Coccidioidomycosis laboratory tests: Difference between revisions

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==Overview==
==Overview==
The fungal infection can be demonstrated by microscopic detection of diagnostic cells in body fluids, exudates, [[sputum]] and [[biopsy]]-tissue. With specific [[nucleotide]] primers ''C.immitis'' [[DNA]] can be amplified by [[PCR]]. It can also be detected in culture by morphological identification or by using molecular probes that hybridize with ''C.immitis'' [[RNA]].
The [[fungal infection]] can be demonstrated by microscopic detection of diagnostic [[Cells (biology)|cells]] in body [[fluids]], [[Exudate|exudates]], [[sputum]] and [[biopsy]]-tissue. With specific [[nucleotide]] primers ''C.immitis'' [[DNA]] can be amplified by [[PCR]]. It can also be detected in culture by morphological identification or by using [[molecular]] probes that hybridize with ''[[Coccidioides immitis|C.immitis]]'' [[RNA]].<ref name="pmid26739609">{{cite journal |vauthors=Stockamp NW, Thompson GR |title=Coccidioidomycosis |journal=Infect. Dis. Clin. North Am. |volume=30 |issue=1 |pages=229–46 |year=2016 |pmid=26739609 |doi=10.1016/j.idc.2015.10.008 |url=}}</ref><ref name="pmid26398540">{{cite journal |vauthors=Twarog M, Thompson GR |title=Coccidioidomycosis: Recent Updates |journal=Semin Respir Crit Care Med |volume=36 |issue=5 |pages=746–55 |year=2015 |pmid=26398540 |doi=10.1055/s-0035-1562900 |url=}}</ref><ref name="pmid25577855">{{cite journal |vauthors=DiCaudo DJ |title=Coccidioidomycosis |journal=Semin Cutan Med Surg |volume=33 |issue=3 |pages=140–5 |year=2014 |pmid=25577855 |doi= |url=}}</ref><ref name="pmid24575994">{{cite journal |vauthors=Malo J, Luraschi-Monjagatta C, Wolk DM, Thompson R, Hage CA, Knox KS |title=Update on the diagnosis of pulmonary coccidioidomycosis |journal=Ann Am Thorac Soc |volume=11 |issue=2 |pages=243–53 |year=2014 |pmid=24575994 |doi=10.1513/AnnalsATS.201308-286FR |url=}}</ref>
==Laboratory Findings==
===CBC===
*CBC with differential shows  [[Eosinophilia|peripheral eosinophilia]]
===Serology===
*These form the mainstay of commercial testing for the diagnosis of coccidioidomycosis.
*Several techniques are available such as the older Tube-[[precipitin]] method as well as the newer CF ([[Complement fixation test|complement fixation]]), [[Immunodiffusion]] and EIA ([[enzyme immunoassay]]).
*EIA assay picks up [[IgM]] and [[IgG|IgG antibodies]] against the coccidioidal [[antigens]]. [[IgM]] [[antibodies]] are found early in the disease progression and are not useful for assessing prognosis, while [[IgG]] antibodies appear late and persist longer.
*[[Complement-fixation|CF]] titres can be used as a measure of disease progression and to diagnose [[meningitis]] by measuring CF antibodies in [[CSF]].
{| class="wikitable" !Type of test !Specificity !Sensitivity !Comment |- |EIA | ++++ | ++++ |IgM and IgG  |- |CF | ++++ | +++ |Used to confirm EIA IgG |- |IDCF | ++++ | +++ |Used to confirm EIA IgG |- |IDTP | +++ | +++ |Not employed now |} EIA based rapid diagnostic commercial kits are available but are not as sensitive or specific as lab based tests and have a risk of false positives.|}
{| class="wikitable"
!Type of test
!Specificity
!Sensitivity
!Comment
|-
|EIA
|<nowiki>++++</nowiki>
|<nowiki>++++</nowiki>
|
* Detects both IgM and IgG
|-
|CF
|<nowiki>++++</nowiki>
|<nowiki>+++</nowiki>
| rowspan="2" |
* Used for confirming EIA IgG
 
