O&G SAQs · Urogynaecology — infection
Recurrent urinary tract infection — structured SAQ (15 marks)
FRANZCOG-format structured SAQ on recurrent UTI in a young sexually active woman: definition and threshold, re-infection vs persistence, first-line antibiotic, non-antibiotic prevention and antibiotic prophylaxis strategy.
On this page
Study tools
Target exams
FRANZCOGMRCOGABOG
Prompt
A 38-year-old woman presents with her fifth culture-confirmed Escherichia coli cystitis in the last 14 months. She is sexually active, uses a spermicide-coated diaphragm, and has no chronic medical conditions. She is not pregnant. Her examination is unremarkable. (a) State the definition of recurrent urinary tract infection and the threshold for symptomatic urinary tract infection on urine culture in women. (2 marks) (b) Outline the distinction between re-infection and persistence, and what each implies for management. (4 marks) (c) List the first-line acute antibiotic regimen you would prescribe, naming the agent, dose, route and duration. (3 marks) (d) Outline your non-antibiotic preventive strategy, naming three options with their mechanism of action. (4 marks) (e) State which antibiotic prophylaxis regimen you would recommend for this patient, and why. (2 marks)
How this SAQ is marked
Twelve SAQs, 180 marks, two 2-hour papers — roughly 15 marks and 20 minutes each. Marks come from specifics: definition, threshold, named agent, dose, route, duration, named non-antibiotic option, mechanism. Write in short labelled points, not prose paragraphs. Answer the sub-part you are asked. [1]
Reveal model answer and mark schemeShowHide
(a) Definition and threshold (2 marks)
- Definition of recurrent UTI: ≥2 culture-confirmed infections in 6 months, or ≥3 in 12 months (AUA/CUA/SUFU 2019, EAU 2024).[1][6]
- Symptomatic UTI threshold in women: ≥10^3 cfu/mL of a single uropathogen with symptoms (EAU 2024); the classical Kass threshold of ≥10^5 cfu/mL was derived from asymptomatic women and is not the symptomatic threshold.[6]
(b) Re-infection vs persistence (4 marks)
- Re-infection (~80% of recurrences): new organism or new strain of E. coli, ascending from the periurethra, usually >2 weeks after treatment. The urinary tract is structurally normal; the issue is biology and behaviour (spermicide, sexual activity, Lactobacilli depletion).[1]
- Persistence (uncommon): the same organism recurs within 2 weeks of treatment; implies a nidus within the urinary tract — stone, diverticulum, abscess, fistula, foreign body, obstruction.[1][6]
- Management implication of re-infection: modify triggers, prevent with non-antibiotic measures, offer antibiotic prophylaxis (continuous, post-coital, or self-start).[1]
- Management implication of persistence: image (renal ultrasound, CT urogram) and consider cystoscopy to identify and treat the nidus; antibiotic prophylaxis alone will fail.[1]
(c) First-line acute antibiotic regimen (3 marks)
- First-line agent: nitrofurantoin 100 mg modified-release orally twice daily for 5 days.[1]
- Alternatives: trimethoprim 300 mg orally once daily for 3 days (if local resistance under 30%); fosfomycin 3 g orally single dose.[1]
- Avoid fluoroquinolones as first-line for uncomplicated cystitis — resistance, tendon rupture, aortic dissection, WHO AWaRe "Watch" list.[1]
(d) Non-antibiotic preventive strategy (4 marks)
One mark per option with mechanism. [2][3][4][5]
- Cessation of spermicide and diaphragm use — spermicide depletes vaginal Lactobacilli and increases periurethral E. coli colonisation; switch to an alternative contraceptive.[1]
- Cranberry — high-proanthocyanidin content (≥36 mg/day); proanthocyanidins inhibit E. coli fimbrial attachment to uroepithelium. Modest effect, heterogeneous trial evidence.[2]
- Methenamine hippurate — converted to formaldehyde in acidic urine; the ALTAR trial showed non-inferiority to low-dose antibiotic prophylaxis.[3]
- Uro-Vaxom (OM-89) immunostimulant immunoprophylaxis — oral lyophilised bacterial extract; modulates mucosal immune response to uropathogens; modest reduction in rUTI frequency.[4]
(Plus, in post-menopausal women, vaginal oestrogen — restores vaginal Lactobacilli and thickens urethral/vaginal epithelium; not relevant in this 38-year-old patient.)[5]
(e) Antibiotic prophylaxis recommendation (2 marks)
- Post-coital antibiotic prophylaxis is the most efficient strategy in a young sexually active woman whose UTIs cluster around intercourse.[1][6]
- Regimen: a single dose of nitrofurantoin 50–100 mg, OR trimethoprim 100 mg, OR cephalexin 250 mg, taken within 2 hours of intercourse.[1][6]
- Combined with cessation of spermicide and a non-antibiotic adjunct (methenamine hippurate or cranberry).
References6ShowHide
- [1]Anger J, Lee U, Ackerman AL, et al. Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline J Urol, 2019.PMID 31042112
- [2]Fu Z, Liska D, Talan D, et al. Cranberry Reduces the Risk of Urinary Tract Infection Recurrence in Otherwise Healthy Women: A Systematic Review and Meta-Analysis J Nutr, 2017.PMID 29046404
- [3]Harding C, Chadwick T, Homer T, et al. Methenamine hippurate compared with antibiotic prophylaxis to prevent recurrent urinary tract infections in women: the ALTAR non-inferiority RCT Health Technol Assess, 2022.PMID 35535708
- [4]Brodie A, El-Taji O, Jour I, et al. A retrospective study of immunotherapy treatment with Uro-Vaxom (OM-89) for prophylaxis of recurrent urinary tract infections Curr Urol, 2020.PMID 33224005
- [5]Fox KA, Lokken EM, Reed SD, et al. Evaluation of systemic estrogen for preventing urinary tract infections in postmenopausal women Menopause, 2021.PMID 33973539
- [6]Anger JT, Bixler BR, Holmes RS, et al. Updates to Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline Amendment J Urol, 2022.PMID 35942788