Recurrent urinary tract infection (rUTI) in women

It is a Monday afternoon in general gynaecology clinic. A 28-year-old teacher sits down and opens with: "I'm back again." She has had four culture-positive Escherichia coli cystitis episodes in the last nine months — each triggered by sex, each settling with a three-day course of trimethoprim. She is sexually active, uses a spermicide-coated diaphragm, and is frustrated. The art is to recognise the dominant pattern (re-infection, ascending from periurethra), modify the risk factors she can change (spermicide), and offer her the right prevention strategy (post-coital prophylaxis is the most efficient single-dose answer in young sexually active women).^[1][12]

Overview and definition

Recurrent urinary tract infection (rUTI) is two or more culture-confirmed infections within six months, or three or more within twelve months — the working definition adopted by AUA/CUA/SUFU (2019, amended 2022), EAU 2024, NICE NG109 and most contemporary guidelines.^[1][2][14]

The definition matters for three reasons:^[1][14]

• It separates women who need prevention from those with isolated cystitis.^[1]
• It forces a culture-confirmed diagnosis, which protects against labelling a sterile bladder pain episode as UTI.^[1]
• It delineates when to investigate for an underlying cause.^[1]

Re-infection vs persistence — the discrimination you must make: ^[1][12]

• Re-infection (~80% of recurrences): a new organism, or a new strain of E. coli, ascending from the periurethra, usually more than two weeks after the last infection. The urinary tract is structurally normal; the issue is biology and behaviour.
• Persistence (uncommon): the same organism recurs within two weeks of treatment, implying a nidus within the urinary tract — stone, diverticulum, abscess, fistula, foreign body, obstructed kidney, or chronic prostatitis in men. Persistence demands imaging and often intervention.^[1]

Uropathogens: ^[1][8]

• Escherichia coli (the dominant pathogen; uropathogenic strains with P-fimbriae and type-1 fimbriae).^[1][8]
• Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, Staphylococcus saprophyticus (the young sexually active cohort), group B Streptococcus, Citrobacter, Pseudomonas (in catheter-associated or healthcare-associated infection).^[1][8]