This study aimed to evaluate the use of conventional polymerase chain reaction (cPCR)
and real-time quantitative PCR (qPCR) in the diagnosis of human strongyloidiasis from
stool samples in tropical areas. Stool samples were collected from individuals and
were determined to be positive for Strongyloides stercoralis (group I), negative for
S. stercoralis (group II) and positive for other enteroparasite species (group III).
DNA specific to S. stercoralis was found in 76.7% of group I samples by cPCR and in
90% of group I samples by qPCR. The results show that molecular methods can be used
as alternative tools for detecting S. stercoralis in human stool samples in tropical
areas.
SUMMARYStrongyloidiasis is a potentially serious infection in immunocompromised patients.
Thus, the availability of sensitive and specific diagnostic methods is desirable,
especially in the context of immunosuppressed patients in whom the diagnosis and
treatment of strongyloidiasis is of utmost importance. In this study, serological and
molecular tools were used to diagnose Strongyloides stercoralis
infections in immunosuppressed patients. Serum and stool samples were obtained from
52 patients. Stool samples were first analyzed by Lutz, Rugai, and Agar plate culture
methods, and then by a quantitative real time polymerase chain reaction (qPCR). Serum
samples were evaluated by an enzyme-linked immunosorbent assay (ELISA) using a
soluble (AS) or a membrane fractions antigen (AM) obtained from alkaline solutions of
the filariform larvae of Strongyloides venezuelensis. Of the 52
immunosuppressed patients, three (5.8%) were positive for S.
stercoralis by parasitological methods, compared to two patients (3.8%)
and one patient (1.9%) who were detected by ELISA using the AS and the AM antigens,
respectively. S. stercoralis DNA was amplified in seven (13.5%)
stool samples by qPCR. These results suggest the utility of qPCR as an alternative
diagnostic tool for the diagnosis of S. stercoralis infection in
immunocompromised patients, considering the possible severity of this helminthiasis
in this group of patients.
Complementary examinations of the parasitological method demonstrated excellent results in the context of the diagnosis of strongyloidiasis, especially in asymptomatic patients with irregular larval release in the feces.
Strongyloidiasis can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection, principally in immunosuppressed patients. Our study aimed to evaluate the application of conventional polymerase chain reaction (cPCR) and real-time PCR (qPCR). Polymerase chain reaction (PCR) and real-time PCR (qPCR) targeting the 18S rRNA gene for detection of Strongyloides stercoralis infection among transplant candidates were applied in stool samples obtained from 150 transplant candidates, preliminarily analyzed by parasitological methods. S. stercoralis larvae were visualized in 15/150 (10.0%) transplant candidates by parasitological methods. DNA from S. stercoralis was amplified in 26/150 (17.3%) and 49/150 (32.7%) stool samples of transplant candidates, using cPCR and qPCR, respectively. The results suggest that molecular methods, especially qPCR, should be used as an additional tool for diagnostic of S. stercoralis infection among transplant candidates.
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