What is the recommended approach to diagnose and treat a urinary tract infection (UTI) in a patient presenting with symptoms such as dysuria, frequent urination, and abdominal pain, considering factors like age, medical history, and potential antibiotic resistance?

Diagnosis of Urinary Tract Infection

Diagnose UTI in women with typical symptoms (dysuria, frequency, urgency) without vaginal discharge based on clinical presentation alone—no urinalysis needed. 1, 2

Clinical Diagnostic Criteria

For Women (Non-Elderly)

• Dysuria plus frequency or urgency without vaginal discharge has >90% accuracy for UTI diagnosis 1, 3
• Presence of vaginal discharge substantially decreases likelihood of UTI and suggests alternative diagnosis (cervicitis, vaginitis) 4, 2
• Additional supportive symptoms include suprapubic pain, hematuria, and new/worsening incontinence 1, 5
• No laboratory testing required for uncomplicated cases with typical presentation 2

For Elderly/Frail Patients (≥65 years)

The diagnostic approach differs substantially in this population:

• Require presence of fever (>37.8°C oral, >37.5°C rectal, or 1.1°C increase from baseline) OR rigors/shaking chills OR clear-cut delirium PLUS recent-onset dysuria 6
• If systemic symptoms present, add one of: frequency, incontinence, urgency, costovertebral angle pain/tenderness 6
• Do NOT diagnose UTI based solely on: cloudy urine, urine odor, change in urine color, nocturia, decreased urinary output, suprapubic pain alone, agitation, mental status change without delirium criteria, decreased intake, malaise, fatigue, weakness, or dizziness 6
• Critical pitfall: Nonspecific symptoms in elderly are commonly misattributed to UTI, leading to overtreatment of asymptomatic bacteriuria 6

For Men

• All men with lower UTI symptoms require antibiotics for 7 days with mandatory urine culture 7
• Consider prostate examination if prostatitis cannot be excluded 1
• Consider urethritis as alternative diagnosis 2

Upper Tract Involvement (Pyelonephritis)

Suspect when lower tract symptoms accompanied by:

• Fever >37.8°C 7
• Flank pain or costovertebral angle tenderness 1, 7
• Systemic symptoms: rigors, shaking chills, malaise, vomiting 6, 1

Laboratory Testing: When and What

Urinalysis Indications

Obtain urinalysis for: 1, 2

• Atypical presentations
• Diagnostic uncertainty
• Elderly or frail patients
• Suspected pyelonephritis
• Complicated infection risk factors

Interpreting Urinalysis

• Negative nitrite AND negative leukocyte esterase together effectively rule out UTI 6, 7
• Nitrites are more sensitive and specific than other dipstick components, particularly in elderly 3
• Pyuria alone does NOT differentiate infection from colonization—commonly present with incontinence, irritation, stones 1, 3
• Bacteriuria is more specific and sensitive than pyuria for detecting UTI 3

Urine Culture Indications

Mandatory urine culture for: 1, 2

• All men with UTI symptoms
• Complicated UTIs (see below)
• Recurrent UTIs
• Pregnant patients
• Patients ≥65 years
• Treatment failure
• When diagnosis uncertain
• History of resistant organisms

Pediatric threshold: Requires ≥50,000 CFU/mL of single uropathogen plus pyuria or bacteriuria 1

Risk Stratification: Complicated vs. Uncomplicated

Complicated UTI Factors (Require Culture)

Any of the following classify UTI as complicated: 1

• Anatomical abnormalities (cystoceles, diverticula, fistulae)
• Catheterization (indwelling or recent)
• Male sex
• Pregnancy
• Diabetes mellitus
• Immunosuppression
• Recent urinary tract instrumentation
• Healthcare-associated infection
• Multidrug-resistant or ESBL-producing organisms

Uncomplicated UTI Definition

• Noncatheterized, nonpregnant adult 2
• No urologic abnormalities 2
• No immunocompromise 2
• No signs of systemic illness or pyelonephritis 2

Special Population Considerations

Pediatric Patients

• Presentation often nonspecific, similar to neonatal sepsis 6, 1
• Not all children present with fever 6
• Concomitant bacteremia occurs in 4-36.4% of cases 6, 1
• High incidence of urinary anomalies, especially vesicoureteral reflux 6

Pregnancy

• Screen and treat any bacteriuria (including asymptomatic) 8
• Urine culture is test of choice 3
• Positive dipstick specific for asymptomatic bacteriuria but culture still required 3

Catheter-Associated UTI

• May present with fever, altered mental status, malaise, lethargy, flank pain, or pelvic discomfort 1
• Pyuria has poor predictive value in catheterized patients 1

Critical Diagnostic Pitfalls

Do NOT treat asymptomatic bacteriuria in: 8

• Women without risk factors
• Postmenopausal women
• Elderly institutionalized patients
• Patients with recurrent UTIs
• Diabetic patients
• Exception: Pregnancy and before urological procedures breaching mucosa 8

Asymptomatic bacteriuria is transient, often resolves without treatment, and is not associated with morbidity or mortality in non-pregnant adults 9