FIG. 1.
Dendrogram based on similarity of PFGE patterns. Isolates shaded in gray (n = 8) make up a branch of the dendrogram representing related K. pneumoniae isolates that have disseminated in the Midwestern United States, thus far identified in Illinois, Missouri, and now Michigan. The other isolates (n = 20) were selected to represent the CDC's PFGE database of KPC-producing K. pneumoniae, consisting of over 400 isolates, primarily of ST 258. KPC subtyping was determined via bidirectional sequencing of the blaKPC gene by using previously described primers (13). MLST results marked with an asterisk indicate isolates that were not typed by MLST but demonstrated PFGE patterns closely related to those of known ST 14 isolates.