Counting/Measuring & Controlling Microorganisms Flashcards
Explain Plate Count
add measured amount of sample (can be body fluid, tissue, food, H2O, etc) to growth media, then count colonies that form
Explain Membrane Filtration
Filter organisms onto membrane with a grid. Count org in a few grids (requires microscope) and multiply by number of grids
Name the direct method of counting
- Plate Count
- Membrane filtration
Name the indirect counting methods
- Turbidity
- Luceferin
Explain Indirect Methods
Measures some metabolic activity, not numbers
Explain Turbidity
- For use in clear fluids
- Measures cloudiness of sample
- Only works for high concentrations
Explain Luceferin
- Detects presence of bacteria in foods or on surface
- Really only measures ATP
- Really not a count, Just confirming if bacteria is present or not
- This is quality control tool
- Spray luceferin spray on surfaces, contaminated areas will glow when exposed to a UV/Black light
Define: Sterilization
Kills/neutralizes all organisms
Including spores and viruses
Define: Disinfection
Kills vegetative organisms
Does not kill spores
Designed to kill harmful organisms
Define: Pasteurization
use heat to bring bacterial counts down to “acceptable levels”
Kills most pathogens, extends shelf life
Define: Bacteriostatic
doesn’t kill the bacteria just prevents the bacteria from growing, reproducing, and spreading
Define: Bacteriocidal
Kills Bacteria
Define: Antiseptic
Chemical for destroying harmful microbes but safe to use on living body tissue
Example: Listerine Mouthwash
Define: Sanitation
Lower microbe count to “safe public health levels”
Used for glassware, utensils, etc
Name the 2 types of Radiation
- Ionizing
- Non-Ionizing
Explain Ionizing Radiation
high Energy light (x-rays, gamma rays)
Very effective, high penetration, don’t have to heat
Works by Knocking electrons off atoms & than rearranges them
Used to sterilize medical devices, heat sensitive substances (spices)
Will sterilize food, but not well accepted.
Explain Non-ionizing Radiation
Refers to UV light
- Does not penetrate well
- Good for surfaces, water
- Causes DNA damage (Skin Cancer)
Explain Filtration
Useful for liquids and gases
- Membrane filtration
- Example: HEPA air filters
Explain the Chemical Control & it’s properties: Alcohol
- Disinfectant
- Dehydrates proteins & dissolves lipids
- Mildly effective
- Mostly washes organisms away
Explain the Chemical Control & it’s properties: Heavy Metals
– Disinfectant
- Includes Hg (Mercury), Ag (Silver), Cu (copper)
- Binds proteins together, cellularmetabolism is disrupted
- Only mildly effective
- Higher toxicity
- Not very popular anymore (mostly used for waste disposal)
* Silver nitrate (AgNO3) was used as an antiseptic and disinfectant in newborn eyes to prevent Neisserria gonorrhoeae transferal from mother to baby. Irritates eyes. Not as popular anymore
Explain the Chemical Control & it’s properties: Phenolics
- Phenol = first disinfectant used
- Standard for comparing all disinfectants
- Activity is reduced in the presence of organic matter
- Expensive, odiferous, caustic to skin, not used much as an antiseptic
- Example: Old formula Lysol
Explain the Chemical Control & it’s properties: Cresols
- Phenol derivatives
- Disinfectant
- Greater germicidal activity with lower toxicity
- Used as wood preserver
What are the common Phenol derivatives?
- Cresols
- Hexylresorcinol
- Bisphenols
- Chlorhexidine
- Triclosan
Explain the Chemical Control & it’s properties: Hexylresorcinol
- Phenol derivatives
- Disinfectant & Antiseptic
- Reduces surface tension by loosing the bacteria from tissue which allows for greater penetration
- Found in: Mouthwash, topical antiseptics & Throat lozenges
Explain the Chemical Control & it’s properties: Bisphenol’s
- Combination of 2 phenol molecules:
1. Orthopheylphenol- Commonly found in: Lysol
- Hexachlorophene
- Commonly found in: Dial soap
- Commonly found in: Lysol
- Since Bisphenols are a combination of Phenol molecules its technically a Phenol derivative making it a disinfectant
Explain the Chemical Control & it’s properties: Triclosan
- Bisphenol derivative therefore making it a Phenol derivative
- Disinfectant & Antiseptic
- Effective against pathogenic bacteria
- Only partially effective against Fungi & Viruses
- Broad spectrum, works by blocking the synthesis of lipids
- Commercially known as Irgasan and Ster-Zac
- Fairly mild and non-toxic.
- Found in: Antibacterial Soaps, Lotion, Mouthwashes, lots of common household products
- This poses a concert for bacterial resistance forming
What are 2 common Bisphenol chemical controls?
- Chlorhexidine
- Triclosan
Explain the Chemical Control & it’s properties: Chlorhexidine
- Bisphenol derivative therefore making it a Phenol derivative
- Disinfectant & Antiseptic w/ Antiplaque & Antigingivitis properties
- Commonly found in: Surgical Scrub, hand wash, skin & wound cleanser
- Common Product: Nolvasan
- Bacteria may actually grow in it!
