Pulse field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used to do molecular typing for 43 isolates of Staphylococcus aureus, and antibiotics protection assay and flow cytometry internalization assay were used to determine the diversity of in vitro invasion abilities of Staphylococcus aureus clinical isolates with different genotypes.

A total of 43 isolates of Staphylococcus aureus were classified into 12 PFGE genotypes according to 80% similarity, among which type Ⅰ and type Ⅱ were the predominant types and accounted for 25.6% (11/43)and 34.9%(15/43), respectively. Other non-predominant types accounted for 39.5%(17/43). In vitro antibiotics susceptibility test results showed that type Ⅰ and other non-predominant types were mainly composed of methicillin-sensitive Staphylococcus aureus (MSSA)(85.7%, 24/28), while type Ⅱ were mainly composed of methicillin-resistant Staphylococcus aureus (MRSA)(100.0%, 15/15). MLST revealed that type Ⅱ isolates were all ST-239 type, but type Ⅰ and other types belonged to diverse ST types. Antibiotics protection assay showed that the invasion rates of the 3 isolates with the strongest invasion abilities were 3.27%, 3.15% and 3.09%, respectively. The in vitro invasion abilities of type Ⅰ and type Ⅱ isolates were significantly higher than those of other non-predominant types (P<0.01).

Staphylococcus aureus clinical isolates with different genotypes shows the diversity of in vitro invasion abilities,and the predominant clones revealed stronger in vitro invasion abilities,especially for ST-239 type.The units with higher Staphylococcus aureus isolation rates should pay more attention to this clone and strengthen infection control measures.