After incubation serial dilutions were plated on Mueller-Hinton agar plates and visible colonies were counted after 48-72 hours of incubation at 37°C. Killing was expressed in percentage of bacteria that were killed by incubation with respective peptide concentrations compared to incubation with solvent of the antibacterial substance (0,01% acetic acid or water). LD90 denotes the lowest peptide concentration leading to a =90%
reduction of CFU counts. CFU assays were at least performed three times and final results selleck kinase inhibitor are displayed as mean value of all assays. Killing activity (CFU counts after incubation with solvent vs. CFU counts after incubation with highest concentration of AMPs or levofloxacin) was analysed by Student’s t-test. A p-value < 0.05 was considered significant. For testing N. brasiliensis, CFU assays were additionally performed by adding a protease inhibitor mix (Complete Mini, Roche, Mannheim, Germany). 10 μl of the protease
inhibitor mix were added to the standard inoculum during the 16 h incubation period. Further testing was performed as described above. Acknowledgements This study was supported in part by click here research grant RIE520/06 of the Medical Faculty of Freiburg University, Germany. References 1. Saubolle MA, Sussland D: Nocardiosis: review of clinical and laboratory experience. J Clin Microbiol 2003, 41:4497–4501.PubMedCrossRef 2. Roth A, Andrees S, Kroppenstedt RM, Harmsen D, Mauch H: Phylogeny of the genus Nocardia based on reassessed 16S rRNA gene sequences reveals underspeciation and division of strains classified as Nocardia asteroides into three established species and two unnamed taxons. J Clin Microbiol 2003, 41:851–856.PubMedCrossRef 3. Wellinghausen N, Pietzcker T, Kern WV, Essig A, Marre R: Expanded spectrum of Nocardia species causing clinical nocardiosis detected
by molecular Farnesyltransferase methods. Int J Med Microbiol 2002, 292:277–282.PubMedCrossRef 4. Brown-Elliott BA, Brown JM, Conville PS, Wallace RJ Jr: Clinical and laboratory features of the Nocardia spp. based on current molecular taxonomy. Clin Microbiol Rev 2006, 19:259–282.PubMedCrossRef 5. Beaman BL, Beaman L: Nocardia species: host-parasite relationships. Clin Microbiol Rev 1994, 7:213–264.PubMed 6. Harder J, Bartels J, Christophers E, Schroder JM: Isolation and characterization of human beta -defensin-3, a novel human inducible peptide antibiotic. J Biol Chem 2001, 276:5707–5713.PubMedCrossRef 7. Schonwetter BS, Stolzenberg ED, Zasloff MA: Epithelial antibiotics induced at sites of inflammation. Science 1995, 267:1645–1648.PubMedCrossRef 8. Diamond G, Zasloff M, Eck H, Brasseur M, Maloy WL, Bevins CL: Tracheal ubiquitin-Proteasome degradation antimicrobial peptide, a cysteine-rich peptide from mammalian tracheal mucosa: peptide isolation and cloning of a cDNA. Proc Natl Acad Sci USA 1991, 88:3952–3956.PubMedCrossRef 9. Ganz T, Selsted ME, Szklarek D, Harwig SS, Daher K, Bainton DF, et al.: Defensins. Natural peptide antibiotics of human neutrophils. J Clin Invest 1985, 76:1427–1435.