[Quality controls in medical mycology]. / Les contrôles de qualité en mycologie médicale.

The Quality Management System in medical mycology refers to the systematic monitoring with internal and external quality controls: it needs to be organized in the laboratory. ISO 15189 standard is not precise in how to demonstrate the correctness of tests, in terms of frequency and requirements for quality controls QC. That's why the COFRAC, the French Accreditation Committee has published guides to which we should refer. The laboratory has to apply internal Quality Control Programs. They consist of various tests to check the reagents including the culture media. Reference strains have to be provided and preparations of homemade reagents are needed, because few are commercialized. Maintaining the competence of the technical staff through identification of unknown strains is also required. In the fungal serology field, home made antibodies with pooled sera or antigen controls are needed. This monitoring has to follow the recommandations from the Cofrac technical guide LAB GTA 06. For quantitative analysis, the Levey-Jennings chart is a graph with quality control data plotted on to give a visual indication. Some external QC references, besides the national quality control AFSSAPS, are available. Data evaluation, corrective actions in case of out of range results and preventive actions have to be determined in the Quality System documents and presented in the annual management review.

Diagnosis of congenital toxoplasmosis: prenatal and neonatal evaluation of methods used in Toulouse University Hospital and incidence of congenital toxoplasmosis

The aim of this study was to determine the incidence of congenital toxoplasmosis (CT) and to assess the performances of prenatal and neonatal diagnoses. From 1994-2005, in Toulouse University Hospital, France, amniocentesis was performed on 352 pregnant women who were infected during pregnancy. All women were treated with spiramycin and pyrimethamine-sulfadoxine when prenatal diagnosis was positive. Among the 275 foetuses with follow-up, 66 (24 percent) were infected. The transmission rates of Toxoplasma gondii were 7 percent, 24 percent and 59 percent in the first, second and third trimesters, respectively. The sensitivity and specificity of PCR on amniotic fluid (AF) were 91 percent and 99.5 percent, respectively. One case was diagnosed by mouse inoculation with AF and six cases were diagnosed by neonatal or postnatal screening. The sensitivity and specificity of PCR on placentas were 52 percent and 99 percent, respectively. The sensitivity of tests for the detection of specific IgA and IgM in cord blood was 53 percent and 64 percent, respectively, and specificity values were 91 percent and 92 percent. In conclusion, PCR performed on AF had the highest levels of sensitivity and specificity for the diagnosis of CT. This permits an early diagnosis of most cases and should be recommended.

Prediction of congenital toxoplasmosis by polymerase chain reaction analysis of amniotic fluid.

OBJECTIVE: To determine the accuracy of polymerase chain reaction (PCR) analysis of amniotic fluid for fetal toxoplasmosis according to clinical predictors of outcome and study centre. DESIGN: Prospective cohort study. SETTING: Nine European centres. POPULATION: Women with suspected toxoplasma infection identified by prenatal screening. METHODS: Logistic regression was used to examine the effects of gestational age at maternal seroconversion, treatment and timing of amniocentesis, on PCR accuracy, and to calculate the post-test probability of congenital toxoplasmosis. MAIN OUTCOME MEASURES: Infants had congenital toxoplasmosis if specific IgG persisted beyond 11.5 months. Uninfected infants had undetectable IgG in the absence of anti-toxoplasma treatment. RESULTS: Of 593 PCR results, 64 were positive (57 confirmed infected), and 529 were negative (23 confirmed infected). The likelihood ratio for a positive PCR result decreased significantly with trimester at seroconversion, but did not change significantly for a negative result. Weak associations were detected between sensitivity and, inversely, with specificity, and gestational age at maternal seroconversion. There was no significant association between sensitivity and centre, type or duration of treatment, or timing of amniocentesis. Specificity differed significantly between centres (P < 0.001). The change in pre- to post-test probability of infection was maximal for a positive PCR after first trimester seroconversion, affecting 1% of women tested, and a negative PCR after third trimester seroconversion, affecting half the women tested. CONCLUSIONS: Prediction of the risk of congenital toxoplasmosis should combine estimates of test accuracy and maternal-fetal transmission, which take account of the gestational age at which the mother seroconverted. Local laboratory standards will affect the generalisability of these results.