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Neisseria meningitidis

Neisseria meningitidis

Meningococcal disease is an acute, potentially severe illness caused by the bacterium Neisseria meningitidis.  Annually, there are between 1,400 and 2,800 cases of meningococcal disease in the U.S., with over 250 cases occurring among 11- to 18-year-olds. N. meningitidis colonizes the nasopharynx mucosal surfaces and is transmitted from person to person through direct contact or respiratory droplets.[1,2]  Common symptoms of meningococcal disease include high fever, neck stiffness, confusion, nausea, vomiting, photophobia, lethargy, and petechial or purpuric rash. [2,3]  An estimated 8% to 20% of the general population are asymptomatic carriers of N. meningitidis at any one time.[4]

In Florida, historical trends show seasonal peaks in disease occurrence during the winter dry season, November to May.[5]  From 1997 to 2006, there has been a gradual decline in cases of meningococcal disease in Florida, largely due to the availability of the vaccine.  However, there remains an increased concern about the risk of meningococcal disease among adolescents and young adults.  For this reason, the Advisory Committee on Immunization Practices (ACIP) recommends use of the meningococcal conjugate vaccine (MCV4) for children 11 to 12 years of age and all children 13 -18 years of age who have not been previously vaccinated. Due to their high risk of contracting this disease, children between the ages of 2 and 10 with immune system disorders are also recommended to be vaccinated against N. meningitidis; meningococcal vaccines are only effective against serogroups A, C, Y, and W-135.

The currently recommended chemoprophylactic antibiotics for adults are rifampin, ciprofloxacin, ceftriaxone, and azithromycin;[4] these antibiotics are 90% to 95% effective in reducing nasopharyngeal carriage of N. meningitidis.[1]

National surveillance has detected N. meningitidis isolates with reduced susceptibility to commonly used antimicrobials. Penicillin-intermediate strains (those with a reduced susceptibility to penicillin) have been described in the U.S. as well as internationally. However, high-dose penicillin remains an effective treatment against moderately susceptible meningococci and is still the recommended treatment in the U.S.[6]  Resistance to other antimicrobial agents used for therapy of meningococcal infections or prophylaxis of contacts has been reported in several countries; reported resistance has occurred for chloramphenicol, sulfonamides, tetracycline, and rifampin [1, 9]. Resistance has not been recognized to ceftriaxone or ceftoxamine, and only a few cases with fluoroquinolone-resistance (ciprofloxacin) have been identified.[6, 4]

The emergence of fluoroquinolone-resistant N. meningitidis in the U.S. has raised important questions regarding current chemoprophylaxis guidelines and highlights the expanding threat of antimicrobial resistance in bacterial pathogens. The Centers for Disease Control and Prevention (CDC) responded to this threat by forming MeningNet, an enhanced meningococcal surveillance system that will be used to monitor antimicrobial susceptibility. Florida began participating in MeningNet in late 2008. As a part of this project, Florida forwards all isolates to CDC for susceptibility testing.

Links:

·        Part 1 - Epidemiology of Neisseria meningitidis isolates, Florida, 2008-2009 - Florida Department of Health, Bureau of Epidemiology Epi Update, November 2010 (page 3)

·        Part 2 - Epidemiology of Neisseria meningitidis isolates, Florida, 2008-2009: Antimicrobial Susceptibility Testing Results - Florida Department of Health, Bureau of Epidemiology Epi Update, December 2010 (page 4)