Antimicrobial stewardship principles

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Core Principles - Stewardship's Super Strategy

Antimicrobial Stewardship (AMS) comprises coordinated interventions designed to improve antimicrobial use. The core goals are to optimize clinical outcomes and minimize unintended consequences, such as toxicity and resistance.

This strategy is guided by the 4 Ds of antimicrobial therapy:

  • Drug: Selecting the correct agent for the pathogen and site of infection.
  • Dose: Optimizing the dose based on pharmacokinetics/pharmacodynamics (PK/PD).
  • Duration: Using the shortest effective course of therapy.
  • De-escalation: Narrowing antimicrobial therapy based on culture results.

⭐ A key outcome of effective AMS programs is the significant reduction of nosocomial infections; for instance, they can decrease Clostridioides difficile infection rates by over 30%.

AMS Interventions - Hospital Bug Busters

The Antimicrobial Stewardship Program (ASP), typically led by an ID physician and clinical pharmacist, champions optimal antimicrobial use. Key interventions include:

  • Prospective Audit with Feedback: Active, real-time review of antimicrobial orders with direct recommendations to prescribers to refine therapy.
  • Formulary Restriction & Pre-authorization: Requires prior approval for specific broad-spectrum or high-cost agents, guiding initial empiric choices.

📌 The 4 D's of Stewardship: Right Drug, Dose, Duration, and De-escalation.

⭐ De-escalation is a cornerstone of stewardship. It involves narrowing antibiotic therapy from broad- to narrow-spectrum based on culture results, which minimizes toxicity and resistance pressure.

Diagnostics & Metrics - Data-Driven Dosing

  • Antibiogram: A cumulative summary of local bacterial isolate susceptibility.
    • Use: Guides empiric therapy to target likely pathogens and minimize "collateral damage" (harm to normal flora).
    • Hospital Antibiogram: Susceptibility by Organism & Drug
  • Rapid Diagnostics & Biomarkers: Facilitate early de-escalation to targeted therapy.
    • Rapid Tests: MALDI-TOF (fast species ID), PCR panels (resistance gene detection).
    • Biomarkers: Procalcitonin (PCT) guides duration. A falling trend supports stopping antibiotics. A PCT <0.25 ng/mL argues against bacterial infection.
  • Core Metric:
    • Days of Therapy (DOT): The sum of days a patient receives any dose of an antibiotic; a key measure of use.

High-Yield: Procalcitonin (PCT) is most useful for guiding antibiotic cessation in lower respiratory tract infections. Its utility is limited in patients with renal failure or those who are severely immunocompromised.

Clinical Scenarios - Beyond the Ward

  • Outpatient Antimicrobial Stewardship (OAS):
    • A primary challenge is avoiding antibiotic prescriptions for viral upper respiratory infections (URIs), a major driver of resistance.
  • Surgical Antibiotic Prophylaxis:
    • Timing: Administer IV antibiotics within 60 minutes before incision.
    • Agent: Cefazolin is a common choice, targeting skin flora.
    • Duration: Discontinue within 24 hours post-surgery.
  • Special Populations (Immunocompromised, Elderly):
    • Emphasizes cautious drug selection and dosing to account for altered metabolism and increased risk of adverse events.

⭐ Vancomycin is added to the standard surgical prophylaxis regimen (like Cefazolin) if the patient is a known carrier of MRSA or in facilities with high MRSA prevalence.

High‑Yield Points - ⚡ Biggest Takeaways

  • Antimicrobial stewardship aims to optimize antibiotic use-improving outcomes, reducing resistance, and decreasing costs.
  • Core tenets: use the narrowest spectrum agent possible and the shortest effective duration.
  • De-escalation of therapy based on culture and sensitivity results is a critical practice.
  • Source control (e.g., abscess drainage) is paramount and can be more important than antibiotic choice.
  • Avoid antibiotics for viral syndromes or asymptomatic bacteriuria unless specific indications exist.

Practice Questions: Antimicrobial stewardship principles

Test your understanding with these related questions

A 64-year-old woman with a past medical history of poorly managed diabetes presents to the emergency department with nausea and vomiting. Her symptoms started yesterday and have been progressively worsening. She is unable to eat given her symptoms. Her temperature is 102°F (38.9°C), blood pressure is 115/68 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for left-sided costovertebral angle tenderness, and urinalysis demonstrates bacteriuria and pyuria. The patient is admitted to the hospital and started on IV ceftriaxone. On day 3 of her hospital stay she is afebrile, able to eat and drink, and feels better. Which of the following antibiotic regimens should be started or continued as an outpatient upon discharge?

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Flashcards: Antimicrobial stewardship principles

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_____ is a -lactamase producing bacteria resistant to penicillin.

TAP TO REVEAL ANSWER

_____ is a -lactamase producing bacteria resistant to penicillin.

Staph aureus

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