Explain the Chemical Control & it’s properties: Iodine
- Effective, low toxicity, stains skin
- Disinfectant & Sanitizer
- Iodine is often used in combination w/ other forms of chemical control like detergent
- Tincture of Iodine
¬ Antiseptic for wounds
¬ Iodine + ethyl alcohol
- Tincture of Iodine
- Iodine can be used for purifying drinking water
- Iodine is used in restaurants for disinfecting eating utensils versus using a dishwasher
Explain the Chemical Control & it’s properties: Iodophors
- Iodine detergent complex/mixtures
- Detergent part loosens organism from surface and iodine kills them
- Allows for long term release of iodine
- Doesn’t stain skin
- Examples:
ø Loprep: Presurgical Scrub
ø Losan: Used in dairy farm sanitation,
ø Betadine – local wound Antiseptic - Can be combined with non-detergent carrier molecules stabilizing the Iodine which is called Povidine.
- Gives Pseudomonas a great carbon source allowing it to slowly grow in Povidine solution
Explain the Chemical Control & it’s properties: Chlorine
- Chlorine comes in a Gas (Cl2) or Liquid (bleach) form
- 2 types:
- Inorganic: Sodium Hypochlorite: (NaOCl) – used as a bleaching agent for textiles. Used in dilute formula for drinking water, swimming pools, factory
- Organic: Chloramine T: Releases chlorine slowly making it more stable and safe for general wound antiseptic and root canal therapy
- Effective broad spectrum including some Viruses, Fungi, & Protozoa
- NOT effective against Spores/Non Sporicidal
Explain the Chemical Control & it’s properties: Quaternarys
– Ammonium Chloride
- Common Products: Parvosol, Roccal-D, 409 - Mixing with soap reduces activity
- Broad spectrum effectiveness including viruses, bacteriostatic (does not kill), especially affective against Gram (+) organisms
- Good for food processing plants, hospitals
- Less corrosive than chlorine
- Low toxicity, moderately expensive
What are the 3 main Oxidizing Agents?
- Peroxide
- Ethylene Oxide
- Glutaraldehyde
Explain the Chemical Control & it’s properties: Peroxide
- Oxidizing Agent
- Disinfectant
- Used in food processing plants, skin disinfectant
- Bubbles help with mechanical removal of organisms
- Low toxicity
- Many organisms have enzymes capable of breaking down peroxide, must use in high enough concentration to overcome this
Explain the Chemical Control & it’s properties: Ethylene Oxide
- Oxidizing Agent
- Highly explosive gas
- Used in a chamber to sterilize medical instruments, bedding, etc
- Very toxic. Must be aired out before using or will cause “cold burns”
- Best for Plastics that can’t hold up against high heat like autoclaving.
- Petri Dishes, Plastic syringes
Explain the Chemical Control & it’s properties: Glutaraldehyde
- Oxidizing Agent
- Very toxic – carcinogen
- Kills spores
- Good for surface sterilization of heat sensitive objects
- Delicate instruments such as fiber optics
What are the bodies structural barriers against invading organisms and/or toxins?
- Skin
- Mucous Membranes
- Mouth
What are the bodies chemical compound barriers against invading organisms and/or toxins?
- Salt
- Acids
- Lysozymes
- Digestive Enzymes
- Complement Systems
- Interferon
Salt on the skin surface provides the body a structural barrier how?
Salt on the surface of skin affects the osmotic pressure in the environment.
*Remember: Gram (-) do not like salty environments & Gram (+) really love salty conditions
How is Hydrochloric Acid used as a structural barrier?
- Acid in the stomach with the strongest PH level of 1-2 therefore killing most bacteria & helping digest food.
*Helibacter pylori causes peptic ulcers in humans
Lysozyme are found where & provide defense how?
- Helps digest cell walls especially Gram (+) organisms
- Found in mucus, tears, saliva, & phagocytes
What 3 Digestive Enzymes help protect against invading pathogens?
- Amylase: Digest Starch
- Lipase: Digest Fat
- Trypsin: Digest Protein
*All three digestive enzymes help digest & upset cell membrane & cell walls of invading microbes while the Bile Acids help remove the organisms
The Complement System has how many proteins? & assists the immune system how?
- Set of 20 proteins in circulation
- Assists with immune system by attracting Phagocytes, Lymphocytes, and helps digest other cells
Interferon is produced by?
White Blood Cells - Specifically Monocytes
Interferon provide protection against invading pathogens how?
- Interferon is secreted by virally infected body cells that trigger surrounding health cells to produce antiviral proteins which gives the body warning by limiting the virus from spreading to other cells while waiting for the Killer T-Cells to come in & take over.
*Interferon injections can be given to first responders but it is expensive & very painful
Leukocytes aid in immunity how?
Leukocytes/White Blood Cells are specialized cells acting against specific antigens(pathogens)
1. Granulocytes “Granules in Cytoplasm”
∆ Neutrophils
∆ Eosinphils
∆ Basophils
2. Agranulocytes “No Granules in Cytoplasm”
∆ Monocytes
∆ Lymphocytes
