Q fever laboratory tests: Difference between revisions
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===Polymerase chain reaction (PCR)=== | ===Polymerase chain reaction (PCR)=== | ||
*[[PCR]] can be used to detect [[Coxiella burnetii|C. | *[[PCR]] can be used to detect ''[[Coxiella burnetii|C.]] [[Coxiella burnetii|burnetii]]'' [[DNA]] in [[Culture medium|cultures]] and clinical samples. | ||
*[[PCR]] is positive in the first week of infection, thus it can be used to diagnose Q fever in patients who are [[Serology|serologically]] negative in the early stages of the disease.<ref name="pmid10515901">{{cite journal |vauthors=Maurin M, Raoult D |title=Q fever |journal=Clin. Microbiol. Rev. |volume=12 |issue=4 |pages=518–53 |year=1999 |pmid=10515901 |pmc=88923 |doi= |url=}}</ref> | *[[PCR]] is positive in the first week of infection, thus it can be used to diagnose Q fever in patients who are [[Serology|serologically]] negative in the early stages of the disease.<ref name="pmid10515901">{{cite journal |vauthors=Maurin M, Raoult D |title=Q fever |journal=Clin. Microbiol. Rev. |volume=12 |issue=4 |pages=518–53 |year=1999 |pmid=10515901 |pmc=88923 |doi= |url=}}</ref> | ||
*Quantitative [[PCR]] also can be used in patients whom [[Immunoglobulin G|anti phase II IgG antibodies]] are persistently positive to detect chronic Q fever. | *Quantitative [[PCR]] also can be used in patients whom [[Immunoglobulin G|anti phase II IgG antibodies]] are persistently positive to detect chronic Q fever. | ||
===Cultures=== | ===Cultures=== | ||
*[[Coxiella burnetii|C. | *''[[Coxiella burnetii|C.]] [[Coxiella burnetii|burnetii]]'' doesn’t grow on ordinary [[blood cultures]] but can be cultivated on special media as embryonated eggs or [[cell culture]]. | ||
*[[Coxiella burnetii|C. | *''[[Coxiella burnetii|C.]] [[Coxiella burnetii|burnetii]]'' is extremely infectious and samples should be handled with caution. | ||
===Liver function tests=== | ===Liver function tests=== | ||
Revision as of 16:17, 26 July 2017
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Ahmed Younes M.B.B.CH [2]
Overview
Laboratory findings consistent with the diagnosis of Q fever include positive serology for antibodies (especially Indirect immunofluorescence (IIF), positive PCR, and elevated liver enzymes.
Laboratory tests
Serologic testing for Q fever
- Indirect immunofluorescence (IIF) is the method of choice for antibody detection and is preferred over ELISA and complement fixation.[1][2]
- Antibodies starts to be detected after 7-14 days of infection with most patients testing positive by the third week.
- Anti phase II antibodies are tested first. If positive, anti phase I antibodies are tested.
- After acute infection, serologic follow up for serum anti phase I IgG antibodies. The test is done twice every 3 months for 2 years. If it's positive, Transesophageal echo should be done to rule out endocarditis.[3]
- All serologic test results should be used in the context of clinical data because false positive test results are seen in many other diseases (e.g. leptospirosis).
Polymerase chain reaction (PCR)
- PCR can be used to detect C. burnetii DNA in cultures and clinical samples.
- PCR is positive in the first week of infection, thus it can be used to diagnose Q fever in patients who are serologically negative in the early stages of the disease.[4]
- Quantitative PCR also can be used in patients whom anti phase II IgG antibodies are persistently positive to detect chronic Q fever.
Cultures
- C. burnetii doesn’t grow on ordinary blood cultures but can be cultivated on special media as embryonated eggs or cell culture.
- C. burnetii is extremely infectious and samples should be handled with caution.
Liver function tests
References
- ↑ "Diagnosis of Q Fever".
- ↑ Dupont HT, Thirion X, Raoult D (1994). "Q fever serology: cutoff determination for microimmunofluorescence". Clin. Diagn. Lab. Immunol. 1 (2): 189–96. PMC 368226. PMID 7496944.
- ↑ Derrick EH (1983). ""Q" fever, a new fever entity: clinical features, diagnosis and laboratory investigation". Rev. Infect. Dis. 5 (4): 790–800. PMID 6622891.
- ↑ Maurin M, Raoult D (1999). "Q fever". Clin. Microbiol. Rev. 12 (4): 518–53. PMC 88923. PMID 10515901.