NEISSERIA Flashcards
Give the properties/characteristics of Neisseria.
Gram-negative; diplococci
What are the pathogenic species of Neisseria?
- N. meningitidis
- N. gonorrhoeae
What is the morphology of N. meningitidis?
- Gram-negative, bean-shaped, diplococci
- Do not possess flagella or spores
- Capsulated and possess pili
- 0.8 x 0.6 um in diameter
N. meningitidis is an aerobic organism. True or False?
True
What type of metabolism does N. meningitidis do?
Oxidate metabolism
Give the 3 vital enzymes of N. meningitidis.
- Catalase
- Oxidase
- Cytochrome
Growth of N. meningitidis in culture is improved by addition of ______ or ______. Also by incubation in the presence of ?
blood or serum; 2-8% CO2
What is the growth temperature of N. meningitidis and its pH range?
36-39 ; 6-8 pH
Describe the colonies of N. meningitidis.
- Colonies are 1-2 mm in diameter, convex, grey, and transparent.
- No hemolysis in blood agar
N. meningitidis is maltose fermenter. True or False?
True
N. meningitidis produces beta lactamases. True or False?
False
What are the 3 important virulence factors of Neisseria?
- Polysaccharide capsule. It is antiphagocytic in nature.
- The endotoxin of N. meningitidis is a lipopolysaccharide. It induces septic shock by causing release of cytokines.
- IgA protease. It cleaves the IgA antibodies present in respiratory mucosa.
Who is the natural host for N. meningitidis?
Humans
N. meningitidis are transmitted by ?
Airborne droplets
Give the pathogenesis of N. meningitidis.
- Transmission of airborne droplets.
- Colonize the nasopharynx and become transient flora of the upper respiratory tract.
- From the nasopharynx, the organism can enter the bloodstream and spread to meninges and grow in cerebrospinal fluid.
What are the diseases induced by N. meningitidis?
- Meningitis (ages of 2 and 18 yrs.)
- Meningococcemia (multiplication of bacteria in the blood stream)
*Outbreaks of meningitis are most common in winter and early spring and favored by close contact between individuals.
What are the different diagnostic methods for N. meningitidis?
- It is frequently isolated from samples such as blood and CSF.
- Gram staining
- Culture
- Oxidase test
- Fermentation test
- Latex agglutination test
In oxidase test, upon the addition of Kovac’s reagent, the colonies of N. meningitidis changes into what color?
Purple (within 10 seconds)
N. meningitidis can’t ferment maltose. True or False?
False
This test detects capsular polysaccharide in the spinal fluid.
Latex agglutination test
What are the drugs of choice for N. meningitidis infection?
- Penicillin G
- Sulphonamides
If the individual is allergic to penicillin, what will you recommend?
- Cholramphenicol
- Third generation cephalosporin such as cefotaxime or ceftriaxone
Is meningococcal vaccine availble?
Yes
*Meningococcal vaccine is available which contains the capsular polysaccharide.
