Meningococcal Infections

Key Features

Essentials of Diagnosis

• Fever, headache, vomiting, convulsions, shock (meningitis)

• Fever, shock, petechial or purpuric skin rash (meningococcemia)

• Diagnosis confirmed by culture of normally sterile body fluids

General Considerations

• Meningococci (Neisseria meningitidis) may be carried asymptomatically for months in the upper respiratory tract

• Less than 1% of carriers develop disease

• Meningitis and sepsis are the two most common forms of illness

• However, septic arthritis, pericarditis, pneumonia, chronic meningococcemia, otitis media, conjunctivitis, and vaginitis also occur

• Patients deficient in one of the late components of complement (C6, C7, C8, or C9) are uniquely susceptible to meningococcal infection, particularly group A meningococci

• Deficiencies of early and alternate pathway complement components also are associated with increased susceptibility

Demographics

• Meningococcal cases in the United States have declined recently; currently there are about 800–1000 cases annually

• Highest attack rate for meningococcal meningitis is in the first year of life, with a secondary peak during the teen years

• In the United States, serogroups B, C, and Y each account for about 30% of cases; however, this distribution varies significantly with age

• In infants about half the cases are caused by serogroup B

• In adolescents, serogroups B, C, and W-135 cause most cases

Clinical Findings

Symptoms and Signs

Meningococcemia

• A prodrome of upper respiratory infection is followed by high fever, headache, nausea, marked toxicity, and hypotension

• Purpura, petechiae, and occasionally bright pink, tender macules or papules over the extremities and trunk are seen

• Rash may occasionally be absent but usually progresses rapidly

• Fulminant meningococcemia

  • Characterized by disseminated intravascular coagulation (DIC), massive skin and mucosal hemorrhages, and shock

  • May also be caused by Haemophilus influenzae, Streptococcus pneumoniae, or other bacteria

• Chronic meningococcemia

  • Characterized by periodic bouts of fever, arthralgia or arthritis, and recurrent petechiae

  • Splenomegaly often is present

  • Patients may be free of symptoms between bouts

  • Occurs primarily in adults and mimics Henoch-Schönlein purpura

Meningitis

• In many children, meningococcemia is followed within a few hours to several days by symptoms and signs of acute purulent meningitis, with severe headache, stiff neck, nausea, vomiting, and stupor

• Children with meningitis generally fare better than children with meningococcemia alone, probably because they have survived long enough to develop clinical signs of meningitis

Differential Diagnosis

• The skin lesions of H influenzae or pneumococci, enterovirus infection, endocarditis, leptospirosis, Rocky Mountain spotted fever, other rickettsial diseases, Henoch-Schönlein purpura, and blood dyscrasias may be similar to meningococcemia

• Severe S aureus sepsis has been reported in some patients in whom purpura is present

Diagnosis

Laboratory Findings

• Peripheral WBC count may be either low or elevated

• Thrombocytopenia may ...