Samyuktha Parthasarathy
Research Mentor: Michael Bachman
Mentor Department: Pathology, Medicine
Author(s): Samyuktha Parthasarathy, Simon Sanchez-Paiva, Ashley Lefebvre, Evan Snitkin, Michael Bachman
Session: Session 5 (2:00 PM – 2:50 PM)
Presentation Type: Poster 40
Abstract
Antibiotic resistance in Gram-negative bacteria is a growing public health issue, especially as resistance to carbapenems continues to spread. Carbapenems are used to treat severe Gram-negative infections that are resistant to other antibiotics. Carbapenem resistance is caused by carbapenemase enzymes encoded by plasmids, small pieces of circular DNA that can be transmitted between bacteria. Some bacteria with these plasmids have become highly successful, epidemic strains in Michigan, whereas others have appeared then disappeared. The goal of this project is to determine how carrying carbapenem resistance plasmids impacts the fitness of Gram-negative bacteria, and why certain strains are so successful. To do this, we removed the plasmids from strains that were successful and unsuccessful, and compared their fitness to their plasmid-carrying ancestors. These strains were grown in both rich and minimal media, and growth was measured over time to generate growth curves. Preliminary results of these comparisons showed mixed outcomes. In some cases, plasmid-carrying strains showed reduced growth, suggesting a fitness cost, while in others plasmid carriage had neutral or potentially beneficial effects. These early findings suggest that carbapenem resistance plasmids may have a fitness cost in some bacteria but not others. Additional experiments will be conducted in order to determine how consistently these effects occur. Understanding these relationships can help explain why certain epidemic strains are so successful and inform strategies to combat antibiotic resistance.
