Detecting laboratory DNA contamination using polyester-rayon wipes: a method validation study

Area of Science:

• Molecular Biology
• Laboratory Science

Background:

• Polymerase chain reaction (PCR) assays are highly sensitive and prone to false positives from extraneous DNA.
• Laboratory surface sampling using gauze wipes is a common method to detect environmental DNA contamination.

Purpose of the Study:

• To evaluate the performance of a gauze wipe method for detecting extraneous DNA on laboratory surfaces.
• To assess the accuracy, precision, limit of detection, linearity, and robustness of the wipe test method and its processing steps.

Main Methods:

• The study utilized E. coli genomic DNA to quantify the performance of the wipe test method.
• Key performance parameters including limit of detection and recovery efficiency were analyzed.
• Robustness was tested through deliberate protocol modifications.

Main Results:

• The wipe test method achieved a limit of detection of 10^8 DNA copies, corresponding to 4.5x10^5 copies/area sampled.
• A significant DNA loss (>58%) was observed during the wipe wash step, leading to a low recovery efficiency of 22±10%.
• The method demonstrated robustness, maintaining consistent performance despite protocol variations.

Conclusions:

• The gauze wipe method is robust for detecting extraneous DNA on laboratory surfaces.
• Significant DNA loss during the wash step limits the method's accuracy and necessitates protocol optimization for improved recovery.