The clinical significance of culturing Toxoplasma gondii on blood and other organic media

BACKGROUND: The aim of this study was to determine the value of the Toxoplasma gondii culture in blood and in other organic fluids in HIV positive and negative patients. METHODS: Retrospective analysis (October 1990-May 1992) was carried out including all patients with positive cultures for T. gondii admitted to the Hospital Central of Asturias. The parasite was identified by monoclonal antibodies against the tachyzoite membrane. All patients with positive cultures were treated with pyrimethamine and sulphadiazine. RESULTS: Three hundred two samples from 256 patients, seropositive and seronegative for HIV, were analyzed. Of the seropositive group 8/45 (18%) had positive cultures for T. gondii versus 9/211 (4.3%) of the seronegative group (p = 0.002). Of the 19 positive samples, 15 were from blood, 3 from bronchoalveolar lavage and one from the vitreous fluid. Four out of 9 patients (44%) with AIDS and encephalic toxoplasmosis (ET) had blood cultures positive for T. gondii. Another 4 patients with AIDS presented toxoplasmenia without visceral involvement. Of the 9 HIV seronegative patients (3 immunodepressed patients), 4 had pulmonary toxoplasmosis, one ocular toxoplasmosis, and other clinical forms of toxoplasmosis were seen in the remaining 4. All the patients evolved to cure except 2 cases coinfected by cytomegalovirus who died. CONCLUSIONS: The identification of Toxoplasma gondii may be performed by blood cultures in half of the patients with AIDS and encephalic toxoplasmosis and in an undetermined percentage of the other clinical forms both in immunocompetent and immunodepressed subjects. In addition, toxoplasmemia has been registered in AIDS patients preceding any other organic seating of the parasite. Early antitoxoplasma therapy may, therefore, be effective.