Meningococcal infections
Two major meningococcal infections (meningitis and meningococcemia) are caused by the gram-negative bacteria Neisseria meningitidis, which also causes primary pneumonia, purulent conjunctivitis, endocarditis, sinusitis, and genital infection. Meningococcemia occurs as simple bacteremia, fulminating meningococcemia and, rarely, chronic meningococcemia. It commonly accompanies meningitis. (See “Meningitis,” page 172.) Meningococcal infections may occur sporadically or in epidemics; particularly virulent infections may be fatal within a matter of hours.
Causes and incidence
Meningococcal infections usually occur among children (ages 6 months to 1 year) and men, usually military recruits or those enrolled at institutions, such as colleges, because of overcrowding.
N. meningitidis has seven serogroups (A, B, C, D, X, Y, and Z); group A causes most epidemics. Transmission takes place through inhalation of an infected droplet from a carrier (an estimated 2% to 38% of the population). The bacteria localize in the nasopharynx. After incubating approximately 3 to 4 days, they spread through the bloodstream to joints, skin, adrenal glands, lungs, and the central nervous system. The tissue damage that results (possibly due to the effects of bacterial endotoxins) produces symptoms and, in fulminating meningococcemia and meningococcal bacteremia, hemorrhage, thrombosis, and necrosis.
Signs and symptoms
Features of meningococcal bacteremia include sudden spiking fever, headache, sore throat, cough, chills, myalgia (in back and legs), arthralgia, tachycardia, tachypnea, mild hypotension, and a petechial, nodular, or maculopapular rash. Headache and stiff neck can also occur as the infection extends to the meninges.
In about 10% to 20% of patients, the disease progresses to fulminating meningococcemia, with extreme prostration, enlargement of skin lesions, disseminated intravascular coagulation (DIC), and shock. Without prompt treatment, death from respiratory or heart failure occurs in 6 to 24 hours.
Characteristics of the rare chronic meningococcemia include intermittent fever, rash, joint pain, and an enlarged spleen.
Diagnosis
CONFIRMING DIAGNOSIS Gram-negative diplococci, on blood or cerebrospinal fluid (CSF) Gram stain, are highly suspicious for N. meningitidis. Isolation of N. meningitidis through a positive blood culture, CSF culture, or lesion scraping confirms the diagnosis, except in nasopharyngeal infections because N. meningitidis is part of the normal nasopharyngeal flora.
Tests that support the diagnosis include counterimmunoelectrophoresis of CSF or blood, low white blood cell count and, in patients with skin or adrenal hemorrhages, decreased platelet and clotting levels. Diagnostic evaluation must rule out Rocky Mountain spotted fever and vascular purpuras.
Treatment
As soon as meningococcal infection is suspected, treatment begins with high doses of aqueous penicillin G, ampicillin, or ceph-alosporins such as ceftriaxone; or, for the patient who is allergic to penicillin, I.V. chloramphenicol. Therapy may also include mannitol for cerebral edema, I.V. heparin for DIC, dopamine for shock, and digoxin and a diuretic if heart failure develops. Supportive measures include fluid and electrolyte maintenance, ventilation (maintenance of a patent airway and oxygen, if necessary), insertion of an arterial or central venous pressure (CVP) line to monitor cardiovascular status, and bed rest.
Prophylaxis with ciprofloxacin or rifampin aids health care personnel who work in close contact with the patient, such as those administering cardiopulmonary resuscitation or assisting with intubation or suctioning without wearing a surgical mask.
Special considerations
❑Give I.V. antibiotics, as ordered, to maintain blood and CSF drug levels.
❑Enforce bed rest in early stages. Provide a dark, quiet, restful environment.
❑Maintain adequate ventilation with oxygen or a ventilator, if necessary. Suction and turn the patient frequently.
❑Keep accurate intake and output records to maintain proper fluid and electrolyte levels. Monitor blood pressure, pulse, arterial blood gas levels, and CVP.
❑Watch for complications, such as DIC, arthritis, endocarditis, and pneumonia.
❑If the patient is receiving chloramphenicol, monitor complete blood count.
❑Check the patient's drug history for allergies before giving antibiotics.
To prevent the infection’s spread:
❑Impose droplet precautions until the patient has had antibiotic therapy for 24 hours.
❑Label all meningococcal specimens. Deliver them to the laboratory quickly because meningococci are very sensitive to changes in humidity and temperature.
❑Report all meningococcal infections to public health department officials.
❑The meningococcal vaccine can be administered to first-year college students living in dormitories as a preventative measure.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
Other Book Chapters Related to Encephalitis
Read excerpts from these other book chapters related to Encephalitis:
Medical Books Excerpts
- Meningitis
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
- Kernig's sign
- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
- [ read ]
Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Encephalitis
» Next page: Encephalitis (Professional Guide to Diseases (Eighth Edition))
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