AWWA WQTC71354

The U.S. Environmental Protection Agency (USEPA) recently conducted an interlaboratory validation study of a quantitative polymerase chain reaction (qPCR) method for Helicobacter pylori to characterize method performance across multiple laboratories and drinking water matrices, evaluate reproducibility, and to develop quantitative quality control (QC) acceptance criteria. Five volunteer participant laboratories and a referee laboratory participated in the study. Each laboratory spiked drinking water and reagent-grade water samples with referee-prepared Helicobacter pylori (H. pylori) cells and/or BioBalls-KS10 containing thirty cells of Escherichia coli (E. coli) with a modified H. pylori DNA fragment in a single copy plasmid. Mean laboratory-specific recoveries of H. pylori from reagent-grade water spiked with referee-prepared H. pylori and BioBalls-KS10 was 219% and 303% for 15 and 100 H. pylori cells, respectively. In addition, each laboratory also spiked and analyzed the same drinking water matrix from each of three different sites. For drinking water from Site 1 that was spiked with 15 H. pylori cells or 100 H. pylori cells, overall mean recoveries were 255% and 230%, respectively; and, overall median recoveries were 99% and 68%, respectively. Mean overall recoveries of H. pylori from Site 2 drinking water spiked with 15 H. pylori cells or 100 H. pylori cells were 39% and 122%, respectively; and, overall median recoveries were 21% and 17%, respectively. For drinking water from Site 3 spiked with 15 H. pylori cells or 100 H. pylori cells, overall mean recoveries of H. pylori were 119% and 154%; and, overall median recoveries were 30% and 74%, respectively. Includes tables.