Relatedness of <i>spa</i> types among hospital MRSA isolates.

<p>Relatedness computed using the Based Upon Repeat Pattern (BURP) algorithm. Clusters of linked <i>spa</i> types correspond to <i>spa</i> clonal complexes (<i>spa</i>-CC). <i>spa</i> types are clustered into a <i>spa</i>-CC when their repeat patterns differ by no more than 4 repeats. BURP sums up ‘costs’ (a measure of relatedness based on the repeat pattern) to define a founder-score for each <i>spa</i> type in a <i>spa</i>-CC. The founder (black node) is the <i>spa</i> type with the highest founder-score in its <i>spa</i>-CC, and the subfounder (dark gray node) is the <i>spa</i> type with the second highest founder-score. <i>spa</i>-CC008 has founder t008, and <i>spa</i>-CCNF refers to a <i>spa</i>-CC with no founder. Each node represents a <i>spa</i> type. Node size represents the number of clustered strains that belong to that <i>spa</i> type. The shading of the branches represents the ‘costs’ (similarities in repeat patterns) between two <i>spa</i> types; the darker the branch, the lower the cost (more similar repeat patterns).