Detection of Toxoplasma gondii in venous blood from AIDS patients by polymerase chain reaction

Abstract

Detection of Toxoplasma gondii in blood by means of the polymerase chain reaction (PCR) may facilitate the diagnosis and follow-up of cerebral toxoplasmosis in patients with AIDS. We evaluated this approach with seven patients with tissue culture-proven parasitemia, 14 patients with presumptive cerebral toxoplasmosis, and 17 healthy human immunodeficiency virus-positive controls. Each sample of blood was assayed on three different occasions by a PCR assay based on detection of the gene encoding the P30 surface protein. A positive PCR diagnosis required positivity in at least two of the three PCR tests. None of the controls had a positive PCR diagnosis, but six of the seven patients with parasitemia did. Cerebral toxoplasmosis was confirmed in 13 of the 14 patients with a presumptive diagnosis; diagnosis by PCR was positive before treatment for 9 of these 13 patients, whereas tissue culture was positive for only 1 patient. During treatment, blood samples were taken from 14 patients at regular intervals until day 12. PCR diagnosis became negative on ethidium-stained gels, but persistent signals were observed after hybridization, in some cases, for up to 12 days after initiation of therapy. PCR on venous blood could thus be a sensitive and noninvasive method for the diagnosis of cerebral and disseminated toxoplasmosis in AIDS patients and could be a potential tool for monitoring the effects of treatment.

Multicenter Comparative Evaluation of Five Commercial Methods for Toxoplasma DNA Extraction from Amniotic Fluid

“…Molecular methods play an important role in the microbiological diagnosis of infectious diseases due to their high sensitivity and specificity (1,5). Among these, PCR is now recognized as an essential diagnostic tool for congenital toxoplasmosis (1,8,11,19,20) as well as for toxoplasmosis in immunocompromised individuals (9,16) and ocular toxoplasmosis (22,26). Multicenter comparative evaluations have shown sensitivity differences in the PCR detection of Toxoplasma gondii in amniotic fluid (AF), especially when parasite loads were low (Ͻ10 T. gondii cells/ml [T/ml]) (2,14).…”

Screening for active toxoplasmosis in patients by DNA hybridization with the ABGTg7 probe in blood samples

“…Using blood samples isolated from subjects with ATL, Guy and Joynson (15) detected T. gondii parasitemia by PCR with B1 gene primer pairs in 53% of 17 ATL patients when the initial blood samples were collected within the first 5 weeks of illness. Dupuoy-Camet et al (10) obtained positive PCR results for blood samples from 9 of 14 patients with presumptive CT (68%) using P30 gene-derived primer pairs. Dupon et al (9) obtained positive PCR results for 10 of 13 CT patients (76.9%) using both CSF and blood samples and a ribosomal DNA sequence, but their data obtained in tests with blood showed only a 40% detection ability.…”

Prevalence and risk factors profile of seropositiveToxoplasmosis gondiiinfection among apparently immunocompetent Sudanese women

“…Though T. gondii parasite stay in a dormant stage called bradyzoites (3), the parasite transforms into an active form when the immune system becomes compromised which leads to the clinical manifestation that known as toxoplasmosis (4). Decreased immunity could be attributed to infections such as HIV (5, 6), disease e.g. fatty liver disease (7), or normal alterations in physiological response as in case of pregnancy (8–11), Congenital toxoplasmosis is another form of toxoplasmosis defined by the vertical transmission T. gondii tachyzoites parasite from an infected pregnant woman to a fetus through the placenta (12).…”