Fig 1.

Minimum evolution tree of the concatenated sequences from the 29 sequence types (STs) comprising 195 N. gonorrhoeae isolates. The 5 lineages shaded in gray represent the major clonal complex identified in the population of N. gonorrhoeae isolates from Saskatchewan over the study period. The evolutionary history was inferred using the minimum evolution method (21). The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The minimum evolution tree was searched using the close-neighbor-interchange algorithm (18) at a search level of 1.