Routine urine testing: It’s a culture problem

September 26th, 2019

Urinary tract infections (UTI) are painful, uncomfortable, and if untreated, can lead to kidney infection and even kidney failure. However, overdiagnosis and overtreatment of UTI are prevalent, leading to unnecessary antibiotic prescriptions. This is because having bacteria in the urine is common, especially for people with diabetes and older people. These bacteria may not be causing any symptoms, and in fact may be beneficial, but once they are found, they are usually treated with antibiotics regardless. 

In a recent update, the US Preventive Services Task Force (USPSTF) clarified their recommendations around screening patients for bacteria in the urine presenting without UTI symptoms (clinically known as asymptomatic bacteriuria, or ASB).

The USPSTF identified a moderate net benefit (Grade B) for screening pregnant women for ASB in their first trimester, because this condition is more common during pregnancy, and more likely to lead to kidney infection and low birth weight. Studies have shown that women who are not screened for ASB are 2-3 times more likely to have a kidney infection compared to screened cohorts (1.8-2.2% rate of infection in non-screened group compared to 0.5% of screened group).

However, the USPSTF also acknowledged that the benefit of screening in pregnant women may not be as large as previously thought. They cite a 2015 study in the Netherlands that found limited benefit from screening and treating ASB in pregnant women at low risk of UTI. The USPSTF also pointed out that we don’t know much about the harms of overtreating ASB; for example, we don’t know how often antibiotics for ASB removes “good bacteria” from the body and the consequences of disrupting the microbiome. They recommend more research in this area so that clinicians and patients can more accurately assess the benefits and harms of ASB screening in pregnant women. 

For non-pregnant adults, however, the evidence is clear–screening for UTIs has to stop. As Dr. Jerome Lewis and Dr. Christine Soong at the University of Toronto write in a JAMA Internal Medicine editorial, there is no evidence to show that treating ASB in non-pregnant people has any benefit, and yet screening people for ASB and treating with antibiotics is all too common. Not only is there no benefit to treating ASB, there are numerous potential harms of overtreatment: antibiotics can increase the risk of serious side effects such as tendonitis, nerve damage, and hypoglycemia for older adults, and in some cases, overuse of antibiotics can lead to patients developing an antibiotic-resistant infectionThe USPSTF gave this screening a “D” Grade, clearly recommending against this practice. 

The USPSTF and many other clinical organizations have recommended against treating ASB in non-pregnant adults for years, so why do doctors keep doing it? It’s not an awareness problem, it’s a culture problem, Lewis and Soong write. Doctors often send patients’ urine for testing for no specific reason, then when they find bacteria in the urine, they treat for UTI even when the patient has no UTI symptoms. Further, Lewis and Soong write that “UTI is frequently evoked as the scapegoat” for common symptoms such as delirium, falls, or fever, which leads to overtesting for UTI when there are other more likely explanations.

How do we break the habit of overtesting and overtreating ASB? Lewis and Soong include several recommendations to help change the “culture of culturing urine”:

  • Institutions and guidelines should change the threshold for bacteria levels for low-risk urine cultures.
  • Guidelines should include recommendations for how to stop doing routine urine cultures, not just recommend to not do them.
  • Trainees should be advised against using UTIs as the “scapegoat” in medical school and training.
  • Hospitals should strive to make their environments safer and more comfortable, to reduce delirium among patients that often leads to urine testing.
  • Medications that cause delirium in older adults should be avoided, to reduce unnecessary urine testing.
  • Patients and caregivers should be told about the harms of the “urine culturing cascade” so they can help avoid it.

With these changes, we can begin to change the damaging problem of routine urine culture testing and ASB overtreatment.

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