ZSFG AM Report Pearls 12/19/2017: It’s the BLOB, no that’s just Mucoid Klebsiella

Sorry for the late post. Catching up on some of those awesome peri-Holiday reports. Thanks for your patience team! Thank you to our ZSFG Team for presenting a case of “mucoid” Klebsiella (also called hypervirulent (hypermucoviscous) Klebsiella pneumoniae. 


Thanks to Lekshmi Santhosh, whose prior pearls are integrate here

Hypermucoviscous Klebsiella pneumoniae:

  • Originally from the Pacific Rim, but it’s here now, so brace yourselves
  • Defining Clinical Features:
    • Serious, life-threatening community acquired infections
    • Often in younger, healthy hosts
    • Metastatic Spread! (Remember that this is very unusual for Gram-negative bacilli – and essentially acts like STAPH)
      • Liver abscess
      • Pneumonia
      • Meningitis
      • Endophthalmitis
  • Klebsiella pneumonia is an encapsulated GNR and the K antigen is the capsular polysaccharide
    • It has a mucoid appearance and one of the main determinants of virulence
  • The hypermucoviscosity (HV) Phenotype is determined by the string teste. formation of viscous strings when a loop is used to stretch a colony from an agar tape https://www.youtube.com/watch?v=_LP5KoguPC0
  • This hypermucoviscosity phenotype has been seen more commonly in patients from East Asia esp Taiwan – DM is also a very common risk factor


  • It does not appear that there are clear clinical guidelines about a standard work-up (confirmed with local expert Lisa Winston)
  • Work-up for metastatic disease should be guided by clinical suspicion


  • Fortunately, most strains have been susceptible to antimicrobials, except Amoxicillin (sensitivity testing is important)
  • Source control is essential, and since this can cause abscesses remember that those need to be drained




  • Shon AS, Bajwa RPS, Russo TA. Hypervirulent (hypermucoviscous) Klebsiella pneumoniae: A new and dangerous breed. Virulence. 2013;4(2):107-118. doi:10.4161/viru.22718.



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