[4] Microbial Control

• Acclimatization


  process in which an individual organism adjusts to a change in its environment
• Microbial control


  controlling the spread of pathogenic

  microorganisms such as bacteria, virus, and fungi
• Not all bacteria or viruses are pathogenic because

  the human body is also full of microorganisms called microflora that will not cause sickness as it is naturally present
• Microflora or normal flora like the ones found in our

  skin are also capable of fighting against pathogens; should not be killed
• Bacteriostatic


  inhibits growth of bacteria but does not kill; biological or chemical agent that stops bacteria from reproducing
• Antibiotics


  Drugs taken to fight against bacteria, not effective for viruses (colds); not all antibiotics can kill bacteria since some are bacteriostatic
• Bactericidal


  antibiotics that kill the bacteria
• Overuse or misuse of antibiotics causes the

  microorganisms to build resistance against it
• Aside from vaccines, building an good immune system, rest, proper diet can help make your body more healthy thus make it able to produce cells that can fight the viruses such as phagocytes
• Innate Human Response


  “eat” the pathogenic microorganisms; natural part of the body and has no memory
• Phagocytes such as neutrophils, eosinophils, and

  macrophages are just some of the cells that make up innate immune response
• Acquired Immune Response


  Builds up antibodies and constant exposure over time of an illness can lead to a recall of an antibody that fight against it; has memory
• Human Gut Microbiome

  • In our gut, a lot of bacteria is present and they help in the defense against foreign microorganisms that enter our body
  • Poor diet can lead to the death of that bacteria since these microflora need good/natural food to function well
  • Exercising under the sun in the early morning is good since the sunlight, which is converted into Vitamin D, is absorbed and used by the body
• CBC (Complete Blood Count) 


  Differential count of the components of the blood such as hemoglobin, WBC, and more
• Growth curve of bacteria

  1. Lag phase - acclimatization
  2. Exponential or Log phase - active division of cells
  3. Stationary phase - growth stops when dying = dividing cells
  4. Death phase - bacterium loses reproductive ability; dead > living cells

  
• Cleaning


  Macroscopic bodies such as dirt and debris, which can interfere with sterilization, are removed; does not kill microscopic organisms
• Cleaning involves water and soap (has enzymatic actions which remove foreign materials from surfaces and objects; kills only some and does not remove all bacteria)
• Cleaning can be done on organic (blood) and inorganic (debris, dust) materials
• Disinfection


  Process of eliminating several microorganisms except spore formers (ex: anthrax, clostridium botulinum, etc.)
• Spore formers


  bacteria able to form endospores (spores), which act as protection of bacteria; quiescent cells able to survive at conditions lethal for other cells (high temperatures and harsh environments)
• Disinfectant


  for inanimate objects; cannot kill all living forms
• Antiseptic


  used on living tissues (ex: mouthwash, feminine wash)
• Alcohol is both a disinfectant and an antiseptic
• Chemical disinfection


  use chemical agents such as bleach (should be at least 10% and remains soaked in the contaminated area for around 30 minutes to 1 hour)
• In phlebotomy, after applying alcohol to the extraction site, avoid rubbing. Allow the alcohol to dry for better disinfectant/antiseptic action, ensuring absorption to effectively kill bacteria.
• Wet pasteurization


  equipment should be immersed in water at around 70°C for at least 30 minutes
• Sterilization


  complete killing of all forms of life, even spore formers
• Steam


  uses non-toxic, low-cost, moist heat in the form of steam under pressure, which is fast, microbicidal, and sporicidal
• Steaming requirements: 121-132 ̊C for 15-30 minutes at 15psi (longer time and higher temperature for decontamination)
• Moist Heat


  Destroys microorganism through irreversible coagulation (bacteria are proteins → coagulate) and denaturation of enzymes and structural proteins
• Dry Heat


  Destroys microorganisms through irreversible

  coagulations, and denaturation of enzymes and structural proteins, but without steam under pressure
• Dry heat is usually applied in oven and pressure cooker; uses moisture-free heat to remove microorganisms; usually on powdered items
• Dry heat requirements: 160°C for 2 hours or 170°C for 1 hour.
• Boiling


  Most of the bacteria could be killed by boiling at 100 ̊C for at least 20 minutes; does not eliminate spores and some viruses; some viruses could resist boiling temperature
• Radiation


  disinfections at the surface level
• Non-ionizing radiation uses ultraviolet (UV) radiation applied to the surface of aseptic work areas
• Ionizing radiation is used for several medical products, including pharmaceuticals and utilizes cobalt 60 gamma rays or electron accelerators to sterilize
• Chemical Methods


  Use chemical to treat surgical and medical supplies to prevent transmission of infection to patients; glass and most medical supplies are heat sensitive
• Ethylene Oxide (ETO)


  gas sterilant; like an autoclave but needs gas to function; takes 2.5 hours excluding aeration time (allow evaporation and removal of residual ETO) to perform EO sterilization; kill spores by interfering with metabolic processes
• Formaldehyde


  liquid sterilant; can be in aqueous and gaseous form; composed of 10% formalin solution; used for sterilization of bacterial vaccines and preparation of toxoids from toxins