Linezolid resistance among Staphylococcus aureus has emerged almost exclusively in those organisms with methicillin resistance (MRSA). To our knowledge, recovery of linezolid‐resistant (LR) methicillin‐susceptible S. aureus (MSSA) from humans has been described in only a single case.
Case presentation:
A 63‐year‐old Japanese man was referred for removal of an infected cardiac resynchronization device. He had received a 2‐week administration of linezolid approximately 6 months previously. LR MSSA (linezolid MIC = 8 μg ml−1) was recovered from purulent materials around the exposed generator and removed electrode leads, concurrently with linezolid‐susceptible (LS) MRSA and LS MSSA. The LR MSSA and LS MRSA demonstrated close genetic relatedness in a macrorestriction analysis and were categorized into the same molecular types (multilocus sequence type 239 and spa type t137), suggesting that they originated from an identical ancestor. The LR MSSA had a G2576T mutation in the 23S rRNA genes in two of five rrn operons.
Conclusion:
Linezolid resistance may occur not only among multidrug‐resistant Gram‐positive organisms but also in those for which a number of antibiotics are still effective.
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