As an infectious disease physician, I get multiple phone calls, curbsides, and consults every day from providers looking for help in diagnosing or managing urinary tract infections (UTIs). Occasionally, there are complicated clinical scenarios or surprising culture results that warrant input from an expert, and I'm happy to share my recommendations.
Mostly, though, the questions or consults are related to urine samples indicative of asymptomatic bacteriuria (ASB), contaminated specimens leading to false-positive cultures, or misinterpretation of a patient's complaints. I previously wrote a blog entry about ASB, so I won't belabor the topic again here. Suffice it to say that we order too many urine samples on too many people who have no indications for urinary screening, and then we treat too many of those people inappropriately with antibiotics.
As medical providers and antimicrobial stewards, we need to stop checking the urine of asymptomatic people (except, as I noted in my previous blog, pregnant women and patients who plan to undergo endoscopic urologic procedures associated with mucosal trauma). We also need to improve the way in which we collect urine in those who do have signs or symptoms that may represent true infection.
For healthy young children and adults, a clean-catch sample (ideally, midstream after proper aseptic preparation) may be adequate. However, non–toilet-trained infants/children and many older, disabled, or debilitated patients can't manage this technique; in these cases, suprapubic aspiration or sterile urethral catheterization are more appropriate methods.
For patients with indwelling catheters, urine should never be sampled for culture from the collection bag; it should be obtained with proper aseptic technique via the collection port if the catheter has been in place less than 14 days (if the catheter has been present for longer than this, it should probably be replaced prior to urine collection). Of note, the CDC offers strategies to help reduce inappropriate urine collection in patients with indwelling catheters, as well as tips on differentiating between catheter-associated asymptomatic bacteriuria (CA-ASB) and catheter-associated urinary tract infection (CAUTI).
There's a saying in infectious disease that I often share with residents rotating on our service: Diagnosis drives therapy. If you can't identify the infection correctly, you can't offer appropriate treatment. In the case of possible UTI, the first step is to make sure the urinalysis and urine culture aren't simply indicative of ASB. While we all remember the classic UTI signs and symptoms, it should be reiterated that abnormal appearance (cloudy or discolored) or odor of the urine are not indicators of infection. In addition, evidence now suggests that nonspecific signs or symptoms such as falls, change in functional status, and altered mentation in older or debilitated patients are not reliable predictors of UTI.
If a symptomatic patient has a presentation suggestive of UTI, then both a urinalysis and urine culture should be obtained via aseptic technique, which could require suprapubic aspiration or sterile urethral catheterization. Almost all patients with UTI have pyuria; if pyuria is not present on urinalysis, an alternative diagnosis should be considered.
Finally, if the clinical scenario and the urine specimens are consistent with infection, then antibiotics should be considered. Unfortunately, we're not as good at this step as we might think. A recent study published in Open Forum Infectious Diseases suggests that in over 670,000 young women diagnosed with uncomplicated UTI, almost half received an antibiotic that was inappropriate, and more than 75% were prescribed antibiotics for a longer duration than considered necessary.
My suggested approach is to review trusted guidelines that help "match the bad bug with the right drug" based on individual patient presentation. In young, healthy women with uncomplicated cystitis, automatically reaching for a fluoroquinolone is an outdated strategy, while empiric therapy for a critically ill patient with acute complicated UTI may require impressive broad-spectrum coverage (especially if the patient has risk factors for multidrug-resistant pathogens).
Once urine culture results are finalized, the antibiotic regimen should be tailored to ensure an appropriate bug-drug match and to avoid specific patient allergies or interactions. Dosing of antibiotics should be based on guideline recommendations and patient parameters. Duration of treatment is dependent on clinical response and choice of antibiotic (for example, in uncomplicated cystitis, fosfomycin is given as a one-time dose, nitrofurantoin is usually recommended for 5 days, and trimethoprim-sulfamethoxazole requires only 3 days of treatment). Checking a follow-up urine "for proof of cure" is unnecessary and reserved for patients who have hematuria, worsening or persistent symptoms on treatment, or recurrent symptoms within a few weeks of treatment.
The Infectious Diseases Society of America (IDSA) publishes clinical practice guidelines that are amazingly helpful for the practicing clinician, regardless of specialty; these include an updated guideline for management of ASB and an archived guideline for the diagnosis, prevention, and treatment of CAUTI in adults. Currently, IDSA is in the process of developing a new guideline for treatment of acute uncomplicated cystitis and pyelonephritis in women, but access to the older guideline is still available here.
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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Roni K. Devlin. Why Is It So Hard to Accurately Diagnose and Treat UTIs? - Medscape - Sep 15, 2022.