Micro 2

Question 1

Haemophilus influenza morphology, transmission, growth

Answer 1

• -gram (-) coccoid rods
• -aerosol transmission
• -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

Question 2

What does Haemophilus influenza cause?

Answer 2

haEMOPhilus influenza causes:

Epiglottitis (“cherry red” in children)
Meningitis
Otitis media
Pneumonia

Nontypeable strains cause mucosal infections: otitis media, conjunctivitis, bronchitis

**H. influenza does not cause the flu

Question 3

How do you treat Haemophilus influenza?

Answer 3

Treat mucosal infections with: amoxicillin +/- clavulanate

Treat meningitis with ceftriaxone; rifampin as prophylaxis in close contacts

Question 4

Is there a vaccine for H. influenza?

Answer 4

Yes. It contains type B polysaccharide conjugated to diphtheria toxoid or other protein.

This vaccine is given between 2 and 18 months of age

Question 5

What do we see for H. influenza on radiographic image?

Answer 5

Thickening of the epiglottis (*“thumbprint sign” on lateral neck radiograph

Question 6

What are two gram (+) that form long, branching filaments that resemble fungi?

Answer 6

Actinomyces Israelii

Nocardia

Question 7

Characteristics of Actinomyces israelii

Answer 7

• -anaerobic
• -not acid fast
• -normal oral flora
• -treat with penicillin
• -causes oral/facial abscesses that drain through the sinus tracts, forms yellow “sulfur granules”

Question 8

Characteristics of Nocardia

Answer 8

• -aerobic
• -acid fast
• -found in soil
• -treat with sulfonamides
• -causes pulmonary infections in immunocompromised and cutaneous infections after trauma in immunocompetent

Question 9

IgA protease

Answer 9

Enzyme that cleaves IgA

Secreted by:

Streptococcus pneumoniae
Haemophilus Influenzae
Neisseria meningitidis
Neisseria gonorrhoeae

Question 10

Protein A

Answer 10

Binds Fc region of IgG and prevents opsonization by phagocytosis.

Expressed by S. aureus

Question 11

M protein

Answer 11

Helps prevent phagocytosis.

Expressed by group A streptococci

Question 12

Microbe that produces a blue-green pigment

Answer 12

Pseudomonas aeruginosa

“aerugella” is green

Question 13

Microbe that produces yellow pigment

Answer 13

S. aureus

aureus is latin for gold

Question 14

Microbe that produces red pigment

Answer 14

Serratia marcescens

think: marachino cherries

Question 15

Microbe that forms yellow “sulfur” granules, which are composed of filaments of bacteria

Answer 15

Actinomyces israelii

think: Israel has yello sand

Question 16

Which bugs are urease positive?

Answer 16

CHuck norris hates PUNKSS

Cryptococcus
Helicobater pylori

Proteus
Ureaplasma
Nocardia
Klebsiella
Staphylococcus epidermidis
Staphylococcus saprophyticus

Question 17

The significance of catalase positive organisms

Answer 17

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

Question 18

What is chronic granulomatous disease (brief definition)

Answer 18

NADPH oxidase deficiency

Question 19

What are some catalase positive organisms that are common in chronic granulomatous disease?

Answer 19

Peudomonas
Listeria monocytogenes
Aspergillus
Candida
E. Coli
S. aureus
Serratia marsescens
Nocardia

Question 20

Clinical significance of encapsulated bacteria

Answer 20

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.

Question 21

What are examples of encapsulated bacteria?

Answer 21

SHiNE SKiS

Streptococcus pneumoniae
Haemophilus influenzaw
Neisseria meningitidis
E. Coli

Salmonella
Klebsiella
group b Strep