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Journal of Clinical Microbiology, March 2006, p. 720-724, Vol. 44, No. 3
0095-1137/06/$08.00+0     doi:10.1128/JCM.44.3.720-724.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Comparison between Two Amplification Sets for Molecular Diagnosis of Toxoplasmosis by Real-Time PCR

S. Cassaing,^1* M. H. Bessières,¹ A. Berry,¹ A. Berrebi,² R. Fabre,¹ and J. F. Magnaval¹

Service de Parasitologie-Mycologie, Centre Hospitalier Rangueil, Toulouse, France,¹ Service de Gynécologie-Obtétrique, Hôpital Paule de Viguier, Toulouse, France²

Received 15 September 2005/ Returned for modification 11 October 2005/ Accepted 8 December 2005

PCR is now commonly applied to the diagnosis of toxoplasmosis. Although several methods are available, comparative studies are few, making it difficult to compare the performance of each technique. We compared the sensitivities of two real-time PCR assays through a prospective study on fetuses, neonates, and immunocompromised patients and on the ocular diagnosis of toxoplasmosis. The first system targeted the widely used B1 gene (GenBank accession number AF179871) while the second (RE) targeted a more recently described sequence repeated roughly 200 to 300 times (GenBank accession number AF146527). We demonstrated that molecular diagnosis requires the duplication of PCR assays, especially with the B1 system, as only one PCR was positive in 33.3% of cases. Our study showed that the RE target was more sensitive for all biological samples (amniotic fluid, placenta, aqueous humor, whole blood, and cerebrospinal and bronchoalveolar fluids) and significantly improved the performance of the diagnosis of toxoplasmosis. Taking into consideration all clinical samples, the mean gain in the crossing point value was 4.2 ± 1.7 cycles and was even more significant for amniotic fluid (5.8 ± 1.7 cycles).

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* Corresponding author. Mailing address: Service de Parasitologie-Mycologie, Centre Hospitalier Universitaire Rangueil, TSA 50032, 31059 Toulouse cedex 9, France. Phone: 33-5-61-32-28-92. Fax: 33-5-61-32-20-96. E-mail: cassaing.s{at}chu-toulouse.fr.

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Journal of Clinical Microbiology, March 2006, p. 720-724, Vol. 44, No. 3
0095-1137/06/$08.00+0     doi:10.1128/JCM.44.3.720-724.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

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