Population structure of colonizing and invasive Staphylococcus aureus strains in northern Vietnam

Abstract

<i>Staphylococcus aureus</i> is an important global health problem worldwide. There is still scarce information on the population structure of <i>S. aureus</i> strains in Asia, where the majority of the world population lives. This study characterized the diversity of <i>S. aureus</i> strains in northern Vietnam through multilocus sequence typing (MLST). Eighty-five carriage isolates from the community and 77 invasive isolates from the clinical setting were selected and tested for meticillin resistance and the presence of Panton-Valentine leukocidin (PVL). MLST was performed on these isolates, of which CC59 (25.4 %), CC188 (17.3 %) and CC45 (16.7 %) were the predominant clonal complexes (CCs). CC59 carriage isolates had significantly lower rates of meticillin-resistant <i>S. aureus</i> (MRSA) than their corresponding clinical group isolates (32 vs 83 %). There were no significant differences in rates of MRSA between carriage isolates and clinical isolates of CC45 and CC188. CC59 carriage isolates were significantly lower in rates of PVL⁺ than CC59 clinical isolates (32 vs 83 %), but the converse was shown in CC45 isolates (14 vs 0 %, respectively). This study revealed vast differences in the molecular epidemiology and population structure of <i>S. aureus</i> in community and clinical settings in Vietnam. Nevertheless, the data underline the spread of virulent and/or resistant strains (MRSA and/or PVL⁺) in the community, suggesting the necessity for further surveillance to determine the mechanism of transmission of these strains (i.e. MRSA/PVL⁺) outside clinical settings.