A patient in Boston was the first to become infected with a strain of Staphylococcus aureus bacteria resistant to the latest generation of antibiotics, according to a letter in the July 21 issue of The Lancet.
The U.S. Food and Drug Administration approved the powerful antibiotic linezolid in early 2000. It has become the last line of defense against infections by various gram-positive bacteria, including methicillin-resistant S. aureus, or MRSA, and vancomycin-resistant enterococci, or VRE. Linezolid resistance in VRE was reported in April, but this was the first reported incidence of resistance in S. aureus.
In The Lancet letter, coauthor Mary Jane Ferraro, Ph.D., reported that an MRSA isolate resistant to linezolid had been recovered from an 85-year-old man treated for dialysis-associated peritonitis with this antibiotic. The bacterium also was resistant to methicillin. However, the patient could be treated with more commonly used antibiotics, which usually is not possible.
This is the only reported case of linezolid-resistant S. aureus so far, according to The Lancet letter.
"Methicillin-resistant strains account for more than one-fourth of S. aureus bloodstream isolates and most of the nosocomial S. aureus infections in intensive care patients in the United States," said the authors at the conclusion of their letter. "The emergence of resistance to linezolid in MRSA is an unwelcome development."
