Diagnosis of Toxoplasma gondii infection in AIDS patients by a tissue-culture technique.

Toxoplasma gondii infection was investigated in 14 AIDS patients with neurological involvement who showed clinical and computer tomographic scan signs suggestive of toxoplasmic encephalitis or extraneuronal localization suggestive of toxoplasmic infection. Blood, lung secretion (bronchoalveolar lavage and/or induced sputum sample) and cerebral spinal fluid (CSF) samples were cultured, and the results compared with the results of direct examination by Giemsa and by immunofluorescence of lung secretions and CSF. Toxoplasma gondii were observed directly in only four patients by immunofluorescence in bronchoalveolar lavage, induced sputum and CSF samples, and in three of these patients by Giemsa staining of bronchoalveolar lavage and CSF smears. In contrast, parasites were detected after 48 h in blood cultures from 11 of the 14 AIDS patients, in CSF cultures from eight of them and also in cultures of bronchoalveolar lavage and induced sputum from the six patients with respiratory and radiological features indicative of lung tissue damage. The findings indicate the value of tissue culture for diagnosis of toxoplasmosis as well as for monitoring the effects of treatment and also indicate that culture of induced sputum could be a powerful tool in establishing the incidence of pulmonary toxoplasmosis in AIDS patients.