microbio

• Sterilization


  The killing or removal of all viable organisms from a growth medium or surface including endospores and viruses
• Decontamination


  The treatment of an object or surface to make it safe to handle
• Disinfection


  Directly targets pathogens although it might not eliminate all microorganisms
• Methods for inhibiting rapid microbial growth


  • Sterilization
  • Decontamination
  • Disinfection
• Disinfectants


  Specialized chemical or physical agents that can kill microorganisms or inhibit microbial growth
• Microbial control in vivo is much more difficult
• Bactericidal agents


  Kill microorganisms
• Bacteriostatic agents


  Inhibit microbial growth

  
• Bacteriolytic agents


  Some bactericidal agents are also bacteriolytic agents
• Depending on the type of microorganism or pathogen to be controlled, the terms can also be applied to fungi (e.g., fungicidal) and viruses (e.g., viricidal)

  
• Minimum inhibitory concentration (MIC)


  Determines the smallest amount of agent needed to inhibit the growth of the test organism

  
• Disk diffusion technique


  A technique for measuring antimicrobial activity
• Categories of chemical antimicrobial agents


  • Antimicrobial products used to control microorganisms in industrial and commercial environment
  • Products designed to prevent growth of human pathogens in inanimate environments and on external body surface

  
• Sterilants


  Destroy all forms of microbial life, including endospores
• Disinfectants


  Kill microorganisms but not necessarily endospores and are used on inanimate objects
• Sanitizers


  Agents that reduce but may not eliminate microbial numbers to levels considered to be safe
• Antiseptics and germicides


  Chemical agents that kill or inhibit growth of microorganisms and that are nontoxic enough to be applied to living tissue
• Only sterilants are effective against bacterial endospores
• Some bacteria such as Mycobacterium tuberculosis are resistant to the action of common disinfectants because of the waxy nature of their cell wall
• Categories of antimicrobial agents


  • Synthetic agents
  • Antibiotics
• Selective toxicity


  Ability to inhibit or kill a pathogen without affecting the host
• Growth factor analogs


  Structurally similar to growth factors but do not function in the cell
• Growth factor analogs


  • Analogs similar to vitamins, amino acids, and other compounds
• Sulfa drugs


  First widely used growth factor analogs that inhibit growth of bacteria
• Isoniazid


  A growth analog effective only against Mycobacterium that interferes with synthesis of mycolic acid, a mycobacterial cell wall component

  
• Nucleic acid base analogs


  Have been formed by the addition of bromine or fluorine (Blocks nucleic acid synthesis) atom
• Quinolones


  Antibacterial compounds that interfere with DNA gyrase, preventing the supercoiling of DNA
• Antibiotics


  Naturally occurring antimicrobial drugs produced by microorganisms
• The majority of antibiotics (>99%) are not clinically useful without structural modifications in the laboratory, a process that creates semi-synthetic antibiotics
• Broad-spectrum antibiotics


  Find wider medical use than a narrow-spectrum antibiotics
• Novel antibiotics continue to be discovered and/or synthesized by modifying current drugs
• β-Lactam antibiotics


  One of the most important groups of antibiotics, including penicillins and cephalosporins, that target cell wall synthesis

  
• Penicillins


  Primarily effective against gram-positive bacteria, some synthetic forms are effective against some gram-negative bacteria
• Cephalosporins


  Produced by fungus Cephalosporium, same mode of action as the Penicillins, commonly used to treat gonorrhea
• Aminoglycosides


  Useful against Gram negative bacteria, target the 30S subunit of the ribosome, not commonly used today due to neurotoxicity and nephrotoxicity
• Macrolides


  Example: erythromycin, broad-spectrum antibiotic that targets the 50S subunit of ribosome

  
• Tetracyclines


  Broad-spectrum antibiotics, inhibiting almost all gram-positive and gram-negative bacteria, inhibit functioning of 30S ribosomal subunit
• Daptomycin


  Depolarizes bacterial cell membranes and is used mainly against gram-positive bacteria

  
• Platensimycin


  Inhibits a key enzyme in bacterial fatty acid biosynthesis, thus disrupting lipid biosynthesis
• Antimicrobial drug resistance


  The acquired ability of a microorganism to resist the effects of an antimicrobial agent to which it is normally susceptible