USMLE

Klebsiella pneumoniae

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Bacteria - Gram Negative
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Klebsiella pneumoniae 

  • Note: contrast vs. Klebsiella granulomatis which causes donovanosis (sexually-transmitted disease)
  • Characteristics
    • Gram negative rod
      • First test in algorithm, narrows scope of bacteria
    • Lactose-fermenting 
      • Second test in algorithm
    • Facultative anaerobe
    • Urease positive
  • Component of normal intestinal flora (enteric bacteria)
  • Presentation
    • Pneumonia
      • Usually lobar in distribution
      • Commonly affects immunocompromised individuals
        • Elderly, alcoholics and diabetics
      • Common cause of aspiration pneumonia
      • Associated with dark red “currant jelly” sputum
        • Dark red color comes from mixture of blood, sputum, and mucus
        • Forms mucoid colonies caused by abundant polysaccharide capsules
    • UTIs
      • Common in healthcare settings with indwelling catheters
      • Can lead to formation of struvite stones
        • Due to alkalinization of urine by urease, which reduces solubility of struvite
    • Also implicated in abdominal infections (biliary tree infections, peritonitis)
    • May cause bacteremia and sepsis
      • Shock may occur due to LPS endotoxin from gram-negative cell membrane
  • Treatment 
    • Evolving due to rapid evolution of multidrug resistance
      • Treatment is mostly dependent on antibiotic susceptibility
    • Third-generation cephalosporins (ceftriaxone) are most commonly used
    • Carbapenems, aminoglycosides, and quinolones may also be used