Table 1. Evaluation of selection acting upon genes associated with MexXY- and MexAB-OprM efflux systems of P. aeruginosa.
| Gene | p0 | p1 | p2 = 1 − p0 − p1 | ΔLRT | p | |
|---|---|---|---|---|---|---|
| oprM | p | 0.996 | 0.001 | 0.003 | 0.000 | 1.000 |
| ω | 0.010 | 1.000 | 1.000 | |||
| mexA | p | 1.000 | 0.000 | 0.000 | 0.000 | 1.000 |
| ω | 0.005 | 1.000 | 1.000 | |||
| mexB | p | 0.989 | 0.000 | 0.011 | 2.677 | 0.102 |
| ω | 0.004 | 1.000 | 1.000 | |||
| mexX | p | 0.971 | 0.014 | 0.015 | 3.631 | 0.057 |
| ω | 0.023 | 1.000 | 1.000 | |||
| mexY | p | 0.316 | 0.636 | 0.048 | 170.230 | <0.001 |
| ω | 0.000 | 1.000 | 17.849 |
A bioinformatics approach tested whether data from published P. aeruginosa genomes showed conservation among oprM, mexAB and mexXY genes. p: proportion of variable sites assigned to each class in the selection model, ω: the overall dN/dS ratio for the variable sites which fit into each site class for each alignment. Selection models P0: purifying selection, P1: neutral selection: P2: positive selection. ΔLRT: the difference in likelihood ratios between fixed and estimated ω values and associated p value for the presence of positive selection.