Dissimilar distribution of Trypanosoma cruzi clones in humans after chemotherapy with allopurinol and itraconazole

Abstract

Objectives: The aim of this work was to study the distribution of Trypanosoma cruzi clones after treatment failure with itraconazole or allopurinol in infected humans. Methods: Blood samples from treated and untreated individuals were used to detect T. cruzi by PCR assays and were confirmed by hybridization tests using total kinetoplast DNA as a universal probe. Also, xenodiagnosis (XD) tests were performed with Triatoma infestans fed from the same group of patients. We performed Southern-blot analyses of PCR products from blood or XD samples using a panel of four genotype-specific probes: corresponding to T. cruzi clones Tcl, Tcllb, Tclld and Tclle. The membranes were hybridized with radiolabelled probes and exposed in a Personal Molecular Imager.

Results: When comparing the presence of T. cruzi clones in the allopurinol-treated group with the non-treated group significant differences were only observed for XD samples. Clone TO was present in 9/13 (69.2%) of the XD samples of the treated group, but only in 8/27 (29.6%) in the non-treated group (P = 0.0178). When the itraconazole-treated group and the control group were compared, significant differences were found in both the blood and XD samples. In blood, the clone Tcllb was detected in 6/17(35.5%) of the treated group and in 18/27 (66.7%) of the non-treated group (P = 0.0207). When XD samples were analysed, the clone Tcl was observed in 14/17 (82.3%) of the itraconazole-treated group but only in 8/27 (29.6%) of the control group (P = 0.0006), which suggests resistance of this clone to itraconazole.

Conclusions: We detected a dissimilar distribution of T. cruzi clones in treated and untreated groups of patients. The presence of Tcl increased in patients treated with allopurinol and itraconazole, whereas the presence of Tcllb decreased in itraconazole-treated patients. The type of T. cruzi clone that prevails suggests that Tcl is resistant to both drugs and that Tcllb is susceptible to itraconazole.