Differential contribution of two [Fe-Ni] hydrogenases to Proteus mirabilis fitness during single-species and polymicrobial catheterized urinary tract infection

Proteus mirabilis is a common uropathogen and a leading cause of catheter-associated urinary tract infections (CAUTIs), which are often polymicrobial. Through a genome-wide screen, we identified two putative [NiFe] hydrogenases (Hyf and Hyb) as candidate fitness factors for P. mirabilis CAUTI. In this study, we generated single and double knockouts of each hydrogenase and assessed their contribution to growth and fitness in vitro and during experimental CAUTI. Since P. mirabilis is typically present as part of a polymicrobial community in the urinary tract, we also examined the impact of two common co-colonization partners, Providencia stuartii and Enterococcus faecalis, on the contribution of each hydrogenase to fitness. We demonstrate that Hyf and Hyb are both functional [NiFe] hydrogenases in P. mirabilis strain HI4320, and disrupting both systems abrogates hydrogenase activity in vitro. While hydrogenase activity was not critical for P. mirabilis growth or fitness in urine in vitro, at least one functional hydrogenase is required for fitness during experimental infection. We further demonstrate that polymicrobial interactions with P. stuartii and E. faecalis alter the contribution of Hyf and Hyb to P. mirabilis fitness, which has implications for pursuing [NiFe] hydrogenases as a therapeutic target against P. mirabilis.