What are the symptoms and treatment options for a complicated urinary tract infection (UTI)?

Symptoms and Treatment of Complicated Urinary Tract Infections

Definition of Complicated UTI

A complicated UTI occurs when structural/functional urinary tract abnormalities or host factors increase the risk of therapeutic failure, including all UTIs in men, presence of catheters, obstruction, recent instrumentation, pregnancy, diabetes, immunosuppression, or anatomical anomalies. 1, 2

Symptoms of Complicated UTI

Lower Tract Symptoms (Cystitis)

• Dysuria (painful urination) 3, 4
• Urinary frequency and urgency 3, 4
• Suprapubic pain or discomfort 3, 4
• Hematuria (blood in urine) 1

Upper Tract Symptoms (Pyelonephritis)

• Fever (temperature >38°C/100.4°F) 3, 4
• Flank pain or costovertebral angle tenderness 3, 4
• Nausea and vomiting 3, 4
• Systemic symptoms including malaise 3, 4

Systemic/Severe Presentation (Urosepsis)

• Assess for urosepsis using qSOFA score: respiratory rate ≥22 breaths/min, altered mental status, or systolic blood pressure ≤100 mmHg 1
• Signs of organ dysfunction (increased SOFA score by ≥2 points) 1
• Hemodynamic instability or septic shock 5, 4

Catheter-Associated Symptoms

• New onset fever without other identifiable source 1
• Acute hematuria 1
• Suprapubic or flank pain in catheterized patients 1

Important caveat: Asymptomatic bacteriuria in catheterized patients should NOT be treated except before traumatic urological procedures 1

Diagnostic Approach

Essential Testing

• Obtain urine culture and susceptibility testing BEFORE initiating antibiotics in all complicated UTI cases 1, 6
• Urinalysis showing pyuria (>10 WBC/hpf) and bacteriuria 3, 4
• Quantitative urine culture with >100,000 CFU/mL (or >10,000 CFU/mL in catheterized patients) 1, 7

Additional Testing for Severe Cases

• Two sets of blood cultures when systemic symptoms present 1
• Assess SOFA or qSOFA score for sepsis evaluation 1
• Early imaging (ultrasound or CT scan) to identify obstruction, abscess, or anatomical abnormalities 1

Microbial Spectrum

The pathogen spectrum is broader than uncomplicated UTI with higher antimicrobial resistance rates 1, 6, 2:

• Escherichia coli (most common, ~75% of cases) 1, 6
• Klebsiella species 1, 6
• Proteus species 1, 6
• Pseudomonas aeruginosa 1, 6
• Enterococcus species 1, 6
• Serratia species 6

Treatment Approach

Initial Empirical Therapy for Complicated UTI WITHOUT Systemic Symptoms

For mild-moderate complicated UTI, use oral therapy when possible:

• Ciprofloxacin 500 mg PO twice daily ONLY if local resistance <10% AND patient has not used fluoroquinolones in last 6 months 1
• Trimethoprim-sulfamethoxazole 160/800 mg PO twice daily (if susceptibility known or local resistance <20%) 8, 9
• Cefpodoxime 200 mg PO twice daily 8
• Ceftibuten 400 mg PO once daily 8

Duration: 7-14 days 1, 6

Initial Empirical Therapy for Complicated UTI WITH Systemic Symptoms

For severe complicated UTI or systemic symptoms, initiate IV therapy:

First-line parenteral options 1, 6:

• Ceftriaxone 1-2 g IV every 24 hours 6
• Cefotaxime 2 g IV every 8 hours 6
• Cefepime 1-2 g IV every 12 hours 6, 10
• Piperacillin-tazobactam 2.5-4.5 g IV every 8 hours 6

Alternative combinations 1, 6:

• Amoxicillin plus aminoglycoside (gentamicin 5 mg/kg IV every 24 hours OR amikacin 15 mg/kg IV every 24 hours) 1, 6
• Second-generation cephalosporin plus aminoglycoside 1, 6

Critical point: Do NOT use fluoroquinolones empirically in urology department patients or those with recent fluoroquinolone use (last 6 months) due to high resistance rates 1

Treatment for Multidrug-Resistant Organisms

For carbapenem-resistant Enterobacteriaceae (CRE):

• Ceftazidime-avibactam 2.5 g IV every 8 hours for 5-7 days 6, 8
• Meropenem-vaborbactam 4 g IV every 8 hours 6, 8
• Imipenem-cilastatin-relebactam 1.25 g IV every 6 hours 6, 8
• Plazomicin 15 mg/kg IV every 12 hours (shows lower mortality 24% vs 50% and less acute kidney injury 16.7% vs 50% compared to colistin-based regimens) 6

For carbapenem-resistant Pseudomonas aeruginosa:

• Ceftazidime or cefepime 6
• Piperacillin or piperacillin-tazobactam 6
• Ciprofloxacin or levofloxacin (if susceptible) 6
• Amikacin 6

Duration of Treatment

Standard duration: 7-14 days 1, 6

Specific considerations:

• For men when prostatitis cannot be excluded: 14 days 1, 8
• Shorter duration (7 days) acceptable if patient afebrile within 48 hours with clear clinical improvement 1, 8
• For CRE infections: 5-7 days 6
• For patients with hemodynamic stability and afebrile ≥48 hours: 7-10 days 6

Source Control and Adjunctive Management

Mandatory interventions 1, 2:

• Remove or replace indwelling catheters before starting antimicrobial therapy 1
• Relieve any urinary tract obstruction (stones, strictures, prostatic hyperplasia) 1, 2
• Drain significant abscesses within the urinary tract 1
• Correct underlying anatomical or functional abnormalities 1, 2

Common Pitfalls to Avoid

• Failing to obtain urine culture before antibiotics - this complicates management if empiric therapy fails 1, 8
• Treating asymptomatic bacteriuria in catheterized patients - only treat if symptomatic or before traumatic procedures 1
• Using fluoroquinolones when local resistance >10% or recent use - leads to treatment failure 1
• Inadequate treatment duration - particularly problematic when prostatic involvement possible, leading to recurrence 1, 8
• Not addressing underlying urological abnormalities - infection will persist or recur without source control 1, 2
• Using single-dose aminoglycoside therapy - only appropriate for simple cystitis, not complicated UTI 6
• Ignoring possibility of multidrug-resistant organisms - especially in patients with prior antibiotic exposure, healthcare-associated infections, or urology department patients 1, 6

Therapy Adjustment

Once culture and susceptibility results available:

• De-escalate to narrowest spectrum effective agent 1, 6
• Consider oral step-down therapy after clinical improvement (afebrile 48-72 hours, hemodynamically stable) 6
• Reassess need for continued therapy if fever resolves but patient remains neutropenic >7 days 10