Disseminated intravascular coagulation and purpura fulminans secondary to infection

Waterhouse-Friderichsen syndrome following a dog bite in an asplenic patient: case report and review of the literature

The Waterhouse-Friderichsen syndrome represents a critical condition characterized by a septic shock associated with a disseminated intravascular coagulation causing the plugging of the microvascular network virtually all organs and systems, including the skin, the kidneys, the liver, and adrenal glands; the mortality rate is elevated, and survivors often must undergo multiple limb amputations. Here, we describe the uncommon case of an asplenic patient who developed this syndrome after a superficial wound caused by a dog bite causing an initial infection due to Capnocytophaga canimorsus that is part of the normal oral microbiome of pets. The clinical and pathological findings and the current and future therapeutic options are reviewed and discussed.

Purpura Fulminans: Mechanism and Management of Dysregulated Hemostasis

Purpura fulminans (PF) is a highly thrombotic subtype of disseminated intravascular coagulation that can accompany severe bacterial, and more rarely, viral infections. PF is associated with an extremely high mortality rate, and patients often die of overwhelming multisystemic thrombosis rather than septic shock. Survivors typically experience amputation of involved extremities and significant scarring in affected areas. Despite the devastating clinical course associated with this hemostatic complication of infection, the mechanism of PF remains poorly understood. Severe acquired deficiency of protein C and dysfunction of the protein C-thrombomodulin pathway as well as other systems that exert a negative regulatory effect on coagulation have been implicated. Management of PF involves treatment of the underlying infection, aggressive anticoagulation, and robust transfusion support aimed at correcting acquired deficiencies in natural anticoagulant proteins. In this review, we address the diagnosis and management of PF with a focus on a rational approach to this condition informed by the available data. Proposed mechanisms underlying the dysregulation of coagulation seen in PF are also covered, and implications for therapy are discussed.

Update on the Treatment of Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is characterized by an acute generalized, widespread activation of coagulation, which results in thrombotic complications, due to the intravascular formation of fibrin, as well as diffuse hemorrhages, due to the consumption of platelets and coagulation factors. In this review, we briefly report the present knowledge about the treatment of DIC. We focus on the current standard treatment of overt DIC in clinical practice. Moreover, particular attention is made to novel therapeutic strategies, who reflect the important progresses in the understanding of the pathogenesis of this syndrome in the last few years.

Meningococcal group A sepsis associated with rare manifestations and complicated by Kawasaki-like disease

Neisseria meningitidis serogroup A septicemia and the development of Kawasaki disease in a 10-month-old male infant are described. The patient also experienced a number of primary/septic manifestations as consequences of the direct infectious assault and secondary/hypersensitivity immune-mediated complications. The present observation indicates an etiological relationship between invasive meningococcal infection group A and Kawasaki disease, an association in favor of superantigen-induced theory for the latter occurrence.

Nonpalpable purpura within a setting of anticoagulant therapy and metastatic carcinoma

The anticoagulant warfarin can produce a skin necrosis that is clinically indistinguishable from the skin necrosis caused by purpura fulminans associated with disseminated intravascular coagulation (DIC) and heparin-induced thrombocytopenia (HIT). The similar clinical and histologic findings observed in each of these skin necroses create a challenge for diagnosis and eventual treatment. The authors report a patient with significant risk factors for warfarin-induced skin necrosis, DIC, and HIT presenting with painful, purpuric patches beginning on her feet and extending proximally before becoming hemorrhagic bullae on her lower extremities.

Recent acquisitions in the pathophysiology, diagnosis and treatment of disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a disorder characterized by both acute generalized, widespread activation of coagulation, which results in thrombotic complications due to the intravascular formation of fibrin, and diffuse hemorrhages, due to the consumption of platelets and coagulation factors. Systemic activation of coagulation may occur in a variety of disorders, including sepsis, severe infections, malignancies, obstetric or vascular disorders, and severe toxic or immunological reactions.

In this review, we briefly report the present knowledge about the pathophysiology and diagnosis of DIC. Particular attention is also given to the current standard and experimental therapies of overt DIC.

Management of septic shock in childhood

OBJECTIVE

The object of this review is to discuss the recognition and treatment of septic shock in children based on principles of resuscitation, antibiotic use and recent therapeutic advances.

METHODS

A comprehensive literature search combining these

METHODS

on-line searches of Ovid, PubMed, and Medline; hand searches of 25 international journals; a trawl of 26 textbooks; searches of reference lists of pertinent articles; and scans of abstracts of recent international meetings. Various national and international units were contacted with regard to current research therapeutic strategies, both published and unpublished.

CONCLUSIONS

Septic shock remains a leading cause of morbidity and mortality in children. Early administration of empirical antibiotic therapy reduces mortality. The keystone of resuscitation is aggressive volume replacement. Adjunctive therapies to modulate the inflammatory response may further enhance outcome, but do not replace principles of resuscitation.

