ANTIBIOTICS 101 Infection Preventionists User Guide

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ANTIBIOTICS 101Infection Preventionists User
Guide

• Susan M. Burns BSMT, CIC
• SMB CONSULTING LLC
• Henry Ford Hospital
• New Center Community Mental Health

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ANTIBIOTIC BASICS

• Antimicrobial Any agent that will inhibit the
  growth or kill microorganisms.
• Antibiotic An antimicrobial agent that is
  either natural or semisynthetic in origin.
• Antibacterial An antimicrobial that inhibits
  (bacteriostatic) or kills (bactericidal) a
  pathogenic bacteria.
• Not all antibacterial agents are antibiotics.
• All have selective toxicity the ability to work
  without damaging host cells.

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ANTIBIOTIC CHARACTERISTICS

• SPECTRUM
• targeted
• broad
• ROUTE OF ADMINISTRATION
• Intravenous
• Intramuscular
• Oral
• PLASMA LEVELS
• Levels should reach above the MIC to maintain
  effectiveness
• TISSUE PENETRATION

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ANTIBIOTIC CHARACTERISTICS

• PROTEIN BINDING
• Unbound
• Protein bound
• HALF-LIFE
• Short multiple dosing requirements
• Long less frequent longer acting
• ROUTE OF EXCRETION
• Kidney may be toxic with renal impairment
• Liver may cause severe diarrhea

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Antibiotic Targeting

• 1st generation cephalosporins are more active
  against gram-positives, 3rd generations against
  gram-negatives
• The 2nd genration chephalosporins cefoxitin,
  cefotetan are active against gram-negative
  anaerobes (B. fragilis)
• Ceftazidime and cefepime are the most active
  against Ps. aeruginosa

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Antibiotic Targeting

• Levofloxacin, gatifloxacin, moxifloxacin are more
  active against Strep pneumoniae
• Ciprofloxacin is the most active against Ps.
  Aeruginosa

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Antibiotic Targeting
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PHARMACODYNAMICS

• Clinical effect
• Therapeutic effects are intended
• (treat or prevent a disease/relieve symptoms)
• Adverse effects are not intended
  (shakes/fevers/allergic reactions)
• Mechanism of Action
• Method that drug exerts its effects
• Most drugs utilize a receptor site within a cell
• Cell membranes
• Enzymes

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PHARMACODYNAMICS

• Measurement of Drug effects
• Dose-response curve
• (minimum effective dose maximum dose)
• Potency
• (relative amount of drug required to produce an
  effect)
• Time-Response Curve
• Onset of action
• Duration of action

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PHARMACODYNAMICS

DOSE PERCENT CURVE ED50 (median effective dose)
is the dose at which 50 of a group of pts show
the effect.
TIME-RESPONSE CURVE Curve illustrates onset of
action and duration of action
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PHARMACOKINETICS

• Absorption
• Process by which a drug enters the circulatory
  system
• Intravenous immediate absorption
• Oral prolonged absorption
• Drug dosage
• Acidity/Alkalinity of stomach/intestine
• Rate of gastric emptying
• Presence of food in the stomach

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PHARMACOKINETICS

• DISTRIBUtion
• Transport of drug thoughout the body
• Blood flow to tissues
• Heart, liver, and kidneys - high amount of blood
  flow
• Muscle, fat low amount of blood flow
• Lipid solubility
• How effective the drug will dissolve cell
  membranes
• Plasma-protein Binding
• High protein bound drug has a smaller amount of
  drug free to act at the receptor site
• Drug interactions can occur if two highly bound
  drugs are administered together they cancel
  the binding and may cause adverse side effects

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PHARMACOKINETICS

• METABOLISM
• Chemical transformation of a drug into another
  form metabolite.
• Excretion
• Removal of drug and drug metabolites from the
  body.
• Liver
• Kidneys

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THERAPEUTIC LEVELS OF DRUG

• Bioavailability
• Measure of the rate extent of drug absorption

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THERAPEUTIC LEVELS OF DRUG

• Drug Elimination
• Removal of active drug from the blood thru
  metabolism and excretion.
• Half-life time for ½ of the concentration of
  drug to be eliminated.
• Steady-state Concentration
• Drug level in blood becomes relatively stable
• Loading dose
• Maintenance dose
• Dosing time intervals

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THERAPEUTIC LEVELS OF DRUG

• Time above the MIC

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ANTIBIOTIC STEWARDSHIP

• Choosing the right drug for the patient
• Antibiotic
• Administration route
• Maintain plasma levels of the drug
• Monitor kidney and liver function
• Microbiology susceptibility rates monitor
  repeat culture results
• Narrow antibiotic spectrum whenever possible

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Sometimes something worth doing is worth overdoing

• David Letterman