In vitro Antimicrobial Activity of Linezolid (Zyvox(R)) against Multidrug Resistant Gram-Positive Organism / 감염과화학요법

ABSTRACT

BACKGROUND: The emergence of multi-drug resistant Gram-positive cocci, such as MRSA, VRE, and VRSA, necessitated to develop new antibiotics, which could replace the glycopeptide. As a result, a new antibiotics named linezolid was developed. Linezolid is different line of oxazolidinones with a good oral bioavailability, compared to other antibiotics. Since appropriate oral antibiotics are not presently available for MRSA, which is a major cause of nosocomial and community acquired infections, the introduction of linezolid will have favorable effect on treatment of infections such as pneumonia or skin infections. In this study, we investigated the antibiotic effect of linezolid on MRSA and VRE isolated from patients who were treated in Korea University Guro Hospital. MATERIAL AND METHODS: By using broth microdilution and agar dilution method we measured minimum inhibitory concentration (MIC) with sixty S. aureus, forty three Enterococcus spp., and twenty five S. pneumoniae isolates from patients who were diagnosed as skin, soft tissue, respiratory, and urinary infections in Korea University Guro Hospital from January, 1998 to December, 2002. RESULTS: All of S. aureus used in this study were MRSA, and MIC90 of linezolid was below 2 microgram/ml (MIC ranged between 1-2 microgram/ml). All of Enterococcus spp. were VRE, and had MIC90 of 2 microgram/ml (MIC ranged between 1 to 4 microgram/ml). One of the VRE showed intermediate susceptibility with MIC of 4 microgram/ml. However, none was resistant with MIC breakpoint above 8 microgram/ml. All of S. pneumoniae were resistant to penicillin, but they were susceptible to linezolid with MIC90 of 1 microgram/ml(MIC range 0.5-1 microgram/ml). CONCLUSION: In conclusions, linezolid has an excellent in vitro antibiotic effect on multi-drug resistant Gram-positive cocci, such as MRSA, PRSP, and VRE.