Meningococcemia

Meningococcemia
Synonyms	Meningococcal septicaemia
Caption	Gram stain of Neisseria meningitidis, the causative bacterium.
Field	Infectious disease
Symptoms	Fever, petechial rash, hypotension, altered mental status
Complications	Waterhouse–Friderichsen syndrome, Disseminated intravascular coagulation, Gangrene, Meningitis
Onset	Sudden
Causes	Neisseria meningitidis
Risks	Complement deficiency, Asplenia, Close contact with carrier, Crowding
Diagnosis	Blood culture, Polymerase chain reaction
Differential	Rocky Mountain spotted fever, Henoch–Schönlein purpura, Idiopathic thrombocytopenic purpura
Prevention	Meningococcal vaccine, Antibiotic prophylaxis
Treatment	Intravenous antibiotics, intensive care
Medication	Ceftriaxone, Penicillin G, Ciprofloxacin
Prognosis	High mortality if untreated
Frequency	Sporadic and epidemic

Meningococcemia is a life-threatening bloodstream infection caused by the bacterium Neisseria meningitidis. It often presents as a rapid-onset sepsis syndrome, characterized by fever, a distinctive petechial rash, and circulatory collapse. The disease can progress to fulminant septic shock with high mortality, even with prompt medical intervention, and is a significant cause of morbidity worldwide, particularly in the Meningitis belt of sub-Saharan Africa.

Signs and symptoms

The initial presentation often mimics a non-specific viral illness, with sudden onset of fever, chills, myalgia, and vomiting. The pathognomonic sign is a rapidly evolving petechial or purpuric rash, which may coalesce into larger ecchymoses. Patients can rapidly deteriorate into septic shock, manifesting as hypotension, tachycardia, and cold clammy skin. Altered mental status is common and may indicate concomitant meningitis. Severe complications include Waterhouse–Friderichsen syndrome (adrenal hemorrhage), disseminated intravascular coagulation, and peripheral gangrene, sometimes necessitating amputation.

Causes and pathophysiology

Meningococcemia is caused exclusively by the gram-negative diplococcus Neisseria meningitidis. Transmission occurs through respiratory droplets from asymptomatic carriers or infected individuals. The bacterium colonizes the nasopharynx before invading the bloodstream. Its lipooligosaccharide (endotoxin) triggers a massive systemic inflammatory response, leading to endothelial damage, capillary leak, coagulopathy, and multiorgan dysfunction syndrome. Certain factors increase risk, including deficiencies in the complement system (e.g., Properdin deficiency), asplenia, and close-contact settings like military barracks or college dormitories.

Diagnosis

Definitive diagnosis requires isolation of Neisseria meningitidis from a normally sterile site. Blood culture is the primary method, though prior antibiotic administration can yield false negatives. Polymerase chain reaction assays on blood or cerebrospinal fluid offer rapid and sensitive detection. Characteristic laboratory findings include leukocytosis or leukopenia, thrombocytopenia, elevated C-reactive protein, and markers of disseminated intravascular coagulation such as prolonged prothrombin time. The clinical picture, especially the rash, is often sufficient to initiate empiric therapy before confirmatory results.

Treatment

Immediate administration of parenteral antibiotics is critical and should not be delayed. The drug of choice is a broad-spectrum cephalosporin like ceftriaxone or cefotaxime; penicillin G remains effective for susceptible strains. In settings of septic shock, management requires aggressive intravenous fluid resuscitation and vasopressor support in an intensive care unit. Adjunctive therapy may include corticosteroids for suspected adrenal insufficiency and protein C concentrate, though evidence is limited. Surgical debridement or amputation may be necessary for necrotic tissues.

Prognosis

The prognosis is time-dependent, with mortality rates exceeding 50% in fulminant cases without treatment. Even with appropriate care, mortality ranges from 10-15%, and survivors often face significant sequelae. These can include neurological deficits, sensorineural hearing loss, skin scarring, and psychological post-traumatic stress disorder. The case-fatality rate is influenced by the infecting serogroup, with Group B and Group C often associated with severe disease. Rapid progression from symptom onset to septic shock (within 24 hours) portends a poorer outcome.

Prevention

Primary prevention relies on vaccination. Several conjugate vaccines are available targeting serogroups A, C, W, and Y, and a protein-based vaccine against Group B. Vaccination is recommended for adolescents, travelers to endemic areas like the Meningitis belt, and individuals with high-risk conditions such as complement deficiency. For close contacts of a case, antibiotic prophylaxis with rifampin, ciprofloxacin, or ceftriaxone is imperative to eradicate carriage and prevent secondary cases.

Category:Infectious diseases Category:Bacterial diseases Category:Medical emergencies