Fig. 4.

Phylogeny of DHFRs from K. pneumoniae strains and other members of the family Enterobacteriaceae. The strain name abbreviations used are defined in Table 2, footnote a. Clades of genes encoding a DHFR that is either trimethoprim sensitive (folA) or resistant (dfrA19) are labeled. Phylogenetic reconstruction was done using MrBayes (18, 48), as well as PROTDIST and NEIGHBOR from the PHYLIP package (11a) (tree shown). Nodes supported by >70% of 1,000 bootstrap replicates and posterior Bayesian probabilities of ≥0.95 are marked by asterisks. The scale bar represents an estimated 0.01 amino acid substitution per site.