Flashcards in Micro 2 Deck (21):
Haemophilus influenza morphology, transmission, growth
--gram (-) coccoid rods
--most invasive disease caused by capsular type B
--produces IgA protease
--growth on chocolate agar requires factor V (NAD+) and factor X (hematin). Can also be grown with s. aureus, which provides factor V
What does Haemophilus influenza cause?
haEMOPhilus influenza causes:
Epiglottitis ("cherry red" in children)
Nontypeable strains cause mucosal infections: otitis media, conjunctivitis, bronchitis
**H. influenza does *not* cause the flu
How do you treat Haemophilus influenza?
Treat mucosal infections with: amoxicillin +/- clavulanate
Treat meningitis with ceftriaxone; rifampin as prophylaxis in close contacts
Is there a vaccine for H. influenza?
Yes. It contains type B polysaccharide conjugated to diphtheria toxoid or other protein.
This vaccine is given between 2 and 18 months of age
What do we see for H. influenza on radiographic image?
Thickening of the epiglottis (*"thumbprint sign" on lateral neck radiograph
What are two gram (+) that form long, branching filaments that resemble fungi?
Characteristics of Actinomyces israelii
--not acid fast
--normal oral flora
--treat with penicillin
--causes oral/facial abscesses that drain through the sinus tracts, forms yellow "sulfur granules"
Characteristics of Nocardia
--found in soil
--treat with sulfonamides
--causes pulmonary infections in immunocompromised and cutaneous infections after trauma in immunocompetent
Enzyme that cleaves IgA
Binds Fc region of IgG and prevents opsonization by phagocytosis.
Expressed by S. aureus
Helps prevent phagocytosis.
Expressed by group A streptococci
Microbe that produces a blue-green pigment
"aerugella" is green
Microbe that produces yellow pigment
aureus is latin for gold
Microbe that produces red pigment
think: marachino cherries
Microbe that forms yellow "sulfur" granules, which are composed of filaments of bacteria
think: Israel has yello sand
Which bugs are urease positive?
CHuck norris hates PUNKSS
The significance of catalase positive organisms
Catalase degrades hydrogen peroxide before it can be converted to microbicidal products (halide radicals) by myeloperoxidase.
People with chronic granulomatous disease have recurrent infections with catalase (+) organisms
What is chronic granulomatous disease (brief definition)
NADPH oxidase deficiency
What are some catalase positive organisms that are common in chronic granulomatous disease?
Clinical significance of encapsulated bacteria
These bacteria's capsule serves as an antiphagocytic virulence factor. They are opsonized, and then cleared by the spleen.
People without a spleen have a decreased opsonizing ability and are at increased risk for severe infections by encapsulated bacteria.
You should give S. pneumoniae, H. influenzae, and N. meningitidis vaccines.