Preventing contamination of PCR-based multiplex assays including the use of a dedicated biosafety cabinet
Résumé
We retrospectively investigated cases of false-positive diagnoses using the BIOFIRE (R) FilmArray (R) meningitis/encephalitis (ME) panel to measure the impact of using a dedicated biosafety cabinet combined with preventive measures to reduce the prevalence of false-positive diagnoses due to pre-analytical in-laboratory contamination. False-positive results were identified by reviewing clinical data, biological parameters and cytology results of cerebrospinal fluid (CSF) samples showing discrepant results between the FilmArray ME panel and routine PCR assays. A total of 327 CSF were analysed over 16 weeks in point-of-care (POC) A and B, over two 8-week periods, periods 1 and 2. The analysis yielded 30 (9 center dot 17%) detection of at least one pathogen including 21/30 (70%) viruses and 9/30 (30%) bacteria. During period 1, POC-A and POC-B manipulated CSF under a non-dedicated hood featuring laminar flow, whereas during period 2, CSFs were manipulated under a dedicated biosafety cabinet without any airflow in POC-A. During period 1, false positives were detected in 3/114 CSF (2 center dot 63%) in POC-A and 1/36 (2 center dot 77%) in POC-B (P = 0 center dot 97); during period 2, false positives were detected in 0/139 CSF (0%) in POC-A and 1/38 (2 center dot 63%) in POC-B (P = 0 center dot 23). All false positives were bacterial. The use of a dedicated cabinet without ventilation along with preventive measures during period 2 in POC-A significantly reduced the number of false-positive results (P = 0 center dot 05). Preventive measures described in this study can mitigate false positives when using PCR-based multiplex assays such as the BIOFIRE FilmArray ME Panel for the diagnosis of meningitis and other infectious diseases.