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Front Microbiol. 2015 Dec 23;6:1437. doi: 10.3389/fmicb.2015.01437. eCollection 2015.

Transposon Mutagenesis Identifies Novel Genes Associated with Staphylococcus aureus Persister Formation.

Author information

1
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Shanghai Medical College of Fudan University Shanghai, China.
2
Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College of Fudan University Shanghai, China.
3
Department of Laboratory Medicine, School of Medicine, Renji Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China.
4
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Shanghai Medical College of Fudan UniversityShanghai, China; Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins UniversityBaltimore, MD, USA.

Abstract

Pathogenic bacterial persisters are responsible for the recalcitrance of chronic and persistent infections to antimicrobial therapy. Although the mechanisms of persister formation and survival have been widely studied in Escherichia coli, persistence mechanisms in Staphylococcus aureus remain largely unknown. Here, we screened a transposon mutant library of a clinical methicillin-resistant Staphylococcus aureus(MRSA)strain, USA500 (ST8), under antibiotic pressure and identified 13 genes whose insertion mutations resulted in a defect in persistence. These candidate genes were further confirmed by evaluating the survival of the mutants upon exposure to levofloxacin and several other stress conditions. We found 13 insertion mutants with significantly lower persister numbers under several stress conditions, including sdhA, sdhB, ureG, mnhG1, fbaA, ctaB, clpX, parE, HOU_0223, HOU_0587, HOU_2091, HOU_2315, and HOU_2346, which mapped into pathways of oxidative phosphorylation, TCA cycle, glycolysis, cell cycle, and ABC transporters, suggesting that these genes and pathways may play an important role in persister formation and survival. The newly constructed knockout strains of ureG, sdhA and sdhB and their complemented strains were also tested for defect in persisters following exposure to levofloxacin and several other stress conditions. The results from these experiments were consistent with the screening results, which indicated that deletion of these genes in MRSA USA500 leads to persister defect. These findings provide novel insights into the mechanisms of persister formation and survival in S. aureus and offer new targets for the development of persister-directed antibiotics for the improved treatment of chronic and persistent infections.

KEYWORDS:

Staphylococcus aureus; antibiotics; persisters; stress conditions; transposon mutant library

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