POLYMERASE CHAIN-REACTION FOR TOXOPLASMA-GONDII DNA IN THE CEREBROSPINAL-FLUID OF AIDS PATIENTS WITH FOCAL BRAIN-LESIONS

Objective: To study the accuracy of polymerase chain reaction (PCR) fo r Toxoplasma gondii DNA in the cerebrospinal fluid (CSF) of AIDS patie nts for the diagnosis of T. gondii encephalitis. Patients: Eighty-two AIDS patients with brain lesions. At autopsy, 19 patients (group A) ha d toxoplasmic encephalitis and 33 (group B) primary brain lymphoma or other infections. Brain histology was not available for 30 patients; c erebral lesions improved after anti-Toxoplasma therapy in 16 (group C) , but there was no improvement in 14 patients (group D). Methods: T. g ondii RH strain was serially diluted in microplate wells. After heat d enaturation, nested PCR was performed on diluted tachyzoites and on 10 mu l CSF with primers flanking the B1 repetitive region of T. gondii genome. Results: DNA from one to five tachyzoites was detected in each experiment. PCR was positive in eight (42.1%) out of 19 group A sampl es, none of the group B samples, 10 (62.5%) out of 16 group C samples and none of the group D samples. Among group A and C patients, PCR was positive in all 11, and in seven out of 24 (29.1%; P < 0.04) patients who had received anti-Toxoplasma therapy for less or more than 1 week at the time of rachicentesis, respectively. Conclusions: Nested PCR f or T. gondii in CSF may improve early differential diagnosis of AIDS-a ssociated focal brain lesions. Higher diagnostic accuracy was achieved when lumbar puncture was performed in the first week of anti-Toxoplas ma therapy.