The Carriage Population of Staphylococcus aureus from Mali Is Composed of a Combination of Pandemic Clones and the Divergent Panton-Valentine Leukocidin-Positive Genotype ST152

Abstract

Staphylococcus aureus is an important human pathogen, but it appears more commonly in asymptomatic colonization of the nasopharynx than in cases of invasive disease. Evidence concerning the global population structure of S. aureus is limited by the overrepresentation in the multilocus sequence testing database of disease isolates recovered from Western Europe, the Americas, Australia, and Japan. We address this by presenting data from the S. aureus carriage population in Mali, the first detailed characterization of asymptomatic carriage from an African population. These data confirm the pandemic spread of many of the common S. aureus clones in the carriage population. We also note the high frequency (approximately 24%) of a single divergent genotype, sequence type 152 (ST152), which has not previously been recovered from nasal carriage isolates but corresponds to a sporadic Panton-Valentine leukocidin (PVL)-positive, community-acquired methicillin-resistant S. aureus clone noted mostly in Central Europe. We show that 100% of the ST152 isolates recovered from nasal carriage samples in Mali are PVL positive and discuss implications relating to the emergence and spread of this virulent genotype.