Ragment PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/29045898 from genomic DNA was used as calibrator. The quantitative data was generated based on different PCR kinetics of samples with different levels of target gene expression. The expression levels of sodA and sodM genes were compared to the data from a standard curve. The standard sample was included in every PCR run to control intra-assay variability.Statistical analysisAuthors’ contributions JN: conceived the study, carried out the experimental work, analyzed the results and drafted the manuscript. EM: carried out experiments. MR: performed real-time PCR experiments. MG: provided technical support and helped to draft the manuscript. AGW: performed statistical analysis. KPB: helped to draft the manuscript. All authors read and approved the final manuscript. Received: 12 July 2010 Accepted: 17 December 2010 Published: 17 December 2010 References 1. Klevens RM, Morrison MA, Nadle J, Petit S, Gershman K, Ray S, et al: Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA 2007, 298:1763-1771. 2. Chang S, Sievert DM, ONO-4059 site Hageman JC, Boulton ML, Tenover FC, Downes FP, et al: Infection with vancomycin-resistant Staphylococcus aureus containing the vanA resistance gene. N Engl J Med 2003, 348:1342-1347. 3. Candeias LP, Patel KB, Stratford MR, Wardman P: Free hydroxyl radicals are formed on reaction between the neutrophil-derived species superoxide anion and hypochlorous acid. FEBS Lett 1993, 333:151-153. 4. Youn HD, Kim EJ, Roe JH, Hah YC, Kang SO: A novel nickel-containing superoxide dismutase from Streptomyces spp. Biochem J 1996, 318(Pt 3):889-896. 5. Dupont CL, Neupane K, Shearer J, Palenik B: Diversity, function and evolution of genes coding for putative Ni-containing superoxide dismutases. Environ Microbiol 2008, 10:1831-1843. 6. Benov LT, Fridovich I: Escherichia coli expresses a copper- and zinccontaining superoxide dismutase. J Biol Chem 1994, 269:25310-25314. 7. Clements MO, Watson SP, Foster SJ: Characterization of the major superoxide dismutase of Staphylococcus aureus and its role in starvation survival, stress resistance, and pathogenicity. J Bacteriol 1999, 181:3898-3903. 8. Valderas MW, Hart ME: Identification and characterization of a second superoxide dismutase gene (sodM) from Staphylococcus aureus. J Bacteriol 2001, 183:3399-3407. 9. Papp-Wallace KM, Maguire ME: Manganese transport and the role of manganese in virulence. Annu Rev Microbiol 2006, 60:187-209. 10. Kehres DG, Maguire ME: Emerging themes in manganese transport, biochemistry and pathogenesis in bacteria. FEMS Microbiol Rev 2003, 27:263-290. 11. Jakubovics NS, Jenkinson HF: Out of the iron age: new insights into the critical role of manganese homeostasis in bacteria. Microbiology 2001, 147:1709-1718. 12. Horsburgh MJ, Wharton SJ, Karavolos M, Foster SJ: Manganese: elemental defence for a life with oxygen. Trends Microbiol 2002, 10:496-501. 13. Mandell GL: Catalase, superoxide dismutase, and virulence of Staphylococcus aureus. In vitro and in vivo studies with emphasis on staphylococcal eukocyte interaction. J Clin Invest 1975, 55:561-566. 14. Schneider WP, Ho SK, Christine J, Yao M, Marra A, Hromockyj AE: Virulence gene identification by differential fluorescence induction analysis of Staphylococcus aureus gene expression during infection-simulating culture. Infect Immun 2002, 70:1326-1333. 15. Kanafani H, Martin SE: Catalase and superoxide dismutase activities in virulent and nonvirulent Staphylococcus aureus isolates. J Clin Mi.
