Microbiology Unit 6: Microbial Control PDF

AHHG2010 Microbiology Unit 6: Microbial Control Terminology Antimicrobial Action: Any means of controlling microbial growth Sterilization: The removal of all microorganisms in a material or in/on an object. No living objects can be found on the object or material Disinfection: The reductio...

AHHG2010 Microbiology Unit 6: Microbial Control Terminology Antimicrobial Action: Any means of controlling microbial growth Sterilization: The removal of all microorganisms in a material or in/on an object. No living objects can be found on the object or material Disinfection: The reduction of pathogenic organisms on an object or in/on a material Reduces the threat of disease Antimicrobial Agents: Any substance that reduces or inhibits the growth of microbes, or kills the microbe Include bacteria, fungi, and viruses Disinfectants: An AMA that can be applied to an inanimate object to disinfect Antiseptics: An agent applied to a living tissue Terminology Bactericidal: To kill bacteria – kill the population Kill: Requires a high concentration of antimicrobial agent Ex: Bactericidal soap Bacteriostatic: To stop bacteria – slow the growth Inhibit: Requires a low concentration of antimicrobial agent Ex: Bacteriostatic cleaner (Lysol or other household cleaner) Sterilization and Healthcare When is sterilization absolutely necessary? “Medical devices that have contact with sterile body tissues or fluids are considered critical items. These items should be sterile when used because any microbial contamination could result in disease transmission” – Centers for Disease Control. When and what tools would this apply when we consider: Pharmacy? Dental Hygiene? Respiratory Therapy? Antimicrobial Agents Two methods of controlling and preventing bacterial growth Physical and chemical The method that is used depends on a couple of factors: 1. The type of microorganism that you are trying to control Bacteria, protozoan, fungi, virus 2. The type of material being treated Skin, steel, glass, fabric, food, water Physical Antimicrobial Methods 1. Heat 1. Moist Heat 2. Boiling 3. Autoclaving 4. Pasteurization 5. Dry Heat 6. Cold 2. Freeze Drying 3. Drying 4. Radiation 5. Filtration 6. Osmotic Pressure 7. UV Physical Antimicrobials Heat (four types): Most preferred method of sterilization Permanently denatures proteins in the microbe 1. Dry Heat – high oven heat – requires long period Used to sterilize glassware and metals Sterilizes oils and powders 2. Moist Heat – moisture and high pressure using heat Temperatures exceed 100 C Autoclaving Kills Spores! Physical Antimicrobials Heat (four types): Most preferred method of sterilization Permanently denatures proteins in the microbe 3. Pasteurization – quickly heat/quickly cool to kill pathogens Useful for some liquids (milk and other dairy products) Does not sterilize food Flash method – heat to 71.6 C for 15 seconds Holding Method – heat to 62.9 C for 30 seconds 4. Ultra High temperatures (UHT) – Physical Antimicrobials Cold – Effects enzyme activity, shutting down metabolism. 1. Refrigeration – store foods at 5°C for short periods Microorganisms can still grow at these temperatures Fungi and some anaerobes 2. Freezing – freeze food to -10°C Growth of microorganisms is slowed but still possible Physical Antimicrobials Freeze Drying: Foods are flash frozen Placed in sealed vessel and pressure reduced The addition of heat causes moisture to sublime Dried food left behind Bacteria killed because moisture removed from cytoplasm Physical Antimicrobials Drying (desiccation): Use dry heat to remove water from the product No Water – No Moisture in Cytoplasm All chemical reactions stop in cell Cannot reproduce or produce energy Enzymes are denatured and rendered useless Physical Antimicrobials Radiation: Using various frequencies to sterilize Ionizing – remove electrons UV – damages the DNA of microbe Prevents survival Spores resistant to UV Visible light – oxidizes molecules in MO Enzymes susceptible Microwave – water molecules absorb energy Water in cytoplasm boils and cell ruptures Physical Antimicrobials Filtration: Substance to be sterilized is passed through a filter Filter collects microorganisms Requires small pores in filter to trap bacteria and viruses Physical Antimicrobials Osmotic Pressure: High concentrations of solute in solution Hypertonic solutions desiccates the cell Cell loses water and dies Most microorganisms are unable to grow in such conditions Chemical Antimicrobials Chemical Antimicrobial Agents: Alcohols Aldehydes Chlorhexidine Organic acids and derivatives Phenol Quaternary ammonium compounds Chemical Antimicrobials Affect microorganisms in a variety of manners Denature Proteins/Inhibit Protein Synthesis Lyse cell membranes/Inhibit function Disrupt cell wall/DNA/Ribosomes/Inhibit Synthesis Inhibits cell wall synthesis Inhibit other metabolic Processes The disruptive nature kills or Chemical Antimicrobials Proteins are important components of cell membranes and cell walls, are also the enzymes that carry out reactions Chemical antimicrobials cause proteins to denature renders them ineffective Substances that denature proteins: Heavy metals – colloidal silver Halogens (Cl, Fl, Br) Alcohols (ethyl alcohol) Phenols (Cresol, hexachlorophene, Pine Tar) Acids/Alkalines – acidic or basic substances Chemical Antimicrobials Agents that disrupt the cell membrane of the microorganism are effective as the cell membrane controls entry and exit to the cell as well as protection. Cell membrane contains phospholipids Substances that denature protein or interfere with lipids affect the cell membrane Alcohols, phenols, detergents and soaps Surfactants disrupt the membrane, inactivates enzymes Chemical Antimicrobials There are multiple cell components and processes that are impacted by chemical agents: 1. Nucleic acids – alkylating agents will disrupt and destroy DNA/RNA 2. Cell wall formation – lactic acid and propionic acid inhibit fermentation Prevent the production of ATP Infection Control Standard Precautions: Based on risk-assessments, and make use of common sense practices and PPE to protect health care workers from infection as well as prevent spread of infection from patient to patient. Transmission Based Precautions: Used in addition to standard procedures for patients with known or suspected infections. Standard Precautions 1. Hand washing 2. Personal Protective Equipment (PPE) 3. Cleaning of Patient Care Equipment (beds, gurneys, etc) 4. Handling of soiled linens/disposal of “sharps” 5. Patient placement Prevention of Blood Borne pathogens Blood borne pathogens such as Hepatitis B, C, HIV etc. are major concerns in a health care setting. PPE – Gloves, face shield, pocket- mask (in case of CPR) Treat all blood and bodily fluids as if they were infectious. Counselling – Awareness - Education Goals for an infection Control Plan What goals would you expect to see in any infection control plan?