Adult with suspected complicated UTI or pyelonephritis
Urinary infection with signs that it has spread beyond the bladder.
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Infectious DiseaseManagement
Complicated UTI & Pyelonephritis Management (IDSA 2025)
Complicated UTI & Pyelonephritis Management (IDSA 2025): Adult with suspected complicated UTI or pyelonephritis → Confirm complicated UTI (IDSA 2025) → ...
Pathway Overview
24 steps
Algorithm Steps
24 total
01Start 02Action Confirm complicated UTI (IDSA 2025)
cUTI = infection beyond the bladder. Afebrile infection confined to the bladder is uncomplicated UTI, even in men.
- Fever, or other systemic signs (chills, rigors, haemodynamic instability)
- Flank pain or costovertebral angle tenderness (pyelonephritis)
- Systemic symptoms with a urinary catheter (indwelling, suprapubic or intermittent), stent or nephrostomy
- Male sex, diabetes or a urological abnormality alone does not make a UTI complicated
- Catheter with bacteriuria but no symptoms: asymptomatic bacteriuria; do not treat
- Men: consider acute prostatitis (outside IDSA 2025 scope; longer course)
03Action Initial workup
Take cultures before the first dose, but do not delay antibiotics in sepsis.
- Urinalysis and urine culture with susceptibilities (catheter: take it from a new catheter)
- Blood cultures if sepsis or severe illness
- Creatinine and electrolytes, full blood count; pregnancy test if she could be pregnant
- Review prior urine cultures (last 3-6 months) and fluoroquinolone use in the past 12 months
- Ultrasound (CT if hydronephrosis or obstruction suspected) if septic, stone or obstruction suspected, or no response by 48-72 h
04Warning Obstructed infected kidney: urgent decompression, even without sepsis
A urological emergency. Antibiotics alone often fail.
- Signs: hydronephrosis or obstructing stone on imaging, pyonephrosis, or anuria
- Call urology now for a ureteric stent or nephrostomy; do not wait 48-72 h for a response
- Start antibiotics now; do not delay them for imaging or drainage
05Warning Pregnant, child, kidney transplant or neutropenic: different care
IDSA 2025 did not study these groups.
- Pregnant: admit for IV antibiotics and obstetric review (next step)
- Child: use a paediatric UTI guideline; adult doses do not apply
- Kidney transplant or neutropenia: get specialist advice now; do not delay sepsis antibiotics
06Decision Pregnant?
- If Yes
- Pregnant
07Action Pregnant: admit for IV antibiotics and obstetric review
IDSA 2025 does not cover pregnancy. Regimen from SA Health perinatal guideline (based on eTG Antibiotic).
- Amoxicillin or ampicillin 2 g IV 6-hourly PLUS gentamicin 5 mg/kg IV once daily (ideal or adjusted body weight)
- Gentamicin contraindicated or CrCl <40 mL/min: ceftriaxone 1 g IV daily (no ESBL, enterococcal or Pseudomonas cover)
- Known ESBL or high MDR risk: meropenem 1 g IV 8-hourly, with ID advice
- Penicillin allergy: gentamicin alone; most cephalosporins are safe if the allergy was not severe
- IV until afebrile for at least 24 h, then oral by susceptibility: cefalexin 500 mg 6-hourly or amoxicillin 500 mg 8-hourly; 10-14 days in total
- Avoid trimethoprim in the first trimester. Nitrofurantoin does not treat pyelonephritis
- Sepsis: antibiotics within 1 h; obstetric and ICU review; watch for preterm labour
08Outcome Pregnant: complete 10-14 days; repeat urine culture 1-2 weeks after
Not improving by 48-72 h: renal ultrasound, repeat cultures, obstetric and ID review.
If No- Not pregnant
09Warning Before choosing an antibiotic: allergy, kidneys, fluoroquinolone risk
Avoid any drug the last urine isolate resisted, and avoid fluoroquinolones if used in the past 12 months. Do not delay sepsis antibiotics.
- Severe beta-lactam allergy (anaphylaxis, SJS/TEN): no penicillins or cephalosporins; use gentamicin or a fluoroquinolone; get advice
- Kidney impairment: adjust doses; no repeat gentamicin doses if CrCl <40 mL/min
- Fluoroquinolones: caution with aortic aneurysm or its risk factors, older age or steroids (tendon rupture), long QT
10Decision Sepsis or septic shock?
Sepsis = organ dysfunction from infection (SOFA rise of 2 or more). qSOFA or SIRS can screen.
- If Yes
- Sepsis
11Action Sepsis: IV antibiotics within 1 h and source control
Resuscitate per sepsis pathway. Choose one IV agent below, active against any prior urine isolate.
