Neisseria meningitidis
(Meningococcus; Diplococcus intracellularis
meningitidis).
Introduction
• N. meningitidis is a major cause of serious bacterial infections in
children.
• N. meningitidis is a part of the normal nonpathogenic flora in
the nasopharynx of up to 5–15% of adults.
• It is capsulated gram negative cocci in pairs (diplococci)
• Non-sporing
• Non motile
• 0.5- 1µm in size
Figure 1: N. Meningitidis in cerebrospinal fluid.
Transmission
• Through air borne droplets
• Close contact with infectious person
• Reservoir: exclusively human
Diseases it caused
• Meningitis (main disease)
• Meningococcaemia
• Pneumonia
• Arthritis
Pathogenesis
• Meningococci are strict human parasites inhabiting the nasopharynx.
• Infection is usually asymptomatic.
 Stages of meningococcal infections
1. First stage: Nasopharyngeal infection
2. Second stage: Meningococcal septicaemia
3. Third stage: Meningitis
Clinical manifestation
• High temperature, fever, possibly with cold hands and feet
• Vomiting
• Diarrhoea
• Severe headache
• Joint or muscle pains
• Neck stiffness
• Drowsiness
• Light sensitivity
References
• Surinder Kumar (2014). Textbook of Microbiology for Dental Students.
New Delhi. Jaypee Brothers