Klebsiella pneumoniae

Pnuemonia, UTIs and bacteremia
Classic Case: K. pneumoniae Pneumonia

Middle aged patient, alcoholic, presents with fever/chills, productive cough, and difficulty breathing. Sputum has a thick, currant jelly-like consistency. Sputum samples show a Gram-negative, encapsulated, non-motile bacillus that ferments lactose.

Causative Agent of:
  • Pneumonia
  • UTIs
Physical Features
  • Enterobacteriaceae members
  • Gram-negative
  • Rods
  • Non-motile
  • Has a thick polysaccharide capsule
    • = Mucoid colonies
Epidemiology
  • World-wide
  • Second most-common cause of bacteremia post-UTI
    • After E. coli
  • Common hospital-acquired (nosocomial) infection
    • Very commonly isolated in hospitals
Growth Features
  • Facultative anaerobe
  • Lactose fermenter
  • Catalase-positive
  • Antibiotic resistance
    • β-lactamase (all are ampicillin-resistant)
    • Carbapenem-resistance
    • MDR (multi-drug-resistance) increasing
Reservoir
  • Found in soil and water
  • Also normal flora of human GI tract
  • Sometimes the oropharynx as well
  • As high as 40% of general population
Transmission and Risk Groups

Transmission:

  • Person-person
    • Typically in health-care settings
    • Nosocomial (hospital-acquired) infection
  • Pneumonia: Aspiration of bacteria into lung
    • e.g. via ventilators
  • UTI: Bacteria ascend urinary tract
    • e.g. via catheters

Risk Groups:

  • Hospitalized patients
  • Immunocompromised
  • Alcoholics (specific risk of pneumonia)

Clinical

Klebsiella
Symptoms
  • Pneumonia:
    • Usually rapid onset, usually upper lobes
    • Can cause necrotizing/hemorrhagic lesions
    • Sputum: Often called “currant-jelly” (BW)
      • Due to hemorrhaging/blood in sputum
  • Urinary tract infections:
    • Dysuria, abdominal pain
    • Can lead to bacteremia
    • Indistinguishable from other bacterial causes
Complications
  • Bacteremia is greatest risk in UTI patients
  • Meningitis, wound infections possible
VIrulence Factors
  • Capsule: Blocks phagocytosis
    • Adheres to pulmonary, urinary linings
    • Causes mucoid colony appearance
  • Antibiotic resistance:
    • Ampicillin-resistant (chromosomal β-lactamase)
    • Plasmids with β-lactamases, carbapenemases
    • KPC: K. pneumoniae carbapenemase
      • A serious threat: can spread drug-resistance
      • = Carbapenem-resistant Enterobacteriaceae (CRE)
Diagnosis
  • Pneumonia:
    • Sputum analysis, microscopy and isolation
  • UTI:
    • Urine analysis, microscopy and isolation
Prevention
  • Infection-control precautions in healthcare settings
  • Good hygiene
Treatment
  • Multi-drug resistance (MDR) a major problem
    • Especially with nosocomial isolates
    • Tx depends on susceptibility
  • Non-MDR? Cephalosporins, TMP-sulfamethoxazole
    • Fluoroquinolones, aminoglycosides
  • MDR? Carbapenems, 4th-gen cephalosporins
  • Some KPC strains can be resistant to all drugs
Other Klebsiella spp. that cause disease:

K. oxytoca:

  • Also causes nosocomial infections

K. granulomatis:

  • Chronic genital ulcers (genitals, anus)
    • Usually painless
    • Can reach large sizes, cause lymphedema

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