- Ceftriaxone 1-2 g IV daily, OR piperacillin-tazobactam 4.5 g IV 8-hourly, OR a fluoroquinolone (only if no fluoroquinolone in past 12 months)
- Known ESBL, or MDR colonisation or risk: meropenem 1 g IV 8-hourly (not piperacillin-tazobactam)
- Australia (TG Antibiotic): gentamicin 4-5 mg/kg IV (ideal or adjusted body weight; up to 7 mg/kg in septic shock) PLUS amoxicillin 2 g IV 6-hourly
- Obstruction or infected hydronephrosis: urgent decompression (stent or nephrostomy) with urology
- Australia, gentamicin contraindicated: ceftriaxone 1 g IV daily (1 g 12-hourly if critically ill)
- Gentamicin: empirical use no longer than 48 h; no repeat doses if CrCl <40 mL/min
- Add Pseudomonas, enterococcal or MRSA cover only if suspected (prior culture, device) or the source is unclear
12Decision Urinary catheter, stent or nephrostomy?
No device: go to culture-guided treatment, which applies to every patient.
- If Yes
- Catheter or device
13Action Catheter present: remove or replace it
Catheter-associated UTI.
- Remove the catheter if no longer needed
- In place 2 weeks or more and still needed: replace it (before antibiotics if this causes no delay); culture from the new catheter
- Stent or nephrostomy: discuss with urology
- Do not treat asymptomatic bacteriuria in catheterised patients
14Action Tailor treatment to culture results
Do this for every patient as soon as results arrive.
- Narrow to an effective drug with a targeted spectrum
- Switch IV to oral when improving, can take oral drugs, and an effective oral drug exists
- Bacteraemia: switch when afebrile, stable and any obstruction is relieved
- Best oral options: fluoroquinolone or TMP-SMX; oral beta-lactams are less effective (use high doses)
15Decision Improving by 48-72 h?
- If Yes
- Improving
16Action Improving (not pregnant): complete a short course
Count days from the first effective dose.
- cUTI and pyelonephritis: 7 days, or 5-7 days of a fluoroquinolone
- Gram-negative bacteraemia from a urinary source: 7 days
- Catheter-associated UTI: 7 days if prompt response; up to 14 days if slow
- Febrile man with suspected acute prostatitis: consider 10-14 days (limited evidence)
- Abscess, undrained obstruction or immunocompromise: individual course with specialist advice
17Outcome Course complete
No routine test-of-cure urine culture.
If No- Not improving
18Action Not improving by 48-72 h: look for a source
Check drug choice against culture results.
- CT (or ultrasound) for obstruction, abscess or stone; drain or decompress
- Repeat urine and blood cultures
- Change antibiotic to match susceptibilities; consider a resistant organism
- Reconsider the diagnosis (other infection source, prostatitis)
- Urology and ID advice
19Outcome Specialist-guided treatment
Duration set by source control and response.
If No- No device
- Path rejoins step 14Shared downstream outcome
If No- No sepsis
20Decision No sepsis: risk of a resistant organism?
Yes if any: prior urine isolate resistant to the planned drug; fluoroquinolone in the past 12 months; known ESBL or MDR colonisation; recent high-risk travel.
- If Yes
- Resistance risk
21Action Resistance risk: choose a drug active against the prior isolate
No sepsis. Prior resistant isolate, fluoroquinolone in past 12 months, or ESBL risk. Use prior culture results; narrow when new results arrive.
- Prior ESBL, oral option: TMP-SMX, ciprofloxacin or levofloxacin if the isolate is susceptible
- Prior ESBL, IV needed or no oral option: ertapenem 1 g IV daily
- No ESBL (recent fluoroquinolone only, or other resistance): an active non-fluoroquinolone drug, such as ceftriaxone 1-2 g IV daily; no carbapenem needed
- ESBL alternatives: an aminoglycoside (watch kidney function) or piperacillin-tazobactam (not if bacteraemic or critically ill)
- Do not use cefepime for ESBL cUTI
- Keep ceftazidime-avibactam, ceftolozane-tazobactam and similar agents for carbapenem-resistant organisms, with ID advice
- Path rejoins step 12Shared downstream outcome
If No- Low risk
22Decision Low resistance risk: well enough for oral treatment at home?
Yes needs all: no sepsis, takes oral drugs, no vomiting, no obstruction or abscess, can return if worse.
- If Yes
- Oral at home
23Action Low risk, oral at home: fluoroquinolone or TMP-SMX
Not for pregnancy, obstruction, abscess or vomiting. Check local resistance.
