Gloria is an 80 years old lady with a history of mild cognitive impairment, osteoporosis, hypertension, diabetes who often presents with an urinary tract infection (UTI) monthly. It is very unpleasant with the typical symptoms such as burning sensation, increased urinary frequency as well as slightly increased in irritability. Upon treatment with antibiotic, the symptoms go away quickly. Who wants to have a urinary tract infection monthly?
So the physician prescribed Nitrofurantoin 100mg po daily as a prophylaxis for recurrent urinary tract infection. The frequency of UTIs quickly went from once every month to once every few months. Is the use of antibiotic prophylaxis justified? Many treatment guidelines do not strongly encourage the use of antibiotic prophylaxis given the risk of resistance development. However, some of these anecdotal experiences continue to encourage clinicians to prescribe them for their patients. In fact, there is evidence to support the use of low dose antibiotic prophylaxis for the prevention of urinary tract infection in specific circumstances.
Dason et. al. have published an article describing their recommended management guidelines for recurrent urinary tract infection in women here.
A UTI may be recurrent when it follows the complete clinical resolution of a previous UTI. A threshold of 3 UTIs in 12 months is used to signify recurrent UTI.
See figure below for the evaluation of recurrent urinary tract infection. It includes reviewing the history and physical exam findings, analysis of urine culture results as well as assessment of risk factors for complicated UTIs and other investigations.
If the patient is deemed to have uncomplicated recurrent UTIs, below is a figure depicting the management of recurrent urinary tract infection:
In this guideline, the suggested continuous antibiotic prophylactic regimens are as follow:
- Trimethoprim/sulfamethoxazole (TMP/SMX) 40mg/200mg daily or thrice weekly
- Trimethoprim 100mg po daily
- Ciprofloxacin 125mg po daily
- Cephalexin 125-250mg po daily
- Cefaclor 250mg po daily
- Nitrofurantoin 50-100mg po daily
- Norfloxacin 200mg po daily
- Fosfomycin 3 gram every 10 days.
In regards to postcoital antibiotic prophylaxis (within 2 hours of coitus), below are some of the recommended regimens:
- Trimethoprim/sulfamethoxazole (TMP/SMX) 40mg/200mg to 80mg/400mg
- Ciprofloxacin 125mg
- Cephalexin 250mg
- Nitrofurantoin 50-100mg po daily
- Norfloxacin 200mg
- Ofloxacin 100mg
What about other strategies such as cranberry products or topical estrogen-based therapy?
The guidelines also suggest other options such as cranberry products and / or vaginal estrogen cream or ring for postmenopausal women. Interestingly, the Canadian Agency for Drugs and Technologies in Health (CADTH) has recently completed a rapid response report detailing the evidence for these two options. In this report, the evidence has been mixed for the use of cranberry product in UTI prophylaxis. However, there are at least two high quality studies to support the use of topical estrogen-based product for the treatment of UTIs in post-menopausal women. In Ontario, Premarin Vaginal Cream 0.625mg/g is covered by the Ontario Drug Benefits Program. The recommended regimen is 0.625mg vaginally every night for 2 weeks, then twice a week for 8 months.
Many patients I encounter in long term care facilities are often on some cranberry products. If UTI continues to occur frequently, some individuals eventually go on antibiotic prophylaxis. However, there are often side effects including chronic diarrhea and potential drug interactions with other medications. Given the long term safety of antibiotic use is not well established, I think we should explore the use of estrogen vaginal cream as another prevention option for UTI in postmenopausal women before resorting to prescribing antibiotic prophylaxis. But again, the decision must be individualized based on the patient’s comfort with the benefits and risks of each of these treatment options.