Computerized quality assurance of decisions to transfuse blood components to critically ill patients

BACKGROUND

In critically ill patients optimal transfusion therapy for most clinical settings has not been determined. The objective of this study was to evaluate the impact of a computerized audit on transfusion decisions of red blood cells (RBC), fresh frozen plasma (FFP), and platelets among critically ill patients.

METHODS

Two hundred and ninety consecutive patients admitted to nine-bed medical-surgical intensive care unit at a university hospital were included in this prospective study. Prior to the study, the criteria for transfusions of RBCs, FFP and platelets were established. Phase I, the first 3-month period served as a control period. During phase II the fulfilment of these criteria was prospectively monitored by an audit software belonging to the computerized blood request program. If the predefined transfusion criteria were not met the audit software was automatically activated. The last 3-month period, phase III, was to assess if possible effects on transfusion decisions were permanent.

RESULTS

The proportion of RBC transfusions administered according to predefined trigger during the study phases I, II, and III were 55.9%, 75.1% and 67.9%, respectively (P < 0.001). The proportion of FFP and platelet transfusions according to a predefined trigger did not differ statistically significantly between the study phases. Logistic multiple regression analysis revealed an independent effect of the audit phase on the decision to transfuse RBCs and FFP.

CONCLUSIONS

The data suggests that a computerized prospective transfusion audit has impact on the realisation of predefined transfusion decisions.

Analysis of pathogen-host cell interactions in purpura fulminans: expression of capsule, type IV pili, and PorA by Neisseria meningitidis in vivo

The pattern of meningococcal surface structure expression in different microenvironments following bloodstream invasion in vivo is not known. We used immunohistochemistry to determine the expression of capsule, type IV pili, and PorA by meningococci residing in the skin lesions of children with purpura fulminans. All the skin biopsy samples showed evidence of thrombosis and, frequently, a perivascular inflammatory cell infiltrate consisting of neutrophils (elastase positive) and monocytes/macrophages (CD68 positive). Modified Gram staining revealed 20 to over 100 gram-negative diplococci in each 4-microm-thick section, usually grouped into microcolonies. Immunoperoxidase staining demonstrated that the invading meningococci expressed PorA, capsule, and type IV pilin. Expression of these antigens was not restricted to any particular environment and was found in association with meningococci located in leukocytes, small blood vessels, and the dermal interstitium. Confocal laser scanning microscopy demonstrated coexpression of pilin and capsule by numerous microcolonies. However, there was some discordance in capsule and pilin expression within the microcolonies, suggesting phase variation. The strategy employed in this study will be helpful in investigating invasive bacterial diseases where antigenic and phase variation has a significant impact on virulence and on vaccine design.

Predictive value of antithrombin III and serum C-reactive protein concentration in critically ill patients with suspected sepsis

OBJECTIVE

To evaluate at admission the performance of serum antithrombin III, serum C-reactive protein, white blood cell and platelet counts, and thromboplastin time values in prediction of hospital mortality rates in critically ill patients with suspected sepsis.

DESIGN

Prospective, cohort study.

SETTING

University hospital medical-surgical intensive care unit.

PATIENTS

One hundred eight consecutive critically ill patients with suspected sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The outcome measure was hospital mortality rate. Hospital survivors (n = 66) and nonsurvivors (n = 42) differed statistically significantly in admission antithrombin III activity (percentage of normal): survivors' median 66% (interquartile range, 48% to 82%) vs. nonsurvivors' median 46% (37% to 65%, p =.0002 by Mann-Whitney test). Analysis revealed similarly statistically significant differences between survivors and nonsurvivors in admission platelet count, admission thromboplastin time, day 1 Logistic Organ Dysfunction score, and Acute Physiology and Chronic Health Evaluation III score, but not in serum C-reactive protein concentrations or in white blood cells. However, the areas under the receiver operating curves (AUC) showed significantly worse discriminative power for admission antithrombin III concentration (AUC, 0.71; SE, 0.05), platelet count (AUC, 0.67; SE, 0.05), thromboplastin time (AUC, 0.65; SE, 0.05), C-reactive protein concentration (AUC, 0.60; SE, 0.05), and white blood cell count (AUC, 0.53; SE, 0.06) than did the day 1 Logistic Organ Dysfunction score (AUC, 0.82; SE, 0.04) and the Acute Physiology and Chronic Health Evaluation III score (AUC, 0.84; SE, 0.04). Multivariate logistic regression analysis revealed that only the Acute Physiology and Chronic Health Evaluation III score was independently associated with hospital mortality rate.

CONCLUSIONS

Admission antithrombin III concentrations, but not C-reactive protein concentrations, differ significantly between hospital survivors and nonsurvivors among critically ill patients with septic infection. However, in prediction of hospital mortality rate, the discriminative power of admission antithrombin III concentration is poor, as judged by analysis of areas under the receiver operating curves, and is not independently associated with hospital mortality rate.

