· Meningococcemia is a bloodstream infection cause by the bacterium.
· is a contagious bacterium and is spread from person to person via respiratory secretions.
· Initially, patients present with fever and general aches. A rash is often present. Patients with meningococcemia are seriously ill.
· Complications include shock, failure of multiple organs, lack of circulation to the extremities, and death. Patients may also develop or present with meningitis.
· Meningococcemia is treated with intravenous antibiotics.
· Case fatality rates are as high as 19% in industrialized countries. Early treatment reduces the risk of complications and death.
· A vaccine is available to help prevent four of the five most common serogroups that cause meningococcemia. The vaccine is recommended at 11 years of age, with a booster dose at 16 years of age.
· People who have a certain type of immune deficiency in the complement system and people with missing or damaged spleens are at increased risk and should be vaccinated.
· People who travel to areas where outbreaks are occurring should be vaccinated before travel.
· People who have had close contact with an infected patient (for example, a household member with face-to-face contact, a child's playmate, etc.) should receive antibiotics to reduce the risk of disease. These "prophylactic" antibiotics should be started as soon as possible but certainly within two weeks of exposure.
Meningococcemia is a bacterial infection of the blood due to . This bacterium is most famous for causing meningococcal meningitis which may also be present in meningococcemia. Bloodstream infections are sometimes called "blood poisoning" or septicemia. Many bacteria can cause bloodstream infections including staphylococci, Streptococcus B, or Streptococcus A. In addition, other bacteria can cause meningitis, including or leptospirosis. However, is concerning because it is more contagious than these other bacteria and typically infects older children andadolescents.
As mentioned, the bacterium that causes meningococcemia is called , also known as "meningococcus." Meningococcemia may also be called meningococcal bacteremia. Under the microscope, the bacteria may appear in pairs, looking like two small kidney beans side by side. is surrounded by a capsule made of complex carbohydrates called polysaccharides. These polysaccharides stimulate the immune system, which helps the body fight the infection. There are several different types (serogroups) of meningococci. Most human disease is caused by serogroups A, B, C, Y, and W135. Bacteria from other serogroups are called "nonpathogenic," meaning that they do not cause disease.
Transmission of is from person to person through respiratory secretions. Some people can harbor the bacteria in their throats and not get sick, which is called a "carrier" state. In others, the bacteria rapidly invade the tissues and bloodstream, causing disease.
Children and adolescents 5 to 19 years of age are at highest risk for meningococcemia. Newborns acquire antibodies from their mothers via the placenta, although these antibodies fade after a few weeks or months. Toddlers are not immune, and there have been several exposures in day-care settings. As children age, they gradually gain immunity to meningococcal strains by coming into contact with milder strains of the bacteria. However, because this immunity is imperfect, it is still possible for adults to get meningococcemia.
The immune system is critical in fighting off the bacteria. Patients who have a history of a specific genetic deficiency in the complement system are at high risk for severe disease. The spleen is also needed for an effective immune response, so people are at higher risk for severe disease if they have had their spleens taken out or have spleens that function poorly.
People who have been in close contact with an infected patient are at increased risk to acquire the disease themselves. People who live together in close quarters such as military barracks are at especial risk for disease. One study showed that the attack rate in household contacts was 500 times greater than that of the general population.
In some parts of the world, outbreaks of meningococcal disease occur regularly. This is true of a group of countries in sub-Saharan Africa, which is known as the "meningitis belt." Because travelers from this area visit Saudi Arabia during the Hajj, there have been outbreaks associated with the pilgrimage. Saudi Arabia now requires proof of vaccination before admitting pilgrims.
After an average incubation period of three to seven days (range one to 10 days), infected patients initially experience fatigue, fever, headache, and body aches, similar to those experienced by people with influenza, including swine flu or bird flu. Shaking chills may be present. Rash is common and appears like small red dots (petechiae) associated with low platelet counts or a bleed into the skin (purpura) associated with vasculitis. The rash may appear anywhere on the body, even on the palms or soles or inside the mouth.
In addition to the rash, physical examination reveals a fast heart rate and often a low blood pressure and other signs of shock. Laboratory examination shows increases in white blood cell counts and may show low platelet counts (thrombocytopenia). The bacteria may spread to the heart, causing myocarditis. In severe cases, multiple organ systems may fail, including the kidneys, lungs and airways, liver, or heart. Uncommonly, the bacteria may cause a low-grade bloodstream infection (chronic meningococcemia) with fever, joint pain, and rash that lasts one to three weeks.
