[Retrospective evaluation of the detection of Toxoplasma gondii by polymerase chain reaction in AIDS patients].

OBJECTIVES

We retrospectively evaluated routine detection of Toxoplasma gondii by polymerase chain reaction (PCR) amplification of the B1 gene and the TGR 1E sequence in blood and CSF samples from patients with acquired immune deficiency syndrome (AIDS) and suspected toxoplasmosis.

METHODS

From January 1993 to February 1994, 93 blood, 33 cerebrospinal fluid (CSF) and 1 aqueous humor samples were obtained from 83 HIV-positive patients with CD4 counts under 200/mm3 and suspected toxoplasmosis.

RESULTS

Authentic cerebral toxoplasmosis was confirmed by response to specific treatment in 18/29 patients with typical focal brain lesions. Blood samples were available in 17/18 and CSF in 6. PCR was positive for both B1 and TGR (23.5% sensitivity, 100% specificity) in 4/17 blood samples and for either B1 or TGF (58.9% sensitivity, 72.7% specificity) in 10/18. PCR of CSF was positive in only 1/6 patients with cerebral toxoplasmosis. PCR (TGR 1E only) was positive in 3/11 blood samples and in one CSF sample from patients without cerebral toxoplasmosis. Five out of 21 patients with diffuse neurologic symptoms and presumed HIV encephalitis had positive Toxoplasma detection in blood or CSF. However, no clinical improvement was obtained after specific antitoxoplasmic therapy. Two out of 38 patients with unexplained fever with or without pneumonia had a proven disseminated toxoplasmosis. These two patients had PCR-positive blood samples. One of them was cured by a specific anti-toxoplasmic treatment and the other died two days later. Seven other patients had a positive PCR result in blood or CSF. Three of them improved with specific treatment and 2 died before treatment could be initiated. The one patient with toxoplasmic retinitis was PCR-positive both in blood and aqueous humor.

CONCLUSION

PCR detection of Toxoplasma gondii appears to add little to the diagnosis of cerebral toxoplasmosis but could be helpful in the diagnosis of cerebral toxoplasmosis associated with extracerebral reactivation and in disseminated toxoplasmosis.