Urinary tract infection (UTI)
Urinary tract infection (UTI) denotes bacterial infection anywhere in the urinary tract (kidneys to bladder) producing characteristic local and/or systemic symptoms with significant bacteriuria. UTIs are common in the emergency department but diagnosis and management are nuanced: recognise upper versus lower disease, obtain appropriate samples, start guideline‑based empiric therapy where indicated, and safety‑net patients for deterioration.
This section summarises pathogenesis, clinical classification, investigations, ED management priorities and the high‑yield NICE‑based prescribing points clinicians must know (NICE NG109, NG111, NG113, NG224). Always check local antimicrobial susceptibility before selecting empiric therapy.
Pathogenesis and common organisms
- Most community UTIs result from peri‑anal/GI organisms ascending the urethra.
- Less commonly infection is haematogenous or introduced via instrumentation/catheters.
- Common pathogens:
- Escherichia coli (majority).
- Staphylococcus saprophyticus (young women).
- Proteus mirabilis (associated with stones/structural disease).
- Klebsiella and other Enterobacterales.
- Pseudomonas and Candida are more likely in healthcare‑associated or catheterised patients.
Clinical classification - why it matters
- Lower UTI (cystitis): dysuria, frequency, urgency, suprapubic discomfort, sometimes haematuria. Systemic features usually absent.
- Upper UTI (pyelonephritis): fever, rigors, flank/loin pain, nausea/vomiting, systemic toxicity. Any lower UTI with systemic features should prompt consideration of upper tract infection and broader assessment.