Purpose: The study sought to determine the accuracy, limit of detection, limit of quantification, and linearity of up to 4 sample bacterial species on the rapid instrument. All tests were performed in an independent ISO17025-certified test laboratory and compared to FDA BAM equivalent methods for Aerobic Plate Count (APC).
Methods: Parallel tests were performed on the rapid instrument and standard plate counting methods. All samples were single ATCC bacterial strain inocula into Tryptic Soy Broth (TSB). The strains used were E. coli 25922, L. innocua 33090, P. aeruginosa 10145, and S. aureus 25923. Serial dilutions for a single strain or a cocktail of strains from 10⁷ CFU to 101 CFU in 5 replicates where made and the results tabulated for each performance parameter.
Results: Accuracy of a 4-strain cocktail compared to standard plating methods was found to be above 90%. There was a coefficient of linearity of (R²) = 0.9533. The limit of detection for P. aeruginosa was 0.87 CFU/ml and the same organism gave limit of quantification of 8.7 CFU/ml, both over the range 2 to 7 log CFU/ml.
Significance: The results reveal that this rapid system can be used at very low levels of detection when classical enumeration methods are ineffective. Therefore, the system can enhance quality control by correctly flagging more positives while reducing time-to-result.