new definition based on the PIRO system has been widely acknowledged, although it is not yet applicable in clinical practice. This includes genomic information for stratifying subgroups of patients, and a broader field of laboratory diagnostics due to clinical studies and basic research on the cellular mechanisms of inflammation and organ dysfunction. Early diagnosis is important for a fast implementation of specific therapies, and it has been confirmed that the time until the start of therapy has an impact on patient outcome. Thorough data analysis of successful trials with activated protein C has revealed encouraging details on long-term outcome and subgroup effects. Together with new findings on low-dose hydrocortisone, this stresses the relevance of adjunctive therapy in severe sepsis and septic shock.

SUMMARY

Scientific progress in areas of sepsis has been continuing throughout 2003, although the challenges are still enormous. The identification of more specific markers and new therapeutic approaches will hopefully improve the diagnosis, monitoring of therapy, and outcome in the septic patient.

The epidemiology of invasive group A streptococcal disease in Victoria, Australia

OBJECTIVE

To estimate the incidence and severity of invasive group A streptococcal infection in Victoria, Australia.

DESIGN

Prospective active surveillance study.

SETTING

Public and private laboratories, hospitals and general practitioners throughout Victoria.

PATIENTS

People in Victoria diagnosed with group A streptococcal disease notified to the surveillance system between 1 March 2002 and 31 August 2004.

MAIN OUTCOME MEASURE

Confirmed invasive group A streptococcal disease.

RESULTS

We identified 333 confirmed cases: an average annual incidence rate of 2.7 (95% CI, 2.3-3.2) per 100,000 population per year. Rates were highest in people aged 65 years and older and those younger than 5 years. The case-fatality rate was 7.8%. Streptococcal toxic shock syndrome occurred in 48 patients (14.4%), with a case-fatality rate of 23%. Thirty cases of necrotising fasciitis were reported; five (17%) of these patients died. Type 1 (23%) was the most frequently identified emm sequence type in all age groups. All tested isolates were susceptible to penicillin and clindamycin. Two isolates (4%) were resistant to erythromycin.

CONCLUSION

The incidence of invasive group A streptococcal disease in temperate Australia is greater than previously appreciated and warrants greater public health attention, including its designation as a notifiable disease.

Acute bacterial skin infections and cellulitis

PURPOSE OF REVIEW

Acute bacterial skin infections are very common, with various presentations and severity. This review focuses on deep skin infections. We separate acute nonnecrotizing infections of the hypodermis (erysipelas), forms with abscesses or exudates and necrotizing fasciitis. These three types actually differ in risk factors, bacteriology, treatment and prognosis.

RECENT FINDINGS

Leg erysipelas/cellulitis occurs in more than one person/1000/year. It remains mainly due to streptococci. Foot intertrigo is an important risk factor. Necrotizing fasciitis is much rarer and usually occurs in patients with chronic diseases. Staphylococci, especially community-acquired methicillin-resistant strains in some areas, play a growing role in the intermediate form of cellulitis with abscesses and exudates. For erysipelas or noncomplicated cellulitis, antibiotic treatment at home, when feasible, is much less expensive and as effective as hospital treatment. Intermediate cases with collections and exudates often require surgical drainage. For necrotizing fasciitis early surgery remains essential in order to decrease the mortality rate.

SUMMARY

Antibiotic treatment of deep skin infections must be active on streptococci; the choice of a larger spectrum of activity depends on clinical presentation, risk factors and the burden of methicillin-resistant staphylococci in the environment.

Group A streptococcal infections in children

The group A streptococcus causes the widest range of disease in humans of all bacterial pathogens. Group A streptococcal diseases are more common in children than adults with diseases ranging from pharyngitis and impetigo to invasive infections and the post-streptococcal sequelae--acute rheumatic fever and acute post-streptococcal glomerulonephritis. The global burden of severe group A streptococcal disease is concentrated largely in developing countries and Indigenous populations such as Aboriginal Australians. Control of group A streptococcal disease is poor in these settings and the need for a vaccine has been argued. With an ever-increasing understanding of the group A streptococcus at a molecular level, new and sophisticated vaccines are currently in human trials and the next decade holds exciting prospects for curbing group A streptococcal diseases.

