Accuracy of SRST2 allele calling at low read depths and with expanded MLST database size. MLST analysis of public S. aureus data. (N = 10 read sets; each sampled 100 times to different depths; details in Methods). Tests were grouped by read depth and accuracy rates (y-axis, correct allele calls as a proportion of all tests), calculated at each depth (x-axis, red slashes indicate scale change from 1 to 10). Red, real S. aureus MLST database; blue, expanded S. aureus MLST database (see Methods); grey, unsampled data from five species mapped to real databases (as shown in Figures 1 and 3).