spa clonal complexes (spa-CCs) of S. aureus isolates in the prospective study. This figure demonstrates the clonal relatedness of all 50 spa types of the 2,319 S. aureus isolates from 14 CF patients during the study period (two CF centers). The analysis was performed using the BURP algorithm as implemented in the Ridom StaphType software (BURP, Ridom StaphType software; Ridom GmbH, Würzburg, Germany). The main founder spa type is shown in blue in the middle of each cluster. The size of each circle demonstrates the number of isolates with the respective spa type. Colored loops surrounding the circles indicate the patient with the respective spa type. For CC6 to CC9 isolates, the software could not determine a founder spa type, and therefore, the isolates with these respective spa types are presented as “no founder.” Eight spa types could not be related to other spa types and were therefore determined as “singletons.” t005, t084, t091, t267, t1204, t2202, t3127, and t13342 were singletons. spa types with less than five repeats were excluded, which resulted in the exclusion of one spa type (t463).