Microbiology - Bacterial Pneumonia I and II Flashcards
What are the unique presentations of Pseudomonas aeruginosa in special populations?
P. aeruginosa has a few community-acquired presentations: endocarditis in IV drug addicts,
Otitis externa in underchlorinated hot tubs,
Osteochondritis in sneaker punctures,
corneal infections under contact lenses
How is infection (pneumonia) with a pseudomonad treated?
Treat with latest combinations of antibiotics, test Ab sensitivity both before and during treatment.
All, but particularly P. aeruginosa, have extreme antibiotic resistance from combination of low-permeability outer membrane and efflux pumps.
How is infection (pneumonia) with pseudomonas diagnosed?
Diagnose by culture and Gram stain
Where is pseudomonas aeruginosa infection most commonly found?
Hospitals
All pseudomonas infections can present as septicemia/pneumonia with poor prognosis.
P. aeruginosa and B. cepacia have minimal growth requirements ➔ contaminate hospital sol’ns
Where is B. cepacia (pseudomonas) most commonly found?
CF centers
All can present as septicemia/pneumonia with poor prognosis.
In what populations is B. pseudomallei (pseudomonas) most commonly found?
B. pseudomallei in previously-ill travelers/immigrants or Vietnam veterans
All can present as septicemia/pneumonia with poor prognosis.
In what population is B. mallei most commonly found?
B. mallei in previously-ill travelers/immigrants with animal handling history.
All can present as septicemia/pneumonia with poor prognosis.
What are the pseudomonas pathogens?
Four P/B pathogens:
P. aeruginosa a common&serious nosocomial pathogen;
B. cepacia common, serious in context of CF;
B. pseudomallei and B. mallei rare in US but can be lethal
How is P. aeruginosa unique when growing it in culture?
P. aeruginosa produces green pyocyanin in culture.
Are the pseudomonads gram + or -?
All Gram(-), strict aerobes, nonfermenters, Oxidase(+), grow easily in culture.
What is the treatment for chlamydial pneumonia?
Treat with tetracyclines (doxycycline) EXCEPT for pregnant/pediatric/allergic patients, who get erythromycin or other alternatives. Patients who get alternatives may need follow-up testing and retreatment.
What are the unique factoids about chlamydia?
Chlamydia is a small, obligate intracellular bacterium (so must use drugs that penetrate the human cell membrane).
How does chlamydia replicate?
Chlamydia replicate in a unique manner beginning with tiny, infectious, rugged, elementary bodies which “unpack” into reticulate bodies after infection.
Reticulate bodies form intracellular inclusions that are visible on microscopy; within the inclusions they multiply by binary fission, forming new reticulate bodies and later new elementary bodies.
What special virulence factor does chlamydia have?
Unusual life cycle complicates research; one known virulence factor is T3SS used for entry & establishing inclusion body.
What kind of chlamydia causes the urogenital infection?
C. trachomatis is the cause of several human diseases, particularly the common urogenital infection (safe sex practices!)
C. pneumoniae, C. psittaci, and C. trachomatis can all cause _______
These are the chlamydias that cause pneumonia.
What is problematic about P. aeruginosa as a nosocomial infection?
A Extreme antibiotic resistance
B Propensity to grow in low-nutrient aqueous solutions
C Ability to cause bacteremia
D All of the above
1: D: P aeruginosa is a formidable opponent for your hospital infection control
What is SIMILAR about B. cepacia and B. pseudomallei?
Normally freeliving water microbes
- To which patient(s) is a B. cepacia infection dangerous despite treatment?
A A pediatric CF patient
B A geriatric cancer patient
C A previously-healthy woman undergoing urinary catheterization
D A and B not C
E All of the Above
2: A: Cystic Fibrosis is the most important predisposition for poor outcomes of cepacia infection.
Why has Legionella only recently emerged as a human pathogen?
Humans have created a new, human-proximal, habitat for it
All these patients have Legionella infections – which is at highest risk for a bad outcome?
22yr old previously-healthy female with a fever
55yr old previously-healthy female with pneumonia
77yr old smoker male with pneumonia
77yr old smoker male with pneumonia
Mycoplasma pneumonia resolves: Spontaneously With antibiotic treatment With antitoxin treatment With antiviral treatment
Spontaneously; and
With antibiotic treatment
What kind of bacteria is legionella?
Gram (-) rod;
Free-living form is motile (flagella); intracellular form is non-motile;
Opportunistic facultative intracellular pathogen with variable infection outcome
How do you trace a legionella outbreak?
LD outbreaks trace to contaminated locations (NOT people)
