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Preventing contamination of PCR-based multiplex assays including the use of a dedicated biosafety cabinet
A Bouam1,2, J J Vincent3, M Drancourt2,3
1POCRAMé, Marseille, France.
Abstract:
We retrospectively investigated cases of false-positive diagnoses using the BIOFIRE® FilmArray® 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 (9·17%) 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 (2·63%) in POC-A and 1/36 (2·77%) in POC-B (P = 0·97); during period 2, false positives were detected in 0/139 CSF (0%) in POC-A and 1/38 (2·63%) in POC-B (P = 0·23). 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 = 0·05). 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.
Insights
Implementing a dedicated biosafety cabinet and preventive measures significantly reduced false-positive results from the BIOFIRE® FilmArray® meningitis/encephalitis (ME) panel. This improvement minimizes diagnostic errors in infectious disease testing.
Area of Science:
- Clinical Microbiology
- Infectious Disease Diagnostics
- Laboratory Science
Background:
- The BIOFIRE® FilmArray® meningitis/encephalitis (ME) panel is a multiplex PCR assay for diagnosing central nervous system infections.
- Pre-analytical contamination can lead to false-positive results, impacting patient management and healthcare costs.
- Reducing false positives is crucial for accurate and efficient infectious disease diagnosis.
Purpose of the Study:
- To evaluate the impact of a dedicated biosafety cabinet and preventive measures on reducing false-positive results from the BIOFIRE® FilmArray® ME panel.
- To assess the prevalence of false-positive diagnoses in cerebrospinal fluid (CSF) samples.
- To determine the effectiveness of specific laboratory workflow modifications in improving diagnostic accuracy.
Main Methods:
- Retrospective investigation of 327 CSF samples analyzed over 16 weeks across two point-of-care sites (POC-A and POC-B).
- Comparison of false-positive rates between a standard laminar flow hood (period 1) and a dedicated biosafety cabinet without airflow (period 2).
- Identification of false positives through clinical data review, biological parameters, and cytology of discrepant CSF samples.
Main Results:
- A total of 30 (9.17%) samples showed pathogen detection, with 70% viruses and 30% bacteria.
- During period 1, false positives were detected in 2.63% (POC-A) and 2.77% (POC-B) of CSF samples.
- During period 2, the implementation of a dedicated biosafety cabinet in POC-A significantly reduced false positives to 0% (P=0.05), while POC-B maintained a rate of 2.63%.
Conclusions:
- The use of a dedicated biosafety cabinet, coupled with preventive measures, effectively mitigates pre-analytical contamination and reduces false-positive results in multiplex PCR assays.
- These findings demonstrate a practical strategy to enhance the reliability of the BIOFIRE® FilmArray® ME panel and similar diagnostic tools.
- Implementing targeted laboratory controls is essential for improving the accuracy of infectious disease diagnostics.
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