GPR: 2021 - Week 20

From MGH Learn Pathology

Clinical history

48 yo F with PMHx of metastatic lung cancer on immunochemotherapy p/w fever + SOB. Legionella urine antigen testing is negative. BCYE agar from sputum is shown below +/- UV light. Gram stain shows thin GNRs.


GPR21-16-ec13bcf4-6cc2-4c31-a8bc-a197faf0fd94.png


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GPR21-16-ec13bcf4-6cc2-4c31-a8bc-a197faf0fd94.png

 
Legionella anisa
  • Blue-white autofluorescence
  • One of the most common environmental isolates of Legionella
  • Generally non-pathogenic in immunocompetent hosts
  • Numerous case reports of LD in immunosuppressed hosts
 

GPR21-16-846a3d23-4c48-495b-bdbd-18d968b031af.png

 

Legionella pneumophila

  • Most common cause of LD
  • Legionella urine antigen test only detects Legionella pneumophila (serogroup 1)
  • 80-90% of LD is due to pneumophila with 70% due to serogroup 1
  • Weak (yellow) to no autofluorescence
 

GPR21-16-e41ac550-6f15-42b3-90eb-49b601551124.png

 

Legionella erythra

  • Non-pathogenetic species
  • Characteristic red autofluorescence
 

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Legionella clemsonensis

  • Green autofluorescence
  • Isolated in 2006 from a pt with LD
 
Julian Villalba Leif Helland
Plamar et al. 2016. Legionella clemsonensis sp. nov.: a green fluorescing Legionella strain from a patient with pneumonia. Microbiol Immunol.

Fallon et al. 1990. Legionnaires' disease due to Legionella anisa. Journal of Infection.

Select Images from: http://www.biomerieux-culturemedia.com/product/95-legionella-agar-with-l-cysteine--bcye--and-without-l-cysteine--bcy-

https://imgur.com/gallery/lfMQZXp

This week's Gross Pathology Roundup was presented by Daniel Pearson, MD, PhD on Mon, May 17, 2021.