Comparison of respiratory virus shedding by conventional and molecular testing methods in patients with haematological malignancy.

Respiratory viruses (RV) are a leading cause of infection-related morbidity and mortality for patients undergoing treatment for cancer. This analysis compared duration of RV shedding as detected by culture and PCR among patients in a high-risk oncology setting (adult patients with haematological malignancy and/or stem cell transplant and all paediatric oncology patients) and determined risk factors for extended shedding. RV infections due to influenza virus, parainfluenza virus (PIV), human metapneumovirus (HMPV) and respiratory syncytial virus (RSV) from two study periods-January 2009-September 2011 (culture-based testing) and September 2011-April 2013 (PCR-based testing)-were reviewed retrospectively. Data were collected from patients in whom re-testing for viral clearance was carried out within 5-30 days after the most recent test. During the study period 456 patients were diagnosed with RV infection, 265 by PCR and 191 by culture. The median range for duration of shedding (days) by culture and PCR, respectively, were as follows-influenza virus: 13 days (5-38 days) versus 14 days (5-58 days), p 0.5; RSV: 11 days (5-35 days) versus 16 days (5-50 days), p 0.001; PIV: 9 days (5-41 days) versus 17 days (5-45 days), p ≤0.0001; HMPV 10.5 days (5-29 days) versus 14 days (5-42 days), p 0.2. In multivariable analysis, age and underlying disease or transplant were not independently associated with extended shedding regardless of testing method. In high-risk oncology settings for respiratory illness due to RSV and PIV, the virus is detectable by PCR for a longer period of time than by culture and extended shedding is observed.