Given the history of fever and rash, the patient had a complete blood count, electrolytes, BUN, Cr, glucose, PT/PTT, and blood cultures drawn. Antibiotics were started to cover Streptococcus pneumoniae, Staphylococcus aureus, and Neisseria meningitidis. His laboratory work revealed him to be anemic, severely thrombocytopenic, and in renal failure. He was admitted to the hospital with the two leading diagnoses of thrombotic thrombocytopenic purpura and meningococcemia.
His condition deteriorated, and he required intubation, pressor support, and dialysis. Four days after first arriving in the ED, the patient's blood cultures were positive for gram negative diplococci, which ultimately was confirmed to be Neisseria meningitis. The patient also received hydrocortisone for acute adrenal insufficiency and human recombinant activated protein C. He improved steadily, and was discharged after a 17-day hospital stay.
Neisseria meningitidis is an aerobic, nonmotile, small gram negative diplococcus. While it can cause a variety of conditions, the three most common manifestations are meningitis, meningitis with meningococcemia, and meningococcemia without meningitis. This patient was proven not to have meningitis, but did have meningococcemia.
The human upper respiratory tract is the only known reservoir for N. meningitidis, and transmission is through the respiratory route with exposure to pharyngeal secretions. Transmission is greatest among close contacts such as families and younger school-aged children. Overcrowded living conditions and other close living situations, such as in military camps and dormitories, have increased transmission rates. Whether one develops invasive disease depends largely on the host's serum bactericidal activity. Those patients with complement deficiencies, functional or anatomic asplenia, and immunoglobulin deficiencies are at increased risk for invasive disease.
The majority of N. meningitidis organisms are surrounded by an outer polysaccharide capsule. This capsule is associated with the organism's virulence as well as serving as a means for serogrouping. At least 13 different serogroups have been identified. A, B, C, W 135, and Y account for the majority of invasive disease. The vaccine commonly used for patients at increased risk to exposure and infection contains four polysaccharide serogroups, A, C, Y, and W 135. Unfortunately, group B polysaccharide is poorly immunogenic to humans, and no vaccine for serogroup B has been effective. It is estimated that 45 percent of meningococcal infections in the U.S. are caused by this serogroup.
The pathogenesis of invasive disease depends on host, bacterial, and environmental factors. Once exposure occurs, bacteria may adhere to the mucosal membranes of the oropharynx. Penetration of the mucosa may then result with subsequent invasion into the bloodstream. In the majority of patients, the serum's bactericidal activity destroys the bacteria. In some, however, the bacteria can multiply and disseminate. Meningococci can be found in endothelial cells and neutrophils with damage to the vascular beds, resulting in the skin changes seen with infection. The meningococcal cell wall antigen, lipo-oligosaccharide, serves as a potent endotoxin. The lipo-oligosaccharide interacts with macrophages, monocytes, and endothelial cells to secrete tumor necrosis factor, multiple interleukins, and interferon. These together with other inflammatory mediators result in endothelial damage, capillary leakage, intravascular clotting, and thrombosis.
The clinical manifestations with meningococcal infection depend on the primary sites of involvement. Patients with meningitis may complain of severe headaches, neck stiffness, photophobia, nausea, and vomiting. In contrast, patients with meningococcemia without meningitis may lack the classic headache and neck stiffness, but rather present with more vague complaints such as fatigue, myalgias, and arthralgias.
These patients may initially feel somewhat better with supportive measures (intravenous fluids, analgesia), but will quickly deteriorate. The classical petechial rash may be present on arrival, and careful examination of not only the skin but also mucosal surfaces should be done. One to two millimeter petechiae can be seen on the lower extremities, palpebral surfaces, and at areas of pressure on the skin. Examination of the soles may reveal subcutaneous ecchymosis. Petechiae and purpura may progress and coalesce so that much of the skin is involved.
Purpura fulminans is seen with fulminant meningococcemia. These patients will have large areas of cutaneous hemorrhage and necrosis secondary to vascular thrombosis and DIC, and may require subsequent amputations. Other complications of disseminated meningococcal infection may include adrenal hemorrhage (Waterhouse-Friderichsen syndrome), septic shock, DIC, ARDS, neurologic abnormalities, and myocardial depression.
The mainstay of treatment for meningococcal infection is prompt antibiotics and aggressive supportive care. Antibiotics should not be withheld for lumbar puncture, but rather should be administered once blood cultures are drawn. In the United States, third-generation cephalosporins such as ceftriaxone are typically the first choice. In much of the U.S., N. meningitidis is still susceptible to penicillins, but until cultures and sensitivities are known, a broad-spectrum antibiotic should be administered. Chloramphenicol is recommended for those patients with hypersensitivity reactions to penicillins and cephalosporins. Other therapies to be considered and discussed with infectious disease and critical care specialists include heparin, steroids, and activated protein C.
Chemoprophylaxis should be administered to close contacts of infected patients. These include household and other intimate contacts, children in school, persons in dormitories and training facilities, and those health care workers who had direct exposure to respiratory secretions. Most adults can be given a single dose of ciprofloxacin while children are given intramuscular ceftriaxone or oral rifampin.Copyright © 2005 Wolters Kluwer Health, Inc. All rights reserved.