Detection of high levels of resistance to linezolid and vancomycin inStaphylococcus aureus
Both methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) are rapidly overcoming the current array of drugs. One hundred and fifty isolates from a hospital were studied for resistance towards linezolid and vancomycin. Fifty-four (36.0%) isolates were MRSA. Both MRSA and MSSA showed high resistance towards linezolid when using the disc diffusion method, with the figures being 48.1 and 29.2%, respectively. The figures for the E-test were 46.3 and 27.0%, respectively. The vancomycin resistance was remarkable in MRSA (14.8%), but relatively low in MSSA (3.1%). The E-test results were 13.0 and 4.16%, respectively. The cfr gene was detected in 78% of linezolid-resistant isolates and the vanA operon was detected in 74% of vancomycin-resistant isolates. This level of resistance against linezolid and vancomycin is unprecedented. These results are alarming and highlight the threat of non-treatable S. aureus strains.