Polymerase chain reaction for diagnosis of cerebral toxoplasmosis in cerebrospinal fluid in HIV-positive patients.

It is important but sometimes difficult to establish a diagnosis of toxoplasma encephalitis (TE) in an HIV-positive immunodeficient patient. The most promising non-invasive method is polymerase chain reaction (PCR) for Toxoplasma gondii in cerebrospinal fluid (CSF). In a retrospective study PCR was used to analyse CSF for the presence of T. gondii DNA in 5 HIV-infected patients with a clinical suspicion of TE (group 1), 8 patients with other HIV-associated symptoms (group 2) and 7 other patients with neurological disorders (group 3). PCR was positive in 2/4 patients with a final diagnosis of TE and negative in all remaining patients in all 3 groups. The 2 patients with positive PCR had a fulminant course and experienced treatment failure. The albumin index was elevated in 4/5 patients in group 1, of whom 3/4 had a final diagnosis of TE, with suspected TE in 1. This small study confirms earlier data indicating that the PCR test has a low sensitivity but a high specificity.