The Brief Case: False-Positive Rapid Malaria Antigen Test Result in a Returned Traveler

PURPOSE The Truquant BR radioimmunoassay (RIA) (Biomira Diagnostics Inc, Rexdale, Canada) uses the monoclonal antibody B27.29 to quantitate the MUC-1 gene product (CA 27.29 antigen) in serum. We evaluated CA 27.29 antigen in a controlled, prospective clinical trial for its ability to predict relapse in stage II and stage III breast cancer patients. PATIENTS AND METHODS Over a 2-year period, 166 patients who had completed therapy for stage II (80.1%) or III (19.9%) breast cancer and were clinically free of disease were serially tested for CA 27.29 antigen levels. The study was double-masked and cancer recurrence was documented based on clinical findings. Patients with two consecutive CA 27.29 antigen test results above the upper limit of normal were considered positive. RESULTS The Truquant BR RIA had a sensitivity of 57.7%, specificity of 97.9%, positive predictive value of 83.3%, and negative predictive value of 92.6%. The recurrence rate was 15.7%. A Cox regression analysis showed that the only variable to correlate with recurrent disease was the CA 27.29 antigen test result. Patients with a positive test result had increased odds of having a recurrence (odds ratio, 6.8; P < .00001). The test was effective in predicting recurrence in patients with both distant and locoregional disease. In a subgroup of patients with bone pain, CA 27.29 antigen level was found to identify reliably patients who would subsequently develop recurrent disease. CONCLUSION These data demonstrate that the Truquant BR RIA can be used as an aid to predict recurrent breast cancer in patients with stage II and III disease.

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Rapid Diagnosis of Vivax Malaria by the SD Bioline Malaria Antigen Test When Thrombocytopenia Is Present

Journal of Clinical Microbiology ◽

10.1128/jcm.02110-07 ◽

2007 ◽

Vol 46 (3) ◽

pp. 939-942 ◽

Cited By ~ 13

Author(s):

S. W. Lee ◽

K. Jeon ◽

B. R. Jeon ◽

I. Park

Keyword(s):

Vivax Malaria ◽

Rapid Diagnosis ◽

Antigen Test ◽

Malaria Antigen

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Likely False-Positive Pneumococcal Antigen Test BinaxNOW Due to Parvimonas micra

CHEST Journal ◽

10.1016/j.chest.2017.12.026 ◽

2018 ◽

Vol 153 (4) ◽

pp. e71-e73 ◽

Cited By ~ 2

Author(s):

Marie-Caroline Ploton ◽

Marion Caseris ◽

Christelle Jost ◽

Yoann Picard ◽

Jean Gaschignard ◽

...

Keyword(s):

False Positive ◽

Antigen Test ◽

Parvimonas Micra ◽

Pneumococcal Antigen

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False positive antigen test for Dirofilaria immitis after heat treatment of the blood sample in a microfilaremic dog infected with Acanthocheilonema dracunculoides

Parasites & Vectors ◽

10.1186/s13071-020-04376-9 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Viktor Szatmári ◽

Martin Willem van Leeuwen ◽

Christine Jantine Piek ◽

Luigi Venco

Keyword(s):

Heat Treatment ◽

Blood Sample ◽

Real Time ◽

Real Time Pcr ◽

False Positive ◽

Dirofilaria Immitis ◽

False Negative ◽

Correct Identification ◽

Test Results ◽

Antigen Test

Abstract Background Dirofilaria immitis is responsible for heartworm disease in dogs in endemic areas worldwide. Screening for this infection is done by blood tests. Antigen testing is the most sensitive method to detect an infection with adult (female) worms. Microscopic examination of a blood smear or Knott’s test can be used to detect circulating microfilariae, the infective larvae. To increase the sensitivity of the antigen test by decreasing the false negative test results, heating of the blood sample has been recommended in recent guidelines. Heating is believed to remove blocking immune-complexes. Circulating microfilariae are not specific findings for heartworm infection, as other nematodes (among others, Acanthocheilonema dracunculoides) can also result in microfilaremia. Although the type of microfilariae cannot be determined by microscopy alone, real-time PCR can reliably identify the infecting nematode species. Correct identification of the parasite is of major importance, as an infection with D. immitis requires antiparasitic therapy, whereas A. dracunculoides is thought to be a clinically irrelevant coincidental finding. The present case report describes a microfilaremic dog where the initial antigen test for D. immitis turned positive after heat treatment, whereas real-time PCR revealed that the microfilariae were A. dracunculoides (syn. Dipetalonema dracunculoides). Results A circa 5-year old, asymptomatic Spanish mastiff dog was referred for heartworm therapy because microfilariae were found via a screening blood test. The dog was recently imported to the Netherlands from Spain, where it had been a stray dog. Antigen tests on a plasma sample for D. immitis were performed with three different test kits, which all turned out to be negative. However, heat treatment of two of these samples were carried out and both of them led to a positive antigen test result. Real-time PCR showed that the circulating microfilariae belonged to A. dracunculoides species. Three administrations of moxidectin spot-on at monthly intervals resulted in a negative antigen and a negative Knott’s tests one month after the last treatment. Conclusions We conclude that heat treatment of initially negative blood samples for D. immitis could lead to false positive antigen test results if the dog is infected with A. dracunculoides.

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Investigation of interference by nonsteroidal anti-inflammatory drugs in urine tests for abused drugs

Clinical Chemistry ◽

10.1093/clinchem/36.4.602 ◽

1990 ◽

Vol 36 (4) ◽

pp. 602-606 ◽

Cited By ~ 34

Author(s):

D E Rollins ◽

T A Jennison ◽

G Jones

Keyword(s):

False Positive ◽

Drugs Of Abuse ◽

Fluorescence Polarization Immunoassay ◽

Dosage Regimens ◽

Chronic Ingestion ◽

Inflammatory Drugs ◽

Anti Inflammatory ◽

Abused Drugs ◽

Positive Results ◽

Test Result

Abstract Anecdotal and uncontrolled studies have suggested that nonsteroidal anti-inflammatory drugs produce false-positive results in immunoassay urine tests for some drugs of abuse. This study was performed in 60 volunteers who took ibuprofen as either a single 400-mg dose, or 200 mg three times a day, or 400 mg three times a day, and in 42 patients taking ibuprofen, naproxyn, or fenoprofen in therapeutic regimens for more than 30 days. Of the 510 urines collected from 102 individuals during these dosage regimens, two gave false-positive tests for cannabinoid by enzyme-mediated immunoassay (EMIA), one after 1200 mg of ibuprofen in three divided doses for one day and one in a patient taking naproxyn on a chronic basis; none was falsely positive for benzodiazepines. Two urines were false-positive for barbiturates by fluorescence polarization immunoassay (FPIA), one in a patient taking ibuprofen and one in a patient taking naproxyn. These data, collected prospectively, demonstrate the small likelihood of a false-positive immunoassay test result for cannabinoids, benzodiazepines, or barbiturates after the acute or chronic ingestion of ibuprofen, or after the chronic ingestion of naproxyn or fenoprofen.

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