Bacterial Pneumonia 1

Question 1

what are the four pseudomonas pathogens? how common are they?

Answer 1

P aeruginosa (common and serious nosocomial pathogen), B cepacia (common and serious in context of CF), B pseudomallei and b mallei (rare in US but can be lethal)

Question 2

what is the morphology, metabolism, oxidase testing and culturability of the pseudomonas strains?

Answer 2

all gram negative, strict aerobes, nonfermenters, oxidase positive and grow easily in culture.

Question 3

what does P aerginosa look like in culture?

Answer 3

it produces green pyocyanin

Question 4

describe the antibiotic resistance in the pseudomonads.

Answer 4

all have extreme antibiotic resistance except for P aeruginosa. It is caused by low permeability outer membrane and efflux pumps denying the AB access.

Question 5

which of the pseudomonads are the easiest to grow? what is the consequence of this?

Answer 5

P aeruginosa and B cepacia have minimal growth requirements and can contaminate hospital solutions

Question 6

what community acquired presentations does P aeruginosa demonstrate?

Answer 6

endocarditis in IV drug addicts, Otitis externa in underchlorinated hot tubs, oseteochondritis in sneaker punctures and corneal infections under contact lenses

Question 7

where are the most common presentations for serious disease with P aeruginosa?

Answer 7

hospitals

Question 8

where are the most common presentations for serious disease with B cepacia?

Answer 8

in CF centers

Question 9

what are the most common presentations for serious disease with B pseudomallei?

Answer 9

in previously ill travelers/immigrants or vietnam veterans

Question 10

what are the most common presentations for serious disease with B mallei?

Answer 10

in previously ill travelers/ immigrants with animal handling history

Question 11

what is the poor prognosis presentation of the pseudomonads?

Answer 11

septicemia/pneumonia

Question 12

how are pseudomonads diagnosed and treated?

Answer 12

diagnosed by culture and gram stain

treat with combinations of antibiotics while testing for antibiotic sensitivity both before and during treatment

Question 13

describe the morphology and growth of chlamydia? what implication does this have on antibiotic use?

Answer 13

small obligate intracellular bacterium

drugs must penetrate the human cell membrane.

Question 14

what is the life cycle of Chlamydia?

Answer 14

they begin with small infectious elementary bodies that unpack into reticulate bodies after infection (visible on microscopy). they then multiply by binary fission and form new RB and later EB

Question 15

what is the known virulence factor for Chlamydia?

Answer 15

T3SS that helps the EB enter and establish itself in inclusion bodies

Question 16

what chlamydia strains can cause pneumonia?

Answer 16

C pneumonia, C psittaci and C trachomatis

Question 17

what is the basis of treatment for most chlamydia infections? in what situations is it different?

Answer 17

often initiated based on physical findings. additional diagnostics for C trachomatis in rape victims (tissue culture) or to differentiate pneumonias (serology or microimmunofluorescence)

Question 18

how are chlamydia pneumonias treated?

Answer 18

with tetracyclines except for pregnant/peds/allergic patients that get erythromycin or other alternatives. these patients may need follow up testing and retreatment