Infection and musculoskeletal conditions: Infectious myositis

Infectious myositis, an infection of the skeletal muscle(s), is uncommon. This clinical entity may be caused by viral, bacterial, fungal, and parasitic pathogens. Viral etiologies typically cause diffuse myalgias and/or myositis, whereas bacteria and fungi usually lead to a local myositis which may be associated with sites compromised by trauma or surgery and are more common among immunocompromised patients. Localized collections within the muscles are referred to as pyomyositis. Other pyogenic causes of myositis include gas gangrene, group A streptococcal myonecrosis, and other types of non-clostridial myonecrosis. Early recognition and treatment of these conditions are necessary as they may rapidly become life-threatening.

Streptococcal pancreatitis and toxic shock syndrome in a 2-month-old infant

The rare clinical scenario of an infant with group A streptococcal pancreatitis associated with toxic shock syndrome is reported. The presentation, evaluation, and management of this unusual clinical entity are discussed.

Streptococcus pyogenes: Insight into the function of the streptococcal superantigens

The group A streptococcus produces a number of highly potent exoproteins that act as superantigens. The cascade of pro-inflammatory events that follow invasive streptococcal infection is greatly enhanced by production of such toxins, leading to profound hypotension and multi-organ failure in some cases. Superantigens such as streptococcal mitogenic exotoxin Z (SMEZ) interact with host MHC class II and the T cell receptor, leading to activation events in both cells. In vitro, these interactions lead to expansion and cytokine production by specified T cell subsets. Studies using humanized HLA class II transgenic mice and isogenic streptococcal strains have characterised the in vivo responses to superantigens produced in the context of live infection. Notwithstanding the obvious deleterious role of superantigens in toxic shock, the evolutionary advantage conferred by these toxins remains a subject of speculation.

Intravenous polyclonal IgM-enriched immunoglobulin therapy in sepsis: a review of clinical efficacy in relation to microbiological aetiology and severity of sepsis

The efficacy of intravenous polyclonal immunoglobulin (IVIG) as adjunct therapy in sepsis has long been debated. Clinical trials have yielded contradicting results, in part due to the varying study design and varying microbiological aetiologies. In most trials, the study drug has been IVIG containing polyclonal IgG. However, in recent reports, the efficacy of IgM-enriched IVIG as adjunct therapy in sepsis has been highlighted. Here we review studies on IgM-enriched IVIG therapy in sepsis and we discuss the clinical efficacy in relation to microbiological aetiology and severity of sepsis. The results suggest that patients most likely to benefit from IgM-enriched IVIG therapy are those with Gram-negative septic shock.

Emerging drugs for the treatment of sepsis

Septic shock still places a major burden on the healthcare system, although recent years have been marked by the demonstration that corticosteroids and activated protein C may substantially improve survival in selected populations. This review discusses the current management of septic shock and the potential development of new therapeutics following impressive advances in the pathomechanisms of septic shock.

Dynamics of the immune response against extracellular products of group A streptococci during infection

The immune response against the infecting group A streptococcus (GAS) extracellular products (EP) was determined in acute- and convalescent-phase sera from 75 patients with different clinical manifestations of GAS infection. All EP elicited a high proliferative response in human peripheral blood mononuclear cells. In patients with bacteremia, low neutralization in acute-phase sera was associated with development of streptococcal toxic shock syndrome. Lack of neutralization in acute-phase sera was more common in patients infected with the T1emm1 serotype. The majority of patients did not develop the ability to neutralize the mitogenic activity of their infecting isolate despite a significant increase in enzyme-linked immunosorbent assay titer in early convalescent-phase sera. In patients with the ability to neutralize GAS EP, the immune response remained high over at least 3 years. In contrast, the neutralization capacity conferred by intravenous immunoglobulin and/or plasma treatment disappeared within 3 months.

Severe skin and soft tissue infections and associated critical illness

Skin and soft tissue infections (SSTIs) span a broad spectrum of clinical entities from limited cellulitis to rapidly progressive necrotizing fasciitis, which may be associated with septic shock or a toxic shock-like syndrome. These infections may manifest initially as pyodermas that then progress; alternatively, they may arise from metastatic spread of microorganisms from a distant focus. Regardless of the source, SSTIs may lead to critical illness. The complex interplay of environment, host, and pathogen are important to consider when evaluating SSTIs and planning appropriate therapy. The keys to a successful outcome are early identification of risk factors for specific pathogens and early initiation of empiric antimicrobial therapy. For certain types of SSTIs, surgical intervention for diagnosis and/or therapy is also required.

