Urinary Tract Infections (UTIs)

These materials are intended for general clinical education and guidance. They are not a substitute for a clinician’s knowledge, skill or judgment in treating patients.

Note: This document does not apply to patients with catheter-associated UTI (CAUTI), acute bacterial prostatitis, urinary tract instrumentation, neutropenia or pregnancy.

Background

• Urinary tract infection (UTI) is classified by anatomic site according to revised IDSA 2025 criteria.
• An uncomplicated UTI is an infection confined to the bladder with symptoms such as dysuria, increased frequency, urgency, and suprapubic pain.
  • These infections can still occur in males, in people with structural or functional abnormalities of the genitourinary tract, and in those who are immunocompromised.
• A complicated UTI is an infection that extends beyond the bladder and causes systemic features such as fever, flank pain, costovertebral angle tenderness, and nausea or vomiting, with or without lower urinary tract symptoms.
• Asymptomatic bacteriuria is the presence of bacteria in the urine without symptoms. This guidance document addresses cystitis and pyelonephritis only.

Initial assessment

• Symptom-based testing of urine culture is essential. Routine urine culture is not recommended for:
  • cloudy or foul-smelling urine
  • older adults with mental status changes or falls without localizing UTI symptoms or systemic features of infection
  • abnormal urinalysis results (pyuria, positive nitrites) in the absence of symptoms
• At Mount Sinai Hospital, urine cultures from inpatients without an indwelling urinary catheter are not processed unless the microbiology laboratory is called within 48 hours of receipt.
• Asymptomatic bacteriuria is a major driver of inappropriate antimicrobial use. The diagnosis of UTI should be primarily based on clinical symptoms.
• Pyuria (urinalysis positive for white blood cells or leukocyte esterase) has a low positive predictive value and is not diagnostic of UTI. However, the absence of pyuria has a high negative predictive value and can effectively rule out infection in non-neutropenic patients.

Common pathogens

Enterobacterales: E. coli (most common), Klebsiella pneumonia, Proteus mirabilis

Empiric therapy

*Ceftriaxone-resistant organism(s) isolated in prior blood or urine cultures (higher positive predictive value if within three months) per shared electronic medical records (e.g., Connecting Ontario).

Targeted therapy for pyelonephritis

Listed in order of preference, based on susceptibility results:

• Cephalexin 1 g PO QID (preferred)
  • Alternative if adherence is a concern: Cefadroxil 1 g PO BID
• Amoxicillin 1 g PO TID (for Enterococcus spp. and ampicillin-susceptible E. coli and P. mirabilis)
• TMP-SMX DS 1 tab PO BID
• Ciprofloxacin 500 mg PO BID

Duration of treatment (pyelonephritis)**

• Five days: If using a fluoroquinolone agent.
• Seven days: If using a non-fluoroquinolone agent.
• Seven days: Associated bacteremia

**These durations are sufficient if the patient improves clinically within 72 hours, is afebrile and hemodynamically stable, and there are no concerns for an ongoing or uncontrolled source of infection (e.g., an infected stone, abscess or obstruction). Febrile patients with prostates should be evaluated for acute prostatitis, which would require a longer duration of treatment.

Clinical pearls

• In elderly patients with delirium and a positive urinalysis or culture who are clinically stable, consider alternative diagnoses and watchful waiting before starting antibiotics
• Consider ID consult if obstruction, abscess or gangrenous/emphysematous pyelonephritis
• If urine culture + for S. aureus, order two sets of blood cultures to rule out bacteremia
• Empiric Enterococcus spp. coverage should be considered in septic patients with significant risk factors for enterococcal UTI (e.g., intermittent catheterization or recent exposure to antibiotics)