Staphylococcus aureus has become a leading cause of community-and hospital-acquired pneumonia. Furthermore, infection with community-and health care-acquired strains of methicillinresistant S. aureus (MRSA) is increasingly common and limits antimicrobial options (13,25,29,31). Tedizolid phosphate (TR-701) is a novel oxazolidinone prodrug. The active moiety, tedizolid (TR-700), exhibits potent activity against Gram-positive bacteria, including MRSA (48). The goals of our studies were to identify the pharmacodynamic (PD) target (AUC/MIC ratio) for TR-700 against methicillin-susceptible S. aureus (MSSA) and MRSA strains in a neutropenic murine pneumonia model and compare the PD targets of TR-700 to that of the only FDA-approved oxazolidinone antibiotic, linezolid. MATERIALS AND METHODSBacteria, media, and antibiotics. Eleven isolates of S. aureus were utilized for these experiments. The strains included four MSSA strains (ATCC 6538P, ATCC 25923, ATCC 29213, and ATCC Smith), one hospital-acquired MRSA strain (ATCC 33591), and six community-acquired MRSA strains (MW2, R2527, 04-045, 04-154, 05-051, and UW 307109). Organisms were grown, subcultured, and quantified in Mueller-Hinton broth (Difco Laboratories, Detroit, MI) and Mueller-Hinton agar (Difco Laboratories, Detroit, MI). Linezolid was obtained from the University of Wisconsin pharmacy. Tedizolid (TR-700) and tedizolid phosphate (TR-701) were supplied by the manufacturer (Trius Therapeutics, San Diego, CA). Prior to in vivo treatment studies, TR-701 was dissolved in sterile water at the appropriate drug concentrations. TR-700 was dissolved in sterile dimethyl sulfoxide (DMSO) and diluted with medium to the appropriate concentration for in vitro susceptibility testing.In vitro susceptibility studies. The MICs of linezolid and TR-700 were determined three times in duplicate using Clinical and Laboratory Standards Institute (CLSI) microdilution methods M07-A8 (15). The duplicates were identical, and the final results were reported as the median value of the three MIC tests (see Table 1).Murine infection model. All animal studies were approved by the Animal Research Committees of the University of Wisconsin and William S. Middleton Memorial VA Hospital. Six-week-old, specific-pathogenfree, female ICR/Swiss mice weighing between 24 and 27 g (Harlan Sprague-Dawley, Indianapolis, IN) were used for all studies. Three mice were utilized for each treatment and control group. Mice were rendered neutropenic (absolute neutrophil count of Ͻ100/mm 3 ) by injecting cyclophosphamide (Mead Johnson Pharmaceuticals, Evansville, IN) intraperitoneally 4 days (150 mg/kg of body weight) and 1 day (100 mg/kg) prior to experimental infection. Previous studies have shown that this regimen produces persistent neutropenia in this animal model for 5 days (3). Broth cultures of freshly plated bacteria were grown to logarithmic phase. The inoculum for each organism was diluted to a 0.3 absorbance at 580 nm. Viable plate count confirmation of the inoculum ranged from 10 6 to 10 7 CFU/ml. Anima...

PURPOSE: Functional polymorphisms of the UGT1A1 gene, particularly the UGT1A1*28 variant, are associated with the severity of the bone marrow suppression in patients with metastatic colorectal cancer receiving irinotecan. This study assesses the cost-effectiveness of screening for UGT1A1*28 polymorphism associated with primary prophylactic Granulocytes Colony Stimulating Factor in patients homozygous for the *28 allele. The effectiveness was estimated based on the number of neutropenia avoided. METHODS: We modelled a theoretical population treated with combined 5-fluorouracil, leucovorin and irinotecan (FOLFIRI) for metastatic colorectal cancer. A decision tree simulated the health outcomes, measured by the prevalence of neutropenic events for two strategies, with or without UGT1A1 genotype screening. The model incorporated direct hospital costs and was validated with a sensitivity analysis. We calculated the cost-effectiveness ratio: CE=∆C / ∆E = "genotyping" cost – "no genotyping" cost / number of febrile neutropenia avoided. RESULTS: In the "genotyping strategy", the cost to avoid one febrile neutropenia event per 1000 patients treated was € 942.8 to € 1090.1. The sensitivity analysis showed a better CE ratio of € 733.4 to € 726.6 per febrile neutropenic event avoided.CONCLUSIONS: UGT1A1 genotype screening before irinotecan treatment is a cost-efficient strategy for the hospital. Systematic genotyping prior to chemotherapy, and administration of CSF in patients homozygotes for the *28 allele allow to avoid 91 febrile neutropenias at an acceptable cost.

BI 409306 increased rapidly in plasma and was subsequently detected in CSF, resulting in dose-dependent increases in cGMP levels in CSF. Results indicate BI 409306 efficiently crosses the blood-CSF barrier, with an acceptable level of AEs.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain MW2 harbors a plethora of toxins to mediate its virulence. However, toxin expression and regulation with simulated clinical antimicrobial exposures are unclear. This study evaluated these relationships using an in vitro pharmacodynamic hollow-fiber infection model. Clinical doses of clindamycin, linezolid, minocycline, trimethoprim-sulfamethoxazole (SXT), and vancomycin were simulated over 72 h against MW2 in the hollow fiber model. Expression levels of lukSF-PV and enterotoxin genes sec4, sek, seq, and sel2 were quantified by realtime PCR. Panton-Valentine leukocidin (PVL) was quantified by enzyme-linked immunosorbent assay (ELISA), and cytotoxicity was determined on polymorphonuclear cells (PMNs). Vancomycin produced the maximum MW2 killing (2.53 log 10 CFU/ml) after the first dose, but the greatest sustained killing over 72 h occurred with linezolid and clindamycin. Vancomycin and minocycline induced gene upregulation from 0 to 8 h, followed by downregulation for the remaining simulation period. Clindamycin decreased gene expression in the first 24 h, followed by moderate increases (2.5-fold) thereafter. Linezolid increased gene expression 11.4-to 200.4-fold but inhibited PVL production (0.6 ؎ 0.3 versus 5.9 ؎ 0.2 g/ml, linezolid versus control at 72 h; P < 0.05).