KLEBSIELLA–ENTEROBACTER– SERRATIA GROUP

Question 1

Disease

Answer 1

• opportunistic pathogens-> nosocomial infections, pneumonia &
  UTI.

Question 2

Important Properties

Answer 2

• Klebsiella pneumoniae, Enterobacter cloacae, & Serratia
  marcescens
• found in large intestine, present in soil & water.
• K.pneumoniae-> large capsule polysaccharide -> mucoid colonies.
• Serratia marcescens-> red colonies

Question 3

Pathogenesis & Epidemiology

Answer 3

• K. pneumoniae-> primary, nonopportunistic pathogen-> antiphagocytic capsule.
  -advanced age, chronic respiratory disease, diabetes, or alcoholism.
• carried in respiratory tract of healthy people prone to pneumonia
  if host defenses are lowered.

Enterobacter & Serratia->
intravenous catheterization, respiratory intubation, &
urinary tract manipulations.

• Serratia pneumonia-> contamination of water in respiratory therapy devices.
• Prior to extensive use of these procedures, S. marcescens->
  harmless organism isolated from environmental sources (water).
• endocarditis in drug injectors.

Question 4

Clinical Findings

Answer 4

• UTIs & pneumonia, bacteremia
  & secondary spread to meninges & liver occur.
• Difficult to distinguish; exception of Klebsiella pneumonia -> thick, mucoid, bloody sputum (“currant-jelly” sputum)-> necrosis & abscess
  formation.
• K.ozaenae-> atrophic rhinitis
• K.rhinoscleromatis-> destructive granuloma of nose & pharynx.

Question 5

Laboratory Diagnosis

Answer 5

• lactose-fermenting (colored)
  colonies on MacConkey’s or
  EMB
• Serratia-> late lactose fermenter-> negative reaction.

Question 6

Treatment

Answer 6

• aminoglycoside (gentamicin)
  & cephalosporin (cefotaxime) used
  until test results are known.
• severe Enterobacter infections-> imipenem with gentamicin

Question 7

Prevention

Answer 7

• changing intravenous catheter sites, removing urinary catheters when no longer needed, & proper care of respiratory therapy devices.
• no vaccine.