Q fever laboratory tests: Difference between revisions
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===Serologic testing for Q fever:=== | ===Serologic testing for Q fever:=== | ||
*Indirect immunofluorescence (IIF) is the method of choice for antibody detection and is preferred over ELISA and complement fixation. | *Indirect immunofluorescence (IIF) is the method of choice for antibody detection and is preferred over ELISA and complement fixation.<ref name="urlDiagnosis of Q Fever">{{cite web |url=http://jcm.asm.org/content/36/7/1823.short |title=Diagnosis of Q Fever |format= |work= |accessdate=}}</ref><ref name="pmid7496944">{{cite journal |vauthors=Dupont HT, Thirion X, Raoult D |title=Q fever serology: cutoff determination for microimmunofluorescence |journal=Clin. Diagn. Lab. Immunol. |volume=1 |issue=2 |pages=189–96 |year=1994 |pmid=7496944 |pmc=368226 |doi= |url=}}</ref> | ||
*Antibodies starts to be detected after 7-14 days of infection with most patients testing positive by the third week. | *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. | *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. | *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.<ref name="pmid6622891">{{cite journal |vauthors=Derrick EH |title="Q" fever, a new fever entity: clinical features, diagnosis and laboratory investigation |journal=Rev. Infect. Dis. |volume=5 |issue=4 |pages=790–800 |year=1983 |pmid=6622891 |doi= |url=}}</ref> | ||
*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). | *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). | ||
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*PCR can be used to detect C. brutenii DNA in cultures and clinical samples. | *PCR can be used to detect C. brutenii 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. | *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.<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 anti phase II IgG antibodies are persistently positive to detect chronic Q fever. | *Quantitative PCR also can be used in patients whom anti phase II IgG antibodies are persistently positive to detect chronic Q fever. | ||
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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]
Lab 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. brutenii 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. brutenii doesn’t grow on ordinary blood cultures but can be cultivated on special media as embryonated eggs or cell culture.
- C. brutenii is extremely infectious and samples should be handled with caution.
Liver function tests:
- 2-3 fold increase in AST and ALT is seen in most of the patients.
- ↑ "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.