Treatment & Future Directions
Currently the first line of attack against bacterial meningococcal meningitis involves the use of intravenous antibiotics, the most popular of which is penicillin G; other antibiotics may include: cefuroxime, ceftriaxone, cefotaxime, cefoxitin, ciprofloxacin, and rifampin (MedInfo). While a simple antibiotic regiment has traditionally shown decent success, the process of diagnosis can be a highly painful one for patients, usually involving a spinal tap; the spinal fluid is examined and tested for diplococcus bacterium via a gram stain or methylene blue (MedInfo). Interestingly, various strains of N. meningitidis are sowing increasing levels of beta-lactam antibiotic resistance, especially in using penicillin G (over 20% resistance in some locations) as a means of removing carriage (Yazdankhak et al., 2004); however, most of the other antibiotics tend to work very effectively.
Although antibiotics may serve well for treatment of meningococcal meningitis, the vast majority of current research is examining vaccination against the disease. Within the United States, there are currently two separate vaccines used to prevent N. meningitidis infection: meningococcal polysaccharide vaccine (Menomune or MPSV4) and meningococcal conjugate vaccine (Menactra or MCV4) (MedInfo). The former has been widely used for the past twenty-five years (and is actually required by many colleges and universities for incoming students), while the latter is still growing in its popular acceptance; both vaccinations are capable of preventing infection from the A, C, Y, and W-135 serotypes of the bacterium (Pichichero). Menomune has a published efficacy of roughly 86% and is very safe, however it has numerous limitations - such as not inducing immune system memory, among other things (Pichichero). Menactra, on the other hand, has received much more recent praise and appears to be very a promising and effective vaccine. It exhibits the effects of a T-cell-dependent immune response, immune memory, persistance of protection, booster effect, reduction of nasopharyngeal carriage, herd immunity, and lack of hyporesponsiveness; Menomune, on the other hand, does not exhibit any of these effects (Pichichero).
In more general applications, N. meningitidis is even currently being researched for it's ability to elicit an immune response; researchers in the Netherlands are studying a certain mutant variant of N. meningitidis that purportedly exhibits strong adhesion and internalization capabilities regarding dendritic cells due to truncations seen on the lacto-N-neotetraose outer core of the lipopolysaccharide (Steeghs, 316). Resultantly, the researchers found that the structure of the bacterium's lipopolysaccharide is indeed a key player in dendritic cell function, and that "the IgtB oligosaccharide may be a powerful new tool to specifically target DC-SIGN generating a beneficial Th1 response and increase vaccine efficacy" (Steeghs, 317). This would undoubtedly be an excellent area for further research.
Another direction in which future research should be applied would be to study the cellular immunity and cytokine production in greater depth, as there currently very little information on the subject. Some researchers have argued for further study of the immune response resulting from carriage, as any findings would be valuable in developing mucosal immunization strategies, ultimately allowing for more effective measures in controlling the diseases associated with N. meningitidis (Yazdankhak et al., 2004).
Finally, a vaccination for serotype B (of which there is none currently available) would be highly useful, as its specific incidence of infections is increasing rapidly worldwide (Robinson et al., 2002).
References:
"Neisseria meningitidis" MedInfo, University of Florida, College of Medicine, Office of Medical Informatics. (2006) <http://medinfo.ufl.edu/year2/mmid/bms5300/bugs/neimeni.html> Accessed 04/29/07.
Pichichero, Michael E. "The new meningococcal conjugate vaccine." Journal of Postgraduate Medicine 119.1 (2006).
Robinson, K., et al. "Characterization of humoral and cellular immune responses elicited by meningococcal carriage." Infection & Immunity 70.3 (2002): 1301–09.
Steeghs, Liana, et al."Neisseria meningitidis expressing IgtB lipopolysaccharide targets DC-SIGN and modulate dendritic cell function." Cellular Microbiology 8.2 (2006): 316-325.
Yazdankhak, Siamak P., and Dominique A. Caugant. "Neisseria meningitidis: an overview of the carrier stage." Journal of Medical Microbiology 53 (2004): 821-32.
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Email questions or comments to Jordan Sullivan.