Emergence of Unusual Bloodstream Infections Associated with Pig-Borne–Like Staphylococcus aureus ST398 in France

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TO THE EDITOR—Staphylococcus aureus ST398 is a zoonotic agent primarily described in Europe that is becoming a worldwide threat associated with livestock, their human contacts, and food products. In animals, carriage is frequent, but infections are rare. In humans, infections consist in nosocomial bloodstream and wound infections [1] that are associated with spa types 011 or 034, tetracycline resistance, and the absence of panton-valentine leukocidin (PVL). Recently, a new population of ST398 strains has been isolated in China and from children adopted from China [2] that is responsible for pneumonia and skin and soft-tissue infections in patients without association with animals or animal farming and which is characterized by spa type 571, tetracycline susceptibility, and variable presence of PVL [3].

Annual surveys of bloodstream infection are performed in the center region of France [4, 5]. In 2009, we observed the emergence of cases associated with t571, TetS, and PVL-negative ST398 strains. Examination of patient histories revealed exposure to animals in 1 case, a fatal idiopathic community-acquired bloodstream infection in an 84-year-old man who lived on a farm at which 1 pig was being raised. The remaining cases were hospital-acquired and included 1 case of catheter-associated infection observed in a 58-year-old man with advanced multiple myeloma, 1 case following elective digestive tract surgery in a 69-year-old woman, and 1 case following cardiac surgery in a 68-year-old man.