The UTI That Isn’t
Rob Orman MD and Dave Glaser MD
Take Home Points
§ Asymptomatic bacteriuria is very common in adults, occurring in up to 20% of healthy women and 50% of long term care residents.
§ A urinary tract infection is a positive urinalysis with signs and symptoms of a urinary tract infection.
§ Watchful waiting is an appropriate strategy in asymptomatic patients. The likelihood of cystitis progressing to pyelonephritis is 1 in 38.
● An 80-year-old female presents after mechanical fall resulting in a pelvic fracture. She denies dysuria or increased frequency and urgency. She is afebrile and asymptomatic. As part of her work-up, she receives a urinalysis that shows 10-15 wbc/hpf and bacteria. Diagnosis? Pelvic fracture and urinary tract infection. She is sent home with a walker and a script for antibiotics.
● You have two 80 year old patients. Both patients have 3+ bacteria and 15 wbc/hpf. One patient has dysuria and the other does not. Does it make a difference? We view urinary tract infection as a laboratory diagnosis. We forget that the differential of a positive urinalysis also includes asymptomatic bacteriuria. We have been trained that bacteria and white blood cells in the urine indicate an infection. This is wrong.
● What is the prevalence of asymptomatic bacteriuria in adults? It is very common. It is bacteria with or without white blood cells in the urine and no infection. Asymptomatic bacteriuria is more common with older age. A study found a rate of asymptomatic bacteriuria of 5% in sexually active young women. This rate increases with age. Up to 20% of healthy women in the community will have asymptomatic bacteriuria. 15% of men over the age of 75 will have it. The incidence can reach 50% of women and 40% of men in the long-term care population.
o Hooten, TM et al. A prospective study of asymptomatic bacteriuria in sexually active young women. N Engl J Med. 2000 Oct 5;343(14):992-7. PMID: 11018165
● There are commensal bacteria that live in happy harmony in the bladder of these patients. This may not be continuous. Patients may clear their bacteria only to have recurrence later.
● What is a urinary tract infection? UTI is a positive UA (usually a positive urine culture or at least 10 wbc/hpf and bacteria) with signs and symptoms of a urinary tract infection. Older patients may have altered mental status and not genitourinary symptoms. We are often happy to ascribe vague symptoms in the elderly such as dizziness, nausea or falls to a positive urinalysis and treat as an infection. Older patients may not develop specific urinary tract symptoms. However, you need some clinical symptom in the otherwise healthy, alert patient population to call it a UTI. We are probably doing harm by treating these patients.
● The degree of positivity doesn’t help in the diagnosis of UTI. Patients in long-term care or chronic incontinence are likely to have asymptomatic bacteriuria. It is the clinician’s job to determine if they have a urinary tract infection. It is likely pyelonephritis if you are going to ascribe altered mentation or other systemic symptoms to urinary tract infection. Simple cystitis does not cause systemic symptoms.
● Watchful waiting is a good idea in many of these patients. Some studies have shown that 25-50% of women with typical cystitis symptoms and positive urinalysis will have spontaneous resolution of their cystitis within a week. The likelihood of progressing from cystitis to pyelonephritis has been cited as 1 in 38 times. Often times a positive urinalysis will not have positive cultures.
o Christiaens, TC et al. Randomised controlled trial of nitrofurantoin versus placebo in the treatment of uncomplicated urinary tract infection in adult women. Br J Gen Pract. 2002 Sep;52(482):729-34. PMID: 12236276
o A study found 43% of patients with a diagnosis of urinary tract infection did not have positive urine cultures. 95% of these were given antibiotics.
o Gordon, LB et al. Overtreatment of presumed urinary tract infection in older women presenting to the emergency department. J Am Geriatr Soc. 2013 May;61(5):788-92. PMID: 23590846
● There is concern for complications of antibiotic use such as C. difficile. Some believe that some bacteria may be uroprotective and keeping more pathogenic bacteria at bay. Killing these bacteria may increase the risk of infection with more pathogenic bacteria. We like to act on findings but this can result in harm over a global population.
● If asymptomatic bacteriuria grows out bacteria on culture, is it considered a UTI? No. The culture does not distinguish between asymptomatic bacteriuria or infection. You need the clinical signs and symptoms.
● When should you send urine? If the patient presents with symptoms of infection, they need urinalysis. If the patient is elderly with a fall but alert without urinary tract symptoms, they don’t need a UA. The specificity of UA for a UTI is quite low.
● What should you do with patients with indwelling catheters? These are always positive for everything. These patients have a higher rate of asymptomatic bacteriuria. You need to decide clinically if they are infected. If they don’t have any other signs of infection, you are better off not sending the urine.
● Get the urinalysis if they have signs and symptoms referable to a urinary tract infection or as part of work-up of stone. Don’t get the urinalysis for vague symptoms. You will overtreat and hurt a lot of your patients. Don’t treat the lab, treat the patient.