* Quantitative analysis
 
* Also employed for CSF analysis of diagnosis
 
* Used for follow up response of treatment
|-
|IDCF
|<nowiki>++++</nowiki>
|<nowiki>+++</nowiki>
|-
|IDTP
| +++
| +++
|Not employed now
|-
| colspan="4" |IDCF-Immuno diffusion compliment fixation, IDTP -Immuno diffusion tube-precipitin
|}
{| class="wikitable" !Type of test !Specificity !!Sensitivity ! |- | | | | |- | | | | |- | | | | |} These form the mainstay of commercial testing for the diagnosis of coccidioidomycosis.


===Staining & Culture===
===Staining & Culture===
Usual KOH staining doesn't help in diagnosis of this fungal infection but organisms can be stained by using special stains such as papanicolaou stain or gomori methamine silver stain on sputum or other respiratory fluids.
*The gold standard for diagnosis of coccidioidomycosis is positive culture or histopathological identification of the organism in clinical specimens.
Even biopsy specimens can be stained by methamine silver stain to demonstrate spherules surrounded by inflammation.  
*Usual [[KOH test|KOH]] staining doesn't help in diagnosis of this fungal infection but organisms can be stained by using special stains such as papanicolaou stain or gomori methamine silver stain on sputum or other respiratory fluids.
Coccidioides is easy to culture, grows in about 3-7 days at 37°C  on simple media such as blood agar, however precautions needs to be exercised as it poses a significant health hazard to lab personnel.
*Even biopsy specimens can be stained by methamine silver stain to demonstrate spherules surrounded by inflammation.  
*Coccidioides is easy to culture, grows in about 3-7 days at 37°C  on simple media such as blood agar, however precautions needs to be exercised as it poses a significant health hazard to lab personnel.


[[Image:Lab culture.jpg|frame|center|Laboratory culture of Coccidioides immitis]]
[[Image:Lab culture.jpg|frame|center|Laboratory culture of Coccidioides immitis]]
[[Image:Coccidioidomycosis27.jpeg|center|500px]]
===PCR based methods===
*[[PCR]] assays are useful to detect a target gene one [[DNA]] has been extracted from the target tissue.
*It is highly sensitive and much safer compared to lab cultures.
*The [[Coccidioides immitis|C.immitans]] DNA can be amplified by PCR and then hybridised to molecular probes to aid in identification.


===Serology===
===Antigen Testing===
* These form the mainstay of commercial testing for the diagnosis of coccidioidomycosis.
*Galactomannan antigen testing techniques employed for more rapid diagnosis but is limited due to their crossreactivity to other endemic fungi, leading to false positive cases.
* Several techniques are available such as the older Tube-precipitin method as well as the newer CF(complement fixation), Immunodiffusion and EIA(enzyme immuno assay) assays.
*It can detect antigen even in blood, urine sample specimens.
* EIA assay picks up IgM and IgG antibodies against the coccidioidal antigens. IgM antibodies are found early in the disease progression and are not useful for assessing prognosis, while IgG antibodies appear late and persist longer.
* CF titres can be used as a measure of disease progression and to diagnose meningitits by measuring CF antibodies in CSF.
*  {| class="wikitable" !Type of test !Specificity !Sensitivity !Comment |- |EIA | ++++ | ++++ |IgM and IgG  |- |CF | ++++ | +++ |Used to confirm EIA IgG |- |IDCF | ++++ | +++ |Used to confirm EIA IgG |- |IDTP | +++ | +++ |Not employed now |} EIA based rapid diagnostic commercial kits are available but are not as sensitive or specific as lab based tests and have a risk of false positives.


