Alexis McCalla
Program: Molecular Microbiology and Microbial Pathogenesis
Current advisor: Mario F. Feldman, PhD
Undergraduate university: University of Oklahoma
Research summary
Acinetobacter baumannii is a pathogen that can cause severe, multidrug resistant infections, and as such is classified as an urgent antibiotic resistance threat by the CDC. An alternative method of treating A. baumannii infections is with phage therapy. However, phage therapy can be challenging as phages often have a narrow host range and bacteria can rapidly develop resistance. Most A. baumannii phages characterized to date utilize the highly variable bacterial capsule as a receptor, which limits their host range. I am studying three A. baumannii phages which each have distinct receptors and interactions with capsule. One, utilizes capsule as a receptor, another utilizes the capsule or an alternate protein receptor, and a third requires a distinct bacterially-produced polysaccharide for infection. I am studying these distinct interactions and also how knowledge of these interactions can be leveraged to logically design phage cocktails to treat A. baumannii and limit development of phage resistance.
Another focus of my research is on plasmids, which are important contributors to the development of antibiotic resistance as they often encode antibiotic resistance cassettes and can transmit resistance between bacteria. I am studying a family called the Large Conjugative Plasmids (LCPs), which are carried by multiple A. baumannii clinical isolates. In addition to imparting resistance to multiple antibiotics, these plasmids can modify bacterial tropism, replicative ability in macrophages, activity of the type VI secretion system, activity of the quorum sensing system, and other virulence factors. I am studying how these plasmids regulate these and other virulence factors, the conjugative capabilities of these plasmids, and the impact of regulation by the plasmids on their own transmission.
Graduate publications