Utility of molecular and serodiagnostic tools in cerebral toxoplasmosis with and without tuberculous meningitis in AIDS patients: A study from South India

Abstract

Background:Antemortem diagnosis of cerebral toxoplasmosis, the second most common opportunistic infection (OI) in HIV-infected individuals in developing countries is a challenge.Materials and Methods:Toxoplasma gondii (T.gondii) -specific serology and nested polymerase chain reaction (nPCR) were evaluated in sera and ventricular/lumbar cerebrospinal fluid (CSF) of 22 autopsy confirmed cases of cerebral toxoplasmosis with HIV and 17 controls. Frequency of concomitant T.gondii infection was investigated in 17 cases of HIV-associated tuberculous meningitis (TBM).Results:The sensitivity, specificity, and positive and negative predictive values of T. gondii IgG on CSF (ventricular and lumbar) and sera was 100% in histology proven cerebral toxoplasmosis (concentrations: 258 ± 50, 231 ± 36, and 646 ± 243 IU/mL, respectively); majority (94%) being high avidity type, suggesting reactivation/reinfection. The sensitivity of B1 nPCR was 100% on ventricular CSF, whereas it was only 77% on lumbar CSF. Based on histology, nPCR, and IgG serology, T. gondii co-infection with TBM was observed in 65% (11/17) of cases.Discussion and Conclusion:CSF IgG serology and nPCR are tests with high sensitivity and specificity for the diagnosis of cerebral toxoplasmosis. TBM and cerebral toxoplasmosis can coexist and should be considered in the background of HIV infection in developing countries.

Usefulness of stereotactic biopsy and neuroimaging in management of HIV-1 Clade C associated focal brain lesions with special focus on cerebral toxoplasmosis

“…In an earlier study from our Centre, we found serological tests for toxoplasmosis to be valuable for diagnosis especially when lumbar puncture is contraindicated as a diagnostic procedure [23]. …”

Diagnosis of cerebral toxoplasmosis

“… The negative controls were from cases of road traffic accident (RTA) victims who were tested for toxoplasmosis. [ 2 ] These cases on testing were found to be negative for toxoplasmosis—it was not a deliberate selection. The cerebrospinal fluid samples from RTA cases are not collected at autopsy as the sample is usually contaminated with blood and will not be an ideal sample, to test.…”

“…The serum IgG titers in the patients of group I (cases of confirmed central nervous system [CNS] toxoplasmosis) ranged from 196 to 1016 IU/mL [Table 2]. [ 2 ] We do agree that the mean serum IgG titers in our study were very high (646 IU/mL) since they were all terminally ill cases; however, a serum IgG titer of >200 IU/mL is considered positive in recrudescence cases indicating active disease and is useful in the antemortem diagnosis of CNS toxoplasmosis. [ 4 ] Our findings are in agreement with this observation indicated in literature.…”

“…gondii -specific IgG), although this has not been reiterated in our article. [ 2 ] A study from Mumbai in HIV-positive patients with a clinical diagnosis of cerebral toxoplasmosis also showed a mean serum IgG titer of 250 IU/mL. [ 5 ] Lumbar puncture is often contraindicated in the clinical setting of cerebral toxoplasmosis with multiple intracranial lesions with perilesional edema.…”

“…This aspect has been discussed in the manuscript. [ 2 ] Early cases of cerebral toxoplasmosis are often not recognized as they remain subclinical. We used the term cerebral toxoplasmosis to denote patients with clinical manifestations of an encephalitic process of variable degree.…”