Neisseria gonorrhoeae and Neisseria meningitides are Gram negative diplococci (kidney bean-shaped) with flattened sides. They are characteristically found inside polymorphonuclear leucocytes. They are non-sporing, non-motile and oxidase positive.
They have exacting growth requirements and do not grow on ordinary media. Growth occurs on media enriched with blood or serum like Chocolate Agar, Thayer Martin Agar and Modified New York City Medium.
Some of the notable differences between them are:
| Characteristics | Neisseria gonorrhoeae (Gonococci) | Neisseria meningitides (Meningococci) |
| Capsule | No polysaccharide capsule | Yes (has a prominent polysaccharide capsule; and is divided in to 13 serologic groups on the basis of capsular antigens) |
| Pili | Yes (One of the most important virulence factor; nonpiliated strains are avirulent) | Yes |
| Portal of Entry | Genital | Respiratory |
| Disease |
|
Meningitis and meningococcemia |
| Glucose Fermentation | Yes | Yes |
| Maltose Fermentation* | No | Yes |
| Β-Lactamase Production | Common | Rare (Penicillin G is the treatment of choice for meningococcal infection) |
| Vaccine available | No | Yes (Conjugate vaccine and unconjugate vaccine is available) |
* The differentiation between Neisseria meningitidis and Neisseria gonorrhoeae is made on the basis of sugar fermentation: meningococi ferment maltose (MM), whereas gonococci do not.
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