Évaluation de deux trousses commerciales EIA pour le diagnostic de l’hépatite C dans les conditions d’un laboratoire de virologie

A Recent Human Immunodeficiency Virus Outbreak Among People Who Inject Drugs in Munich, Germany, Is Associated With Consumption of Synthetic Cathinones

Background

Needle and syringe sharing among people who inject drugs (PWID) can result in a rapid regional spread of a human immunodeficiency virus (HIV) variant. Such outbreaks have been identified recently in several countries and have raised public health attention because of an association with new psychoactive substances (NPS).

Methods

Dried serum spots from approximately 60% of newly diagnosed HIV cases in Germany in 2013–2018 were received together with statutory notification data. Samples were sequenced in the pol-region, genotyped, and viral phylogenies were analyzed. For selected samples, the hepatitis C virus (HCV) status and the presence of NPS were determined.

Results

An outbreak of closely related 27 subtype C infections with a core of 11 cases with almost identical sequences was identified using phylogenetic analyses. The first case of the outbreak was diagnosed in 2015, and the last one was in 2018. With exception of 3 infections, all were reported from Munich, the capital of the federal state of Bavaria. Of 26 analyzed outbreak members, 24 (92.3%) had a resolved or viremic HCV coinfection. In 8 of 18 (44%) cases, α-pyrrolidinopentiothiophenone and/or the related substance α-pyrrolidinoheptiophenone was identified.

Conclusions

Despite harm reduction services in place, HIV outbreaks of considerable size can occur in PWID. The establishment of a real-time molecular surveillance is advised to rapidly identify outbreaks and target prevention measures.

Validation of a strategy for HCV antibody testing with two enzyme immunoassays in a routine clinical laboratory

BACKGROUND

Centers for Disease Control (CDC) guidelines require confirmation of hepatitis C virus (HCV) screening-test-positive sera with a low signal/cut-off (S/CO) ratio by recombinant immunoblot or PCR. The UK Health Protection Agency has suggested that a second enzyme immunoassay (EIA) could be used as an alternative for confirmation in non-immunocompromised patients.

OBJECTIVE

To evaluate the UK HPA approach in 17,936 consecutive in-house sera submitted for HCV testing.

STUDY DESIGN

AxSYM-positive sera (S/CO> or =1.0) were tested with Monolisa Plus. AxSYM-positive sera of patients that were confirmed PCR-positive were considered HCV+. All other AxSYM-positive sera were confirmed with immunoblot according to CDC guidelines.

RESULTS

17,299 sera were negative with AxSYM. Of the 637 AxSYM-positive sera, 384 were from patients confirmed as PCR-positive. Of other 250 sera, 120 were negative with immunoblot, 103 were positive and 30 were indeterminate. All 30 immunoblot-indeterminate sera were PCR-negative. Two patients were Monolisa Plus+ and immunoblot- and PCR-. One patient was known as immunoblot-, while the other patient was diagnosed with non-A non-B hepatitis in 1980s. Nine sera from HCV-positive patients were Monolisa Plus-. Two PCR- sera were from immunocompetent patients who were PCR- for > or =8 years and six PCR- sera and one PCR+ serum were from immunocompromised patients. Sensitivity and specificity of confirmation with Monolisa Plus were 98.15% and 98.33% and the positive and negative predictive values were 99.58% and 92.91% in AxSYM-positive sera (excluding immunoblot-indeterminate/PCR-negative sera). If immunocompromised patients that were false-negative were excluded, sensitivity was 99.58%.

CONCLUSION

Monolisa Plus can be used as an alternative to immunoblot for the confirmation of AxSYM-positive sera.

[Development of a Web-based Program to Calculate Sample Size for Evaluating the Performance of In Vitro Diagnostic Kits.]

BACKGROUND

Many studies evaluating the performance of in vitro diagnostic kits have been criticized for the lack of reliability. To attain reliability those evaluation studies should be preceded by sample size calculation ensuring statistical power. This study was intended to develop a web-based system to estimate the sample size, which was often neglected because it would require expert knowledge in statistics.

METHODS

For sample size calculation, we extracted essential parameters from the performance studies on the 3rd generation anti-hepatitis C virus (HCV) kits reported in the literature. We developed a system with PHP web-script language and MySQL. The statistical models used in this system were as follows; one sample without power consideration (model 1), one sample with power consideration (model 2), and two samples with power consideration (model 3).

RESULTS

Among the articles published between 1989 and 2005, 13 articles that evaluated the performance of anti-HCV kits were identified by searching with Medical Subject Headings (MeSH). The diagnostic sensitivity was 83-100% with a median of 145 samples (range; 12-1,091) and the specificity was 97-100% with a median of 1,025 samples (range; 33-4,381). The estimated sample size would be 280 in the model 1, 817 in the model 2, and 1,510 in the model 3, when we set 2% prevalence of HCV infection, 95% sensitivity of a conventional kit, 97% sensitivity of a new kit , 95% significance level (two-sided test), 2% allowable error, and 80% power.

CONCLUSIONS

Our study indicates that an insufficient sample size is still a problem in performance evaluation. Our system should be helpful in increasing the reliability of performance evaluation by providing an appropriate sample size.

[Hepatitis C virus screening: performances characteristics of a commercial automated chemiluminescent microparticle immunoassay (CMIA-ARCHITECT anti-HCV)]

OBJECTIVES

In spite of improvement of the third-generation enzyme immunoassay (EIA) for screening HCV antibodies, some non-specific reactions persist. With commercialisation of a new chemiluminescence microparticle immunoassay (CMIA), we assessed the specificity of 2 assays providing by Abbott Diagnostics: CMIA-ARCHITECT anti-HCV and MEIA-AxSYM HCV 3.0 for qualitative detection of HCV antibodies in serum sample of patients collected in CHU of Caen.

PATIENTS AND METHODS

Anti-HCV results of 9753 serum samples tested by MEIA-AxSYM V.3 (2004), 6135 tested by CMIA-ARCHITECT1 (April to December 2005) and 5598 tested by CMIA-ARCHITECT2 (February to August 2006) were retrospectively analysed. Prevalences were calculated according to S/C ratio. The serum samples with an average S/C ratio from 1 to 2 for CMIA-ARCHITECT2 were confirmed with an immunoblot assay (Chiron RIBA HCV 3.0 SIA).

RESULTS

The CMIA-ARCHITECT assays showed a strong discrimination between negative and positive samples. We observed a tiny distribution of negative results. The percentage of "low positive" was respectively 1.26% for the MEIA-AxSYM, 0.68% for the CMIA-ARCHITECT1 and 0.36% for the CMIA-ARCHITECT2. Thirty-three of 54 (61%) samples yielding S/C ratio between 1 and 2 in the initial screening analysis with the CMIA-ARCHITECT1 were tested negative with CMIA-ARCHITECT2. Among the 21 remaining, 62% of RIBA results were interpretable.

CONCLUSION

CMIA-ARCHITECT assays improve the anti-HCV screening with a decrease of low-positive reactivity. However, low-positive results persist for which it is difficult to distinguish false-positive from low titer of antibodies. Supplemental assays such as immunoblot can be recommended in particularly context to more improve specificity and HCV-RNA detection should exclude a seroconversion.