Linezolid resistance has increasingly been described in coagulase negative staphylococci (CoNS) in recent years. Here, we describe the molecular mechanism of linezolid resistance in Staphylococcus haemolyticus using whole genome sequencing. Three S. haemolyticus isolates (VB5326, VB19458, and VB840) carried G2576T mutation at the domain V of the 23S rRNA. In addition, VB5326 and VB19458 carried the cfr gene in the chromosome. The presence of cfr gene, in combination with G2576T mutation in 23S rRNA, resulted in a high linezolid Minimum inhibitory concentration (MIC) of > 256 µg/ml. Three mutations, including D471E, I527M, and S532N, in rpoB contributed to an increased rifampicin MIC of 32 µg/ml. Subsequent development of linezolid and rifampicin resistance in S. haemolyticus is worrisome and greatly limits clinical management.
Keywords: 23S rRNA; Staphylococcus haemolyticus; cfr; linezolid resistance; rifampicin.