urinary%20tract%20infection%20-%20uncomplicated
URINARY TRACT INFECTION - UNCOMPLICATED
Acute uncomplicated urinary tract infection (UTI) is one of the most common bacterial infections in adults that may involve the lower or upper urinary tract or both.
Acute cystitis is an infection limited to the lower urinary tract while acute pyelonephritis is an infection that involves the upper urinary tract (renal parenchyma & pelvicaliceal system) that usually has significant bacteriuria.
Recurrent UTI is characterized by 2 episodes of uncomplicated UTI in the last 6 months or ≥3 episodes with positive cultures in the last 12 months in patients with no structural or functional abnormalities.

Diagnosis

  • Screening for or management of asymptomatic bacteriuria in women with no risk factors and premenopausal nonpregnant or postmenopausal women is not recommended  
  • 1st trimester screening for bacteriuria in pregnant women is recommended
    • Pregnant women may be screened for asymptomatic bacteriuria and treated with standard short-course therapy
  • In healthy pregnant women, diagnostic criteria for acute cystitis and pyelonephritis are the same to that of nonpregnant women
  • An extensive workup is not done in women with recurrent UTI and no risk factors 

Physical Examination

  • Often unrevealing in women with urinary tract infection (UTI) but may be useful in ruling out more serious illnesses (eg PID and nephrolithiasis)

Laboratory Tests

Urinalysis
  • Recommended for routine diagnosis of acute uncomplicated pyelonephritis in premenopausal nonpregnant women
    • Includes assessment of white and red blood cells, and nitrites
    • Result showing ≥10 WBC/mm3 suggests urinary tract infection (UTI)
Urine Dipstick
  • An alternative to culture for diagnosis of acute uncomplicated cystitis
  • A rapid and inexpensive method to check for leukocyte esterase or nitrite
    • Positive nitrite usually indicates an infection (Enterobacteriaceae converts nitrate to nitrite) with 19-48% sensitivity and 92-100% specificity
    • Leukocyte esterase is produced by neutrophils which indicates pyuria associated with UTI that has 72-97% sensitivity and 41-86% specificity
  • A good screening test but false-negative results are common
  • May help guide treatment decisions for healthy women <65 years of age that present with mild or ≤2 symptoms of UTI
Urine Culture
  • Used to identify the causative agent and its sensitivity to antibiotics
    • Culture of bladder urine obtained by suprapubic needle aspiration is the gold standard method to diagnose bacteriuria
      • Has minimal risk for urine specimen contamination
  • Recommended in patients with suspected acute pyelonephritis, symptoms that do not resolve within 48 hours of antibiotic use, symptoms recurring within 2-4 weeks after the completion of treatment, and patients with atypical symptoms
    • Should also be done in symptomatic pregnant patients before empiric antibiotic treatment is started and 7 days after completion of treatment as test of cure
    • Helps tailor treatment in patients given empiric therapy or those with initial treatment failure
  • Growth of ≥103 cfu/mL from a midstream urine specimen is a significant result in patients with acute cystitis, recurrent UTI and symptomatic pregnant women and growth of ≥104 cfu/mL in acute uncomplicated pyelonephritis
    • Growth of bacteria in any count is relevant in a specimen obtained from suprapubic bladder puncture
  • Not for routine use in patients presenting with symptoms of lower UTI
  • Midstream urine culture and sensitivity should be done in patients with recurrent UTI during the 1st presentation of their symptoms to establish a correct diagnosis
    • >100,000 cfu/HPF is considered culture-positive for UTI but result showing >1,000 cfu/HPF is enough to document infection in a symptomatic woman

Imaging

  • Additional diagnostic studies should be considered in patients with atypical symptoms, patients who fail to respond to appropriate antibiotics, and in women with infections secondary to Proteus sp, Pseudomonas sp, Enterobacter sp, or Klebsiella sp due to possibility of structural abnormalities
    • Ultrasound may be done to rule out urinary obstruction or renal stones
      • In pregnant women, kidney and urinary tract ultrasound is needed if pyelonephritis is suspected
    • Helical computed tomography (CT) scan, excretory urography, dimercaptosuccinic acid (DMSA) scanning may be performed in patients who still have fever after 72 hours of treatment or with suspected complications such as sepsis
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