Therapies and vaccines for emerging bacterial infections: learning from methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging bacterial infection worldwide, and community-acquired MRSA (CA-MRSA) infection, which has increased dramatically in frequency in many areas, is of particular clinical and public health concern. CA-MRSA outbreaks and severe infections have been reported more frequently in children, often manifesting in one of two distinct clinical syndromes, furunculosis or necrotizing pneumonia. This article outlines the molecular biology of MRSA, how molecular biology has contributed to the understanding of MRSA infections, current therapy and prevention of MRSA, and the prospects for a vaccine against S aureus.

The role of high mobility group box-1 protein in severe sepsis

PURPOSE OF REVIEW

Despite medical advances, mortality in severe sepsis remains high. As our understanding of the innate immune system has expanded, clinical trials have focused on inhibiting cytokines present early in the infectious process such as interleukin-1 and tumor necrosis factor-alpha, although with disappointing results. There is evidence that the nuclear protein high mobility group box-1 protein, when released extracellularly, acts as a persistent mediator of sepsis and is therefore a promising candidate for therapeutic intervention. This review summarizes current knowledge of the protein and highlights recent relevant findings.

RECENT FINDINGS

High mobility group box-1 protein may be released into the circulation either due to necrosis of cells or by active release from macrophages and endothelial cells. Models of experimental sepsis in mice have shown a strong association between extracellular high mobility group box-1 protein and lethality. Treatments against the biological activities of high mobility group box-1 protein reduce lethality in these models. Other studies have shown high mobility group box-1 protein as a key regulator in acute and chronic inflammation. Recent findings confirm that high mobility group box-1 protein is persistently elevated in human patients with severe sepsis.

SUMMARY

Despite all efforts, mortality in severe sepsis remains high. A massive amount of evidence indicates high mobility group box-1 protein as a delayed and important propagator of inflammation. Recent studies confirm persisting high levels of high mobility group box-1 protein in serum up to 1 week after hospitalization. Reducing levels of the protein by anti-high mobility group box-1 protein treatment may be one way to moderate uncontrolled inflammation seen in sepsis.

[Indications for intravenous immunoglobulins]

Intravenous immunoglobulins (IgIV) are therapeutic preparations of polyclonal human IgG, obtained from a pool of plasma from more than 1000 healthy donors. This article discusses only some of the recognized indications (Group I) and some of those currently under evaluation (Group II) for the treatment of autoimmune and systemic inflammatory diseases. Perspectives for IgIV use are approached through three diseases, each providing a different model of immune system modulation: ocular cicatricial pemphigoid, where an autoimmune reaction is modulated; alloimmunization of chronic hemodialysis patients, where alloreactivity can be modulated; and streptococcal toxic shock, where anti-infectious immunity may be modulated.

Therapies for necrotising fasciitis

Necrotising fasciitis is a rare but life-threatening infectious disease emergency. Delays in diagnosis and treatment are common, and mortality rates often exceed 30%. Successful management of this disease requires high clinical suspicion and aggressive action. The mainstays of therapy include early and wide surgical debridement, antibiotics and supportive care, with prompt surgical intervention. Adjunctive modalities, such as protein synthesis inhibitors, hyperbaric oxygen and intravenous immunoglobulin, may have a role, but their effectiveness remains unproven. New rapid diagnostic tools are emerging that promise to revolutionize early detection of necrotising fasciitis. Research into the molecular microbiology, especially regarding group A streptococcus, are providing novel insights into the pathogenesis of necrotising soft tissue infections and identifying future targets for rationally designed interventions.

[Strategies of management of necrotizing soft tissue infections]

Necrotizing soft tissue infections represent a group of rapidly progressive diseases requiring early and repeated debridement, associated with broad spectrum antibiotics. Delay in surgery or inadequate therapy are the main risk factors for death. Most patients need aggressive critical care management and intensive nutritional support. The management of these patients by experimented senior surgeons is mandatory. A plastic surgeon can help debridement in order to preserve possibilities of later myocutaneous or rotational skin flaps. Intravenous immunoglobulins are an efficacious adjunctive therapy for severe group A streptococcal infection.

Protocol Recommendations for Administration of Intravenous Immunoglobulin in Canada

A group of Canadian nurses and transfusion safety officers developed 10 recommendations for the infusion of intravenous immunoglobulin (IVIG) in acute care hospitals and clinics. The recommendations address issues related to documentation, patient consent, difference among IVIG brands, selection of a brand on the basis of patients' risk factors, contraindications, needs, action plans for adverse events, rapid infusion protocols, and setup of infusion pumps, tubing, and filter equipment. The Canadian group encouraged institutions to include nurses on committees that examine infusion protocols.

