Urine production rate is critical in a model for catheter-associated urinary tract infection

Abstract

AbstractCatheter associated urinary tract infections (CAUTI) are of great societal and economic importance, yet there is limited understanding of how CAUTI develops. We present a mathematical model for bacterial colonisation of a urinary catheter, that integrates population dynamics and fluid dynamics. Our model describes bacteria growing and colonising the extraluminal surface, spreading into the bladder and growing there before being swept through the catheter lumen. In this scheme, the rate of urine production by the kidneys emerges as a critical parameter, governing a transition between regimes of high and low bacterial density in the bladder. This transition occurs at urine production rates close to that of the average human, highlighting the therapeutic importance of increasing fluid intake. Our model reveals how the time to detection of bacteriuria (bacteria in the urine) and the time to formation of a biofilm that may subsequently block the catheter depend on characteristics of the patient, the catheter, and the infecting bacterial strain. Additionally, patterns of bacterial density on infected catheters may provide clues about the source of infection.