Issa SY

Assistant research scientist @ the Institute of Medical Microbiology and Hygiene in Homburg-Saar


Assistant research scientist at the Institute of Medical Microbiology and Hygiene in Homburg-Saar, Germany. I held a Master of Science in Clinical and Environmental Microbiology from the University of Lorraine in Nancy, France. My current research pertains to the identification of helminths of medical and veterinary importance using MALDI-TOF MS.

Identification of Trematodes species using MALDI-TOF MS

Routine diagnosis of parasites relies on macroscopic identification of adult worms in infected tissue of slaughtered animals, and microscopic detection of eggs in faecal samples of animals and humans.

However, the diagnostic accuracy of morphological techniques and stool microscopy is low. Molecular diagnostics (e.g., polymerase chain reaction (PCR)) are more reliable, but these techniques are not routinely available in clinical microbiology laboratories. During the past decades, Matrix-assisted laser/desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has been a widely used technique for identification of bacteria, fungi and yeast; yet, standardized protocols and databases for parasite detection need to be developed. The purpose of this study was to develop and validate an in-house database for species-specific identification of Trematodes species. To achieve this goal, the posterior parts of seven adult F. gigantica, one adult F. hepatica and 10 eggs of F. gigantica were processed and subjected to MALDI-TOF MS to create main spectra profiles (MSPs). As well, S. mansoni paired larvae (male+female) were also assessed with 1 MSP created from one paired larvae samples isolated from mice. Repeatability and reproducibility tests were performed to develop the database. A principal component analysis revealed significant differences between the spectra of F. gigantica and F. hepatica. Subsequently, 128 adults and 22 eggs of Fasciola, and 7 larvae of Schistosoma samples were analyzed by MALDI-TOF MS using the previously developed database, out of which 98.7% (n = 74),100% (n = 3) and 100% (n=7) were correctly identified as F. gigantica, F. hepatica and S. mansoni, respectively. Log score values ranged between 1.73 and 2.40, thus indicating a reliable identification. We conclude that MALDI-TOF MS can provide species-specific identification of medically relevant trematodes species.

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