September 2019

Antimicrobial Guidelines

Download the Antimicrobial Stewardship Bulletin PDF for this release.

Respiratory

Community Acquired Pneumonia (CAP)

  • Mild (CURB 0 – 1) CAP is usually treated empirically with a beta-lactam (amoxicillin or cefalexin) alone. Azithromycin is added if risk factors for Legionella spp., (updated, as below) are present. If microbiological testing identifies the likely pathogen, adjust antimicrobial therapy (e.g. stop unnecessary agents) accordingly.
  • Legionella risk factors:
    • Season (spring and summer).
    • Gardening – recent history of using potting mix or compost, or tipping or trowelling of potting mix, or hand-to-face touching eating, drinking or smoking) before handwashing.
    • Water – exposure to potentially contaminated water sources such as humidifiers, air conditioners or hot-water systems.

Acute Pyelonephritis or Complicated Urinary Tract Infection

  • After initial ceftriaxone IV, the recommended empiric oral follow-ons have changed for patients with severe renal failure and those who are pregnant (adjust based on susceptibilities).
  • Severe renal failure (eGFR < 20 mL/min): oral cefalexin is first-line and ciprofloxacin is second-line. Trimethoprim should not be used as E. coli resistance is high (~24%).
  • Pregnancy: Oral cefalexin is first-line; high doses (1000 mg four times daily) are needed to reach adequate concentrations against Gram-negative bacteria in the blood, kidneys, and urine. After 14 weeks' gestation (if susceptible), trimethoprim+sulfamethoxazole is now preferred over trimethoprim alone, to ensure effective concentrations at all three potential sites of infection.

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Topic Code: 667191