Neil Skolnik, MD
DISCLOSURES | December 16, 2024
00:0010:12
This transcript has been edited for clarity.
We often see urinary tract infections in primary care, so these guidelines for the prevention, diagnosis and management of urinary tract infection (UTI) are very helpful to reaffirm our knowledge in the areas where know what we’re doing and update our knowledge in areas of uncertainty. These guidelines are from a new group called the WikiGuidelines group. Ordinarily, I wouldn’t have considered reviewing one of these guidelines, but this one was published in JAMA Network Open. It is evidence based and covers the topic really well.
Diagnosis. Order a urinalysis or a urine culture only if the patient is having symptoms of a UTI. This may seem obvious, but particularly among older individuals, in whom asymptomatic bacteriuria is very common and should not be treated, nonspecific symptoms such as just not feeling well for a day do not warrant obtaining a urinalysis and culture. With no clear way to distinguish between asymptomatic bacteriuria and a true UTI, the first step in making the diagnosis of a UTI accurately is ordering urine studies only in people who have a reasonable chance of having an infection.
The guideline suggests that the diagnosis of UTI should be primarily based on clinical symptoms. A urinalysis can provide further information, but the authors caution us against relying solely on the urinalysis. This is an incredibly important evidence-based recommendation. If you think about it, this supports the common practice of treating UTIs over the phone without having to see the patient or check a urinalysis.
The rationale for this recommendation is that urinalysis is neither a sensitive nor specific test for UTI. The sensitivity of leukocyte esterase is only about 80%, and the specificity is even lower. For positive nitrite on urinalysis, the sensitivity is below 50%, meaning the test would be negative more than half the time when someone actually has a UTI. The specificity of urine nitrate is very high (more than 90%), so if the patient is nitrite positive, they clearly have a UTI. This means that a patient’s report of classic UTI symptoms — urinary burning, frequency, and urgency — is about as good if not a better indicator of a UTI than a urinalysis.
The guidelines also say that in simple uncomplicated cystitis in healthy nonpregnant patients, routine urine cultures are not necessary. A fascinating meta-analysis in JAMA showed that for women presenting to outpatient clinics with at least two symptoms of UTI and absence of vaginal discharge, there was a greater than 90% likelihood of having acute cystitis. A reminder here, however: If a woman is sexually active and at risk for sexually transmitted infections, then consider testing for STIs as well, because the symptoms of an STI can mimic those of a UTI.
Treatment. Treatment for UTI is usually empiric, with treatment initiated before the culture results are known and with cultures being done only for people with complicated infections, such as pyelonephritis, or with recurrent infections. Decisions about what to use for treatment can be influenced by local patterns of resistance and an individual’s risk factors for antimicrobial resistance. As a general rule, for uncomplicated cystitis, nitrofurantoin for 5 days is a reasonable first-line agent. Evidence of efficacy is good, and the risk for antimicrobial resistance is lower vs using antibiotics for other systemic infections.
Other reasonable first-line agents for uncomplicated cystitis include trimethoprim-sulfamethoxazole (TMP-SMX) for 3 days; fosfomycin (oral) single dose; or a beta-lactam (most commonly a first generation cephalosporin), although evidence for duration is unclear. Also mentioned are two unfamiliar antibiotics: pivmecillinam (a beta-lactam agent recently approved by the US Food and Drug Administration [FDA], given for 3 days) and gepotidacin (from a new class of antibiotic that is currently under FDA review). Fluoroquinolones should not usually be first-line agents unless other treatment options are not appropriate.
It’s important to distinguish between uncomplicated cystitis and pyelonephritis. For pyelonephritis (infection of the upper urinary tract), the first decision has to do with setting for care, depending on how sick someone is, and the likelihood of gram-negative bacteremia — all of which help whether the patient needs to be hospitalized for intravenous antibiotics, or can be treated as an outpatient. determine if they need to be admitted for intravenous antibiotics or whether they can be treated as an outpatient. For outpatient treatment of pyelonephritis, the guideline suggests that TMP-SMX or a first-generation cephalosporin are both reasonable first-line agents, with fluoroquinolones being a reasonable choice as well. Ceftriaxone is recommended for first-line therapy for patients who require intravenous treatment.
People often forget that we can do a lot to prevent UTIs, particularly among women with recurrent UTIs. The prevention of UTIs has both nonpharmacologic and pharmacologic approaches.
Nonpharmacologic prevention. One nonpharmacologic strategy is increasing water intake. A randomized controlled trial in women with recurrent cystitis who drank less than 1.5 L of fluid a day showed that the women randomized to consume an additional 1.5 L of water daily had significantly reduced cystitis frequency — approximately 50%. Because this was the only randomized trial to show this effect, this is not a strong recommendation, but there is very little downside in healthy women, so increasing water intake is a reasonable recommendation.
Another commonly discussed intervention is the use of cranberry products. As it turns out, most prospective studies have shown that cranberry products can reduce the risk for symptomatic UTIs in women with recurrent UTI.
Pharmacologic prevention. For postmenopausal women with recurrent UTI, topical vaginal estrogen has a strong base of evidence — more than 30 randomized trials — supporting its effectiveness in UTI: a 50%-90% reduction in the incidence of recurrent UTIs. Topical estrogen has minimal systemic absorption, and there are no concerning safety signals with respect to either thromboembolic disease or cancer (endometrial or breast).
Methenamine hippurate is also recommended and is FDA-approved for prevention of UTIs. It works by releasing formaldehyde in the urine, leading to bacteriostasis, which is how it leads to a decrease in UTIs. Finally, postcoital or daily administration of TMP-SMX, nitrofurantoin, norfloxacin, and ciprofloxacin all have comparable efficacy for prophylaxis, with a meta-analysis showing a decrease in recurrence rate of approximately 85%. The guideline states that there is insufficient evidence to support the use of either probiotics or D-mannose to prevent UTIs.
This is a wonderful update on a common problem. We all have a lot of clinical experience here; please leave your thoughts in the comments section.
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