What is the cause of meningitis due to Gram-negative diplococci bacteria, specifically Neisseria (N.) meningitidis?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Article Review Status
Submitted
Under Review
Approved

Last updated: March 18, 2025 • View editorial policy

From the Guidelines

Neisseria meningitidis is the primary cause of meningitis due to Gram-negative diplococci bacteria. The bacteria colonize the nasopharynx and can rapidly invade the bloodstream and meninges, causing severe inflammation. Key characteristics of N. meningitidis include:

  • Gram-negative diplococci with adjacent flattened sides resembling coffee beans under microscopy
  • Ability to rapidly invade the bloodstream and meninges, causing severe inflammation
  • High mortality rates of 10-15% even with appropriate treatment, as reported in studies such as 1 Some important considerations in the management of N. meningitidis meningitis include:
  • Early recognition and treatment are critical to prevent rapid progression of the disease
  • Initial empiric therapy should include ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 4-6 hours, as recommended in guidelines such as 2
  • Chemoprophylaxis is essential for close contacts and includes rifampin 600mg orally twice daily for 2 days, ciprofloxacin 500mg as a single oral dose, or ceftriaxone 250mg IM as a single dose
  • Reduced susceptibility to penicillin has been observed in some meningococcal strains, and alternative antibiotics such as third-generation cephalosporins may be necessary in these cases, as noted in studies such as 2 It is essential to note that the epidemiology of meningococcal meningitis varies per region of the world, with different serogroups being more common in different areas, as reported in studies such as 1. The introduction of conjugated vaccines has led to a significant reduction in the incidence of meningococcal meningitis in some regions, as shown in studies such as 1. However, the development of reduced susceptibility to antibiotics and the emergence of new serogroups remain significant concerns, highlighting the need for ongoing surveillance and vaccination efforts, as discussed in studies such as 1 and 2.

From the FDA Drug Label

MENINGITIS Caused by Haemophilus influenzae, Neisseria meningitidis or Streptococcus pneumoniae Meningococcal meningitis and / or septicemia Neisseria meningitidis

The cause of meningitis due to Gram-negative diplococci bacteria, specifically Neisseria (N.) meningitidis, is infection with Neisseria meningitidis bacteria.

  • Key points: + Neisseria meningitidis is a Gram-negative diplococci bacterium. + It can cause meningitis and septicemia. + The infection can be treated with antibiotics, such as Ceftriaxone or Penicillin G, depending on the susceptibility of the bacteria [3] [4].

From the Research

Cause of Meningitis due to Neisseria meningitidis

  • Neisseria meningitidis is a gram-negative diplococcus that is the leading cause of bacterial meningitis in children and young adults in the United States, with an estimated 2,600 cases reported each year 5.
  • The infection rates of N. meningitidis are highest in children 3 to 12 months of age 5.
  • Meningitis is the most common pathologic presentation of N. meningitidis infection, associated with fever, headache, and nuchal rigidity, and has a mortality rate of about 5% in children and 10% to 15% in adults 5.

Transmission and Prevention

  • Household contacts have the highest risk of contracting the disease during the first week of a case being detected 6.
  • Prophylaxis is considered for close contacts of people with a meningococcal infection and populations with known high carriage rates 6.
  • Antibiotics such as ciprofloxacin, rifampin, minocycline, and penicillin have been shown to be effective in eradicating N. meningitidis 6.

Treatment

  • A single daily dose of ceftriaxone has been used to treat bacterial meningitis, including cases caused by N. meningitidis, with a mortality rate of 13% 7.
  • Aztreonam has also been used to treat gram-negative bacillary meningitis, including cases caused by N. meningitidis, with a microbiologic cure rate of 94% 8.
  • Pefloxacin has been shown to be effective in treating meningitis caused by gram-negative bacteria, including N. meningitidis, with a clinical response rate of 80% 9.

References

Guideline

escmid guideline: diagnosis and treatment of acute bacterial meningitis.

Clinical Microbiology and Infection, 2016

Research

Antibiotics for preventing meningococcal infections.

The Cochrane database of systematic reviews, 2011

Research

A single daily dose of ceftriaxone for bacterial meningitis in adults: experience with 84 patients and review of the literature.

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 1995

Research

Aztreonam in the treatment of gram-negative bacterial meningitis.

Reviews of infectious diseases, 1991

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.