Limited value of PCR for detection of Toxoplasma gondii in blood from human immunodeficiency virus-infected patients

Abstract

Cerebral toxoplasmosis is a common, opportunistic, and often life-threatening disease in HIV-infected patients. Diagnosis is supported mainly by clinical evidence and computerized tomography or magnetic resonance imaging scans, but brain images may share features with other brain diseases occurring in HIVinfected patients. To determine the diagnostic value of PCR for the detection of Toxoplasma gondii in blood from HIV-infected patients, we examined 89 blood samples from 59 HIV-infected patients. PCR and Southern blot hybridization were done with DNA extracted from blood samples from 20 patients with confirmed cerebral toxoplasmosis and from 10 patients with suspected but not confirmed cerebral toxoplasmosis. The samples were taken before and 7 to 10 days after the beginning of antiparasitic therapy. For 9 patients who suffered from cerebral toxoplasmosis more than 6 months prior to the study and for 20 patients without any evidence for toxoplasmosis only one blood sample per patient was examined. PCR gave positive results with 5 of the 20 blood samples from patients who suffered from cerebral toxoplasmosis. After 7 to 10 days of therapy PCR results became negative in all these five cases. No amplification was seen with DNA from blood samples from the other 54 patients as the target. The results presented here show that PCR testing of blood samples from HIV-infected patients is of limited value for the diagnosis of cerebral toxoplasmosis. The sensitivity was only 25%, but the specificity was very high (100%), so this technique may be useful for discriminating between cerebral toxoplasmosis and other brain diseases which may be mistaken for toxoplasmosis.

Detection of Toxoplasma Gondii Dna and Specific Antibodies in High-Risk Pregnant Women

“…1 Although adultacquired toxoplasmosis is usually mild to asymptomatic, the disease can be severe in the immunocopromised, leading to encephalitis. 2 In addition, the influence of sex-and pregnancyassociated hormones on the severity of T. gondii infection is of particular public health interest due to the ability of this parasite to cause congenital disease if infection occurs during pregnancy. 3 In a study of non-homosexual, human immunodeficiency virus (HIV)−positive Europeans, toxoplasmic encephalitis was found to be a more frequent acquired immunodeficiency syndrome−defining disease in females than in males.…”

Value of PCR for Detection of Toxoplasma gondii in Aqueous Humor and Blood Samples from Immunocompetent Patients with Ocular Toxoplasmosis

“…Those investigators detected T. gondii DNA by PCR in the blood of 9 of 13 patients (69%) with confirmed cerebral toxoplasmosis (6). Moreover, other studies (5,7,8,11) showed sensitivity values of tests with blood of between 10 and 35%. An important question is this: Why was the T. gondii PCR positive with blood from 53% of the patients with reactivated congenital corioretinitis in our study?…”

Guidelines for the diagnosis and management of neurological complications of HIV infection

“…In clinical practice most patients with mass lesion(s) are given two weeks of treatment anyway (including patients with negative serology or a single lesion). Cerebrospinal fluid (CSF) studies, including antibody studies and polymerase chain reaction (PCR) studies, have not produced conclusive results (Franzen et al. , 1997).…”