IgMA-enriched immunoglobulin in neutropenic patients with sepsis syndrome and septic shock: A randomized, controlled, multiple-center trial*

OBJECTIVE

To evaluate the effect of intravenous IgMA-enriched immunoglobulin (ivIGMA) therapy on mortality in neutropenic patients with hematologic malignancies and sepsis syndrome or septic shock.

DESIGN

Multiple-center, prospective randomized, controlled study.

SETTING

Six university hospitals in Germany.

PATIENTS

Patients were 211 neutropenic patients with sepsis syndrome or septic shock after chemotherapy for severe hematologic disorders between 1992 and 1999.

INTERVENTIONS

Patients received 1300 mL of ivIGMA (7.8 g IgM, 7.8 g IgA, and 49.4 g IgG) infused intravenously within a period of 72 hrs or human albumin according to the same schedule as ivIGMA.

MEASUREMENTS AND MAIN RESULTS

All-cause mortality at 28 days, sepsis-related mortality at 28 days, all-cause mortality at 60 days, mortality from septic shock, and mortality from microbiologically proven Gram-negative sepsis and septic shock were recorded. Immunoglobulin had no benefit over human albumin. The 28-day mortality rate was 26.2% and 28.2% in the ivIGMA and control patients, respectively (difference, 2.0% [95% confidence interval, -10.2 to 14.2 percentage points]). Likewise, the 60-day mortality rate did not differ between both arms (29.6% vs. 34.7% in the ivIGMA and control patients, respectively). Mortality rates in patients with sepsis syndrome (17.1% vs. 16.7%) and septic shock (51.9% vs. 54.8%) were also found to be similar between both groups.

CONCLUSIONS

Intravenous ivIGMA had no beneficial effects in neutropenic patients with hematologic malignancies and sepsis syndrome and septic shock.

Management of sepsis in neutropenia: guidelines of the infectious diseases working party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

These guidelines from the infectious diseases working party (AGIHO) of the German Society of Hematology and Oncology (DGHO) give recommendations for the management of adults with neutropenia and the diagnosis of sepsis. The guidelines are written for clinicians and focus on pathophysiology, diagnosis, and treatment of sepsis. The manuscript contains evidence-based recommendations for the assessment of the quality and strength of the data.

Necrotizing fasciitis: pathogenesis and treatment

Necrotizing fasciitis is a rapidly progressive, life-threatening infection and a true infectious disease emergency. Despite much clinical experience, the management of this disease remains suboptimal, with mortality rates remaining approximately 30%. Necrotizing fasciitis rarely presents with obvious signs and symptoms and delays in diagnosis enhance mortality. Therefore, successful patient care depends on the physician's acumen and index of suspicion. Prompt surgical debridement, intravenous antibiotics, fluid and electrolyte management, and analgesia are mainstays of therapy. Adjunctive clindamycin, hyperbaric oxygen therapy and intravenous immunoglobulin are frequently employed in the treatment of necrotizing fasciitis, but their efficacy has not been rigorously established. Improved understanding of the pathogenesis of necrotizing fasciitis has revealed new targets for rationally designed therapies to improve morbidity and mortality.

Polyarteritis nodosa presenting as a febrile rash and severe fatal myocarditis

Polyarteritis nodosa (PAN) is a necrotizing vasculitis of small and medium sized muscular arteries. The spectrum of the clinical presentation can range from an apparently limited disease to fulminant polyvisceral failure. We report a fatal case of isolated cardiac PAN presenting as an acute febrile rash and hypotension.

Fascitis necrosante por Streptococcus pyogenes

Necrotizing fasciitis is a severe infection, with systemic involvement and tissue necrosis. The clinical course is rapid and often fatal. Although this entity is uncommon, early recognition and treatment is essential to improve prognosis. Necrotizing fasciitis should be suspected when there are symptoms of toxicity and there is severe pain, frequently out of proportion to the clinical findings. In addition, in the last few years the incidence of invasive disease due to Streptococcus pyogenes in children has increased. Treatment is based on life support, aggressive debridement, and antimicrobial therapy. Intravenous immunoglobulin (IVIG) as adjunctive therapy seems useful and reduces mortality. The case of an infant with necrotizing fasciitis of four extremities is presented.

