A rare opportunist,Morganella morganii, decreases severity of polymicrobial catheter-associated urinary tract infection

Abstract

AbstractCatheter-associated urinary tract infections (CAUTIs) are common hospital-acquired infections and frequently polymicrobial, which complicates effective treatment. However, few studies experimentally address the consequences of polymicrobial interactions within the urinary tract, and the clinical significance of polymicrobial bacteriuria is not fully understood.Proteus mirabilisis one of the most common causes of monomicrobial and polymicrobial CAUTI, and frequently co-colonizes withEnterococcus faecalis, Escherichia coli, Providencia stuartii, andMorganella morganii. P. mirabilisinfections are particularly challenging due to its potent urease enzyme, which facilitates formations of struvite crystals, catheter encrustation, blockage, and formation of urinary stones. We previously determined that interactions betweenP. mirabilisand other uropathogens can enhanceP. mirabilisurease activity, resulting in greater disease severity during experimental polymicrobial infection. Our present work reveals thatM. morganiiacts onP. mirabilisin a contact-independent manner to decrease urease activity. Furthermore,M. morganiiactively prevents urease enhancement byE. faecalis, P. stuartii, andE. coli.Importantly, these interactions translate to modulation of disease severity during experimental CAUTI, predominantly through a urease-dependent mechanism. Thus, products secreted by multiple bacterial species in the milieu of the catheterized urinary tract can directly impact prognosis.