Urinary Tract Infections

UTI Basics - Tiny Patients, Big Bugs

• Urinary Tract Infection (UTI): Microbial invasion of urinary tract structures.
• Significant bacteriuria criteria:
  • Suprapubic aspirate (SPA): Any gram-negative bacilli or >1,000 CFU/mL gram-positive cocci.
  • Catheter specimen: ≥10⁴ CFU/mL (often ≥5x10⁴ CFU/mL).
  • Clean-catch midstream urine (toilet-trained child): ≥10⁵ CFU/mL of a single uropathogen.
• Common Risk Factors:
  • Age <1 year (esp. uncircumcised males <3 months, then ↑ female incidence).
  • Vesicoureteral reflux (VUR).
  • Posterior urethral valves (PUV).
  • Neurogenic bladder, dysfunctional voiding.
  • Constipation.
• Etiology:

  ⭐ E. coli is the most common uropathogen, accounting for ~80-90% of pediatric UTIs.

  • Others: Klebsiella, Proteus, Enterococcus, S. saprophyticus (adolescent females).

Symptom Spotting - Age Matters

• Neonates (<1 month):
  • Non-specific: fever, hypothermia, poor feeding, vomiting
  • Lethargy, jaundice, irritability, poor weight gain
  • Sepsis-like picture, abdominal distension
• Infants (1 month - 2 years):
  • Fever (often sole symptom), irritability, crying on micturition
  • Poor feeding, vomiting, diarrhea, abdominal pain/distension
  • Strong/foul-smelling urine

  ⭐ Unexplained fever is the most common presentation of UTI in infants and young children (<2 years).

• Preschoolers (2-5 years):
  • Classic lower UTI: dysuria, urgency, frequency, hesitancy
  • New-onset incontinence (enuresis), suprapubic pain
  • Foul-smelling urine, hematuria, fever, vomiting
• School-aged Children & Adolescents (>5 years):
  • Cystitis: dysuria, urgency, frequency, suprapubic pain, incontinence
  • Pyelonephritis: flank/loin pain, CVA tenderness, high fever, chills, malaise

Diagnosis Deep Dive - Labs & Scans

• Urinalysis (UA): Rapid screen.
  • Positive: Pyuria (>5 WBCs/hpf or +Leukocyte Esterase), Nitrites (+ for Gram-neg, e.g., E.coli).
  • Microscopy: Bacteriuria, WBC casts (suggest pyelonephritis).
• Urine Culture (Gold Standard): Essential for diagnosis & sensitivity.
  • Clean catch (mid-stream): ≥10^5 CFU/mL (single organism).
  • Catheter specimen: ≥5 x 10^4 CFU/mL.
  • Suprapubic Aspiration (SPA): Any Gram-neg growth; ≥10^3 CFU/mL Gram-pos. (Most sterile sample).
• Blood Tests (if ill, <3 months, or suspected pyelonephritis): CBC (leukocytosis), CRP/ESR (↑inflammation), Blood Culture, Renal Function Tests (RFTs).

• Imaging Protocol:

> ⭐ For a child <**2** years with a first febrile UTI, a renal and bladder **ultrasound (RBUS)** should be performed.

• RBUS: Initial scan. Detects renal size, hydronephrosis, abscess, gross anomalies.
• VCUG (MCU): Gold standard for Vesicoureteral Reflux (VUR) diagnosis and grading.
• DMSA Scan: Most sensitive for acute pyelonephritis & permanent renal cortical scarring; perform 4-6 months post-UTI to assess permanent damage.

Treatment & Guard - UTI Combat

• Goals: Eradicate infection, prevent renal damage & recurrence.
• Management:
  • Cystitis (Afebrile): Oral Abx (Co-trimoxazole, Nitrofurantoin) for 3-7 days.
  • Pyelonephritis (Febrile):
    • Oral intake OK: Oral Abx (Cefixime) for 7-14 days.
    • Toxic/<3mo/Vomiting: IV Abx (Ceftriaxone), then oral. Total 7-14 days.
• Prophylaxis: For recurrent UTI/VUR Gr III-V (Nitrofurantoin/Co-trimoxazole).
• Supportive: Hydration, timed voiding. Imaging (USG, MCU/DMSA) as indicated.

⭐ Oral antibiotics are as effective as parenteral antibiotics for febrile UTIs in children who are non-toxic and can tolerate oral intake; typical duration for pyelonephritis is 7-14 days.

High‑Yield Points - ⚡ Biggest Takeaways

• E. coli is the most common pathogen in pediatric UTIs.
• Urine culture is gold standard for diagnosis; suprapubic aspirate is preferred in infants.
• Febrile UTI in infants (<2 years) requires renal ultrasound; consider MCU/VCUG for VUR.
• Vesicoureteral reflux (VUR) is a key risk factor for recurrent UTIs and renal scarring.
• Prompt antibiotics are vital to prevent long-term renal damage.
• DMSA scan best detects renal scars and acute pyelonephritis_._