 Gram @-@ positive bacteria usually develop resistance to linezolid as the result of a point mutation known as <unk> , in which a guanine base is replaced with thymine in base pair 2576 of the genes coding for 23S ribosomal RNA . This is the most common mechanism of resistance in staphylococci , and the only one known to date in isolates of E. faecium . Other mechanisms have been identified in Streptococcus pneumoniae ( including mutations in an RNA methyltransferase that <unk> <unk> of the 23S rRNA and mutations causing increased expression of ABC transporter genes ) and in Staphylococcus epidermidis . 
