Proteus mirabilis is a leading uropathogen of catheter-associated urinary tract infections (CAUTIs), which are one the most common health care-associated infections worldwide. CAUTIs account for up to 80% of all nosocomial UTIs and can be further complicated by bladder and kidney stone formation (urolithiasis) causing permanent renal damage, and may lead to life-threatening bacteremia and sepsis. P. mirabilis CAUTIs have proven difficult to treat in part due to their increasing antibiotic resistance, as well as resistant biofilm formation on the catheter surface. Another factor that contributes to bacterial persistence and pathogenicity is the ability to resist reactive oxygen species (ROS). The goal of my research is to determine the role of P. mirabilis catalase in ROS tolerance, biofilm formation, antibiotic resistance and pathogenicity in vivo.