Haemophilus Species & Moraxella Catarrhalis Flashcards
What is PAGE?
- polyacrylamide gel electrophoresis.
- used to identify outer membrane proteins (on Gm- bacteria?)
What portion of the H. Flu type B capsule is used in the HIB vaccine?
-polyribosyl ribitol phosphate
What is lipooligosaccharide (LOS)?
- present in H. influenzae
- like LPS, but much shorter side chain
- damages tissues and stimulates inflammatory response
H. Flu requires X factor to grow. What is X factor?
- hematin, released by lysed RBC’s
- present in chocolate agar
How is chocolate agar made?
-by heating blood
H. Flu requires V factor to grow. What is V factor?
- NAD+ (nicotinamide adenine dinucleotide)
- diffuses from RBC’s -present in chocolate agar
How are H. parainfluenzae and H. Influenzae different in their agar growth requirements?
- parainfluenzae needs only V factor, and can grow on blood agar.
- influenzae grows only on chocolate agar and also needs X factor
What exotoxins are produced by H. influenzae?
- none recognized
- LOS causes inflammation and damages tissues though
How does HITB cause meningitis?
- directly enters CNA via veins or lymphatics
- hematogenously, settling in choroid plexus
What is polyribosyl phosphate?
- located in HITB capsule
- causes high level of resistance to phagocytosis
What is the host immune response to H. influenza type B?
- Antibody to PRP capsule opsonizes for phagocytosis & is bactericidal
- antibodies to LOS and outer membrane proteins are bactericidal to a lesser extent
What is the host immune response to NTHI?
- children who develop otitis initially lack IgG to outer proteins, but develop it
- some antibodies are protective
What is “exacerbation of COPD?”
1 NTHI
-tracheobronchitis and pneumonia in persons with pre-existing chronic lung disease
What two factors are present in chocolate agar that allows H. Influenzae to grow?
- X factor (Hematin)
- V factor (NAD+)
What give HITB high resistance to phagocytosis?
-polyribosyl phosphate located in its capsule
What indicates a highly virulent organism?
- high proportion of colonizations invade
- a high proportion of those who are infected have serious disease
What is puerperal fever?
- infection during birth causing fever
- from organisms in vagina
What diseases are caused by Haemophilus Influenza Type B (HITB)?
- Mningitis
- Acute Epiglottitis
- Septic Arthritis
- Sepsis
- Otitis media
Who is at risk for sepsis caused by HITB?
Children with abent or non-functioning spleens (sickle cell)
*HITB is encapsulated
How do we treat HITB?
For serious infections = 3dr generation cephalosporin
Otitis media = ampicillin/amoxicillin
What disease is caused by H. influenza biogroup aegyptius?
-Brazilian hemorrhagic fever (epidemic)
“cherry red epiglottis”
HITB epiglottitis
Where does HITB colonize?
Nasopharynx
What disease is caused by Haemophilus ducreyi?
-Chancroid
=venerial ulcers
How do we tell apart ulcers that are caused by H. ducreyi vs. T. pallidum (syphilis)?
Syphilis ulcers are not painful, ducreyi chancroids are
Rank in order of virulence: Moraxella, NTHI, HITB, H. parainfluenzae
HITB >> NTHI > Moraxella > H. parainfluenzae
What diseases are caused by Moraxella catarrhalis?
2 exacerbation of COPD
What is the most common cause of exacerbation of COPD?
Non-typable H. influenza
How is H. influenza transmitted?
aerosolized
