Urinary Tract Infections — Classification & Treatment
"UTI" is not one disease — the single most important step is to classify it, because classification drives who needs treating, which drug, for how long, and who needs imaging.
The big picture
"UTI" is not one disease — the single most important step is to classify it, because classification drives everything: who needs treating, which drug, for how long, and who needs imaging. The key splits are uncomplicated vs complicated, lower (cystitis) vs upper (pyelonephritis), and symptomatic vs asymptomatic. Get the category right and the management follows.
The framework: classify (uncomplicated/complicated, lower/upper, symptomatic/asymptomatic) → know the uropathogens → match antibiotic and duration to the category → recognise who needs imaging or source control.
Mechanism pathway
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Diagnostic algorithm
Each step answers one question. Tap to expand.
Board traps
Classify first — uncomplicated vs complicated decides drug, duration, and workup.
E. coli causes most uncomplicated UTIs.
First-line cystitis: nitrofurantoin (5 d), TMP-SMX (3 d, if resistance <20%), fosfomycin (single 3 g dose).
Fluoroquinolones are NOT first-line for simple cystitis — reserve them.
Men/pregnant/catheter/stones = complicated → culture, longer course, source control.
Infected + obstructed = emergency → decompress.