Multicentric comparative assessment of the bio-evolution Toxoplasma gondii detection kit with eight laboratory-developed PCR assays for molecular diagnosis of congenital toxoplasmosis.

The detection of Toxoplasma gondii in amniotic fluid is an essential tool for the prenatal diagnosis of congenital toxoplasmosis and is currently essentially based on the use of PCR. Although some consensus is emerging, this molecular diagnosis suffers from a lack of standardization and an extreme diversity of laboratory-developed methods. Commercial kits for the detection of T. gondii by PCR were recently developed and offer certain advantages; however, they must be assessed in comparison with optimized reference PCR assays. The present multicentric study aimed to compare the performances of the Bio-Evolution T. gondii detection kit and laboratory-developed PCR assays set up in eight proficient centers in France. The study compared 157 amniotic fluid samples and found concordances of 99% and 100% using 76 T. gondii-infected samples and 81 uninfected samples, respectively. Moreover, taking into account the classification of the European Research Network on Congenital Toxoplasmosis, the overall diagnostic sensitivity of all assays was identical and calculated to be 86% (54/63); specificity was 100% for all assays. Finally, the relative quantification results were in good agreement between the kit and the laboratory-developed assays. The good performances of this commercial kit are probably in part linked to the use of a number of good practices: detection in multiplicate, amplification of the repetitive DNA target rep529, and the use of an internal control for the detection of PCR inhibitors. The only drawbacks noted at the time of the study were the absence of uracil-N-glycosylase and small defects in the reliability of the production of different reagents.

[Confirmation by PCR of the existence in Tunisia of Entamoeba histolytica and Entamoeba dispar]. / Confirmation par l'amplification genique de l'existence en Tunisie des deux especes : Entamoeba histolytica ET entamoeba dispar.

AIM: Amibias are illness in Tunisia diagnosed until now on the sole basis of the morphological aspects of the parasite. Our aim is to report the first Tunisian results concerning the molecular identification of E. histolytica/E. dispar, METHODS: 25 stools presenting cysts and/or vegetative shapes of E. histolytica/E. dispar were gathered at the "Laboratoire de Parasitologie Hôpital La Rabta Tunis" between 2001and 2004 for PCR. The stools came from 24 subjects, one of them having two samples: 9 Tunisian patients, 5 adressed to the hospital services for abdominal pains or diarrheas and 4 adressed for a systemic tracking (food manipulation), and 15 foreign students for which a tracking is done each fall. RESULTS: The identification showed thus for the Tunisian patients the presence of : E. histolytica alone for a patient (food manipulator) 11%. E. histolytica associated to E. dispar for two patients 22%. E. dispar alone for six patients 67%. Nearly similar results has been obtained for foreign student's samples: E. histolytica alone in one case (7%), E. histolytica associated to E. dispar in four cases (26%) and E. dispar alone in 10 cases (67%). CONCLUSION: These results show therefore the existence in Tunisia the two species E. histolytica and E. dispar for symptomatic or non symptomatic patients. The distinction between the two species is very important on the therapeutic level as well as the epidemiologic and public health level.