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Microsporidiosis laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmed Younes M.B.B.CH [2]

Overview

Overview

Laboratory findings consistent with the diagnosis of microsporidiosis include microscopic identification of the organism in fecal smears using chromotrope 2R method or “Quick-Hot Gram Chromotrope technique”, positive PCR, and positive serology using indirect immunofluorescence.

Lab findings

Lab findings

Microscopic identification of the organism

Identification of the microorganism in the stool specimens is a quick and cheap method for diagnosis.[1][2]

  • Special stains must be used because spores are not visible with ordinary stains.
  • Chromotrope 2R method is a technique that stains the spore and its wall; in this method spores appear pink with belt-like stripes in the middle of the them. This technique takes about 90 minutes.
  • “Quick-Hot Gram Chromotrope technique” provides better visualization of the organism and cuts down the time needed for staining to 10 minutes. In this method, microorganism appears dark violet and the belt-like stripes are enhanced.
  • Enterocytozoon bieneusi spores measure 0.8 – 1.4 µm while Anncaliia algerae, Encephalitozoon spp., Vittaforma corneae, and Nosema spp spores measure 1.5 – 4 µm.
  • Fecal smears shows no WBCs nor blood unless concomitant infection is present.
Unidentified microsporidia stained with Chromotrope 2R – Source: https://www.cdc.gov/
Enterocytozoon bieneusi spores stained with Chromotrope 2R- Source: https://www.cdc.gov/
Encephalitozoon cuniculi spores stained with Gram Chromotrope – Source: https://www.cdc.gov/

Serologic assays:

Monoclonal antibody-based immunofluorescence identification of Encephalitozoon hellem – Source: https://www.cdc.gov/

PCR

  • Molecular identification of Enterocytozoon bieneusi, Encephalitozoon intestinalis, Encephalitozoon hellem and Encephalitozoon cuniculi using PCR is available.[5][6]
  • PCR is the most sensitive and specific method for diagnosing microsporidiosis, yet it is expensive and not recommended for routine diagnosis.
References

References

  1. Rijpstra AC, Canning EU, Van Ketel RJ, Eeftinck Schattenkerk JK, Laarman JJ (1988). “Use of light microscopy to diagnose small-intestinal microsporidiosis in patients with AIDS”. J. Infect. Dis. 157 (4): 827–31. PMID 3126248.
  2. “CDC – DPDx – Microsporidiosis – Laboratory Diagnosis”.
  3. Fedorko DP, Hijazi YM (1996). “Application of molecular techniques to the diagnosis of microsporidial infection”. Emerging Infect. Dis. 2 (3): 183–91. doi:10.3201/eid0203.960304. PMC 2626796. PMID 8903228.
  4. Franzen C, Müller A (2001). “Microsporidiosis: human diseases and diagnosis”. Microbes Infect. 3 (5): 389–400. PMID 11369276.
  5. Reddy AK, Balne PK, Gaje K, Garg P (2011). “PCR for the diagnosis and species identification of microsporidia in patients with keratitis”. Clin. Microbiol. Infect. 17 (3): 476–8. doi:10.1111/j.1469-0691.2010.03152.x. PMID 21309925.
  6. Weber R, Bryan RT, Schwartz DA, Owen RL (1994). “Human microsporidial infections”. Clin. Microbiol. Rev. 7 (4): 426–61. PMC 358336. PMID 7834600.


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