Mutations at the Ribosomal S10 Gene in Clinical Strains of Staphylococcus aureus with Reduced Susceptibility to Tigecycline

Mutations on the tip of the extended loop of the ribosomal S10 protein have been associated to tigecycline (TGC) resistance in passaged mutants of different bacteria species. This study described the first two clinical TGC-resistant Staphylococcus aureus isolates with these mutations. One strain (TGC MIC = 2 mg/liter) had a 12-nucleotide deletion affecting residues 56 to 59 (HKYK) of the S10 protein. The second strain (TGC MIC = 1 mg/liter) had amino acid substitutions (K57M and Y58F) previously described in S. aureus passaged mutants.