- Ciprofloxacin 500-750 mg oral 12-hourly OR levofloxacin 750 mg oral daily, if no fluoroquinolone in past 12 months (Australia: reserve for resistance; use TMP-SMX or a beta-lactam below first)
- OR TMP-SMX 160/800 mg oral 12-hourly (if the organism is known or likely susceptible)
- Alternatives (less effective): amoxicillin-clavulanate 875/125 mg oral 8-12-hourly, or cefalexin 500-1000 mg oral 6-hourly
- Do not use nitrofurantoin or oral fosfomycin for cUTI or pyelonephritis
- Oral beta-lactam or resistance concern: consider one dose of ceftriaxone 1 g IV first
- Warfarin: TMP-SMX and ciprofloxacin raise the INR. TMP-SMX raises potassium (CKD, ACE inhibitor, ARB, spironolactone)
- Path rejoins step 12Shared downstream outcome
If No- Admit
24Action Low risk, needs admission: IV ceftriaxone or alternative
No sepsis, but cannot take oral drugs, needs monitoring, or has obstruction (decompress urgently).
- Ceftriaxone 1-2 g IV daily
- OR piperacillin-tazobactam 4.5 g IV 8-hourly, OR a fluoroquinolone
- Carbapenems are not first choice without sepsis or resistance risk
- Australia (TG Antibiotic): gentamicin 4-5 mg/kg IV (ideal or adjusted body weight) PLUS amoxicillin 2 g IV 6-hourly, or ceftriaxone 1 g IV daily
- Gentamicin: empirical use no longer than 48 h; no repeat doses if CrCl <40 mL/min
- Path rejoins step 12Shared downstream outcome
Guideline Source
IDSA 2025 Guidelines on Management and Treatment of Complicated Urinary Tract Infections (Trautner BW et al, Clin Infect Dis 2025)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- IDSA 2025 does not cover pregnancy, children, kidney transplant, neutropenia or prostatitis; the pregnancy step follows SA Health (eTG-based) guidance.
- Empiric choice depends on prior urine cultures, recent fluoroquinolone use and local resistance; Australian practice follows TG Antibiotic (gentamicin-based urosepsis regimens; fluoroquinolones restricted).
- Short-course evidence mostly excludes catheterised, obstructed, abscess, immunocompromised and CKD patients.
- Oral beta-lactam step-down is less effective than fluoroquinolones or TMP-SMX.
Contraindicated Populations
Children (use a paediatric UTI guideline)Kidney transplant recipients (specialist advice)Neutropenic patients (specialist advice)
Applicable Regions
USEUAU
AU: Empiric urosepsis (TG Antibiotic, as adapted in the Safer Care Victoria Adult Sepsis Pathway 2025): gentamicin IV PLUS amoxicillin 2 g IV 6-hourly; ceftriaxone if gentamicin is contraindicated; meropenem 1 g IV 8-hourly if high MDR risk (colonisation, or travel to the Indian subcontinent, Asia or Southern/Eastern Europe). Fluoroquinolones are restricted in Australia to infections resistant to other recommended drugs. Check eTG Antibiotic for non-septic pyelonephritis regimens and course length.
EU: EAU Urological Infections guideline gives similar advice; follow local resistance data.
US: IDSA 2025: in sepsis, use a local antibiogram only if it is recent and relevant (aim for at least 90% susceptibility in shock, 80% without shock).
Version 2Next review: 2027-09-30
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Related Resources
Frequently Asked Questions
What is the Complicated UTI & Pyelonephritis Management (IDSA 2025)?
The Complicated UTI & Pyelonephritis Management (IDSA 2025) is a management clinical algorithm for Infectious Disease. It provides a structured decision tree to guide clinical decision-making, based on IDSA 2025 Guidelines on Management and Treatment of Complicated Urinary Tract Infections (Trautner BW et al, Clin Infect Dis 2025).
What guideline is the Complicated UTI & Pyelonephritis Management (IDSA 2025) based on?
This algorithm is based on IDSA 2025 Guidelines on Management and Treatment of Complicated Urinary Tract Infections (Trautner BW et al, Clin Infect Dis 2025) (DOI: 10.1093/cid/ciaf460).
What are the limitations of the Complicated UTI & Pyelonephritis Management (IDSA 2025)?
Known limitations include: IDSA 2025 does not cover pregnancy, children, kidney transplant, neutropenia or prostatitis; the pregnancy step follows SA Health (eTG-based) guidance.; Empiric choice depends on prior urine cultures, recent fluoroquinolone use and local resistance; Australian practice follows TG Antibiotic (gentamicin-based urosepsis regimens; fluoroquinolones restricted).; Short-course evidence mostly excludes catheterised, obstructed, abscess, immunocompromised and CKD patients.; Oral beta-lactam step-down is less effective than fluoroquinolones or TMP-SMX.. Individual patient factors may require deviation from these recommendations.
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