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SIMS21, Poland 2017 - Sage J B Dunham abstract

Sage J B Dunham oral presentation (OB3-Wed2-1-3)

C60-SIMS imaging of Pseudomonas aeruginosa’s small molecule response to aminoglycoside antibiotics

Sage J B Dunham1, Nydia Morales-Soto2, Nameera F Baig3, Joseph F Ellis1, Paul W Bohn3, Joshua D Shrout2, Jonathan V Sweedler3

1 University of Illinois at Urbana-Champaign - Beckman Institute for Advanced Science and Technology, 405 N Mathews Ave, IL 61801 Urbana, United States
2 Department of Civil and Environmental Engineering and Earth Sciences, Department of Biological Sciences, and the Eck Institute for Global Health - University of Notre Dame, Notre Dame, IN 46556 Notre Dame, United States
3 Department of Chemistry and Biochemistry and Department of Chemical and Biomolecular Engineering - University of Notre Dame, University of Notre Dame, IL 46556 Notre Dame, United States


According to statistics from the United States Centers for Disease Control and Prevention, antibiotic resistant microorganisms account for more than 700,000 preventable deaths each year. Antibiotic resistance is a growing threat that requires a multifaceted response: clinicians and food producers need to utilize antibiotics sparingly and responsibly; organic chemists must stay ahead of bacterial evolution through innovative drug design; and analytical chemists and microbiologists need to work together to understand resistance mechanisms and develop new strategies to overcome them. Here we apply Buckminsterfullerene secondary ion mass spectrometry (C60-SIMS) imaging and C60-SIMS product ion imaging to examine the small molecules produced by surface-bound communities of Pseudomonas aeruginosa upon exposure to the aminoglycoside antibiotic tobramycin. P. aeruginosa is an opportunistic pathogen that was recently assigned a Priority 1 status by the World Health Organization because of its adaptive resistance to most available antibiotics, including tobramycin.

A combination of C60-SIMS imaging, principal component analysis (PCA), relative quantification, and support from several complimentary imaging modalities (i.e. confocal Raman microscopy, electron microscopy, live/dead fluorescence staining, and confocal laser scanning microscopy) reveals dramatic changes in spatiochemical profiles and community structure following treatment with a sub-lethal dose of tobramycin. Swarming P. aeruginosa undergoes spatially-specific cell lyses and exhibits motility exclusively in regions away from the antibiotic source. Adjacent to tobramycin the community transitions from a motile swarm into a static biofilm. C60-SIMS imaging reveals changes in several cell-signaling molecules (including Pseudomonas quinolone signal or PQS; see Fig. 1) and the production of several structurally related small molecules which were previously unreported in P. aeruginosa. Swarming motility is one surface exploratory stage employed by P. aeruginosa and other human pathogens prior to the formation of a biofilm. This analysis reveals a role for PQS in antibiotic resistance and biofilm formation and demonstrates the collaborative adaptability of stressed microbial communities.