💊

Pharm (Woods) ABX/ Chemo Part 1

Aug 24, 2025

Overview

This lecture covers the basics of antibiotics, including types, administration processes, testing procedures, possible complications, antibiotic resistance, and key nursing responsibilities.

Types of Antibiotics

  • Two main categories: broad spectrum (act on many bacteria) and narrow spectrum (target specific bacteria).
  • Broad spectrum antibiotics are given initially when the specific bacteria is unknown.
  • Narrow spectrum antibiotics are used once the specific bacteria is identified.

Culture and Sensitivity Testing

  • Culture and sensitivity tests identify the specific bacteria and which antibiotics it is sensitive to.
  • Obtain cultures before starting antibiotics.
  • Preliminary test results may be available in 2-4 hours; final results typically take about 48 hours.
  • After results, switch from broad to narrow spectrum if possible.

Antibiotic Function and Effects

  • Antibiotics only work against bacterial infections, not viruses or fungi.
  • Bactericidal antibiotics kill bacteria; bacteriostatic antibiotics inhibit bacterial growth to aid the immune system.
  • Administration to hard-to-reach areas (brain, abscesses, non-living tissue, poor blood supply, diabetic tissue) can be challenging.

Adverse Reactions & Complications

  • Antibiotics are highly allergenic; allergic reactions and anaphylaxis are possible.
  • Watch for toxic reactions like Stevens-Johnson Syndrome (SJS; severe rash and skin peeling) and acute tubular necrosis (ATN; kidney failure).
  • Superinfections (e.g., oral thrush/candidiasis, C. diff) can develop after antibiotic use.
  • Do not stop antibiotics for superinfections; notify the physician and treat the superinfection.

Antibiotic Administration and Monitoring

  • Always check patient allergy history and monitor for allergic or toxic reactions during infusion.
  • Draw trough levels 30 minutes before the next dose; draw peak levels 30 minutes after infusion finishes.
  • Troughs check if dosage is enough (trough below MEC = underdosed); peaks check for toxicity.

Antibiotic Resistance

  • Resistance occurs when bacteria survive antibiotics and adapt to evade them (e.g., MRSA).
  • Overuse, misuse, or underdosing of antibiotics promotes resistance.
  • Teach patients to take the full antibiotic course as prescribed and not to skip doses.
  • Higher doses kill more bacteria and are preferable to avoid resistance (despite higher risk of side effects).

Key Terms & Definitions

  • Broad spectrum antibiotic — acts against a wide range of bacteria.
  • Narrow spectrum antibiotic — targets a specific type of bacteria.
  • Culture and sensitivity — laboratory process to identify bacteria and effective antibiotics.
  • Bactericidal — kills bacteria directly.
  • Bacteriostatic — inhibits bacterial growth.
  • Stevens-Johnson Syndrome (SJS) — life-threatening skin reaction to drugs.
  • Acute Tubular Necrosis (ATN) — kidney injury due to toxic medications.
  • Superinfection — new infection caused by antibiotic treatment (e.g., C. diff, thrush).
  • MRSA — methicillin-resistant Staphylococcus aureus, a resistant bacteria.
  • Peak level — highest drug concentration, drawn after infusion.
  • Trough level — lowest drug concentration, drawn before next dose.
  • Minimum Effective Concentration (MEC) — lowest blood level at which a drug is effective.

Action Items / Next Steps

  • Know the process for culture and sensitivity and timing of sample collection.
  • Memorize signs of adverse and superinfections to monitor during antibiotic therapy.
  • Review patient teaching for correct antibiotic use: complete full course, do not skip doses.
  • Study key definitions and be able to apply them to clinical scenarios.