Antibiotic Resistance


Antibiotic Resistance, Antibiotic Resistant Infection, Antimicrobial Resistance, Multidrug-Resistant Organism, Multi-Drug Resistant Bacteria, Beta-Lactamase, Minimum Inhibitory Concentration

  • Definitions
  1. Minimum Inhibitory Concentration (MIC)
    1. Minimum concentration of an antibiotic in a culture medium that will suppress Bacterial growth
    2. MIC cutoffs vary by organism and by antibiotic, and are typically categorized as susceptible, intermediate or resistant
    3. One drug's lower MIC values than another drug, does not imply greater efficacy
    4. (2024) Presc Lett 31(1): 2-3
  • Epidemiology
  1. Health Care Associated Infections are caused by multidrug resistant organisms in 16% of cases (especially MRSA)
  • Pathophysiology
  • Factors Affecting Drug Resistance
  1. Antibiotic Overuse
    1. Viral Upper Respiratory Infections
    2. Agricultural antibiotic use
  2. Increasing Incidence of Immunocompromised patients
  3. Food supply globalization
  • Mechanisms
  • Beta-Lactamase
  1. Beta-Lactams (Penicillins and Cephalosporins) inhibit transpeptidase
  2. Transpeptidase cross-links peptidoglycan mesh in the synthesis of the Bacterial cell wall
    1. Beta-Lactams inhibition of Transpeptidase results in lysis and death of the Bacterial cell
  3. Beta-Lactams are inactivated by the enzyme Beta-Lactamase
    1. Beta-Lactamase is produced by beta-lactam resistant Bacteria
  4. Several antibiotics have since been developed to be resistant to Beta-Lactamase
    1. Beta-Lactamase Resistant Penicillins include Dicloxacillin and Nafcillin
  • Prevention
  1. Antibiotic Stewardship
    1. Limit antibiotics to cases in which they are absolutely indicated
  2. Prevent spread
    1. See Health Care-Associated Infection
    2. See Personal Protection Equipment
    3. Practice good Hand Hygiene before and after seeing each paint
    4. Follow contact precautions for colonized or infected patients
    5. Consider culturing for nasal MRSA in high risk hospital settings (e.g. ICU) and decolonization with Bactroban of infected patients
  3. Decolonization
    1. Chlorhexidine baths daily for Intensive Care unit patients (esp. MRSA, VRE patients)
  • Resources
  1. Centers for Disease Control
    1. Patient Education Tools on appropriate antibiotic use
      1. http://www.cdc.gov/antibioticresistance/tools.htm
  2. Patient Education from FamilyDoctor.org
    1. Antibiotic Resistance
      1. http://www.familydoctor.org/handouts/659.html
    2. Antibiotic Indications
      1. http://www.familydoctor.org/handouts/680.html