II. Epidemiology

  1. Asymptomatic Bacteriuria in 2 to 7% of pregnancies
  2. Significant cause of Preterm Labor

III. Etiology

  1. Escherichia coli (most common)
  2. Klebsiella
  3. Proteus miribilis
  4. Pseudomonas aeruginosa
  5. Enterobacter
  6. Staphylococcus saprophyticus
  7. Enterococcus
  8. Group B Streptococcus

IV. History

V. Signs of cystitis (Contrast with Pyelonephritis)

  1. Afebrile
  2. Suprapubic Pain
  3. No Costovertebral angle (CVA) tenderness

VI. Complications

  1. Pyelonephritis (20-40% of untreated bacteriuria)
  2. Preterm Labor
    1. Associated with bacteruria
    2. Confirm with Urine Culture for cure after Urinary Tract Infection treatment
    3. Consider periodic repeat Urine Culture

VII. Labs

  1. Urinalysis
    1. Screen all women at first Prenatal Visit
    2. If negative, then screen later only for symptoms
  2. Urine Culture with Sensitivity
    1. Strongly consider Urinary Catheter specimen
      1. Indicated for recurrent mixed Bacterial species
    2. UTI or Asymptomatic Bacteriuria criteria
      1. Single Bacterial species >50,000 colonies
      2. Group B Streptococcus at any count

VIII. Management: Acute Cystitis and Asymptomatic Bacteriuria

  1. Antibiotic Course:
    1. Initial 10 days
    2. Recurrent 14-21 days
  2. Repeat Urine Culture one month after treatment
  3. Asymptomatic bacteruria found on repeat Urine Culture
    1. Confirm not vaginal contaminant (squamous epithelial cells present)
      1. Especially for mixed Bacterial flora
      2. Consider Urinary Catheter specimen
    2. Repeat Urine Culture monthly
    3. Treat with antibiotics for an additional 10 days
    4. Consider low dose prophylaxis to 2 weeks postpartum
      1. Indicated for 2 episodes Asymptomatic Bacteriuria
  4. First Line Antibiotics in Pregnancy
    1. Nitrofurantoin
      1. First trimester use is weakly and inconsistently associated with heart defects and Cleft Lip
      2. Avoid after 36-38 weeks due to newborn Hemolytic Anemia risk
      3. Macrodantin 100 mg PO tid-qid
      4. Macrobid 100 mg PO bid
    2. Safe antibiotics in any trimester
      1. Keflex (Cephalexin) 250 mg orally three to four times daily
      2. Ceftin (Cefuroxime) 125-250 mg orally twice daily
      3. Fosfomycin (Monurol)
        1. Expensive, single dose option that may be useful in resistant infections
  5. Other agents with lower efficacy (60% against E. coli, consider if sensitive on culture)
    1. Ampicillin 250-500 mg PO qid
    2. Amoxicillin 250-500 mg PO tid or
    3. Amoxicillin 3 grams PO for 1 dose
  6. Other agents with safety precautions
    1. Trimethoprim-Sulfamethoxazole
      1. Consider for use in second and early third trimester
      2. Risk of Neural Tube Defects in first trimester
      3. Hyperbilirubinemia (and Kernicterus risk) in late third trimester

IX. Management: Urinary Tract Infection Prophylaxis

  1. Ampicillin 250 mg PO qhs
  2. Macrodantin 100 mg PO qhs (do not use after 38 weeks)
  3. Cephalexin (Keflex) 250 mg PO qhs
  4. Erythromycin 250 mg PO qhs

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