A Reappraisal of Humoral Immunity Based on Mechanisms of Antibody‐Mediated Protection Against Intracellular Pathogens

Sometime in the mid to late twentieth century the study of antibody-mediated immunity (AMI) entered the doldrums, as many immunologists believed that the function of AMI was well understood, and was no longer deserving of intensive investigation. However, beginning in the 1990s studies using monoclonal antibodies (mAbs) revealed new functions for antibodies, including direct antimicrobial effects and their ability to modify host inflammatory and cellular responses. Furthermore, the demonstration that mAbs to several intracellular bacterial and fungal pathogens were protective issued a serious challenge to the paradigm that host defense against such microbes was strictly governed by cell-mediated immunity (CMI). Hence, a new view of AMI is emerging. This view is based on the concept that a major function of antibody (Ab) is to amplify or subdue the inflammatory response to a microbe. In this regard, the "damage-response framework" of microbial pathogenesis provides a new conceptual viewpoint for understanding mechanisms of AMI. According to this view, the ability of an Ab to affect the outcome of a host-microbe interaction is a function of its capacity to modify the damage ensuing from such an interaction. In fact, it is increasingly apparent that the efficacy of an Ab cannot be defined either by immunoglobulin or epitope characteristics alone, but rather by a complex function of Ab variables, such as specificity, isotype, and amount, host variables, such as genetic background and immune status, and microbial variables, such as inoculum, mechanisms of avoiding host immune surveillance and pathogenic strategy. Consequently, far from being understood, recent findings in AMI imply a system with unfathomable complexity and the field is poised for a long overdue renaissance.

Indications thérapeutiques des immunoglobulines intraveineuses

KEY POINTS

Intravenous immunoglobulins (IVIg) are preparations of normal human IgG obtained from large pools of healthy blood donors. IVIg can be used at low doses to treat patients with primary or secondary immune deficiencies and at high doses as an immunomodulatory agent in many autoimmune and systemic inflammatory diseases, especially hematologic and neurologic diseases. Its mechanisms of action are multiple, complex, and not yet well elucidated. Adverse effects are only rarely associated with IVIg. They are well tolerated, and the risk of transmission of infectious agents appears only theoretical.

Progressive and nonresolving pneumonia

PURPOSE OF REVIEW

Patients with progressive and/or nonresolving community-acquired pneumonia are at risk for increased morbidity and mortality. It is critical to be able to identify patients at risk to institute early appropriate therapy. The purpose of this review is to summarise the most updated developments in this area.

RECENT FINDINGS

This review will glean from the recent literature clinical, laboratory, and radiologic findings that help identify patients at risk for such complications of their pneumonia. New studies will be reviewed that have identified some of the causes for treatment failures including the type of pathogen and discordant antimicrobial therapy. It will also discuss newly recognised and emerging infectious diseases that may result in progressive or nonresponding pneumonia including severe acute respiratory syndrome, avian influenzae, severe group A streptococcal disease, and community-acquired methicillin-resistant Staphylococcus aureus. Promising treatments have been identified for patients with progressive pneumonia due to an overwhelming host immune response including activated protein C and intravenous immunoglobulin.

SUMMARY

Both progressive and nonresolving pneumonia represent treatment failure as a result of inappropriate initial therapy, a noninfectious cause, or an overwhelming immune response. It is critical to be able to identify patients with nonresponding pneumonia and to identify patients at risk for progressive pneumonia to institute appropriate therapy.

Rapidly progressive soft tissue infections

Skin and soft tissue infections are among the most common reasons for people to seek medical advice. They also represent one of the most common indications for antimicrobial therapy and account for approximately 7-10% of hospitalisations in North America. Although non-limb and non-life threatening infections may be treated on an out-patient basis with oral antibiotics, patients with more serious acute skin and soft tissue infections may require admission to hospital for management; this decision is especially true if the infection is rapidly progressive. We provide a concise overview of the differential diagnosis and approach to management of community-acquired rapidly progressive skin and soft tissue infections.

Managing toxic shock syndrome with antibiotics

Toxic shock syndrome (TSS) is a serious disorder with a worldwide prevalence of approximately 3/100,000 persons. TSS is mainly caused by Streptococcus pyogenes or Staphylococcus aureus. Thus, beta-lactam and lincosamides, such as clindamycin, are the first-line drugs. Yet, the mortality rate remains unacceptably high; highlighting the role of bacterial toxin-mediated activation of the inflammatory cascade in TSS pathogenesis. Further strategies should be targeted towards interfering with the interaction between bacterial toxins and host T cells. This paper aims to provide an overview of the epidemiology, pathomechanisms, and clinical presentation of TSS, and criteria for selecting drugs among available antibiotics.