Variation in pulsed-field Patterns of USA100 MRSA. N1 Number of isolates included in the PFT (pulsed-field type) including control strains. Figure 1 Pulsed-field gel electrophoresis classified the majority of the USA100 strains to PFTs 1 (24 isolates including the control strain USA100/NRS382) and PFT 6 (20 isolates). Representative strains for each of the six spa types are shown included three isolates which possessed known repeats but not known repeat patterns and therefore could not be typed (unknown unkA-C). The two typing techniques were not always in agreement as demonstrated by isolates CBD0707 and CBD1031 which possess the same pulsed-field type (Chambers 2005) but different spa types (151 and unkC).