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Objective Staphylococcus aureus (S.aureus) are common organism causing wide variety of infections, ranging from minor skin infection, staphylococcus scalded skin syndrome, urinary tract infections, arthritis, etc. most of HA-MRSA were methicillin-resistant staphylococcus aureus (MRSA) which endangered human health seriously. Therefore, adequate understanding of virulence factors and evolutionary path way of endemic MRSA isolates in the region, which allows monitoring of local outbreaks and wider- scale dissemination of specific dangerous clones , is of now important .The aim of this study was to investigate the virulence factors and evolutionary pattern of MRSA by using rep-PCR technique. This study will play an important role in tracking the genetic changes to chart the spread and evolution of MRSA in this region.Method A total of 53 MRSA isolates were recovered from patients and surrounding with symptoms consistent with MRSA infection by the clinical microbiology laboratory in the first affiliated hospital of Da Lian medical university between 2009 and 2010. In the 53 MRSA isolates, one part is HA-MRSA including 38 MRSA isolated, another part is CA-MRSA including 15 MRSA isolates. mecA PVL ,andα-HL were typed by PCR technique .rep-PCR with the optimization condition was used to analysis homology of MRSA isolates which were isolated from different patients and surrounding.Results In the 53 MRSA isolates, all of these isolates were positive for mecA gene, the rate is 100%;only 2 CA-MRSA of 53 MRSA isolates were positive for PVL toxin, the rate is 3.8%; and 30 of 53 MRSA isolates were positive forα-HL, the rate is 56.6%.The number of amplified DNA fragments by rep-PCR were 6-8,the main type of hospital is type -Ⅰin the rep-PCR classified genotypes. Conclution mecA gene was the regularize drug-resistant gene in MRSA.PVL andα-HL were the important virulence factors of MRSA. CA-MRSA was more easy to carry PVL toxin than HA-MRSA, suggested it greater virulence. The isolated rate of MRSA which were isolated from patients and surrounding was high in this region. The dominant epidemic strain of MRSA was type-Ⅰand clone spread might exist.
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