[Treatment of meningococcal purpura fulminans]

In France, the incidence of meningococcal infections is increasing. The most severe presentation, called purpura fulminans, has a death rate of 20-25%; 5 to 20% of the survivors need skin grafts and/or amputations. Diagnosis of invasive meningococcal infection is very difficult when purpura and "toxic" appearance are absent: one should take into account parents' impression of their ill child. This diagnosis must be evoked in any child presenting with febrile purpura (like in the United Kingdom, parents should be encouraged to use the "tumbler test" to identify a vasculitic rash); a fulminant form is to be suspected in the presence of only one ecchymosis and signs of infection, remembering that recognition of shock is difficult in children. Recently, the Health Authority has recommended to administer a third generation cephalosporin promptly (before biological investigations) for any child with signs of infection and a necrotic or ecchymotic purpura (> 3 mm of diameter), and then to refer the patient to the hospital. By grouping the patients from 7 studies, it can be observed that preadmission antibiotic administration has a protective effect on mortality (odds ratio: 0.36; 95% confidence interval: 0.23-0.56); a negative effect was observed in only one of these series. Children with purpura fulminans should be referred to a paediatric intensive care unit. Management includes antibiotics, steroids, fluid resuscitation and catecholamines (be aware of hypoglycaemia, particularly in infants, and hypocalcaemia). Treatment of cutaneous necrosis and distal ischemia is difficult and still controversial: antithrombin, protein C, tissue plasminogen activator and vasodilator infusion have no proven efficacy. Cases must be rapidly notified to the Public Health Service who will institute chemoprophylaxis for close contacts. Given the predominance of serogroup B in France, we hope that an efficient vaccine will soon become available.

Dysfunction of endothelial protein C activation in severe meningococcal sepsis

BACKGROUND

Impairment of the protein C anticoagulation pathway is critical to the thrombosis associated with sepsis and to the development of purpura fulminans in meningococcemia. We studied the expression of thrombomodulin and the endothelial protein C receptor in the dermal microvasculature of children with severe meningococcemia and purpuric or petechial lesions.

METHODS

We assessed the integrity of the endothelium and the expression of thrombomodulin and the endothelial protein C receptor in biopsy specimens of purpuric lesions from 21 children with meningococcal sepsis (median age, 41 months), as compared with control skin-biopsy specimens.

RESULTS

The expression of endothelial thrombomodulin and of the endothelial protein C receptor was lower in the patients with meningococcal sepsis than in the controls, both in vessels with thrombosis and in vessels without thrombosis. On electron microscopical examination, the endothelial cells were generally intact in both thrombosed and nonthrombosed vessels. Plasma thrombomodulin levels in the children with meningococcal sepsis (median, 6.4 ng per liter) were higher than those in the controls (median, 3.6 ng per liter; P=0.002). Plasma levels, protein C antigen, protein S antigen, and antithrombin antigen were lower than those in the controls. In two patients treated with unactivated protein C concentrate, activated protein C was undetectable at the time of admission, and plasma levels remained low.

CONCLUSIONS

In severe meningococcal sepsis, protein C activation is impaired, a finding consistent with down-regulation of the endothelial thrombomodulin-endothelial protein C receptor pathway.

Coagulation in severe sepsis: a central role for thrombomodulin and activated protein C

OBJECTIVES

To review the mechanisms that cause coagulation abnormalities in sepsis, focusing on the interaction between the vascular endothelium and the circulating coagulation factors, particularly the role of the protein C pathway and thrombomodulin.

DATA SOURCES/STUDY SELECTION

Published research abstracts and review articles on the experimental and clinical investigation of the pathophysiology of disseminated intravascular coagulation in sepsis.

DATA EXTRACTION AND SYNTHESIS

The data provide increasing evidence that the coagulopathy seen in sepsis is a result of a complex imbalance of pro- and anticoagulant pathways. Whereas previous research has largely studied events in the plasma, it is now apparent that reactions on cell surfaces such as the vascular endothelium are important in the control of the regulatory pathways.

CONCLUSIONS

The plasma components of the protein C pathway are down-regulated in sepsis. Decreased thrombomodulin expression may cause defective function of the endothelial component of this pathway in septic patients. Treatments must be designed to overcome any functional defect.

Is immune cell activation the missing link in the pathogenesis of post-diarrhoeal HUS?

Haemolytic uraemic syndrome (HUS), which is caused by Shiga toxin (Stx)-producing Escherichia coli, is the commonest cause of acute renal failure in childhood. It is widely believed that HUS develops following the release of Stx, an AB5 toxin that inhibits protein synthesis and has a direct toxic effect on the kidney endothelium. There remains, however, a mismatch between the current understanding of the pathogenesis of HUS and the evolution of the clinical signs of the disease. Our hypothesis is that Stx-mediated immune cell activation in the gut is the missing link in the pathogenesis of this condition, initiating the characteristic renal pathology of HUS either alone or in synergy with Stx. Validation of this hypothesis could lead to a targeted anti-inflammatory approach aimed at modulating immune cell function in HUS.