Urinary Tract Infections: Types and Treatments

Posted on Mar 13, 2025 in Medicine & Health

Urinary Tract Infections (UTIs)

ITU: Clinical Situations

The most frequent clinical situations are:

  • Acute uncomplicated UTI in women
  • Recurrent lower UTIs in women
  • Acute pyelonephritis
  • Asymptomatic bacteriuria

1. Acute Uncomplicated UTI in Women (Cystitis)

Prevalence:

  • In one year, 11% of women are affected.
  • Approximately 50% will experience a UTI in their lifetime.
  • 25-50% will have another episode.
  • 3-5% will experience recurrent UTIs within one year.

Clinical Presentation:

  • Dysuria and urinary frequency.
  • Hematuria (possibly macroscopic, in both cases without fever).
  • Irritation and vaginal discharge or vaginitis suggest cervicitis, mostly uninterrupted by ITU discharge.

Etiology:

  • Escherichia coli (75-90%)
  • Staphylococcus saprophyticus (5-15%)
  • Enterococcus, Klebsiella pneumoniae, Proteus mirabilis

Risk Factors:

  • Previous episodes of cystitis.
  • Short anatomical length of the female urethra.
  • Recent sexual activity (spermicide use increases risk 2-3 times).
  • Postmenopausal women (due to diabetes mellitus, cystoceles, and urinary incontinence).
  • Elderly and weakened women (due to delayed urination and poor hygiene).

Diagnostic Methods:

  • Not always necessary.
  • Pyuria, bacterial display.
  • Reactive strips (-leukocytes, nitrite, red blood cells, proteins, -leukocytes or nitrite).
  • Urine culture (not necessary in the first episode):
    • Negative strip with high probability of infection.
    • No improvement after treatment.
    • Recurrences within 2-4 months after treatment.
    • Signs of pyelonephritis (PNA).
    • Complicated lower UTI (diabetes mellitus, pregnancy, pre-existing pyelonephritis, duration > 14 days, structural anomalies, immunosuppression).
  • Quantitative culture:
    • > or = 105 CFU/mL: Sensitivity 50%, Specificity 100%.
    • > or = 103 CFU/mL in acute cystitis: Sensitivity >>, Specificity approx. 95%.

Treatment:

  • Norfloxacin 400mg every 12 hours, for 3 days.
  • Ciprofloxacin 250mg every 12 hours, for 3 days.
  • Nitrofurantoin 50mg 1-2 every 6 hours, for 7 days.
  • Fosfomycin/trometamol 3g single dose orally.
  • Amoxicillin-clavulanate 500/125mg every 12 hours, for 7 days.

Monitoring or follow-up urine culture is not typically needed.

2. Recurrent Lower UTIs in Women

Management:

  • Avoid vaginal spermicides.
  • Ensure complete resolution of the previous UTI.
  • Continuous or post-coital prophylaxis (for 6 months).
  • Self-administered treatment of each episode (evaluate if cured after 48-72 hours).

Prophylaxis:

  • Continuous: Norfloxacin 200mg once nightly, Ciprofloxacin 250mg once nightly, Nitrofurantoin 50-100mg once nightly.
  • Post-coital: Ciprofloxacin 250mg once, Nitrofurantoin 50-100mg once.

3. Acute Pyelonephritis

Treatment:

  • No criteria for hospital admission or risk of multidrug-resistant germ: Cephalosporins, fluoroquinolones, or parenteral aminoglycosides. If there is a good initial evolution, complete 14-21 days of treatment orally.
  • No risk of resistant germ and admission criteria: Cephalosporins or aminoglycosides intravenously until fever subsides. Afterward, treatment can be completed at home for 14-21 days orally.
  • Infection by resistant germ in the hospital: Piperacillin/tazobactam.
  • Risk of infection by resistant germ in the community (E. coli ESBL): Intravenous ertapenem. If there is improvement, treatment can be completed at home via the intramuscular route.
  • Community-acquired sepsis: Ertapenem.
  • Nosocomial-acquired sepsis: Imipenem.
  • Urine culture: Always (before treatment).

4. Asymptomatic Bacteriuria

Defined as the presence of bacteria in the urine without symptoms of a UTI. The urinary tract is colonized. Treatment is only indicated in certain cases.

Indications for Treatment:

  • Children < 5 years old.
  • Pregnant women.
  • Prior to surgery or manipulation of the urinary tract.
  • Urological abnormalities.
  • Immunocompromised individuals.
  • Renal transplant recipients.

No Indications for Treatment:

  • Men with indwelling urethral catheters.
  • Non-pregnant, non-diabetic women.

Treatment Duration: 3-7 days.

Urinalysis Findings:

  • Proteinuria (<2g/24h urine).
  • White blood cell (WBC) casts (in acute pyelonephritis).
  • Pyuria (>5 leukocytes/field).
  • Microscopic hematuria.
  • Positive nitrites.