Pneumonia part 2

Question 1

Legionella is a

Answer 1

opportunistic facultative IC pathogen with variable infection outcome (requires silver or IF in tissue sections to see, also gram negative rods)

Question 2

Exposure to legionella is from

Answer 2

aspiration or inhalation of contaminated water (NOT contagious);

think of pipes, cooling towers, hospital with warm water!!

Question 3

Legionella survives ____ by

Answer 3

endocytosis; monocytes and macrophages by altering endosomes (fusion of phagosome and lysosome) so it can multiply in them and then escape

Question 4

What are new environments for legionella?

Answer 4

Cooling towers and whirlpool spas (legionella NOT evolved to live by altering endosomes, so they will die off with the host or by immunity and antibiotics)

Question 5

LD (Legionnaire’s Disease) outbreaks trace to

Answer 5

contaminated LOCATIONS (not people); duh: hospitals (nosocomial)

Question 6

LD pneumonia is

Answer 6

life-threatening even when treated with antibiotics (as opposed to asymp seroconversion or Pontiac fever)

Question 7

Optimal diagnosis of legionella by

Answer 7

BOTH urine antigen test (cell wall component excreted and detect LP1 strain; use tagged secondary Ab) and culture of respiratory secretions (fastidious, special media required: Buffered Charcoal Yeast extract with alpha-ketoglutarate)

Question 8

For geriatric _____ in general, take

Answer 8

community-acquired pneumonias; samples for culture/ELISA first, then start treatment with levofloxacin second, and get labs back third;
Pontiac fever usually resolves on its own

Question 9

Outbreaks in health care for legionella

Answer 9

are common; vulnerable individuals exposed to bad plumbing!!

Question 10

C burnetti is a

Answer 10

small coccus to short rod, zoonotic infection from ruminants (NO VECTOR)

Question 11

C burnetti transmitted by

Answer 11

aerosols, grows in alveolar monocytes/macrophages, survives endolysosomal fusion, extremely infectious, long-lived in environ

Question 12

C burnetti causes

Answer 12

pneumonia/hepatitis = Q Fever;

some complications of pregnancy perhaps

Question 13

Diagnose C burnetti by

Answer 13

IHC (ELISA, IF), treat with tetracyclines or fluroquinolones

Question 14

Mycoplasma unique among bacteria in

Answer 14

lacking a cell wall and including cholesterol in their cell membrane

(fried egg appearance)
Fried egg has a lo of cholesterol

Question 15

Mycoplasma causes

Answer 15

“walking” pneumonia: mild and self-limited

transmission: inhalation of respiratory aerosols

Question 16

CARDS is

Answer 16

exotoxin-induced ciliostasis (dry cough), local inflamm, local tissue destruction, production of “cold agglutinins” targeting RBC’s (risk of anemia)

Question 17

Persistence of mycoplasma through

Answer 17

slow growth and IC hiding

Question 18

Treat mycoplasma

Answer 18

as needed with tetracyclines or macrolides; fluoroquinolones cover mycoplasma
(patient might also be anemic)

Question 19

There are also a few

Answer 19

other mycobacteria that are minor pathogens of the repro and urinary tracts

Question 20

Legionella virulence factors include:

Answer 20

1. Type IV secretion system (alters endosome)
2. Pilus formation (attachment)
3. Zn metalloprotease (escape)

Question 21

Risk factors for LD:

Answer 21

Increasing age, immunosuppression, smoking, chronic heart/lung disease, chronic swallowing disorder, male