LAUSR

To evaluate comparative efficiency of traditional vs automated colony counting methods, cultures of Escherichia coli (ATCC 25945), Staphylococcus epidermidis (ATCC 12225), Streptococcus pyogenes (ATCC19615) and Streptococcus pneumoniae (ATCC49619) were prepared as pure cultures and mixed cultures at 0·5 McFarland standard and serial dilutions were performed. Plates were inoculated in triplicate with 50, 125, 250 and 500 colony forming units and counted by four researchers, visually and using each of the automated counters. Colony count and counting time were recorded. The pattern of efficiency for all bacterial species was similar: plates with low counts were accurate and quick to count for all methods, with an increase in time and a decrease in accuracy and precision as counts rose. Higher counts of single round colonies required less time and had greater precision with automated counters than human visual counting counts with no loss of accuracy; however, counts were reduced in accuracy and increased in time for species with less regular morphology or when plates had mixed species. Surprisingly, a free phone application was only slightly less precise and more time consuming than the high‐end professional counter indicating that automation may be achievable at lower cost than expected.