Microscopy vs. molecular biology in the diagnosis of intestinal protozoal infections, is it time for a change?

Abstract

Introduction. Microscopic examination of the intestinal parasites, from the patient’s concentrated feces, has a lower sensitivity when compared to molecular diagnostic techniques. Therefore, the objective of this study has been to compare both techniques, as well as to evaluate whether there is a correlation between the microscopic examination and the threshold cycles (Ct) obtained for Blastocystis hominis. Material and methods. Retrospective study of the samples received in the Microbiology laboratory during September 2021. The MiniParasep SF® concentration test was performed for microscopic visualization and then PCR was performed with the Seegene AllplexTM Parasite Assay panel. Results. A 27% (n=74) of the samples were positive by molecular diagnosis, with a total of 87 parasites detected. 53% (n=39) were women with a mean age of 47 ± 24 years. In 76% (n=56) of the cases the service of origin was Primary Care. The most frequently found parasite was B. hominis, 85% (n=64), followed by Dientamoeba fragilis 20% (n=15) and Giardia lamblia 11% (n=8). Co-infection by two parasites was detected in 13 cases (B. hominis + D. fragilis in 6 cases, and B. hominis + G. lamblia in 7 cases). In the microscopic diagnosis, 9.5% (n=26) positivity was obtained. The most frequently found parasite was B. hominis, 84% (n=23), followed by G. lamblia, which was seen in three cases by microscopy. D. fragilis was not seen in any case. Coinfection of B. hominis + G. lamblia was observed in one sample. Conclusions. Techniques for molecular diagnosis of intestinal parasites are fast, reliable and more sensitive than microscopic techniques, improving microbiological diagnosis and quality of care.

Técnicas de biología molecular aplicada al diagnóstico de laboratorio de múltiples enfermedades

“…Referencia País Enfermedad Prueba utilizada Hallazgos (Fernández et al, 2023) España Parasitosis Panel Setene AllplexTM Parasite Assay.…”

“…El campo de la biología molecular en la actualidad permite diagnosticar múltiples enfermedades como es el caso del estudio dado por (Fernández et al, 2023) en donde se realizó una comparación entre el examen microscópico para diagnosticar parasitosis intestinales con las técnicas de diagnóstico molecular. En los resultados se observó que en el diagnóstico microscópico se obtuvo un 9,5% (n=26) de positividad.…”

Molecular diagnosis of intestinal protozoa in young adults and their pets in Colombia, South America

“…histolytica , this is similar to other studies in Colombia and other countries using PCR to detect E . histolytica and reporting very little or no detection of the pathogen (0%- 0.39%) [ 37 , 57 , 58 , 68 ]. Worldwide trends reveal a decline in Entamoeba infections although a high burden is still seen in some age groups and low-income regions [ 69 ].…”