Antimicrobial activity of linezolid against Gram-positive cocci isolated in Brazil.

The new oxazolidinone linezolid and other antimicrobial agents used to treat Gram-positive infections were tested against 1,585 Gram-positive cocci; 1,260 staphylococci and enterococci isolates from patients hospitalized in Brazilian hospitals, and 325 S. pneumoniae isolates for patients with community acquired infections. Susceptibility testing was performed using broth microdilution according to NCCLS procedures. Linezolid was the most active compound and the only drug that inhibited 100% of the isolates at the susceptible breakpoint (< or = 4 microg/mL). Resistance to vancomycin was very rare (99.9% susceptibility), and both quinupristin/dalfopristin and gatifloxacin were active against approximately 90% of the strains evaluated. All other compounds inhibited less than 65% of the isolates. The excellent in vitro Gram-positive activity by linezolid, in this study, indicate that this compound may represent an important therapeutic option for the treatment of infections caused by these pathogens in Brazil.