Genotyping of Toxoplasma gondii strains isolated from immunocompromised patients.

The genotypes of Toxoplasma gondii strains isolated from HIV and non-HIV im munocompromised patients with cerebral and extracerebral toxoplasmosis were determined and compared to those of strains isolated from non-immunocompro mised patients in order to identify the possible relationships between para site genotype and morbidity of toxoplasmosis. One hundred and ten strains o f T. gondii were obtained, either by cell culture (n = 73), brain biopsy (n = 17) or mouse inoculation (n = 20). Ninety strains isolated from immunoco mpromised patients (74 HIV+ and 16 non-HIV patients) were compared to 20 st rains isolated from immunocompetent patients (17 cases of congenital toxopl asmosis, and three cases of primary acquired infection). Genotyping was per formed by PCR/RFLP on locus SAG2 and T. gondii strains were classified as T ype I, II or III. Ninety out of 110 strains were successfully genotyped, in cluding 20 strains that had been maintained in mice, 69/73 strains maintain ed in cell cultures, but only 1/17 strains from formalin-fixed paraffin-emb edded brain biopsies. 76.7% of the strains in the study population were of type II, 15.6% were type I and 7.7% were type III. The distribution of stra in genotypes in immunocompromised and non-immunocompromised patients was co mparable: 14.1% and 21% for type I, 76.1% and 79% for type II and 9.8% and 0% for type III, respectively; no correlation could be established between genotype and clinical presentation, i.e., cerebral or extracerebral toxopla smosis. These results suggest that the type of infecting parasitic strain d oes not predominantly influence the pathogenesis of toxoplasmosis in immuno compromised patients and fully supports the need for specific prophylaxis i n patients infected by T. gondii, regardless of the strain genotype. (C) 20 00 Editions scientifiques et medicales Elsevier SAS.