4. Parvobacteria, Haemophilus Flashcards
Parvobacteria is gram ()? And grows (only)! On?
Negative , enriched media.
Are haemophilus motile, and spore forming , capsulated?
They are Non-motile, non spore-forming, most are capsulated.
Haemophilus depend on what to grow?
Blood.
Where are they found?
Upper respiratory tract.
Growth requirements of haemophilus?
X-factor ~> protoporphyrins essential for catalases, peridoxidases and cytochromes of the electron transport chain.
X-factor ~> can be supplied by heat-stable iron containing pigments like “blood containing media”
V-factor is heat-labilesco-enzyme ~> supplied by nicotine adenine di nucleotide (NAD or NADP)
NAD ~> present inside RBC
What’s the media for haemophilus ?
- chocolate agar (heated blood agar)
- blood w/ staph. aureus (satellitism)
- nutrient media with X and V factors
- 5-10% CO2
Haemophili of medical importance include?
- H. Influenzae (real pathogen)
- H. Parainfluenzae (secondry pathogen, needs something to facilitate it)
- H. aegypticus (causes eye infection)
- H. ducreyi (causes sexual diseases)
Haemophilus influenzae pathogenesis?
_Capsule
- 6 types (a, b, c, d, e, f)
What’s the most imp. Type of h. Infleunzae ?
B
It’s associated w/ invasive infections.
most cases w/ children under 2 years of age
What’s the importance of h.infleunzae capsule ?
- virulence factor (anti- phagocytic) resist killing by immune cells ~> severe disease
- antigenic ~> immune cells produce protective antibodies
- direct antigen detection from clinical samples by latex agglutination using anti-capsular antibodies
- vaccine by using capsule as target.
1) Non-capsulated carriage in ()? Who does it effect ?
2) Carriage of Capsulated strains in ?
1) Nasopharynx ~ 25-80% of healthy people.
2) 5-10%
* 50% type b ~ 1-5%
What do you know about meningitis?
- Most common invasive disease
- Droplet infection
- Mortality ~ 5%
- neurological complications ~> hearing loss ~ 10-30%
- Non invasive diseases are mainly caused by non- capsulated strains
- Local infections associated w/ underlying pathology e.g. secomdry to viral infection like?
- otitus media
- sinusitis
- exacerbation of chronic obstructive pulmonary disease COPD
What are the lab diognosis of h. Influenzae?
- CSF, blood, aspirate, from joint, ear , sinuses
- direct microscopy
- direct antigen detection
- culture: grow in chocolate agar
- need X & V factors
Meningitis —> CSF, blood
Arthiritis —> joint aspartate , blood
What is the epidemiology of invasive diseases cause by h. Infleunzae?
- imp. Cause of serious infections in children
- menengitis is more common in winter & low socioeconomic status
- outbreaks of infection in close communities like nursury schools
- nowadays outbreaks are less common ( children are vaxxed in kw)
