Hemocultures for the parasitological diagnosis of human chronic Chagas' disease

Abstract

With the purpose of standardization of an hemoculture technique presenting a higher positive rate in the parasitological diagnosis of chronic Chagas' disease in patients with reactive serology (IFT, HA, CFT) the following schedule was used. Thirty ml of venous blood was collected with heparin and the plasma was separated by centrifugation (2.000 rpm/30'). The packed cells were washed with LIT medium or PBS which was then removed by centrifugation (2.000 rpm/15'). This material was sampled in 6 screw-tubes 18 x 200 with 6 ml of LIT medium and incubated at 28 degrees C. These incubated cultures at 28 degrees C were examined after 15, 30, 45 and 60 days. When the hemoculture was not immediately processed after blood collection, the plasma was removed and the sediment enriched with LIT medium and preserved at 4 degrees C. The Xenodiagnosis was performed according to Schenone's method used here as a reference technique. Among the various groups of patients examined by both techniques the best results obtained were: 55.08% of positivity for hemocultures against 27.5% for xenodiagnosis (X2 = 4.54, p = 0.05), with a tube positivity of 26.6%. Recommendation for screening trials of drug assays is the repetition of method on a same patient 2 or more times in different occasions, as used in xenodiagnosis.

Trypanosoma cruzi: inhibition of alpha-hydroxyacid dehydrogenase isozyme II by N-allyl and N-propyl oxamates and their effects on intact epimastigotes

“…Organism -T. cruzi stock Nayarit strain was isolated from Triatoma picturata captured in the state of Nayarit, Mexico. Faeces of infected bugs were inoculated intraperitoneally, into laboratory mice and cardiac blood was cultured subsequently on either enriched biphasic bloodagar medium or the monophasic liquid medium, liver infusion tryptone broth (LIT) supplemented with 10% heatinactivated fetal calf serum (Chiari et al 1989). Epimastigotes of T. cruzi Nayarit strain were cultivated in the monophasic medium.…”

Cytokine serum levels in patients infected by human immunodeficiency virus with and without Trypanosoma cruzi coinfection

“…Hemoculture was done according to methods previously described 3 . Thirty ml of blood was centrifuged at 4 o C to remove the plasma.…”

Combined parasitological and molecular-based diagnostic tools improve the detection of Trypanosoma cruzi in single peripheral blood samples from patients with Chagas disease

“…In this phase, detection of the parasite is rare due to subpatent and transient parasitemia. Approximately 60-70% of individuals will never develop apparent disease and are characterized as indeterminate; these patients present positive serologic reactivity for T. cruzi, which can sometimes be identified by hemoculture, xenodiagnoses, and polymerase chain reaction (PCR) [4][5][6][7] . Patients within this clinical form present normal 12-lead electrocardiogram (ECG) results, as well as normal radiological examinations of the chest, esophagus, and colon [8][9][10][11] .…”

“…During the acute phase, parasitological methods should be prioritized due to the high number of trypomastigotes in peripheral circulation. In the chronic phase, T. cruzi can only be detected from a limited number of patients by parasitological methods, such as xenodiagnosis or blood culture 4,[20][21][22][23] . Therefore, the development of additional molecular methods is necessary for parasite detection in patients with unclear serology and for better evaluation of the roles of specific trypanocidal treatments in patients with established Chagas' cardiomyopathy [24][25][26] .…”