Micro Basics (Doesn't cover last 2 lectures)

Question 1

What immunoglobulins are present in mucus?

Answer 1

IgA

Question 2

What are the common causative agents of acute bronchitis?

Answer 2

Influenza (a & b); parainfluenza, RSV, rhinovirus, coronavirus

Question 3

What is the most common causative agent of bronchiolitis?

Answer 3

RSV

Question 4

What is the most common causative agent of community-acquired PNA?

Answer 4

S. pneumonia

Question 5

What is a common PNA causative agent in HIV-positive patients?

Answer 5

Pneumocystis jirovecii

Question 6

What is the most common causative agent of hospital-acquired PNA?

Answer 6

S. aureus

Question 7

What are two organisms associated with PNA in cystic fibrosis patients?

Answer 7

Burkholderia and Psuedomonas aeruginosa

Question 8

Your patient recently stayed in a hotel and now has PNA. What organism comes to mind?

Answer 8

Legionella

Question 9

What constitutes a good sputum sample?

Answer 9

From lower respiratory tract
Neutrophils present in good numbers
10 or fewer squamous epithelial cells per low-power field (if shown a picture, look like fried eggs - don’t want many eggs.)

Question 10

What are some virulence factors of Legionella?

Answer 10

Production of biofilms;
Chlorine resistance;
Pore-forming toxin

Question 11

Your patient has PNA symptoms and is an HVAC tech. What are some things the lab needs to take into consideration when culturing the sample you send?

Answer 11

Legionella needs buffered charcoal yeast extract with L-cysteine and iron.

Question 12

You suspect Legionella. What’s the best way to dx?

Answer 12

Urine antigen test

Question 13

What will be seen in a culture positive for Legionella?

Answer 13

Faintly-stained, Gram-negative bacilli; use silver stain or direct antibody fluorescence to better visualize. Ground glass appearance after ~5 days.

Question 14

Which organism is associated with deer fly/tick bites (or with animals bitten by deer flies/ticks)?

Answer 14

Francisella tularensis

Question 15

What special media is used for culture of Francisella tularensis?

Answer 15

Cysteine heart agar

Question 16

What are some virulence factors for F. tularensis?

Answer 16

Capsule
LPS that evades recognition by our TL4s
Replication that can occur in various cell types
Hematogenous spread

Question 17

What organism is associated with birthing of goats, sheep, and cows, or the veterinarians/farmers that are around them?

Answer 17

Coxiella burnetti

Question 18

What organism is associated with ingestion of unpasteurized milk?

Answer 18

Coxiella burnetti

Question 19

What organism causes Q fever?

Answer 19

Coxiella burnetti

Question 20

What are some virulence factors associated with Coxiella burnetti?

Answer 20

Forms spore (stays stable in the environment for long periods of time)

Resists digestive enzymes and the acid pH in phagolysosomes (replicates inside the phagolysosomes)

Question 21

Patient has chest CT with patchy areas of necrotizing consolidation and cavitating nodules. Culture shows a pink, branching organism on acid-fast stain. It looks beaded/chalky on Gram stain. What is a likely organism?

Answer 21

Norcardia asteroides, a type of partially-acid-fast, aerobic actinomycite that causes disease in immunocompromised patients (often fatal).

Question 22

Patient presents with fever, cough, and weight loss. Culture shows a red-staining bacilli on acid-fast stain. What is the likely organism?

Answer 22

Mycobacteria tuberculosis, an acid-fast bacilli.

Question 23

Word association: “Rough, buff, tough” colonies

Answer 23

Mycobacteria tuberculosis

Question 24

College-aged patient presents with PNA-like symptoms but has no fever. What organism do you suspect?

Answer 24

Chlamydia pneumoniae

Question 25

Your patient lives with one thousand parakeets and has fever with a dry cough. What organism/disease do you suspect?

Answer 25

Chlamydophilla psittaci - causes psittacosis

Question 26

You have a young patient with very mild PNA during the summer. What organism do you suspect?

Answer 26

Mycoplasma pneumoniae (not S.pneumo)

Question 27

Which influenza virus is associated with epidemics and severe disease?

Answer 27

A

Question 28

What type of antigenic variation is associated with small outbreaks within a community?

Answer 28

Antigenic drift: occurs because of lack of proof-reading mechanism in RNA replication

Question 29

What type of antigenic variation is associated with epidemics/pandemics?

Answer 29

Antigenic shift (occurs when two strains combine and re-assort within a cell)