E1- Baterial Pneumonia I Flashcards
What type of pneumonia is an acute infection of the pulmonary parenchyma in a patient who is not immunocompromised and has acquired the infection outside of the hospital?
CAP (community acquired pneumonia)
What type of pneumonia occurs 48 hrs or more after admission and did not appear to be incubating at the time of admission or 7-10 days after discharge?
HAP (hospital acquired pneumonia)
What type of pneumonia develops more than 48 to 72 hours after an endotracheal intubation?
VAP (ventilator associated pneumonia)
What are the common causes of CAP?
S. pneumoniae
H. Influenza
K. pneumonia
S. aureus
What is the gold standard for dx of CAP?
Presence of an infiltrate on CXR with supportive clinical and microbiology findings
What can be useful for rapid dx of pneumonia?
Gram stain of sputum
What two main factors are considered with CAP outpatient treatment?
No major comorbidities
No abx in last 3 months
What is pneumonia caused by streptococcus pneumoniae also called?
Pneumococcus
What type of media must streptococcus pneumoniae be grown on? Why?
Blood because it supplies catalase for organism to survive aerobically
Streptococcus pneumoniae grows poorly with what in the media? Why?
Glucose because lactic acidosis builds up
In the growth of streptococcus pneumoniae on blood agar, the breakdown of ____ gives colonies a ____ appearance.
Heme
Green
What are the three virulence factors associated with streptococcus pneumoniae?
Capsule*
Secretory IgA protease
Pneumolysin
How does the thick polysaccharide capsule increase virulence in streptococcus pneumoniae?
Resists opsonization by complement
How does the secretory IgA protease increase virulence in streptococcus pneumoniae?
Prevents organism from getting stuck in mucus of upper respiratory tract
How does the pneumolysin increase virulence in streptococcus pneumoniae?
Produces cytotoxin
A pt presents with sick appearance, high fever, productive cough, and well-defined consolidation on CXR. What do you suspect?
Typical pneumonia
A pt presents with well appearance, low fever, non-productive cough, and non-defined patchy infiltrates on CXR. What do you suspect?
Atypical pneumonia
What is clinically the most important a-hemolytic strep?
Streptococcus pneumoniae
What is used for stereotyping Streptococcus pneumoniae?
Capsule
What is responsible for releasing heme on blood agar in Streptococcus pneumoniae?
Pneumolysin
What virulence factor did Griffith’s experiment show was most important in Streptococcus pneumoniae?
Capsule
Griffith’s experiment discovered what bacterial capability?
Natural competence
What is natural competence?
The ability of bacterial to uptake DNA from the environment
Strep pneumo can do this intra and interspecies
What process is known to cause penicillin resistant Streptococcus pneumoniae?
Natural competence
What induces the alternative pathway of complement in Streptococcus pneumoniae, leading to tissue damage?
Techoic acid and peptidoglycan
What induces the classical complement pathway in Streptococcus pneumoniae, leading to tissue damage?
Pneumolysin
What two vaccines are available for pneumoniae prevention?
Pneumovax 23 and Prevnar 13
What is a possible complication of pneumococcal pneumonia?
Bacteremia
Meningitis caused by what organism is more likely to lead to neurologic effects and mortality?
Streptococcus pneumoniae
How is Streptococcus pneumoniae dx?
Gram stain and CXR +/- culture
Is Streptococcus pneumoniae gram positive or negative?
Gram positive
What test is used to dx bacteremia and meningitis?
Antigen detection
What identifying factors would be noted from a culture with Streptococcus pneumoniae?
Green on blood agar (a-hemolytic)
Lysis by bile
What is the DOC for Streptococcus pneumoniae?
Penicillins (beta-lactam)
Is H. flu gram positive or negative? What shape?
Gram negative rodes
Hib was at one time responsible for 95% of H. flu infections, but that number is now reduced to 2-4%. How did this happen?
Hib Vaccine
What is a major difference between Streptococcus pneumoniae and H. flu?
Streptococcus pneumoniae w/o a capsule are avirulent, but H. flu w/o a capsule are virulent
What are the virulence factors of H. flu?
Capsule LOS Fimbriae Neuraminidase IgA protease
How is H. flu dx?
Gram stain, CXR, +/- culture, +/- LAT
Is Klebsiella pneumoniae gram positive or negative? What shape?
Gram negative bacillus
What is the # cause of pneumoniae in alcoholics? What is a close second?
Streptococcus pneumoniae
Klebsiella pneumoniae
What organism is a major source of abx resistance world wide?
Klebsiella pneumoniae
What are the virulence factors of Klebsiella pneumoniae ?
Slime capsule
LPS
Adhesins
What organism causes necrotizing CAP that is often fatal even with abx treatment?
Klebsiella pneumoniae
How is Klebsiella pneumoniae dx?
Gram stain, CXR (cavities), culture, currant jelly sputum
Susceptibility
What is required for treatment of Klebsiella pneumoniae?
Susceptibility testing
What type of agar should you use to culture Klebsiella pneumoniae? Why?
MacConkey Agar
Selects for gram -
Differentiates b/w lactose +/-
