Characterization of <i>Staphylococcus aureus</i> from Distinct Geographic Locations in China: An Increasing Prevalence of <i>spa</i>-t030 and SCC<i>mec</i> Type III

<div><p><i>Staphylococcus aureus</i> belongs to one of the most common bacteria causing healthcare and community associated infections in China, but their molecular characterization has not been well studied. From May 2011 to June 2012, a total of 322 non-duplicate <i>S. aureus</i> isolates were consecutively collected from seven tertiary care hospitals in seven cities with distinct geographical locations in China, including 171 methicillin sensitive <i>S. aureus</i> (MSSA) and 151 MRSA isolates. All isolates were characterized by <i>spa</i> typing. The presence of virulence genes was tested by PCR. MRSA were further characterized by SCC<i>mec</i> typing. Seventy four and 16 <i>spa</i> types were identified among 168 MSSA and 150 MRSA, respectively. One <i>spa</i> type t030 accounted for 80.1% of all MRSA isolates, which was higher than previously reported, while <i>spa</i>-t037 accounted for only 4.0% of all MRSA isolates. The first six <i>spa</i> types (t309, t189, t034, t377, t078 and t091) accounted for about one third of all MSSA isolates. 121 of 151 MRSA isolates (80.1%) were identified as SCC<i>mec</i> type III. <i>pvl</i> gene was found in 32 MSSA (18.7%) and 5 MRSA (3.3%) isolates, with ST22-MSSA-t309 as the most commonly identified strain. Compared with non-epidemic MRSA clones, epidemic MRSA clones (corresponding to ST239) exhibited a lower susceptibility to rifampin, ciprofloxacin, gentamicin and trimethoprim-sulfamethoxazole, a higher prevalence of <i>sea</i> gene and a lower prevalence of <i>seb</i>, <i>sec</i>, <i>seg</i>, <i>sei</i> and <i>tst</i> genes. The increasing prevalence of multidrug resistant <i>spa</i>-t030 MRSA represents a major public health problem in China.</p>