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

Abstract 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.