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To investigate whether the polymerase chain reaction (PCR) on the BI gene of Toxoplasma gondii could contribute to the diagnosis of cerebral toxoplasmosis in patients with AIDS, we retrospectively tested CSF samples from 20 patients with AIDS suspected of having cerebral toxoplasmosis for the presence of T. gondii. Suspicion of cerebral toxoplasmosis was based on accepted criteria. Nine patients with AIDS with IgG antibodies to T. gondii but who were not suspected of having cerebral toxoplasmosis and four patients with AIDS seronegative for T. gondii served as negative control patients. T. gondii was demonstrated by PCR in the CSF from 13 of the 20 patients with AIDS suspected of having cerebral toxoplasmosis but was not demonstrated in the CSF samples from the nine control patients seropositive for T. gondii and the four control patients seronegative for T. gondii. The data were statistically evaluated. This study shows the value of PCR for the detection of T. gondii in CSF for the diagnosis of cerebral toxoplasmosis in patients with AIDS. [ABSTRACT FROM PUBLISHER]

The aim of the present study was to determine the in-vitro susceptibility of Toxoplasma gondii to dihydrofolate rcductase inhibitors and sulphonamides alone, and in combination. It was found that pyrimethamine had the most potent anti-Toxoplasma activity, while sulphadiazine, sulphamethoxazole and sul-phametrole were approximately equally effective, but only at a high concentration. The 50% inhibitory concentration of sulphamethoxazole was determined using different fixed concentrations of pyrimethamine or trimethoprim. It was found that a ten-fold increment of the concentration of pyrimethamine, reduced the IC50 of sulphamethoxazole 1000 times. The influence of trimethoprim on the IC50 of sulphamethoxazole was less concentration dependent. Addition of dihydrofolate or tetrahydrofolate did not influence the IC50 of pyrimethamine. In conclusion, the present dose recommendations for sulphonamides, when combined with pyrimethamine, may be unnecessarily high. There may be a justification for dose reduction of sulphonamides in order to prevent side effects. [ABSTRACT FROM PUBLISHER]