What is the likely diagnosis and treatment for a female patient with a severe burning sensation during urination and normal vital signs?

Acute Uncomplicated Cystitis (Urinary Tract Infection)

This is almost certainly acute uncomplicated cystitis, and you should initiate first-line antibiotic therapy immediately with either trimethoprim-sulfamethoxazole for 3 days, nitrofurantoin for 5-7 days, or fosfomycin as a single dose, based on local resistance patterns. 1, 2

Diagnostic Approach

Dysuria (burning sensation during urination) is the cardinal symptom with >90% accuracy for UTI in young women when vaginal irritation or discharge is absent. 1 The normal vital signs confirm this is uncomplicated cystitis rather than pyelonephritis or urosepsis. 1

When to Obtain Urine Culture

• Do NOT obtain urine culture for initial uncomplicated UTI - self-diagnosis with typical symptoms is sufficiently accurate 2, 3
• DO obtain culture if: recurrent infections, treatment failure, history of resistant organisms, atypical presentation, or if the patient has risk factors for complicated UTI 1, 2
• Cystoscopy and imaging are NOT indicated for uncomplicated UTI 1

Red Flags Requiring Culture (Complicated UTI)

Obtain urine culture and consider this complicated if ANY of the following are present:

• Fever, flank pain, or systemic symptoms (suggests pyelonephritis) 1
• Pregnancy 1, 4
• Diabetes mellitus 1, 5
• Immunocompromise 1, 5
• Anatomical/functional urinary tract abnormalities 1, 4
• Catheterization or recent instrumentation 1, 5
• Male patient (all UTIs in men are considered complicated) 2, 4

First-Line Antibiotic Treatment

Choose based on local antibiogram and resistance patterns: 1

Preferred Regimens (in order of preference when resistance <20%)

1. Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days 1, 6, 2

   • Most cost-effective when local resistance <20%
   • Avoid if patient used fluoroquinolones in last 6 months 1

2. Nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5-7 days 1, 2, 3

   • Excellent choice with minimal resistance development
   • Minimal impact on vaginal/fecal flora 1

3. Fosfomycin trometamol 3 g single dose 1, 2, 3

   • Convenient single-dose therapy
   • Good for patient adherence concerns

Avoid as First-Line

• Fluoroquinolones should be RESERVED for complicated infections - not appropriate for simple cystitis due to resistance concerns and adverse effects 1, 3
• β-lactams (amoxicillin-clavulanate, cefpodoxime) are less effective than first-line agents 3

Alternative Management Strategy

Delayed antibiotic therapy with NSAIDs for symptom control may be considered in low-risk patients, as complication risk is minimal 2. However, immediate antimicrobial therapy is generally recommended over delayed treatment 3.

Expected Pathogen

Escherichia coli causes approximately 75% of all cystitis cases, with remaining infections from Enterococcus faecalis, Proteus mirabilis, Klebsiella species, or Staphylococcus saprophyticus 5, 7.

Critical Pitfalls to Avoid

• Do not treat based on urinalysis alone without symptoms - this represents asymptomatic bacteriuria, which does not require treatment in most patients 7, 4
• Do not use fluoroquinolones empirically - reserve for complicated infections or documented resistance to first-line agents 1
• Do not treat for longer than 7 days for uncomplicated cystitis - shorter courses (3-5 days) are equally effective and reduce resistance 1, 2
• Do not obtain imaging or cystoscopy unless patient has recurrent infections unresponsive to therapy or risk factors for complicated UTI 1