Micro

• Chemotherapy


  Use of any chemical (drug) to treat any disease or condition
• Antimicrobial agents

  Chemotherapeutic agents to treat infectious diseases
• Types of antimicrobial agents

  • Antibacterial agents
  • Antifungal agents
  • Antiprotozoal agents
  • Antiviral agents
• Antibiotic


  Substance produced by a microorganism that is effective in killing or inhibiting the growth of other microorganisms
• Ideal antimicrobial agent


  • Kill or inhibit the growth of pathogens
  • Cause no damage to the host
  • Cause no allergic reaction in the host
  • Be stable when stored in solid or liquid form
  • Remain in specific tissues in the body long enough to be effective
  • Kill the pathogens before they mutate and become resistant to it
• Mechanisms of action of antimicrobial agents

  • Inhibition of cell wall synthesis
  • Damage to cell membranes
  • Inhibition of nucleic acid synthesis (either DNA or RNA synthesis)
  • Inhibition of protein synthesis
  • Inhibition of enzyme activity
• Bactericidal agents


  Kill microbes
• Bacteriostatic agents


  Arrest the growth of microbes
• Narrow-spectrum antimicrobial agents


  Target specific microbes
• Broad-spectrum antimicrobial agents


  Target a wide range of microbes
• Mechanisms of bacterial resistance to antimicrobial agents

  • Inactivation of the antimicrobial agent
  • Alteration of the antimicrobial target
  • Decreased uptake of the antimicrobial agent
  • Increased efflux of the antimicrobial agent
• MRSA


  Methicillin-resistant Staphylococcus aureus
• MRSE


  Methicillin-resistant Staphylococcus epidermidis
• β-lactam ring


  Structural component of β-lactam antibiotics
• β-lactam antibiotics


  Antibiotics that contain a β-lactam ring
• β-lactamase


  Bacterial enzyme that destroys the β-lactam ring
• Bacterial enzymes that destroy the β-lactam ring

  • Penicillinases
  • Cephalosporinases
• Actions to help in the war against drug resistance

  • Prescribe antimicrobials only when necessary
  • Use the narrowest-spectrum antimicrobial agent possible
  • Avoid subtherapeutic dosing
  • Limit the duration of antimicrobial therapy
  • Implement effective infection control practices
  • Develop new antimicrobial agents
• Empiric therapy


  Antimicrobial treatment initiated before the causative agent is known
• Factors considered before prescribing an antimicrobial agent


  • Suspected pathogen
  • Antimicrobial susceptibility patterns
  • Pharmacokinetics and pharmacodynamics
  • Patient factors (age, pregnancy, renal/hepatic function)
  • Potential for adverse effects
  • Cost
• Undesirable effects of antimicrobial agents

  • Selection of resistant organisms
  • Allergy
  • Toxicity
• Superinfection


  Overgrowth of microorganisms that are resistant to the antibiotic(s) being used
• Diseases that can result from superinfections

  • Yeast vaginitis
  • Clostridium difficile infection
  • Antibiotic-associated diarrhea
• Synergism


  Antimicrobial agents work together to produce a greater effect than the sum of their individual effects
• Antagonism


  Antimicrobial agents interfere with each other, reducing their individual effects