SUMMARY Catheter-associated urinary tract infections (CAUTIs) represent the most common type of nosocomial infection and are a major health concern due to the complications and frequent recurrence. These infections are often caused by Escherichia coli and Proteus mirabilis. Gram-negative bacterial species that cause CAUTIs express a number of virulence factors associated with adhesion, motility, biofilm formation, immunoavoidance, and nutrient acquisition as well as factors that cause damage to the host. These infections can be reduced by limiting catheter usage and ensuring that health care professionals correctly use closed-system Foley catheters. A number of novel approaches such as condom and suprapubic catheters, intermittent catheterization, new surfaces, catheters with antimicrobial agents, and probiotics have thus far met with limited success. While the diagnosis of symptomatic versus asymptomatic CAUTIs may be a contentious issue, it is generally agreed that once a catheterized patient is believed to have a symptomatic urinary tract infection, the catheter is removed if possible due to the high rate of relapse. Research focusing on the pathogenesis of CAUTIs will lead to a better understanding of the disease process and will subsequently lead to the development of new diagnosis, prevention, and treatment options.

Proteus mirabilis inhabits the environment and causes a number of infections including those of the skin, respiratory tract, wounds and urinary tract. These organisms express virulence factors associated with adhesion, motility, immunoavoidance, nutrient acquisition, host damage, as well as biofilm formation. P. mirabilis produces biofilms in diverse habitats with those formed in the human host playing a key role in indwelling device infections. The most studied P. mirabilis biofilms are those formed when the organism is grown in urine, resulting in unique features including the presence of swarmer cells and struvite and hydroxyapatite crystals upon growth in urine. Factors relevant to P. mirabilis biofilm formation include adhesion factors, proteins involved in LPS production, transporters, transcription factors, two component systems, communication factors and enzymes. P. mirabilis biofilm research will lead to a better understanding of the disease process and will subsequently lead to the development of new prevention, and treatment options.

Proteus mirabilis is a ubiquitous bacterium associated with complicated urinary tract infection (UTI). Mutagenesis studies of the wild-type strain HI4320 in the CBA mouse model of ascending UTIs have identified attenuated mutants with transposon insertions in genes encoding the high-affinity phosphate transporter Pst (pstS, pstA). The transcription of the pst operon (pstSCAB-phoU) and other members of the phosphate regulon of Escherichia coli, including alkaline phosphatase (AP), are regulated by the two-component regulatory system PhoBR and are repressed until times of phosphate starvation. This normal suppression was relieved in pstS