Journal of Clinical Microbiology, November 1999, p. 3465-3468, Vol. 37, No. 11
0095-1137/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Servicio de
Microbiología1 and Servicio de
Oftalmología,
Received 4 March 1999/Returned for modification 4 June
1999/Accepted 13 July 1999
Toxoplasma gondii infection is an important cause of
chorioretinitis in the United States and Europe. Most cases of
Toxoplasma chorioretinitis result from congenital
infection. Patients are often asymptomatic during life, with a peak
incidence of symptomatic illness in the second and third decades of
life. Diagnosis is mainly supported by ophthalmological examination and
a good response to installed therapy. However, establishment of a
diagnosis by ophthalmological examination alone can be difficult in
some cases. To determine the diagnostic value of PCR for the detection
of T. gondii, 56 blood and 56 aqueous humor samples from 56 immunocompetent patients were examined. Fifteen patients with a
diagnosis of ocular toxoplasmosis had increased serum anti-T.
gondii immunoglobulin G levels but were negative for
anti-T. gondii immunoglobulin M (group 1), and 41 patients
were used as controls (group 2). Samples were taken before
antiparasitic therapy was initiated, and only one blood sample and one
aqueous humor sample were obtained for each patient. Single nested PCRs
and Southern blot hybridization were performed with DNA extracted from
these samples. The results obtained showed sensitivity and specificity
values of 53.3 and 83%, respectively. Interestingly, among all
patients with ocular toxoplasmosis, a positive PCR result with the
aqueous humor sample was accompanied by a positive PCR result with the
blood sample. This result suggests that ocular toxoplasmosis should not
be considered a local event, as PCR testing of blood samples from
patients with ocular toxoplasmosis yielded the same result as PCR
testing of aqueous humor samples. PCR testing may be useful for
discriminating between ocular toxoplasmosis and other ocular diseases,
and also can avoid the problems associated with ocular puncture.
*
Corresponding author. Mailing address: Servicio de
Microbiología, Hospital Ramón y Cajal, Crta. Colmenar
Viejo Km 9,1, 28034 Madrid, Spain. Phone: 34-1-3368082. Fax:
34-1-3368809. E-mail: germanbou{at}mailcity.com.
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