Red Flags
- Suspected sepsis (qSOFA ≥2, NEWS2 ≥5, hypotension, lactate >2) — sepsis pathway with IV antibiotic within 1 h, fluids, lactate, blood cultures[1]
- Obstructed pyelonephritis with stone or anatomic abnormality — emergency urology, urgent decompression (ureteric stent / percutaneous nephrostomy)[1]
- Complicated UTI in pregnancy, transplant recipient, or with indwelling urinary catheter — broader cover, longer duration; senior input[1]
- Recurrent UTI (≥2 in 6 months or ≥3 in 12 months) — investigate underlying cause; antibiotic stewardship[1]
First-line treatment
Interventions
- Distinguish uncomplicated cystitis from pyelonephritis and complicated UTI[1]Uncomplicated cystitis: short-course oral antibiotic. Pyelonephritis: 7–14 day course, oral or IV. Complicated UTI (CKD, transplant, anatomic abnormality, immunosuppression, men, pregnancy): broader cover and longer course
- Antibiotic stewardship[1]Use narrow-spectrum agents per local resistance data; avoid fluoroquinolones for uncomplicated cystitis; reserve carbapenems for known ESBL or critical illness; review at 48 h with culture sensitivities
- Asymptomatic bacteriuria — selective treatment[1]Treat in pregnancy, before urological intervention with mucosal trauma, after kidney transplant first 1 month. Do NOT treat in healthy non-pregnant women, men, elderly, diabetics, catheterised patients
- Recurrent UTI prevention[1]Behavioural: hydration, post-coital voiding, no spermicide; topical vaginal estrogen postmenopausal; cranberry products (modest); methenamine hippurate; antimicrobial prophylaxis for refractory cases (continuous low-dose, post-coital, or self-start)
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Nitrofurantoin (uncomplicated cystitis)[1] | Furan antimicrobial | 100 mg PO BD × 5 days | ≥3 months: 5–7 mg/kg/day | First-line for uncomplicated cystitis; effective concentration only in urine; avoid eGFR <30 (insufficient excretion); pulmonary fibrosis with prolonged use; safe in pregnancy except at term |
| Fosfomycin (uncomplicated cystitis)[1] | Phosphonic acid antimicrobial | 3 g PO single dose (sachet dissolved in water) | — | Single-dose convenience for uncomplicated cystitis; resistance increasing; useful in suspected ESBL pathogen |
| Co-trimoxazole (uncomplicated cystitis)[1] | Sulfonamide + trimethoprim | 160/800 mg PO BD × 3 days | 8/40 mg/kg/day in 2 divided doses | Use only where local E. coli resistance <20%; avoid in pregnancy near term, G6PD, severe renal impairment |
| Co-amoxiclav (alternative cystitis)[1] | Aminopenicillin + beta-lactamase inhibitor | 625 mg PO TDS × 5 days | 20–40 mg/kg/day amoxicillin component | Useful in penicillin-tolerant; rising resistance; check local antibiogram |
| Ceftriaxone (pyelonephritis or complicated UTI)[1] | Third-generation cephalosporin | 1–2 g IV daily; switch to oral cefuroxime 500 mg BD or per culture × total 10–14 days | 50–80 mg/kg/day IV | First-line for pyelonephritis or complicated UTI requiring IV; switch to oral by culture sensitivity at 48–72 h |
| Piperacillin-tazobactam or meropenem (severe complicated UTI)[1] | Beta-lactam ± beta-lactamase inhibitor / carbapenem | Piperacillin-tazobactam 4.5 g IV every 6–8 h; meropenem 1 g IV every 8 h | Per local protocol | Severe complicated UTI, sepsis, ESBL or AmpC concern; renal dose adjustment; reassess at 48 h with cultures |
| Vaginal estrogen (postmenopausal recurrent UTI)[1] | Local estrogen | Estradiol 25 µg pessary or 0.1 mg cream nightly × 2 weeks then 2× weekly | — | First-line non-antibiotic prevention in postmenopausal women; minimal systemic absorption; safe with most contraindications to systemic HRT |
Nitrofurantoin (uncomplicated cystitis)[1]
Furan antimicrobial
- Adult
- 100 mg PO BD × 5 days
- Paediatric
- ≥3 months: 5–7 mg/kg/day
First-line for uncomplicated cystitis; effective concentration only in urine; avoid eGFR <30 (insufficient excretion); pulmonary fibrosis with prolonged use; safe in pregnancy except at term
Fosfomycin (uncomplicated cystitis)[1]
Phosphonic acid antimicrobial
- Adult
- 3 g PO single dose (sachet dissolved in water)
- Paediatric
- —
Single-dose convenience for uncomplicated cystitis; resistance increasing; useful in suspected ESBL pathogen
Co-trimoxazole (uncomplicated cystitis)[1]
Sulfonamide + trimethoprim
- Adult
- 160/800 mg PO BD × 3 days
- Paediatric
- 8/40 mg/kg/day in 2 divided doses
Use only where local E. coli resistance <20%; avoid in pregnancy near term, G6PD, severe renal impairment
Co-amoxiclav (alternative cystitis)[1]
Aminopenicillin + beta-lactamase inhibitor
- Adult
- 625 mg PO TDS × 5 days
- Paediatric
- 20–40 mg/kg/day amoxicillin component
Useful in penicillin-tolerant; rising resistance; check local antibiogram
Ceftriaxone (pyelonephritis or complicated UTI)[1]
Third-generation cephalosporin
- Adult
- 1–2 g IV daily; switch to oral cefuroxime 500 mg BD or per culture × total 10–14 days
- Paediatric
- 50–80 mg/kg/day IV
First-line for pyelonephritis or complicated UTI requiring IV; switch to oral by culture sensitivity at 48–72 h
Piperacillin-tazobactam or meropenem (severe complicated UTI)[1]
Beta-lactam ± beta-lactamase inhibitor / carbapenem
- Adult
- Piperacillin-tazobactam 4.5 g IV every 6–8 h; meropenem 1 g IV every 8 h
- Paediatric
- Per local protocol
Severe complicated UTI, sepsis, ESBL or AmpC concern; renal dose adjustment; reassess at 48 h with cultures
Vaginal estrogen (postmenopausal recurrent UTI)[1]
Local estrogen
- Adult
- Estradiol 25 µg pessary or 0.1 mg cream nightly × 2 weeks then 2× weekly
- Paediatric
- —
First-line non-antibiotic prevention in postmenopausal women; minimal systemic absorption; safe with most contraindications to systemic HRT
Safety-net
- Drink plenty of water and complete your antibiotic course; symptoms should improve within 48 h — return if worsening, fever, vomiting, or back pain[1]
- If you develop high fever, severe back pain, or systemic features — same-day medical review (pyelonephritis or sepsis)[1]
- Frequent UTIs warrant investigation; do not just take repeat antibiotics — see your clinician for cause and prevention[1]
Referral criteria
- Sepsis or pyelonephritis with deterioration despite IV antibiotic at 48–72 hSenior medical team and urology[1]
- Obstructed pyelonephritis or renal abscessUrology for urgent decompression[1]
- Recurrent UTI requiring underlying-cause workupUrology with imaging and cystoscopy[1]
- Pregnancy with UTI / pyelonephritisJoint obstetric and infection review; pregnancy-safe antibiotic[1]
Clinical summary
Diagnosis and stewardship-focused antimicrobial management of uncomplicated and complicated UTI in adults.