Bacterial Meningitis, What Everyone Should Know

Bacteria causing bacterial meningitis
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An outbreak of bacterial meningitis caused by a specific strain and appearing among HIV-infected gay men has put doctors in New York City on alert. Although the one dozen cases of bacterial meningitis from this special strain have raised great concern, awareness of the dangers of this deadly disease should not be limited to this particular population but to everyone.

Bacterial meningitis can affect anyone

Bacterial meningitis is a serious, frequently deadly disease that attacks the thin membranes (meninges) surrounding the spinal cord and brain. A New England Journal of Medicine article also noted that although the rate of bacterial meningitis declined by 55 percent in the United States in the early 1990s after the introduction of the Haemophilus influenzae type b (Hib) vaccine for infants, bacterial meningitis continues to be a health concern.

Bacterial meningitis is mostly spread through close, direct, and/or prolonged contact with bodily fluids; for example via kissing, sexual intimacy, sneezing on someone, or living in close quarters with an infected individual. The average incubation period can range from two to 10 days.

The disease can cause learning disabilities, brain damage, loss of hearing, or death if the specific bacteria causing the illness are not identified and eradicated. Therefore it is critical for physicians to determine the exact cause of bacterial meningitis, and those causative pathogens can include the following:

  • Haemophilus influenzae, which used to be the most common cause of the disease in infants and young children before the HiB vaccine was introduced.
  • Listeria monocytogenes can infect people of any age, but pregnant women, very young children, and the elderly are at most risk. L. monocytogenes can be acquired through contaminated foods.
  • Neisseria meningitidis is highly contagious and causes meningococcal meningitis. This form is commonly found in children and young adults, including college students living in dorms.
  • Staphylococcus aureus may present itself after head trauma or brain surgery
  • Streptococcus pneumoniae, the most common cause of bacterial meningitis in children, may appear along with pneumonia, an ear infection, or a sinus infection

In addition, a study in the Journal of Research in Medical Sciences in 2011 reported on a new risk factor for bacterial meningitis: CoNS, or coagulase negative staphylococci. CoNS produces enterotoxins, which are toxins produced by bacteria specific for intestinal cells and cause diarrhea and vomiting.

Healthy individuals can carry the bacteria that cause bacterial meningitis in their throat or nose and not experience any symptoms or illness at all.

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Risk factors for bacterial meningitis
Along with knowing the different types of bacteria that can cause bacterial meningitis, it's also important to recognize the risk factors for the disease. They include the following:

  • Age: According to a 2011 study reported in the New England Journal of Medicine, the age group with the greatest number of cases of bacterial meningitis is children younger than 2 years old, followed by adults ages 50 to 64. However, people of any age can get the disease.
  • No vaccine: Individuals who never received the HiB vaccine are at greater risk of the disease.
  • Large groups: The Centers for Disease Control and Prevention (CDC) note that infectious diseases such as bacterial meningitis spread more rapidly among large groups of people, which is why college students who live in dorms, military personnel, and children in child care facilities are at higher risk than the general public.
  • Work exposure: Individuals who regularly work with pathogens that cause bacterial meningitis, such as microbiologists, lab technicians who handle lab animals, or people who work on farms or ranches are at higher risk.
  • Health conditions: Anyone who has experienced a head injury or trauma to the skull or who has recently undergone brain surgery is at increased risk. People with a compromised immune system (e.g., HIV/AIDS) also are at greater risk.
  • Foreign travel: Individuals who travel to sub-Saharan Africa may be an greater risk for meningococcal meningitis.

Symptoms and treatment of bacterial meningitis
Individuals who contract bacterial meningitis typically experience symptoms suddenly, and they may include fever, chills, rash, nausea, vomiting, sensitivity to light, severe headache, stiff neck, and mental confusion. Some people also develop agitation or rapid breathing.

Antibiotics are used to treat bacterial meningitis, and the ones recommended by the CDC are ceftriaxone, rifampin, and vancomycin. Some patients need additional support, and so systemic corticosteroid also may be prescribed.

According to a 2011 report in the New England Journal of Medicine, an average of 4,100 new cases of bacterial meningitis were reported annually during 2003 through 2007, and 500 deaths occurred each year. The death rate in 1998-1999 was 15.7 percent and from 2006-2007, it was 14.3 percent.

Some cases of bacterial meningitis resist treatment with antibiotics. A new study from Johns Hopkins and published in Expert Opinion in Pharmacotherapy reported that while "several new antibiotics have been introduced for the treatment of meningitis caused by resistant bacteria," thus far their use in studies involving people has been limited.

Bacterial meningitis is an uncommon yet serious and frequently deadly illness that can affect anyone, so it's important to have a basic understanding of the disease.

SOURCES:
Ramezan AA et al. Bacterial meningitis: a new risk factor. Journal of Research in Medical Sciences 2011 Feb; 16(2): 207-10
Shin SH, Kim KS. Treatment of bacterial meningitis: an update. Expert Opinion in Pharmacotherapy 2012 Oct; 13(15): 2189-206
Thigpen MC et al. Bacterial meningitis in the United States, 1998-2007. New England Journal of Medicine 2011 May 26; 364(21): 2016-25

Image: Wikimedia Commons

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