The risk of HCV RNA contamination in serology screening instruments with a fixed needle for sample transfer.

Background: Hepatitis C diagnostics involve antibody screening and confirmation of current infection by detection of HCV RNA positivity. In screening instruments with fixed pipetting needle, there is a risk of sample carry-over contamination.

Objectives: The aim of this study was to evaluate the risk of such contamination in a proposed clinical setting.

Study Design: In the present study, known HCV RNA positive (n=149) and negative (n=149) samples were analysed by anti-HCV Abbott in an Architect instrument in an alternating fashion in order to test for contamination.

Results: In subsequent retesting of the previously HCV RNA-negative samples, six samples (4%) were positive by the Cobas Taqman assay with a maximum level of 33 IU/mL. The results show that there is a risk for transfer of HCV in the Architect instrument but they also show that the levels of HCV RNA observed are low.

Conclusions: We conclude that complementary HCV RNA testing on samples identified as anti-HCV positive by screening can be recommended because the complementary results are reliable in the majority of cases when either HCV RNA is negative or HCV RNA is positive with a level >1000 IU/mL. In a minority of cases, with low HCV RNA after anti-HCV antibody screening, cross-contamination should be suspected and a new sample requested for HCV RNA testing. This strategy would reduce the need for obtaining a new sample from the vast majority of patients with a newly discovered HCV antibody positivity.