Molecular identification of a causative parasite species using formalin-fixed paraffin embedded (FFPE) tissues of a complicated human pulmonary sparganosis case without decisive clinical diagnosis

PCR-based molecular diagnosis was made for the identification of causative agents of the clinically suspected pulmonary proliferative sparganosis case found in Thailand using formalin-fixed paraffin-embedded (FFPE) biopsy specimens. As a reference, FFPE biopsy specimen from a typical cutaneous sparganosis case was examined together. DNA samples were extracted from tissues and two partial fragments of cytochrome c oxidase subunit 1 (cox1) gene were amplified for the detection of Spirometra DNA. Two cox1 fragments were amplified successfully for both specimens. After alignment of nucleotide sequences of the PCR-amplicons, the causative agents of both cases were identified as Spirometra erinaceieuropaei.

Graphical abstractMolecular diagnosis was made for Spirometra erinaceieuropaei plerocercoids in the paraffin block of two sparganosis patients in Thailand. After alignment of the nucleotide sequences of the two fragments of PCR-amplified cox1 gene against known sequences of S. erinaceieuropaei (AB369251, AB369249, AB015754, AB369250 and AB374543) and Sparganum proliferum (AB015753), both cases were found to be S. erinaceieuropaei.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► PCR-based diagnosis was applied for clinically suspected pulmonary proliferative sparganosis case. ► As the reference, the worm obtained from the typical cutaneous sparganosis case was used. ► DNA samples were extracted successfully from the paraffin block of biopsied worm preserved for over 15 years. ► Two partial fragments of cox1 gene of Spirometra species were amplified and shown as S. erinaceieuropaei in both cases. ► It can be applied for old formalin-fixed paraffin embedded tissues by an appropriate selection of target genes and primers.