Delirium as a symptom of UTI: physiology or pseudoaxiom?

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Written by: Ashley Amick, MD (NUEM alum '18) Edited by: Michael Macias, MD (NUEM alum '17) Expert commentary by: Alexander S Lo, MD, PhD

Asymptomatic bacteriuria (ASB) is a prevalent condition in the elderly population.  Bacterial colonization of the genitourinary (GU) tract increases with age and institutionalized status.  Though once thought to be pathogenic, randomized trials clearly demonstrate that treatment of ASB with antibiotics does not improve outcomes, except in pregnant patients and those undergoing GU procedures.  Emerging data even suggest there may be a protective effect of colonizing bacteria.  Conversely, there is increasing recognition of the dangers of inappropriate antibiotic use, both to the individual and the general population, and widespread agenda to limit unnecessary antimicrobial use. 

As the antibiotic stewardship movement marches forward, the treatment of ASB continues to be a central focus.  Recent guidelines emphasize that the presence of lower GU symptoms is the key distinction between UTI and ASB.  This strategy may be easily adopted in young otherwise healthy patients, but reaches a major stumbling block when considering the elderly population.  This is in part due to the fact that many clinicians believe that there is a causative relationship between UTI and delirium in the absence of other localizing symptoms or signs of systemic infection.  In other words, delirium is the symptom that substantiates a diagnosis of UTI in the presence of otherwise asymptomatic bacteriuria.  This concept, now generations old, is still taught in many medical school curricula.  The correlation between delirium and UTI is so well established in the minds of clinicians that many have never questioned whether this presumed association is rooted in data.

The concerning truth is that there is no reliable evidence to suggest that such a relationship between delirium and UTI exist.  A recent review of the literature found only five papers addressing this association primarily, all were observational and therefore lacked the ability to make conclusions about the degree of causation.  All studies were severely methodologically flawed, and none were case-control, cohort, or RTCs.  Additionally, there is no physiologic evidence or models to suggest that bacteriuria in the absence of systemic illness, results in cognitive dysfunction.  No known studies have ever shown that treatment of otherwise asymptomatic bacteriuria improves delirium outcomes.  Taking these data into account, the CDC and SHEA created guidelines specifically do not include delirium as a reason to treat potential UTIs in non-catheterized patients.  These represent a departure from earlier guidelines that included altered mental status as a symptom of UTI in the elderly.  The new SHEA recommendations have been tested in a large randomized trail and were found to be safe when compared to standard care.

Despite efforts to shift practice patterns in the direction of a more guideline-based management, ASB continues to be unnecessarily treated at high rates in the elderly.  One reason may be that anecdote is a powerful source of bias.  Many clinicians support their belief of a causative correlation between UTI and delirium by referencing cases where patient presented with confusion and were found to have a UTI.  The problem is, how was that “UTI” diagnosed?  The distinction is more than just semantics.  In the absence of GU symptoms and signs of systemic infection, then the clinician made the diagnosis solely on the basis of a UA and urine culture.  But as previously discussed, both a UA and culture will frequently be positive in both ABS and UTI, and cannot reliably distinguish between the two conditions. 

Many clinicians will cite the fact that the patients may improve following antibiotic administration, thereby confirming their suspicion of a presumed UTI-related delirium.  However, delirium frequently is short lived and self-resolving, therefore improvement is likely to be simply coincidental.  In addition, along with antibiotics administration patients also often receive intravascular volume, thereby improving hydration status, which is a frequent cause of delirium.  These factors confound the ability of the clinician to objectively interpret the causative relationship between the delirium and bacteriuria.  High quality randomized trials will be needed to further clarify these issues and assess is the high rate of concurrence of bacteriuria and delirium is due to causation or simply coincidence.

Expert Commentary

Over 50 million U.S. adults > 65 years of age (“older adults”), account for over 20 million Emergency Departments (ED) visits each year [1].  Many of these patients have unmet and complex underlying medical needs that are often understated by their chief complaints. The tempting application of traditional ‘one complaint; one algorithm’ approach taught to many emergency physicians, may often result in long-term, downstream, adverse outcomes.  One of those relevant to the accompanying blog, is the traditional “if grandma is delirious, look for and treat the UTI” doctrine.  A review of the literature proves that the evidence linking UTI’s to delirium in older adults is lacking [2]. Many older adults are bacteriuric; most do NOT have to be treated [3].  The delirium is not a reason to treat bacteriuria [4].  It is also just as likely that it is the other comorbid conditions causing the delirium, since 75% of older adults have two or more comorbid chronic conditions [5]. many of which have the potential to cause delirium at any time[6].   The patient may likely require admission for the delirium, but a more comprehensive investigation into its etiology is more helpful than treating the easy target of a contaminated urine sample


Alexander S Lo, MD, PhD

Assistant Professor of Emergency Medicine, Northwestern University 

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How to cite this post

[Peer-Reviewed, Web Publication]   Amick A, Macias M (2018, July 30). Delirium as a symptom of UTI: physiology or pseudoaxiom.  [NUEM Blog. Expert Commentary by Lo A]. Retrieved from


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Posted on July 30, 2018 and filed under Infectious Disease.