Pneumonia Part 1 Flashcards Preview

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Flashcards in Pneumonia Part 1 Deck (19):

Four P/B pathogens:

1. P aeruginosa a common and serious nosocomial pathogen (grows in water, vulnerable patients, Ab resistance, VAG)
2. B cepacia common, serious in context of CF
3. B pseudomallei and B mallei are rare in US but can be LETHAL (untreated pseudomallei can be fatal in 7-10 days; milder infections could resolve and reactivate yrs later); latter two are reportable


All the P/B pathogens are

gram negative, strict aerobes, nonfermenters, oxidase +, grow easily in culture; P aeruginosa makes green pyocyanin (its exotoxin) in culture;



All, but particularly P aeruginosa, have

extreme antibiotic resistance from combination of low-perm outer membrane and efflux pumps


P aeruginosa and B capacia have

minimal growth requirements and can contaminate hospital solutions;
(tougher for B capacia to infect otherwise-healthy patients; can lead to outbreaks with cepacia pneumonia in CF centers; NO PYOCYANIN)


P aeruginosa has a few

community-acquired presentations: enducoarditis in IV drug addicts, otitis externa/folliculitis in underchlorinated hot tubs, osteochondritis in sneaker punctures, corneal infections under contact lenses (COOE);

burns, CF, long-term catheterization, immunosuppression;
also has T3SS (exotoxin) and endotoxin that can lead to sepsis; also glycocalyx that's ANTIPHAGOCTYIC


Most common presentations for serious disease with pseudomonas:

1. P aeruginosa in hospitals (CF pneumonia, burns, nosocomia UTI; ecthyma gangrenosum)
2. B cepacia in CF centers
3. B pseudomallei in previously-ill travelers/immigrants or Vietnam vets (melioidosis; contaminated water, soil); also IV drug users
4. B. mallei in previously-ill travelers/immigrants with animal handling history (rare zoonosis; unlikely human-to-human transmission);
ALL can present as septicemia/pneumonia with poor prognosis


Diagnose pseudomonas by

culture and gram stain;

Aeruginosa culture will fail if anaerobic; metallic sheen on triple-sugar-iron agar, green color on nutrient agar (pyocyanin);
for pseudomallei and mallei, think PATIENT HISTORY


Treat pseudomonas with

latest combo of antibiotics, test Ab sens both before AND during treatment

(for aeruginosa, remove/change catheters/IVs)


Chlamydia is a

small obligate IC bacterium (need drugs that can penetrate human cell membrane)


Chlamydia replicate in a

unique manner, beginning with tiny, infectious, rugged elementary bodies which unpack into reticulate bodies after infection


RB's form

IC inclusions that are visible on microscopy: within the inclusions they multiply by binary fission, forming new RB's and later new EB's


Unusual life style

complicates research; one known virulence factor is T3SS used for entry and establishing inclusion body


C trachomatis is the

cause of several human diseases, particularly the common urogenital infection (SAFE SEX PRACTICE)


What three guys can cause pneumonia?

C pneumoniae (retirement communities, adult comm-acquired pneumonia), C psittaci (infected birds like parrots), C trachomatis (birth canal: conjunctivitis and pneumonia)


Treatment of chlamydia can often be

initiated on physical findings, additional diagnostics are available and may be desired in various situations (tissue culture for C trachomatis in rape victims, serology or MIF to differentiate pneumonias);

C psittaci shows consolidation in single lower lobe


Treat chlamydia with

tetracyclines (doxy) EXCEPT for pregnant/pediatric/allergic patients, who will get erythromycin or other alternatives. Patients getting alternatives may need follow-up testing and retreatment

C trachomatis could require oral erythromycin and not just the eye ointment


Prevent P aeruginosa:

1. Keep neutrophil counts up
2. see treatment
3. burn unit precautions
4. handwashing


C pneumoniae has on histo

pear-shaped elementary bodies


C psittaci could show

abrupt onset, Horder spots (erythematous, blanching, maculopapular rash), and then maybe meningitis, encephalitis, endocarditis (hema e)