A 28-year-old woman presents to the emergency department with acute onset dysuria, frequency, and suprapubic tenderness. Urine dipstick shows leukocyte esterase and nitrites. Urine culture is pending. She has no fever, flank pain, or systemic symptoms. What is the most appropriate next step in management?

Explanation

## Clinical Diagnosis This patient presents with classic acute uncomplicated cystitis (lower UTI): - Dysuria, frequency, suprapubic tenderness - Absence of fever, flank pain, or systemic toxicity - Positive leukocyte esterase and nitrites on dipstick (highly suggestive of bacteriuria) **Key Point:** Uncomplicated cystitis in non-pregnant, non-immunocompromised women does NOT require blood cultures, imaging, or IV antibiotics. ## Management Algorithm ```mermaid flowchart TD A[Acute dysuria + suprapubic tenderness]:::outcome --> B{Fever or flank pain?}:::decision B -->|Yes| C[Pyelonephritis suspected]:::urgent C --> D[Blood cultures + IV antibiotics]:::action B -->|No| E[Uncomplicated cystitis]:::outcome E --> F[Urinalysis + microscopy]:::action F --> G[Empirical oral antibiotic]:::action G --> H[Await culture + sensitivities]:::action ``` ## First-Line Empirical Therapy for Uncomplicated Cystitis | Agent | Dosing | Duration | Notes | |-------|--------|----------|-------| | Nitrofurantoin | 100 mg BD | 5–7 days | Excellent for E. coli; avoid if eGFR <30 | | TMP-SMX | 160/800 mg BD | 3 days | If local resistance <20%; check local epidemiology | | Cephalexin | 500 mg QID | 7 days | Alternative if allergy to above | | Fluoroquinolone | Levofloxacin 500 mg daily | 3 days | Reserve for resistant organisms; risk of resistance | **High-Yield:** Most uncomplicated cystitis is caused by **E. coli** (80–90%). Nitrofurantoin and TMP-SMX are first-line because they achieve high urinary concentrations and have low systemic absorption, minimizing collateral damage. **Clinical Pearl:** A positive dipstick (leukocyte esterase + nitrites) in a symptomatic woman is sufficient to start empirical therapy without awaiting culture. Culture is obtained to guide therapy if treatment fails or for epidemiological tracking. ## Why Urinalysis with Microscopy? Microscopy confirms pyuria (≥5 WBC/hpf) and may show bacteria, supporting the diagnosis and ruling out sterile pyuria (which suggests non-infectious causes like interstitial cystitis or urethritis). **Warning:** Do NOT order blood cultures, renal imaging, or IV antibiotics for uncomplicated cystitis — this leads to unnecessary hospitalization, antibiotic escalation, and resistance selection.