As a clinical pharmacist, you will be asked more, which antibiotics should be recommended for urinary tract infections in elderly patients? It depends on whether it's a "complicated" UTI or not. We know all UTIs in older MEN are considered complicated due to possible prostate involvement. UTIs in women can also be complicated due to a catheter, obstruction, immunosuppression, etc.
Antibiotic selection also depends on kidney function, side effects, and possible drug interactions. TMP/SMX is first-line for uncomplicated infections, if local resistance is 20%. Hospital pharmacists can get this number from their lab, and community pharmacists can get it from their hospital colleagues.
Recommend using TMP/SMX DS twice daily for 3 days, and half the dose if kidney function is impaired (CrCl 15 to 30 mL/min). Warn about possible hyperkalemia if TMP/SMX is combined with an ACEI, ARB, or potassium, or increased INR with warfarin. Nitrofurantoin 100 mg BID for 5 days is a good option for uncomplicated UTIs, IF renal function is okay. Avoid nitrofurantoin in patients with a CrCl < 60 mL/min, or for a complicated UTI. Quinolones are the best choice for complicated UTIs and kidney infections, or if patients can't take TMP/SMX or nitrofurantoin. Avoid moxifloxacin, it doesn't get into the urine. Recommend avoiding quinolones if local resistance is over 10%, and adjusting the dose for impaired renal function. Caution about possible adverse CNS effects, hyper- or hypo-glycemia, tendon rupture or increased INR in warfarin patients.
Beta-lactams (amoxicillin, etc) are usually less effective for UTIs. Suggest them only if other antibiotics aren't an option. Expect to see antibiotics given for 3 to 5 days for uncomplicated UTIs, 7 to 14 days for complicated UTIs, and 6 to 12 weeks for men with prostate involvement. Discourage treating patients with bacteria in their urine but NO symptoms. There's no benefit and it increases resistance.
REFERENCES
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Matthews SJ, Lancaster JW. Urinary tract infections in the elderly population. Am J Geriatr Pharmacother. 2011 Oct;9(5):286-309. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1543594611001188?via%3Dihub
Gupta K, Hooton TM, Naber KG, Wullt B, Colgan R, Miller LG, Moran GJ, Nicolle LE, Raz R, Schaeffer AJ, Soper DE; Infectious Diseases Society of America; European Society for Microbiology and Infectious Diseases. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011 Mar 1;52(5):e103-20. Available at: https://academic.oup.com/cid/article/52/5/e103/388285?login=false
Lutters M, Vogt-Ferrier NB. Antibiotic duration for treating uncomplicated, symptomatic lower urinary tract infections in elderly women. Cochrane Database Syst Rev. 2008 Jul 16;(3):CD001535. Available at: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD001535.pub2/full