UTI prophylaxis is a relatively common occurance in geriatrics and long term care. Antibiotic use on a chronic basis comes with some challenges and mistakes can absolutely happen. More meds, more problems. Making sure chronic antibiotics are safe and effective is an important role of a consultant pharmacist. Here are my top 5 practice pearls in UTI prophylaxis.
How Often To Reassess UTI Prophylaxis?
One of the biggest pitfalls is leaving prophylaxis on autopilot. Some guidelines do provide detailed recommendations about how often to reassess UTI prophylaxis. Specifically, the NICE guidelines recommend reassessing at least every 6 months. Another time to have providers review antibiotic prophylaxis is when they find themselves writing a prescription for another antibiotic for UTI treatment. This is something I see more often then I would like.
Renal Function
There are many antibiotics that require adjustments or reevaluation if there is a change in renal function. Nitrofurantoin is a classic example — it doesn’t work well in patients with reduced kidney function (usually CrCl < 30 mL/min). I’ve seen it continued for years in patients with stage 4 CKD, providing little benefit and unnecessary risk. Many other antibitoics may also require dose adjustments so make sure to pay attention to changes in renal function over time.
Drug Interactions
Trimethoprim-sulfamethoxazole (TMP-SMX) can increase potassium, especially in patients on ACE inhibitors, ARBs, or spironolactone. I’ve seen hyperkalemia that could have been avoided with better medication review (Excellent board exam nugget). The use of quinolone antibiotics are also problematic because so many patients take supplements that can bind these drugs and increase the risk of them being ineffective.
GI Problems
Nausea, diarrhea, and loss of appetite can often go unreported by patients but lead to poor adherence (outpatient) or unnecessary discomfort. Worse yet, these adverse effects can lead to the prescribing cascade with the addition of antiemetics, antidiarrheals, and weight promoting medications such as mirtazapine or megestrol.
Long Term Adverse Effects
With acute treatment of UTIs, we typically don’t have to worry about long term risk once the antibiotic is done (maybe with the exception of quinolones). Long-term nitrofurantoin can cause pulmonary toxicity. I’ve learned to pay attention to new and worsening respiratory symptoms in patients who need this medication. Here’s a classic case example of nitrofurantoin induced pulmonary toxicity.
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