An updated clinical approach to diagnosing urinary tract infections (UTIs) that considers five potential phenotype categories instead of the usual three could aid clinical management and better center patient needs, according to the authors of a new study in The Journal of Urology.
The current diagnostic paradigm includes UTI, asymptomatic bacteriuria (ASB), or not UTI, but the researchers believe these categories exclude for more ambiguous clinical cases, such as patients whose bacteria counts are low but who are symptomatic, or when nonspecific symptoms make it difficult to determine whether treatment with antibiotics is appropriate.
“Our findings suggest the need to reframe our conceptual model of UTI vs ASB to recognize clinical uncertainty and reflect the full spectrum of clinical presentations,” Sonali D. Advani, MBBS, MPH, an associate professor of medicine in infectious disease at Duke University School of Medicine, in Durham, North Carolina, and her colleagues wrote. “Recent data suggest that UTI may present as a bidirectional continuum from asymptomatic bladder colonization to a symptomatic bladder infection,” and some populations may lack the signs or symptoms specific to urinary tract or have chronic lower urinary tract symptoms (LUTS) that make it difficult to distinguish between ASB and UTI, they wrote.
Nitya E. Abraham, MD, an associate professor of urology at Albert Einstein College of Medicine and Montefiore Einstein in New York City, agreed the current paradigm has room for refinement.
“The current classification system doesn’t account for certain patients such as patients who have bothersome urinary symptoms, but urine testing comes back negative, or patients with positive urine testing, but who aren’t able to report the presence or absence of symptoms,” Dr. Abraham, who was not involved in the new research, told this news organization.
Boback Berookhim, MD, a urologist at Northwell Health in New Hyde Park, New York, who was also not involved in the research, said the goal with this study appears to be better identifying who will need antibiotics.
“I think this is more of a forward-looking study in terms of trying to identify patients who currently may not be treated or may be over treated and better identifying subsets,” Dr. Berookhim told this news organization.
However, he said the relevance of the work is far greater in hospitals than in outpatient settings.
“I think it’s much more relevant in inpatient environments where a patient is in hospital and whatever antibiotics are being written are going to be overseen and you’re going to see higher resistance patterns,” Dr. Berookhim said. “For the average doctor who’s seeing patients in the office and writing them prescriptions in the office, this doesn’t really affect them.”
Antibiotic Dilemma
A key issue in determining the best approach to UTI diagnosis is assessing the appropriateness of antibiotic treatment. Up to half of hospitalized patients have ASB, for which current practice guidelines advise against antibiotics, Dr. Advani and her colleagues noted. Yet many of these patients receive antibiotics regardless, and research has shown links between treatment and longer length of stay, antibiotic resistance, and infection with Clostridioides difficile.
The challenge comes with patients who do not fit easily into the existing categories. One includes patients who have positive urine cultures but whose symptoms, such as hypotension or fever, are not specific to the genitourinary tract.
While current guidelines advise against treating these patients with antibiotics, the patients are often older adults with cognitive impairment or delirium, and frontline physicians may err on the side of prescribing antibiotics because of their clinical uncertainty. That treatment can lead to tension with hospital antibiotic stewardship teams that recommend withholding antibiotics for those patients.
“These clinical scenarios highlight differences between the frontline clinicians’ and antibiotic stewardship teams’ definitions of ‘asymptomatic,’ highlighting the ambiguity of the term ‘asymptomatic bacteriuria,’” Dr. Advani and her colleagues wrote.
A fever, for example, could signal a viral or bacterial infection or result from a nonurinary source, Dr. Abraham said. “The antibiotic stewardship team likely prefers to observe the clinical course and wait for more data to demonstrate need for antibiotics,” she said. “Hence, there are conflicting priorities and confusion of when to treat with antibiotics for this common dilemma in patients presenting to the ER or urgent care.”
Meanwhile, other patients, particularly women, may present with urinary symptoms and pyuria but have lab results revealing a colony count below the 100,000 CFU/mL threshold that would indicate antibiotic treatment.
“Some of these women are likely suffering from a UTI and may not receive treatment if clinicians focus primarily on the urine culture results,” Dr. Abraham said. She pointed out the existence of other options than urine culture for better identifying UTI, such as urinary cell-free DNA or next-generation DNA testing of the urine. But she also said the 100,000 CFU/mL threshold should not be absolute.
“For example, I will treat patients for UTI with 10,000-50,000 CFU/mL if they also have UTI symptoms like blood in the urine, burning with urination, bladder pain, increased urgency or frequency, and the urinalysis shows a high white blood cell count,” Dr. Abraham said.
Dr. Abraham also noted a third group outside the scope of the new study: People with urinary symptoms who don’t undergo urine tests or who are treated empirically with antibiotics. “It is unclear whether those in this group truly have a UTI, but it is a common scenario that patients are unable to get urine tests and are treated with over-the-phone prescriptions to expedite treatment,” she said.