Comparison of sensitivity and specificity of 4 methods for detection of Giardia duodenalis in feces: immunofluorescence and PCR are superior to microscopy of concentrated iodine-stained samples
| Autor: | Eskild Petersen, Mogens Erlandsen, Helle Gotfred-Rasmussen, Heidi L. Enemark, Marianne Lund |
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| Rok vydání: | 2016 |
| Předmět: |
Giardiasis
0301 basic medicine Microbiology (medical) Immunofluorescence 030106 microbiology 030231 tropical medicine Fluorescent Antibody Technique chemistry.chemical_element Biology Real-Time Polymerase Chain Reaction Diagnostic methods Iodine Polymerase Chain Reaction Sensitivity and Specificity Microbiology law.invention Feces 03 medical and health sciences 0302 clinical medicine law parasitic diseases medicine Humans Polymerase chain reaction Human feces Microscopy medicine.diagnostic_test Giardia Reproducibility of Results General Medicine biology.organism_classification PCR Infectious Diseases CpG site chemistry biology.protein Giardia lamblia Antibody |
| Zdroj: | Gotfred-Rasmussen, H, Lund, M, Enemark, H L, Erlandsen, M & Petersen, E 2016, ' Comparison of sensitivity and specificity of 4 methods for detection of Giardia duodenalis in feces : immunofluorescence and PCR are superior to microscopy of concentrated iodine-stained samples ', Diagnostic Microbiology and Infectious Disease, vol. 84, no. 3, pp. 187-90 . https://doi.org/10.1016/j.diagmicrobio.2015.11.005 |
| ISSN: | 0732-8893 |
| Popis: | For decades, microscopy of feces after formol-ethylacetate (FEA) concentration and iodine staining has been the routine test for intestinal protozoa. Lately, polymerase chain reaction or fluorescence-labeled parasite-specific antibodies have been introduced, but their place in everyday routine diagnostics has not yet been established. We compared FEA and salt–sugar flotation (SSF) concentration followed by microscopy of iodine-stained concentrate and immunofluorescence assay (IFA) and real-time polymerase chain reaction (qPCR) for detection of Giardia duodenalis in human feces. The median number of Giardia cysts found by FEA in 19 Giardia-positive samples was 50 cysts per gram (CPG), by SSF 350 CPG, by IFA 76,700 CPG, and by qPCR 316,000 CPG. We next tested 455 consecutive samples for presence of Giardia cysts. Using IFA as reference, qPCR had a sensitivity of 91%, specificity of 95.1%, a false-positive rate of 50%, a false-negative rate of 0.48%, a positive predictive value of 50%, and a negative predictive value of 99.5%. In conclusion, qPCR and IFA were significantly more sensitive than microscopy of iodine-stained concentrates using either FEA or SSF. We suggest, when using qPCR, that positive samples are verified by IFA to prevent false-positive results. |
| Databáze: | OpenAIRE |
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