Life Sciences Seminar -- Proteus mirabilis and Friends

Proteus mirabilis and Friends: Polymicrobial interactions within the urinary tractDr. Chelsie ArmbrusterAssistant Professor, Department of Microbiology and ImmunologyJacobs School of Medicine and Biomedical SciencesSUNY BuffaloAbstract:Catheter-associated urinary tract infections (CAUTIs) are common hospital-acquired infections and are frequently polymicrobial, which can complicate effective treatment. However, few studies have attempted to experimentally address the consequences of polymicrobial interactions within the urinary tract. The Gram-negative bacterium Proteus mirabilis is one of the most common causes of CAUTI, and this organism frequently co-colonizes with other bacterial species, including Enterococcus faecalis, Escherichia coli, Providencia stuartii, and Morganella morganii. P. mirabilis is well known for its potent urease, which facilitates catheter encrustation, blockage, and formation of urinary stones. It is also capable of forming bacterial biofilm communities on the catheter surface, which can be polymicrobial. Our work explores the interactions between P. mirabilis and other common urinary tract pathogens, the impact of these interactions on disease severity, and identification of targets for disrupting or exploiting polymicrobial interactions as therapeutic targets. We have determined that interactions between P. mirabilis and the majority of other uropathogens lead to an increase in P. mirabilis urease activity and in some cases biofilm formation, which results in greater disease severity during experimental infection. However, M. morganii decreases P. mirabilis urease activity and actively prevents enhancement by other bacterial species, ultimately decreasing disease severity during polymicrobial CAUTI. Thus, identification of the M. morganii secreted products that reduce P. mirabilis pathogenicity may uncover a novel therapeutic strategy to prevent catheter encrustation, urolithiasis, tissue damage, and secondary bacteremia resulting from P. mirabilis catheter colonization.Speaker Bio:Chelsie Armbruster, Ph.D. is an Assistant Professor in the Department of Microbiology and Immunology in the University at Buffalo Jacobs School of Medicine and Biomedical Sciences. She completed her doctoral studies in bacterial pathogenesis at Wake Forest University, and was funded by an NIH F32 fellowship for her postdoctoral studies at the University of Michigan. She was also awarded an NIH K99/R00 to develop her independent research, which focuses on combining basic science techniques with patient-oriented research to investigate the consequences of polymicrobial urine colonization, particularly in catheterized nursing home residents. The goal of this research is to identify the bacterial species (or combinations of species) most likely to cause symptomatic infection and adverse outcomes in patients, and to utilize an experimental model of infection to identify microbe-microbe and host-microbe interactions that contribute to disease severity and have the potential to be targeted for prevention or disruption of severe disease.