Neisseria gonorrhoeae : Basics
Introduction
- N. gonorrhoea infections have a high prevalence and low mortality
- Is “obligate pathogen” and is never part of the normal human flora under any circumstances.
- Gonococci is exclusive to humans
- The only source of infection is a human carrier or less often a patient.
- In women gonococcus usually cause asymptomatic infection
- In men the infection is usually symptomatic.
Morphology
- Gram negative organism.
- Possess pili on their surface:
- facilitate adhesion of cocci to mucosal surface
- promote virulence by inhibiting phagocytosis.
- Need 5-10% CO2
- Selective medium forgrowth is Thayer – Martin medium.
- Four types of colonies have been recognised.
- Type 1 and 2 are virulent
- 3, 4 are non virulent cocci.
Biochemical reactions:
- Ferment
- glucose
- (not maltose Neisseria meningitides ferment maltose)
Rapid carbohydrate utilisation test (RCUT):
- This is a rapid, sensitive and specific test for detection of gonococci.
Pathogenic factors
Outer-membrane protein:
|
Pilli |
Adherence and Virulence |
|
Opacity associated protein (ProteinII) |
Adhesion |
|
Porin (Protein I, III) – |
Surface protein |
|
H.8 Lipoprotein – |
Target for antibody based diagnostic testing |
|
Transferrin and lactoferrin bindingprotein. |
Binding |
|
IgAl protease |
Also produced by meningococci |
Lipooligosaccharide
- Endotoxin
- Resemble human glycosphingolipid
- Contributes to the local cytotoxic effects.
Host factors
- Defeciency of terminal complement components.
Introduction
- Obligate pathogen
- Gonococci is exclusive to humans
Morphology
- Gram negative organism.
- Possess pili on their surface
- Thayer – Martin medium.
- Four types of colonies have been recognised.
- Type 1 and 2 are virulent
- 3, 4 are non virulent cocci.
Biochemical reactions:
- Ferment
- glucose
- (not maltose Neisseria meningitides ferment maltose)
Rapid carbohydrate utilisation test (RCUT):
- This is a rapid, sensitive and specific test for detection of gonococci.
Pathogenic factors
Outer-membrane protein:
|
Pilli |
Adherence and Virulence |
|
Opacity associated protein (Protein II) |
Adhesion |
|
Porin (Protein I, III) – |
Surface protein |
|
H.8 Lipoprotein – |
Target for antibody based diagnostic testing |
|
Transferrin and lactoferrin binding protein. |
Binding |
|
IgAl protease |
Also produced by meningococci |
Lipooligosaccharide
- Endotoxin
- Resemble human glycosphingolipid
- Contributes to the local cytotoxic effects.
Host factors
- Defeciency of terminal complement components.