===PCR based methods===
PCR assays are useful to detect a target gene one DNA has been extracted from the target tissue. It is highly sensitive and much safer compared to lab cultures. The C.immitans DNA can be amplified by PCR and then hybridised to molecular probes to aid in identification.
==Gallery==
==Gallery==
<gallery>
<gallery>
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</gallery>
</gallery>
==References==
==References==
{{Reflist|2}}
{{Reflist|2}}
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{{WS}}


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[[Category:Fungal diseases]]
[[Category:Fungal diseases]]
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Latest revision as of 21:00, 29 July 2020

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

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Overview

The fungal infection can be demonstrated by microscopic detection of diagnostic cells in body fluids, exudates, sputum and biopsy-tissue. With specific nucleotide primers C.immitis DNA can be amplified by PCR. It can also be detected in culture by morphological identification or by using molecular probes that hybridize with C.immitis RNA.[1][2][3][4]

Laboratory Findings

CBC

Serology

  • These form the mainstay of commercial testing for the diagnosis of coccidioidomycosis.
  • Several techniques are available such as the older Tube-precipitin method as well as the newer CF (complement fixation), Immunodiffusion and EIA (enzyme immunoassay).
  • EIA assay picks up IgM and IgG antibodies against the coccidioidal antigens. IgM antibodies are found early in the disease progression and are not useful for assessing prognosis, while IgG antibodies appear late and persist longer.
  • CF titres can be used as a measure of disease progression and to diagnose meningitis by measuring CF antibodies in CSF.
Type of test Specificity Sensitivity Comment
EIA ++++ ++++
  • Detects both IgM and IgG
CF ++++ +++
  • Used for confirming EIA IgG
  • Quantitative analysis
  • Also employed for CSF analysis of diagnosis
  • Used for follow up response of treatment
IDCF ++++ +++
IDTP +++ +++ Not employed now
IDCF-Immuno diffusion compliment fixation, IDTP -Immuno diffusion tube-precipitin

Staining & Culture

  • The gold standard for diagnosis of coccidioidomycosis is positive culture or histopathological identification of the organism in clinical specimens.
  • Usual KOH staining doesn't help in diagnosis of this fungal infection but organisms can be stained by using special stains such as papanicolaou stain or gomori methamine silver stain on sputum or other respiratory fluids.
  • Even biopsy specimens can be stained by methamine silver stain to demonstrate spherules surrounded by inflammation.
  • Coccidioides is easy to culture, grows in about 3-7 days at 37°C on simple media such as blood agar, however precautions needs to be exercised as it poses a significant health hazard to lab personnel.
Laboratory culture of Coccidioides immitis

PCR based methods

  • PCR assays are useful to detect a target gene one DNA has been extracted from the target tissue.
  • It is highly sensitive and much safer compared to lab cultures.
  • The C.immitans DNA can be amplified by PCR and then hybridised to molecular probes to aid in identification.

Antigen Testing

  • Galactomannan antigen testing techniques employed for more rapid diagnosis but is limited due to their crossreactivity to other endemic fungi, leading to false positive cases.
  • It can detect antigen even in blood, urine sample specimens.

Gallery

References

  1. ↑ Stockamp NW, Thompson GR (2016). "Coccidioidomycosis". Infect. Dis. Clin. North Am. 30 (1): 229–46. doi:10.1016/j.idc.2015.10.008. PMID 26739609.
  2. ↑ Twarog M, Thompson GR (2015). "Coccidioidomycosis: Recent Updates". Semin Respir Crit Care Med. 36 (5): 746–55. doi:10.1055/s-0035-1562900. PMID 26398540.
  3. ↑ DiCaudo DJ (2014). "Coccidioidomycosis". Semin Cutan Med Surg. 33 (3): 140–5. PMID 25577855.
  4. ↑ Malo J, Luraschi-Monjagatta C, Wolk DM, Thompson R, Hage CA, Knox KS (2014). "Update on the diagnosis of pulmonary coccidioidomycosis". Ann Am Thorac Soc. 11 (2): 243–53. doi:10.1513/AnnalsATS.201308-286FR. PMID 24575994.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 "Public Health Image Library (PHIL)".

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