UTI in Adults: Uncomplicated vs. Complicated

Most dysuria in otherwise healthy women is an uncomplicated UTI that can be treated empirically. The key is separating uncomplicated cystitis from complicated infection orpyelonephritis, then choosing the shortest effective therapy while avoiding resistance traps.

Definitions (Why It Matters)

• Uncomplicated cystitis: Lower tract symptoms (dysuria, frequency, urgency) in non-pregnant adult women without structural or neurologic urinary abnormalities.
• Complicated UTI: Any UTI with obstruction, stones, catheters, male sex, pregnancy, diabetes with poor control, immunosuppression, or anatomic/functional abnormalities.
• Pyelonephritis: Upper tract infection—fever, flank pain, CVA tenderness, systemic symptoms ± lower tract symptoms.

Diagnosis (Start with Symptoms, Then Targeted Testing)

• Classic cystitis symptoms without vaginal discharge/irritation strongly suggest UTI.
• Urinalysis (UA): Leukocyte esterase and nitrites support diagnosis; pyuria is sensitive but not specific.
• Urine culture: Not always necessary. Obtain for suspected pyelonephritis, recurrent UTIs, treatment failure, pregnancy, men, complicated cases, or before second-line therapy.

Empiric Treatment – Uncomplicated Cystitis (Non-pregnant Women)

• Nitrofurantoin 100 mg twice daily for 5 days (avoid if CrCl <30 mL/min or concern for pyelo).
• Fosfomycin 3 g single dose (useful for multidrug resistance; avoid if pyelo suspected).
• Trimethoprim–sulfamethoxazole (TMP–SMX) 160/800 mg twice daily for 3 days if local resistance to E. coli ≤20% and no sulfa allergy.
• Alternatives (when above unsuitable): Oral beta-lactams (e.g., amoxicillin-clavulanate, cefpodoxime) typically 5–7 days; slightly less effective.
• Avoid routine fluoroquinolones for simple cystitis due to collateral damage and side effects; reserve for selected cases.

Pyelonephritis (Outpatient vs. Inpatient)

• Outpatient candidates: Stable vitals, able to take PO, no pregnancy, no severe comorbidities, reliable follow-up.
• Initial therapy: Oral fluoroquinolone (e.g., ciprofloxacin 7 days or levofloxacin 5 days) if local resistance is low; otherwise a single IV/IM dose of a long-acting cephalosporin (e.g., ceftriaxone) followed by oral agent (e.g., TMP–SMX 14 days or beta-lactam 10–14 days).
• Admit for sepsis, pregnancy, obstruction, inability to tolerate PO, significant comorbidity/immunosuppression, or failed outpatient therapy.
• Always send a urine culture for pyelonephritis and tailor antibiotics when susceptibilities return.

Complicated UTI (Principles)

• Think source control: remove/replace catheters, relieve obstruction (urology consult if needed), manage stones.
• Use broader empiric therapy guided by risk (healthcare exposure, prior ESBL, recent antibiotics) and narrow when culture results are back.
• Typical duration: 5–7 days for responsive lower tract infections with potent agents; 7–14 days for upper tract or slow responders—follow local guidance.

When to Image

• Recurrent pyelo, persistent fever >48–72 h on therapy, suspected obstruction/stone, severe diabetes/immunosuppression, or men with atypical course.
• Modality: CT abdomen/pelvis with contrast if stable; ultrasound if radiation avoidance is preferred or to look for hydronephrosis.

Special Populations

• Pregnancy: Always culture; avoid fluoroquinolones and TMP–SMX near term; consider amoxicillin-clavulanate, cephalexin, or fosfomycin for cystitis; admit pyelo for IV therapy.
• Men: Treat as complicated unless a clear simple cystitis scenario; evaluate for prostatitis if recurrent or systemic symptoms.
• Catheter-associated: Replace catheter, culture from the new device, and treat based on symptoms (avoid treating asymptomatic bacteriuria).
• Asymptomatic bacteriuria: Treat only in pregnancy or before urologic procedures expected to cause mucosal bleeding.

Prevention & Recurrence Strategy

• Hydration, timed voiding, post-coital voiding, manage constipation.
• Consider vaginal estrogen for post-menopausal women with recurrent UTIs (if no contraindication).
• For frequent recurrences: patient-initiated short courses at symptom onset, or prophylaxis (continuous or post-coital) after shared decision-making.

Red Flags (Escalate)

• Sepsis criteria, pregnancy with fever/flank pain, anuria/obstruction, persistent vomiting, known stones with fever, or immunosuppression.

Patient FAQs

“Do I always need antibiotics?” For bacterial cystitis, yes—short, targeted courses are best. For nonspecific dysuria with negative tests, consider vaginitis, urethritis (STIs), irritants, or interstitial cystitis.

“Why did my UTI come back?” Incomplete eradication, reinfection from periurethral flora, sex, spermicides, or an underlying anatomic issue. A prevention plan reduces risk.

References & Notes

This guide reflects common internal medicine and infectious-disease pathways emphasizing short, targeted therapy, culture when it changes management, and avoidance of unnecessary broad agents. Educational only; follow local resistance data and protocols.