Urinary tract infections (UTIs) are a common complaint among older adults, especially women. Due to their shorter urethras, women are up to four times likely than men to experience a UTI. In fact, it is estimated that 60% of women will experience a UTI in their lifetime and 20-40% will experience more than one episode. Due to their prevalence, the prevention of UTIs is a common topic for care teams.
Several antibiotics are used to treat UTIs, including:
However, antibiotics can contribute to bacterial resistance. Broad spectrum cephalosporin use has been linked to additional infections, including resistant infections such as vancomycin resistant enterococcus (VRE), beta-lactam resistant Acinetobacter, and clostridium difficile. Fluoroquinolones have been associated with methicillin resistant staphylococcus aureus (MRSA) and fluoroquinolone resistance to gram-negative bacilli, including Pseudomonas aeruginosa. In addition, SMZ/TMP and fluoroquinolones may significantly affect the fecal microbiome and therefore contribute to antibiotic resistance.
Furthermore, non-adherence to guidelines has also been seen in patients with recurrent UTIs. These practices include using a longer course of antibiotics, using a broader spectrum antibiotic, and increasing the dose of therapy with each recurrence. While these strategies are commonly used, they have not been shown to increase efficacy and have the potential for harm in both the patient and the community.
Furthermore, antibiotic-resistant bacteria may be more prevalent due to the use of antibiotics in the presence of asymptomatic bacteriuria. This is when bacteria is present in the urine, but without UTI symptoms. It is typically not recommended to treat bacteria in the urine without symptoms. Using antibiotics more often may contribute to resistance.
Many antibiotics are not recommended for older adults, specifically when kidney function is impaired. Ciprofloxacin, a common fluoroquinolone used for UTIs, is associated with a higher risk for central nervous system side effects, including seizures and confusion. It is also associated with a higher risk of tendon rupture for older adults with a creatinine clearance of 30 ml/min or lower.
Nitrofurantoin use, especially long-term use, increases the risk of lung and liver toxicity as well as peripheral neuropathy in older adults. SMZ/TMP may be especially dangerous in older adults with low kidney function due to the risk of high potassium levels—especially if they are taking a blood pressure medication, which may increase potassium levels such as ACE-inhibitors or angiotensin receptor blockers. High potassium levels may lead to severe side effects and may even be fatal in some cases.
What can be done to prevent UTIs in older adults that don’t have these risks? According to the American Geriatrics Society, the first line for prevention of UTIs for older women is vaginal estrogen. This is preferred over systemic estrogen and maintenance antibiotics.
Non-pharmacologic options include increased fluid intake—taking into consideration any fluid restrictions. Cranberry products have mixed evidence of effectiveness and may be an option, while considering that FDA oversight of such products may not be guaranteed. There is also some evidence of the use of methenamine for UTI prevention.
Another way to prevent UTIs is to evaluate the patient’s current medication regimen to determine if a drug is causing or increasing the risk of UTIs. Polypharmacy is a possible cause of UTIs and should be evaluated in the workup of a patient experiencing recurrent UTIs.
For instance, there is a newer class of medications known as SGLT2 inhibitors that are used to treat diabetes. These medications work by preventing glucose reabsorption in the kidneys and thereby increasing glucose content in the urine. This increased glucose presence has been shown to increase the risk of both UTIs and genital infections.
Other medications associated with UTIs include those with anticholinergic properties and those that impair the neurogenic control of the bladder. Anticholinergic medications inhibit bladder emptying by limiting contraction. The resulting urinary retention allows for colonization of bacteria in the bladder. There are hundreds of medications which may lead to anticholinergic side effects including urinary retention. Medications that impair bladder control include benzodiazepines, calcium channel blockers, opioids, and non-steroidal anti-inflammatory drugs (NSAIDs). These medications may lead to bladder muscle relaxation and problems with voiding reflexes. Therefore, these medications may also reduce or delay bladder emptying.
There are several other medications which may increase the risk of urinary stones due to the drug or metabolite precipitating in the urine or changing the pH of the urine. These medications include antimicrobials (sulfonamides, ciprofloxacin, ampicillin), calcium, vitamin D and C, laxatives, loop diuretics, acetazolamide, and allopurinol. The formation of bladder stones may also increase the risk of infection.
Clinical decision support tools, such as those used by GalenusCare Precision Pharmacists, may help to identify medications that may be causing or worsening the risk of UTIs. Pharmacists may be utilized in deprescribing decision-making to help prevent UTIs instead of using antibiotic prophylaxis. The pharmacist may be able to help reduce UTIs and improve quality of life, while reducing overall medication risk and antibiotic resistance.