Unspecific Reactivity of IgM Directed Against the Low-Molecular-Weight Antigen of Toxoplasma gondii

Dao, Anne; Azzouz, Nahid; Nga, C. Eloundou; Dubremetz, Jean‐François; Schwarz, Ralph Τ.; Fortier, B

doi:10.1007/s10096-003-0948-9

Cited by 13 publications

(6 citation statements)

References 17 publications

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“…Secondly, all cases of acute toxoplasmosis infection had commercial laboratory IgM results that were positive. Several reports have related a false immunologic reactivity to the low molecular weight antigen of Toxoplasma gondii which is unrelated to acute toxoplasmosis infection and misleads interpretation of results [11,12]. Commercial laboratories do not currently confirm their Toxoplasmosis-specific IgM positive results with any reference laboratory.…”

Section: Discussionmentioning

confidence: 99%

Commercial Laboratory IgM Testing for Toxoplasma gondii in Pregnancy: A 20‐Year Experience

Garry

Elimian

Wiencek

et al. 2005

Infectious Diseases in Obstetrics and Gynecology

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OBJECTIVE: This study was performed to review the clinical utility of commercial laboratory Toxoplasmosis-specific IgM testing during pregnancy and outcomes of the gestation at our institution. METHODS: A retrospective review of all women referred for suspected acute Toxoplasma gondii infection during pregnancy from 1984 through 2004 was performed. Women were diagnosed with suspected acute toxoplasmosis based on commercial laboratory serologic antibody testing. All women had blood sent to a recognized reference laboratory for antibody testing within 2 weeks of the commercial laboratory results. The study protocol was approved by the Institutional Review Board. Chi-square analysis were used with a significance of P < .05. RESULTS: A total of 130 women were evaluated during the study period with 116 IgM positive results from the commercial laboratories. The commercial laboratory antibodies were as follows: IgM positive with IgG negative (n = 20), IgM positive with IgG positive (n = 96), and IgM negative with IgG positive (n = 14). There was a significant reduction in the IgM positive results when comparing commercial laboratory (n = 116) with the reference laboratory results (n = 28; p < .001). Acute toxoplasmosis infection was diagnosed in 7 (5%) of the women. All cases of acute toxoplasmosis infection had a positive commercial laboratory IgM result. The false positive rate for the commercial laboratory IgM was 88.6% and the diagnostic indices were sensitivity 100%, specificity 11.4%, positive predictive value 6% and negative predictive value 100%. CONCLUSION: Commercial laboratory Toxoplasmosis-specific IgM is associated with a high false positive rate. The commercial and reference laboratory IgM results identified all cases of acute toxoplasmosis infection. Commercial laboratories reflexively obtaining reference laboratory confirmation of positive results could reduce costs associated with testing, referrals, retesting, and invasive procedures.

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Section: Discussionmentioning

confidence: 99%

Commercial Laboratory IgM Testing for Toxoplasma gondii in Pregnancy: A 20‐Year Experience

Garry

Elimian

Wiencek

et al. 2005

Infectious Diseases in Obstetrics and Gynecology

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“…The evaluation of IgM antibodies in the acute infection has been discussed since it still can be detected in chronic infection and there is a risk of false-positive results by cross-reactivity with antibodies, rheumatoid factor and other viral and bacterial diseases (Naot et al, 1981;Montoya, 2002;Bichara et al, 2012;Villard et al, 2012). In a study conducted by Dao et al (2003) comparing the reaction of IgM antibodies by ELISA and ISAGA in patients without clinical suspicion of infection by T. gondii, it was observed that 5 samples were positive in ELISA but none in ISAGA. The authors concluded that the different antigen compositions in solid phase reactions may have led to falsepositive results by ELISA (Dao et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…In a study conducted by Dao et al (2003) comparing the reaction of IgM antibodies by ELISA and ISAGA in patients without clinical suspicion of infection by T. gondii, it was observed that 5 samples were positive in ELISA but none in ISAGA. The authors concluded that the different antigen compositions in solid phase reactions may have led to falsepositive results by ELISA (Dao et al, 2003). The difference in the composition of the antigens of ELFA and ELISA kits may also have contributed to the difference finding in our study.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Serological and Molecular Tests Used for the Identification of Toxoplasma gondii Infection in Patients Treated in an Ophthalmology Clinic of a Public Health Service in São Paulo State, Brazil

Murata

Previato

Frederico

et al. 2020

Front. Cell. Infect. Microbiol.

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Ocular toxoplasmosis is one of the most common complications caused by the infection with the parasite Toxoplasma gondii. The risk of developing eye lesions and impaired vision is considered higher in Brazil than other countries. The clinical diagnosis is difficult and the use of sensitive and specific laboratorial methods can aid to the correct diagnosis of this infection. We compared serological methods ELISA and ELFA, and molecular cPCR, Nested PCR and qPCR for the diagnosis of T. gondii infection in groups of patients clinically evaluated with ocular diseases non-toxoplasma related (G1 = 185) and with lesions caused by toxoplasmosis (G2 = 164) in an Ophthalmology clinic in Brazil. Results were compared by the Kappa index, and sensitivity (S), specificity (E), positive predictive value (PPV), and negative (NPV) were calculated. Serologic methods were in agreement with ELISA more sensitive and ELFA more specific to characterize the acute and chronic infections while molecular methods were discrepant where qPCR presented higher sensitivity, however, lower specificity when compared to cPCR and Nested PCR.

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“…We employed chemical synthesis to obtain GPIs14 of defined structure and high purity that are suitable for biochemical assays and medical applications 15. This approach also excludes the possibility of false‐positive test results due to cross‐reactivity against impurities in T. gondii isolates 16. In order to elaborate diagnostic tools based on carbohydrate microarrays17 of GPI‐glycans, an orthogonal handle that ensures regioselective covalent attachment to a solid support was required.…”

Section: Methodsmentioning

confidence: 99%

Diagnosis of Toxoplasmosis Using a Synthetic Glycosylphosphatidylinositol Glycan

et al. 2014

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Around 2 billion people worldwide are infected with the apicomplexan parasite Toxoplasma gondii which induces a variety of medical conditions. For example, primary infection during pregnancy can result in fetal death or mental retardation of the child. Diagnosis of acute infections in pregnant women is challenging but crucially important as the drugs used to treat T. gondii infections are potentially harmful to the unborn child. Better, faster, more reliable, and cheaper means of diagnosis by using defined antigens for accurate serological tests are highly desirable. Synthetic pathogen-specific glycosylphosphatidylinositol (GPI) glycan antigens are diagnostic markers and have been used to distinguish between toxoplasmosis disease states using human sera.

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Unspecific Reactivity of IgM Directed Against the Low-Molecular-Weight Antigen of Toxoplasma gondii

Cited by 13 publications

References 17 publications

Commercial Laboratory IgM Testing for Toxoplasma gondii in Pregnancy: A 20‐Year Experience

Commercial Laboratory IgM Testing for Toxoplasma gondii in Pregnancy: A 20‐Year Experience

Evaluation of Serological and Molecular Tests Used for the Identification of Toxoplasma gondii Infection in Patients Treated in an Ophthalmology Clinic of a Public Health Service in São Paulo State, Brazil

Diagnosis of Toxoplasmosis Using a Synthetic Glycosylphosphatidylinositol Glycan

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