Due to the high precision and discriminatory power of this method
as well as wide variety of the spa types, today, several online
sites are designed to identify the S. aureus type, such
as NCBI and spa Ridom type.
However, one of the problems in these methods is need
for sequencing, which is expensive. In addition, in this
typing method, only X region of the spa gene is considered,
and other changes are forgotten, especially in the
antibody binding site. Therefore, in this study, we sought
to replace the X sequencing using PCR-RFLP (polymerase
chain reaction restriction fragment-length polymorphism)
method for the spa typing (6).
PCR-RFLP of spa for tracking and typing methicillin-resistant
S. aureus (MRSA) was proposed in 2005 by Mitani
(7). Different Enzymes, especially HaeII, have been used
for this purpose; but in this study, we digested the spa
gene product with Bsp143I enzyme. The OLIGO software
version 5 was applied to detect the restriction sites of this
enzyme on the spa gene. The restriction sites are outside
of the X region and digest the GATC sequence. In wild
type isolates, there are at least three restriction sites and
we can find four bands in electrophoresis, according to
the standard S. aureus strain 8325.