Microbiology

Neisseria meningitidis

Neisseria meningitidis

Also known as: Meningococcus

Industry of interest: Healthcare

Classification: Bacteria

Microbiology: Neisseria meningitidis is a Gram-negative diplococcus that is one of the most common causes of bacterial meningitis. Meningitis is an inflammation of the meninges that protect the brain and spinal cord that can be caused by bacteria and viruses. N. meningitidis is a significant cause of morbidity and mortality worldwide.
 

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Biology

Habitat and transmission: N. meningitidis commonly resides in the upper respiratory tract and nasopharynx, often as part of the normal mucosa (Stephens, 2009). However the organism has also been found to reside in the buccal mucosa, rectum, urogenital tract and in dental plaque. It has been estimated that N. meningitidis is carried by between 8-25% of individuals (Stephens, 2009). It is this large carrier population that propagates infection through respiratory droplets from coughing, sneezing and talking or through secretions.

Treatment and antibiotic resistance: For the best clinical outcome it is vital that any suspected meningitis cases are diagnosed and treated as soon as possible. Infected persons should be hospitalised immediately and placed on 3rd generation cephalosporins such as ceftriaxone or cefotaxime (Tunkel et al., 2004). N. meningitidis was thought to be one of the least problematic bacteria with regards to antibiotic resistance. However, there have been reports of reduced susceptibility of N. meningitidis strains to some antibiotics (Oppenheim, 1997). It is thought that this antibiotic resistance was obtained from the closely related Genococcus species. Penicillin was once the antibiotic of choice for bacterial meningitis infections; however resistance of N. meningitidis to penicillin, and also other antibiotics such as the sulphonamides and rifampin have all now been reported (Oppenheim, 1997).

Prevention and control: A preventative conjugate vaccine based on the capsular N. meningitidis serotypes is currently available. In particular the MenC vaccine has had a huge impact in reducing the number of cases of bacterial meningitis (Stephens, 2009). It would also be useful to prepare vaccines for new clonal strains to enhance the coverage of the vaccine. Improving surveillance of the organism is thought to be very important in prevention of transmission of N. meningitidis (Stephens, 2009). Improvement of microbiological testing and more stringent antibiotic prescribing practices should also reduce the likelihood of any antibiotic resistance.

Symptoms/Effects

Disease and symptoms: The incubation period of infection can be anywhere between 1-14 days (Stephens, 2009). Symptoms of N. meningitis infection often resemble Influenza in the first stages. However, rapid onset of disease can occur in the first few hours of symptoms appearing. N. meningitis infection can cause loss of limbs, loss of hearing, visual impairment, cognitive dysfunction, seizures and even death. N. meninigitidis is particularly known for causing infections in infants, adolescents, military personnel and students living in close quarters (Stephens, 2009). Smoking, crowding, complement disorders, asplenia (defective spleen function) and travel to areas where meningitis is epidemic are known to be risk factors for bacterial meningitis (Stephens, 2009).

Technical

References:
Oppenheim B.A. (1997)
Antibiotic resistance in Neisseria meningitidis. Clin Infect Dis. 24 (Suppl 1): S98-101.

Stephens D.S. (2009) Biology and pathogenesis of the evolutionarily successful, obligate human bacterium Neisseria meningitidis. Vaccine. 27(Suppl 12): B71-77.

Tunkel A.R., Hartman B.J., Kaplan S.L., Kaufman B.A., Roos K.L., Scheld W.M. and Whitley R.J. (2004) Practice guidelines for the management of bacterial meningitidis. Clin Infect Dis. 39(9): 1267-1284.
 

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