RHS17 - Respiratory Tract Infections 6

Question 1

List the major types of pneumonia, where those types are likely acquired, and whether they’re usually caused by bacteria or viruses

Answer 1

• Lobar Pneumonia - community acquired - bacteria
• Bronchial Pneumonia - nosocomial - virus
• Interstitial pneumonia - ventilator associated - causes vary

Question 2

List the common bacterial and viral causes of pneumonia. Say which ones are often drug resistant or likely to be nosocomial. Say which ones cause “atypical” pneumonia

Answer 2

• Viral Causes - any virus that can cause a LRTI
• Bacteria
  
  • Streptococcus pneumoniae (can be nosocomial)
  • Klebsiella pneumoniae (often nosocomial)
  • Psudomonas aeruginosa (often nosocomial and drug resistant)
  • Mycoplasma pneumoniae (atypical)
  • Legionella pneumophilia (atypical)
  • Chlamydophila pneumoniae (atypical)
  • Mycobacterium tuberculosis
  • Haemophilus influenzae

Question 3

Answer 3

C

Question 4

What are the clinical features of “typical” community acquired pneumonia (CAP)

Answer 4

• Usually only inolves one lobe (lobar) with signs of consolidation over that lobe - dullness, increased fremitus/egophony/whispered pectoriloquy, bronchial breath sounds
• Acute onset fever
• Acute onset pleuritic chest pain
• Acut onset productive cough

Question 5

What is streptococcus pneumoniae AKA? Give its identifying lab information.

Answer 5

AKA - Pneumococcus (pneumococcal pneumonia) or Diplococcus

• Gram positive diplococci
• Alpha hemolysis
• Sensitive to optochin (taxos P disk)

Question 6

What clinical features would suggest a pneumonia is caused by stretococcus pneumoniae?

Answer 6

• Winter & Early Spring incidence
• Lobar consolidation
• Sinusitis
• Otitis media
• Rusty sputum (S. pneumoniae produces H2O2 which oxidizes iron)

Commonest cause of CAP

Question 7

What are S. pneumoniae’s virulence factors?

Answer 7

• Capsule
• IgA protease
• Pneumolysin & Autolysin
  
  • Inhibitis ciliated epithelium cell activity
  • Binds to cholesterol in alveolar and endothelial cells and punches holes in the membrane
• Transformation - can turn normal flora S. pneumoniae into a pathogenic strain

Question 8

What are the vaccines available for pneumococcal pnuemonia and when are they usually given?

Answer 8

• Pneumococcal Polysaccharide Vaccine (PPSV23)
  
  • Adults >65yo
  • 2-64yo for people with certain medical condition (splenectomy)
  • 19-64yo smokers
• Pneumococcal Conjugate Vaccine
  
  • <2yo
  • >65
  • 2-64yo for people with certain medical conditions (splenectomy)

Question 9

What kind of bacteria is klebsiella pneumoniae? What are its virulence factors?

Answer 9

• Gram negative bacillus
  
  • Large polysaccharide capsule (CPS/K) antigen
  • LPS (O antigen)
    
    • Impedes complement system
    • Necrotization of lung tissue
  • Pili (fimbriae)
    
    • Epithelial attachment

Question 10

What are the clinical features that would suggest a pneumonia was caused by Klebsiella pneumoniae?

Answer 10

• Thick, reddish, tenacious sputum (red currant jelly sputum)
• Foul smelling sputum/breath
• It is a bronchopneumonia
• There are lung abscesses seen on CXR
• Person is an alchoholic, has diabetes, and/or has COPD
• Person has recently been on a ventilator or has had some time of venous/arterial catheter in.

Question 11

How is klebsiella transmitted

Answer 11

Via contact with a fomite (not through air)

Question 12

What Abxs are Klebsiella pneumoniae resistant to and how?

Answer 12

Carbapenem

They produce carbapenemase

Question 13

What kind of bacterium is pseudomonas aeruginosa? How is typically transmitted?

Answer 13

• Gram negative bacilli
• Obligate aerobes
• These bacteria are usually found in still fresh water sources so are usually contracted from water

Question 14

What clinical features would suggest a pneumonia was caused by pseudomonas aeruginosa?

Answer 14

• Recent still fresh water exposure (like from scuba equipment)
• Yellow-Green mucus that may smell like grapes
• Started as Swimmer’s Ear (otitis externa not media)
• Patient has a structural defect in acquired immunity
  
  • Burn victims
  • Cystic fibrosis
  • Recent ventilator use

Question 15

How does atypical CAP usually present?

Answer 15

With milder symptoms than a typical pneumonia which appear in a more gradual way over several days to weeks

Question 16

What type of bacteria is Mycoplasma pneumoniae? What are its virulence factors?

Answer 16

• short bacillus with no cell wall
• Virulence Factors
  
  • P1 adhesin (attachment organelle) which nestles in between cilia causing cilia immobility (causing dry cough)
  • Production of H2O2 to destroy tissue
  • CARDS (community acquired respiratory distress syndrome) toxin is cytotoxic to respiratory epithelium

Question 17

What clinical features would suggest a pneumonia was caused by mycoplasma pneumoniae?

Answer 17

• Young adult (<40) who spends time in crowded institutional settings (military, colleges, prisons, etc)
• Dry to mildly productive cough that is persistent
• Scratchy sore throat

Question 18

How is mycoplasma pneumoniae transmitted? Is it resistant to any drugs?

Answer 18

Transmitted via respiratory droplets

Resistant to beta lactam drugs because it lacks a cell wall

Question 19

How is mycoplasm pneumoniae diagnosed?

Answer 19

Not really any definitive tests

• Serum cold agglutination is positive for about 50-70% of patients. A negative result does not exclude
• >4-fold increase or decrease in titers or a single titer >1:32 supports diagnosis
• Typically, the presence/absence of risk factors is used for diagnosis

Question 20

Answer 20

E