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Urinary Tract Infections in the Elderly

 

Urinary tract infection (UTI) is the second most commonly seen bacterial infection among the elderly population.  Urinary conditions can range from asymptomatic bacteriuria, to symptomatic bladder or kidney infection, to UTI requiring hospitalization.  While there are clinical parameters in place that guide antibiotic use for UTI, there are still many elderly patients that are being over diagnosed and inappropriately treated with antibiotics. Inadequate diagnosis and overuse of antibiotics can lead to increased microbial resistance, which is a growing concern across the country. Many challenges are faced when diagnosing symptomatic UTI in long-term care residents. Chronic genitourinary symptoms and impaired communication make it difficult to identify the urinary symptoms that may be associated with infection. It is important to note that the diagnosis of UTI in elderly adults requires both clinical presentations and laboratory evidence of infection.

 

Risk factors for UTI in older adults

·   Female sex

·   Functional impairment, genitourinary abnormalities, or obstruction

·   Use of indwelling catheter

·   Comorbidities such as diabetes, dementia, or incontinence

·   Sexually active (postmenopausal women)

 

Clinical presentations

·   Bladder infection, cystitis

  -  Dysuria, frequency, hematuria, suprapubic pain, new-onset or worsening incontinence

  -   Can cause delirium in elderly patients

  -   Fever (uncommon)

·   Kidney infection, pyelonephritis

  -   Costovertebral angle tenderness, flank pain

  -   Fever

            

Diagnosis

Clinical symptoms and laboratory evidence are required to establish a diagnosis of UTI.  Differentiating acute urinary symptoms from chronic symptoms unrelated to infection make diagnosing challenging.  In older adults, urinary urgency and incontinence can fluctuate or worsen even without a urinary infection.  Examples of other conditions that can be mistaken for a UTI include benign prostatic hyperplasia, worsening urinary incontinence, and asymptomatic bacteriuria.  When evaluating new urinary symptoms timing, severity, and location are important.  Acute onset of dysuria is often associated with a potential symptomatic UTI.  Suspected clinical presentations indicate a need for further diagnostic evaluation.

 

Urinary dipsticks are convenient and are often used in outpatient settings to test leukocyte esterase and nitrite levels in the urine.  Positive dipstick results may indicate pyuria or bacteriuria; further urine studies are warranted to confirm clinical suspicion of UTI.   A urinalysis is another option for suspected UTI, 10 or more white blood cells per high-powered field is considered positive. Pyuria is often nonspecific in older populations and may be present without bacteriuria. However, the absence of pyuria has a high negative predictive value and can rule out UTI.  These tests have variable results and should only be used to rule out UTI, not to establish a diagnosis.

 

Samples with a positive dipstick or urinalysis should be sent for lab cultures to confirm bacteriuria and to get antibiotic sensitivities.  The most common uropathogen is E.coli (54.6%-69%); other cultured organisms include Klebsiella, P. mirabilis, and enterococcus.

 

Treatment

First-line therapy

TMP/SMX 160/800 mg PO BID for 3-5 days

Nitrofurantoin 100 mg PO BID for 5-7 days

 

Alternative therapy

*Ciprofloxacin 250 - 500 mg PO BID for 7-14 days

*Levofloxacin 250 mg PO QD for 10 days

Amoxicillin-clavulanate 875 mg PO BID for 14 days

Fosfomycin 3 g PO once

 

*Fluoroquinolones are effective against UTI but should be reserved as empiric therapy for patients with severe presentation. Duration of antibiotic therapy may be increased for more complicated cases.

 

Asymptomatic Bacteriuria

The prevalence of asymptomatic bacteriuria (ASB) increases with age and is generally benign in this population.  Women over the age of 80 years old have a prevalence of 20% or more, while the elderly male counterparts have a 5-10% prevalence of ASB.  According to the Infectious Disease Society of America (IDSA), ASB is defined as 2 consecutive voided urine specimens in women or 1 urine specimen in men, with >105 colony-forming units per milliliter of an isolated bacterial strain.  Residents with chronic indwelling catheters are always bacteriuric. Treatment with antibiotics is not indicated in asymptomatic bacteriuria.

 

 

Recurrent UTI Prophylaxis

In residents with recurrent UTI, a prophylactic regimen may be considered. Recurrent UTI is defined as having two or more symptomatic UTIs within 6 months or 3 or more infections within 1 year. For older women with recurrent and uncomplicated UTIs, a low-dose antibiotic regimen may be considered for prevention.  First-line regimens that are used are TMP/SMX 80/400 mg daily or nitrofurantoin 50-100 mg daily for 6 to 12 months.  

 

Vaginal estrogen preparations may also be considered in postmenopausal women.   Estrogen replacement therapy is used to restore vaginal pH and increase the amount of lactobacilli. It is thought that by increasing the amount of “good bacteria” in the vaginal flora, it will decrease the amount of colonization by the uropathogens that commonly cause UTIs.

 

For patients that are urine culture positive for E.coli, cranberry products may be an effective prophylactic strategy.  The active ingredient in cranberries is thought to prevent the adhesion of E.coli to uroepithelial cells, reducing the incidence of UTIs.   A study conducted with older women, showed that 300 mL of cranberry juice daily reduced the laboratory evidence of UTI at 6 months.  Additional studies are needed to determine the optimal dose of cranberry products for UTI prevention.

 

In long-term care residents, symptoms of UTI can be variable and are often nonspecific to infection.  Asymptomatic bacteriuria is highly prevalent among this population and should not be treated.  Increasing efforts towards adequate diagnosis and management of UTIs are necessary to limit inappropriate use of antibiotics.   

 

 

 

Detweiler, Keri et al. "Bacteruria and Urinary Tract Infections in the Elderly." Urologic Clinics of North America 42.4 (2015): 561-68.

Mody, Lona, Manisha Juthani-Mehta. "Urinary Tract Infections in Older Women." JAMA 311.8 (2014): 844-53.

Nicolle, Lindsay E. "Urinary Tract Infections in the Older Adult." Clinics in Geriatric Medicine 32.3 (2016): 523-38.

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