Classification and pathogenesis of meningococcal infections.

The clinical symptoms induced by Neisseria meningitidis reflect compartmentalized intravascular and intracranial bacterial growth and inflammation. In this chapter, we describe a classification system for meningococcal disease based on the nature of the clinical symptoms. Meningococci invade the subarachnoid space and cause meningitis in as many as 50-70% of patients. The bacteremic phase is moderate in patients with meningitis and mild systemic meningococcemia but graded high in patients with septic shock. Three landmark studies using this classification system and comprising 862 patients showed that 37-49% developed meningitis without shock, 10-18% shock without meningitis, 7-12% shock and meningitis, and 18-33% had mild meningococcemia without shock or meningitis. N. meningitidis lipopolysaccharide (LPS) is the principal trigger of the innate immune system via activation of the Toll-like receptor 4-MD2 cell surface receptor complex on myeloid and nonmyeloid human cells. The intracellular signals are conveyed via MyD88-dependent and -independent pathways altering the expression of >4,600 genes in target cells such as monocytes. However, non-LPS molecules contribute to inflammation, but 10-100-fold higher concentrations are required to reach the same responses as induced by LPS. Activation of the complement and coagulation systems is related to the bacterial load in the circulation and contributes to the development of shock, organ dysfunction, thrombus formation, bleeding, and long-term complications in patients. Despite rapid intervention and advances in patient intensive care, why as many as 30% of patients with systemic meningococcal disease develop massive meningococcemia leading to shock and death is still not understood.

[Acute adrenocortical insufficiency]. / Uminis antinksciu zieves nepakankamumas.

Severe acute adrenocortical insufficiency or adrenal crisis are often elusive diagnoses that may result in severe morbidity and mortality when undiagnosed or ineffectively treated. Although more than 50 steroids are produced within the adrenal cortex, cortisol and aldosterone are far the most abundant and physiologically active. In primary adrenocortical insufficiency, glucocorticoid and mineral-corticoid properties are lost; however, in secondary adrenocortical insufficiency (i.e., secondary to disease or suppression of the hypothalamic-pituitary axis), mineralocorticoid function is preserved. Every emergency physician should be familiar with adrenocortical insufficiency--a potentially life-threatening entity. The initial diagnosis and decision to treat are presumptive and are based on history, physical examination, and, occasionally, laboratory findings. Delay in treatment while attempting to confirm this diagnosis can result in poor patient outcomes. This article review data about physiology, pathophysiology of the adrenal cortex, physiologic effects of glucocorticoids, aldosterone, causes of primary and secondary adrenal insufficiency, frequency, clinical picture, laboratory and imaging studies of adrenal crisis, laboratory evaluation of adrenal function and emergency therapy, replacement therapy, mortality/morbidity of this pathology.

Waterhouse-Friderichsen syndrome after infection with group A streptococcus.

We report a case of Waterhouse-Friderichsen syndrome associated with group A streptococcus (GAS) toxic shock syndrome in a previously healthy man. The patient presented with neck pain and fevers of 2 days' duration. Computed tomography of the neck revealed a mass in the retropharyngeal space, suggesting an abscess. Despite prompt treatment with appropriate antibiotics, the patient experienced a fulminant course and died within 8 hours of presentation. Antemortem blood cultures grew GAS positive for exotoxins A, B, and C. Postmortem examination revealed bilateral adrenal hemorrhage, consistent with Waterhouse-Friderichsen syndrome. Immunohistochemical analysis of the adrenal glands revealed the presence of GAS antigens. However, no disseminated intravascular coagulation was evident. This case demonstrates that adrenal hemorrhage can occur without associated coagulopathy and may result directly from the action of bacterial toxins.

The protective effect of brachial plexus palsy in purpura fulminans.

Acute infectious purpura fulminans is reported in a 16-month-old male with a history of posttraumatic asplenia and complete left brachial plexus palsy. This patient developed peripheral necrosis of both lower extremities and the right upper extremity, whereas the left upper extremity was completely spared from ischemia and tissue damage. Amputation of four digits on the right hand and debridement of both lower extremities were required. This patient demonstrated the protective effect of a traumatic sympathectomy, which suggests the requirement of an intact sympathetic reflex in the development of purpura fulminans.

Lethal Waterhouse-Friderichsen syndrome in posttraumatic asplenia.

We herein report a case of fulminant lethal Waterhouse-Friderichsen syndrome in an elderly female patient seven years after posttraumatic splenectomy. In contrast to various reports, this patient had not been vaccinated against Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae, respectively, although infections with these microorganisms are known to cause the main lethal diseases in asplenic patients. Again, we recommend obligatory vaccinations against the mentioned bacteria for it is known that this decreases the risk of fatal septic events in these patients. To optimize prevention, it is imperative to vaccinate patients undergoing splenectomy before discharge from hospital.