Improved Antimicrobial Activity of Linezolid against Vancomycin-Intermediate Staphylococcus aureus
Department of Infection Control Science, Department of Bacteriology, Faculty of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan 113-8421.Antimicrobial Agents and Chemotherapy (Impact Factor: 4.48). 09/2008; 52(11):4207-8. DOI: 10.1128/AAC.00676-08
Linezolid has been used for the treatment of nosocomial and community-acquired pneumonia as well as complicated skin and soft tissue infection caused by methicillin-resistant Staphylococcus aureus (MRSA) including vancomycin-intermediate S. aureus (VISA) (5, 10, 12). ...
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Conference Paper: Antenna diversity in cellular FM radio[Show abstract] [Hide abstract]
ABSTRACT: The performance of diversity in cellular FM radio was analyzed using a digitally simulated FM system which includes such components as a compandor, pre-emphasis and de-emphasis, limiters and filters, as well as the modulation and limiter-discriminator-type demodulation. The propagation model used was a modified Hashemi (1979) model. The simulation using digitized speech provides a method to compare the performance of various diversity combining schemes. The diversity combining methods included selective switching using a switch and stay strategy, audio level combining using two receivers, and equal ratio combining using a cophasing technique. These are compared to the performance of the system with no diversity. Comparisons are made to field trials
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ABSTRACT: Following an initial response to vancomycin therapy, a patient with meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia developed endocarditis, failed a second course of vancomycin and then failed daptomycin therapy. An increase in the vancomycin minimum inhibitory concentrations of four consecutive MRSA blood isolates from 2 microg/mL to 8 microg/mL was shown by Etest. Population analysis of four successive blood culture isolates recovered over the 10-week period showed that the MRSA strain became progressively less susceptible to both vancomycin and daptomycin. Retrospectively, the macro Etest method using teicoplanin indicated a decrease in vancomycin susceptibility in the second blood isolate. The patient improved after treatment with various courses of trimethoprim/sulfamethoxazole, quinupristin/dalfopristin and linezolid. Early detection of vancomycin-heteroresistant S. aureus isolates, which appeared to have clinical significance in this case, continues to be a challenge for the clinical laboratory. Development of suitable practical methods for this should be given priority. Concurrent development of resistance to vancomycin and daptomycin, whilst rare, must be considered in a patient who is unresponsive to daptomycin following vancomycin therapy.
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ABSTRACT: An increase in the distribution of vancomycin MIC values among methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) isolates has been noted. It is postulated that the shift in vancomycin MIC values may be associated with a concurrent rise in the MIC values of other anti-MRSA agents. Scant data are available on the correlation between vancomycin MIC values and the MIC values of other anti-MRSA agents. This study examined the correlation between vancomycin MIC values and the MIC values of daptomycin, linezolid, tigecycline, and teicoplanin among 120 patients with bloodstream infections caused by MRSA at a tertiary care hospital between January 2005 and May 2007. For each included patient, the MIC values of the antibiotics under study were determined by the Etest method and were separated into the following two categories: day 1 (index) and post-day 1 (subsequent). For subsequent isolates, the MIC values for each antibiotic from the post-day 1 terminal isolate were used. Among the index isolates, there was a significant correlation (P value, <0.01) between the MIC values for vancomycin and daptomycin and between the MIC values for vancomycin and teicoplanin. The MIC values for daptomycin were significantly correlated with linezolid, tigecycline, and teicoplanin MIC values. Among the 48 patients with subsequent isolates, vancomycin MIC values were significantly correlated with MIC values for daptomycin, linezolid, and teicoplanin (rho value of >or=0.38 for all comparisons). This study documented an association between vancomycin MIC values and the MIC values of other anti-MRSA antibiotics among patients with bloodstream infections caused by MRSA primarily treated with vancomycin.