FIG 2.

Principal component analysis of E. coli isolates of unknown sequence type. (A) PCA visualization of the E. coli MLST amplicon residual melt profile data from the ABI 7500 Fast PCR thermocycler using the open source R programming language. Data points represent a single run of one 96-well plate from the ABI 7500 Fast thermocycler containing both master reaction mixtures of 45 clinical isolates and 3 comparator ST131 E. coli isolates. Comparator E. coli isolates are indicated by asterisks. Isolates were grouped into clusters based on similarity of PCA profiles, and clusters were subsequently color coded. Black clusters are identified as ST131 isolates, while other colors indicate groups of unknown sequence types. (B) The three 2-D PCA plots for each master reaction mixture were combined into an interactive 3-D model to facilitate analysis. As in panel A, the black clusters represent ST131 E. coli isolates.