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Meningococci ( Neisseria meningitidis) cause meningitis and septicemia. Symptoms, usually severe, include headache, nausea, vomiting, photophobia, lethargy, rash, multiple organ failure, shock, and disseminated intravascular coagulation. Diagnosis is clinical, confirmed by culture. Treatment is penicillin or a 3rd-generation cephalosporin.
Meningococci are gram-negative aerobic cocci that belong to the family Neisseriaceae. There are 13 serogroups; 5 (serogroups A, B, C, W135, and Y) cause most human disease.
Worldwide, the incidence of endemic meningococcal disease is 0.5 to 5/100,000, with an increased number of cases during winter and spring in temperate climates. Local outbreaks occur most frequently in sub-Saharan Africa between Senegal and Ethiopia, an area known as the meningitis belt. In major African epidemics (often caused by serogroup A), attack rates range from 100 to 800/100,000.
In the US, the annual incidence ranges from 0.5 to 1.1/100,000. Most cases are sporadic, typically in children < 2 yr; < 2% occur in outbreaks. Outbreaks tend to occur in semiclosed communities (eg, military recruit camps, college dormitories, schools, day-care centers) and often involve patients aged 5 to 19 yr.
Meningococci can colonize the oropharynx and nasopharynx of asymptomatic carriers. A combination of factors is probably responsible for transition from carrier state to invasive disease. Despite documented high rates of colonization, transition to invasive disease is rare and occurs primarily in previously uninfected patients. Transmission usually occurs via direct contact with respiratory secretions from a nasopharyngeal carrier. Carrier rates rise dramatically during epidemics.
After invading the body, N. meningitidis causes meningitis and severe bacteremia in children and adults, resulting in profound vascular effects. Infection can rapidly become fulminant and is associated with a mortality rate of 10 to 15%. Of patients who recover, 10 to 15% have serious sequelae, such as permanent hearing loss, intellectual disability, or loss of phalanges or limbs.
Children aged 6 mo to 3 yr are the most frequently infected. Other high-risk groups include adolescents, military recruits, college freshmen living in dormitories, people with complement deficiencies, and microbiologists working with N. meningitidis isolates. Infection or vaccination confers serogroup-specific immunity.
Patients with meningitis frequently report fever, headache, and stiff neck (see Acute Bacterial Meningitis). Other symptoms include nausea, vomiting, photophobia, and lethargy. A maculopapular or hemorrhagic petechial rash often appears soon after disease onset. Meningeal signs are often apparent during physical examination. Fulminant meningococcemia syndromes include Waterhouse-Friderichsen syndrome (septicemia, profound shock, cutaneous purpura, adrenal hemorrhage), sepsis with multiple organ failure, shock, and disseminated intravascular coagulation. A rare, chronic meningococcemia causes recurrent mild symptoms.
Neisseria are small, gram-negative cocci readily identified with Gram stain and by other standard bacteriologic identification methods. Serologic methods, such as latex agglutination and coagglutination tests, allow rapid presumptive diagnosis of N. meningitides in blood, CSF, synovial fluid, and urine. However, both positive and negative results should be confirmed by culture. PCR for N. meningitidis has been developed but is not commercially available.
While awaiting definitive identification of the causal organism, immunocompetent adults suspected of having meningococcal infection are given a 3rd-generation cephalosporin (eg, cefotaxime 2 g IV q 6 h, ceftriaxone 2 g IV q 12 h) plus vancomycin 500 to 750 mg IV q 6 h or 1 g IV q 12 h or q 8 h. In immunocompromised patients and patients > 50 yr, coverage for Listeria monocytogenes should be considered by adding ampicillin 2 g IV q 4 h.
Once N. meningitidis has been definitively identified, the preferred treatment is ceftriaxone 2 g IV q 12 h or penicillin 4 million units IV q 4 h.
Corticosteroids decrease the incidence of neurologic complications in children and adults. When corticosteroids are used, they should be given with or before the first dose of antibiotics. Dexamethasone 0.15 mg/kg IV q 6 h in children (10 mg q 6 h in adults) is given for 4 days.
Close contacts of people with meningococcal disease are at increased risk of acquiring disease and should receive a prophylactic antibiotic. Options include
Azithromycin is not routinely recommended, but a recent study showed that a single 500-mg dose was equivalent to rifampin for chemoprophylaxis and so could be an alternative for patients with contraindications to recommended drugs.
Ciprofloxacin-resistant meningococcal disease has been reported in several countries (Greece, England, Wales, Australia, Spain, Argentina, France, India). More recently, 2 US states (North Dakota, Minnesota) reported ciprofloxacin-resistant meningococci and so recommended that ciprofloxacin chemoprophylaxis not be used as preventive treatment for people who have had close contact with someone diagnosed with meningococcal disease.
Several meningococcal conjugate vaccines are available in the US (see Meningococcal Disease: Recommendations of the Advisory Committee on Immunization Practices ). Available vaccines include
2 quadrivalent conjugate vaccines (MenACWY-D) that protect against 4 of the 5 common pathogenic serogroups of meningococcus (all but B)
A bivalent conjugate vaccine that protects against serogroups C and Y and that is available only in combination with a Haemophilus influenzae type b vaccine (Hib-MenCY)
A quadrivalent polysaccharide vaccine (MenACWY-CRM) for use in patients ≥ 56 yr
All children should receive MenACWY-D at age 11 to 12 yr, with a booster dose at age 16. Vaccination is also recommended for people who are aged 19 to 55 and at risk, including military recruits, college freshmen living in a dormitory, travelers to hyperendemic or epidemic areas (a booster dose is given to those whose last vaccination was ≥ 5 yr before), and people with laboratory or industrial exposure to N. meningitidis aerosols. Adults with functional asplenia or persistent complement component deficiencies and patients with HIV infection (not a routine vaccination unless other risk factors are present) should receive 2 doses of MenACWY-D at least 2 mo apart. At-risk people ≥ 56 yr should receive the MenACWY-CRM polysaccharide vaccine.
Children < 11 yr are not routinely vaccinated, but those at high risk should receive Hib-MenCY or MenACWY-D. Vaccine selection varies with age and risk factors (see CDC Vaccination Schedule Birth Through 18 Yr ).
Over 90% of meningococcal infections involve meningitis or septicemia.
An asymptomatic nasopharyngeal carrier state is common; transmission usually occurs via direct contact with respiratory secretions from a carrier.
Most cases are sporadic, typically in children < 2 yr, but outbreaks can occur, primarily in semiclosed communities (eg, military recruit camps, dormitories, day-care centers) and often involve patients aged 5 to 19 yr.
Treat with ceftriaxone or penicillin; add dexamethasone for patients with meningitis.
Give close contacts a prophylactic antibiotic; options include rifampin, ceftriaxone, and a fluoroquinolone.
Vaccinate all children starting at age 11 to 12 yr, and selectively vaccinate high-risk younger children.
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