Although meningococcemia refers to an infection of the bloodstream, it is important to note that some patients with meningococcemia will develop meningococcal meningitis. Meningococcemia poses a higher risk of shock and death than meningococcal meningitis. Thus, although they are defined differently and have different prognoses, there is significant overlap between meningococcemia and meningococcal meningitis.
Patients are often presumptively diagnosed with meningococcemia from the patient's history and physical exam, but a definitive diagnosis is usually sought. This presumptive diagnosis is important because treatment needs to be started as soon as possible if meningococcemia is suspected. Meningococcemia is diagnosed by culturing from a sample of blood. The bacteria grow in one to two days in most cases, and biochemical methods are used to identify them as . Samples of the growth can also be stained and examined under the microscope to detect the characteristic double kidney bean appearance of the bacteria, although the biochemical tests are needed for definitive diagnosis.
In some instances, skin scrapings from pustular lesions can reveal the organisms; other investigators have occasionally used a PCR test to detect .
Intravenous antibiotics are needed to treat meningococcemia. Most strains remain sensitive to older treatments such as ampicillin (Omnipen, Polycillin, Principen) or penicillin G (Bicillin L-A), although a few strains are resistant and require therapy with a newer agent such as ceftriaxone (Rocephin). The laboratory will test the bacteria to see which antibiotics will work best, but treatment will need to start before the results of these antimicrobial sensitivity tests come back. Therefore, doctors usually select antibiotics that are known to work against most strains of .
Blood pressure is supported with intravenous fluids or medications. Meningococcemia often requires treatment in an intensive-care unit.
Recently, a newer agent called drotrecogin alpha (Xigris) has shown some efficacy in reducing complications of severe bloodstream infections, although only a small number of patients with meningococcemia have been tested. This agent has the potential to cause serious bleeding, so it should not be used in patients who are already at increased risk for bleeding. Thus, use of drotrecogin alpha remains controversial.
Case-fatality rates for meningococcemia are as high as 19% in industrialized countries but probably average 8%. Patients who present earlier with milder symptoms and normal immune systems are still at risk, but mortality rates are lower. In developing countries, mortality rates reach 70%. Patients with severe infection may require amputation of limbs due to ischemia or low blood pressure. Other complications may include nerve, muscle and heart problems, and arthritis and rarely, major adrenal hemorrhage (termed Waterhouse-Friderichsen syndrome).
Meningococcemia can be prevented in several ways. People who have come into close contact with an infected patient should strongly consider taking antibiotics to reduce the risk of disease. These antibiotics are usually given in pill form, although sometimes a shot is needed if the organism is resistant to common oral antibiotics. Close contact usually means household contacts, day-care or child-care contacts, or those who have been exposed to potentially infected saliva in the week before the patient got sick. Routine patient care does not warrant prophylaxis in health-care workers, unless the worker has had very close contact with respiratory secretions such as when giving mouth-to-mouth resuscitation or inserting a breathing tube. Prophylaxis should be given as soon as possible after the exposure but certainly within two weeks of the event. The antibiotics eliminate carriage of the bacteria and may also be used in the final step of treatment for infected patients.
For caretakers and health-care workers, frequent hand washing is recommended to minimize the transfer of infected secretions to the mouth or nose. In the hospital, patients with meningococcemia are placed in private rooms and staff will wear surgical masks when approaching the patient.
There is an effective and safe vaccine to protect against most serogroups of meningococcus that cause meningococcemia. Unfortunately, no effective vaccine exists for serogroup B. For the other major disease-causing serogroups (A, C, Y, W135), there are two vaccines available in the United States: the meningococcal polysaccharide vaccine (Menomune, MPSV4) and the meningococcal conjugate vaccine (Menactra, Menveo, MCV4). The choice of vaccine depends on the age of the patient.
The vaccine is recommended starting at 11 years of age. A booster dose is given at 16 years of age. Older teens who have never been vaccinated need only a single dose. The vaccine may be required for admission to college, and students should have received the vaccine less than five years before starting college. Others for whom vaccination is recommended include military recruits, college students living in dormatories, individuals with missing or damaged spleens, people with certain immune deficiencies in the complement system, those traveling to areas where the disease is common, and scientists who perform research on the bacteria.
There is research under way to produce a vaccine that is effective against serogroup B strains of . This serogroup exists throughout the United States, so a vaccine would be a major advance in reducing the disease burden.