Terminology
The removal of all microbial life, including endospores, with the possible exception of prions. (Ex: medical equipment, laboratory media)
What is sterilization?
Achieves reliable sterilization using steam under pressure. It is the preferred method for microbiological media, live bacterial cultures, linens, dressings, and various utensils and equipment.
What is an autoclave? (Ex: moist heat)
Functions through degerming.
What is soap?
Used to sterilize heat-sensitive solutions. High-efficiency particulate air (HEPA) filters can remove microbes like Mycobacterium tuberculosis from the air.
What is filtration?
A paper disk soaked with the disinfectant is placed on an agar plate inoculated with a test bacterium. A clear zone of inhibition around the disk indicates the disinfectant's effectiveness.
What is disk-diffusion method?
A sufficient heat treatment designed to kill Clostridium botulinum endospores in canned food. (Ex: food processing industry)
What is commercial sterilization?
Methods: Includes direct flaming, incineration, and hot-air sterilization. Incineration is a method suitable for prion disposal.
Equivalent Treatments: A hot-air oven requires significantly more time and higher temperatures than an autoclave to achieve the same effect (e.g., 170°C for 2 hours in a hot-air sterilizer is equivalent to 121°C for 15 minutes in an autoclave).
What is dry heat?
Cationic detergents that are bactericidal, denature proteins, and disrupt plasma membranes. They are most effective against Gram-positive bacteria but ineffective against Pseudomonas and Mycobacterium. They are virucidal against enveloped viruses.
What is quaternary ammonium compounds (Quats)?
Used to sterilize food and medical supplies. Can target pathogens like E. coli O157:H7 in food.
What is Ionizing Radiation (X-rays, gamma rays, electron beams)?
Which bacteria is more resistant, gram negative or gram positive?
What is gram-negative bacteria?
The removal of vegetative or non-endospore-forming pathogens. (Ex: describes a chemical used to treat an inert surface or substance)
What is disinfection?
This non-sterilizing heat treatment reduces spoilage organisms and eliminates many pathogens in food and beverages.
What is pasteurization?
Iodine: Available as a tincture or an iodophore (e.g., Betadine for skin degerming).
Chlorine: Used as bleach (hypochlorous acid) or chlorine gas to disinfect water. They are effective against most bacteria, many endospores, fungi, and some viruses.
What are halogens?
Exert oligodynamic action. Examples include silver nitrate, once used to prevent neonatal gonorrheal ophthalmia, and mercurochrome.
What is heavy metals?
Microbe that has the highest level of resistance.
What is endospores/mycobacteria?
The destruction of vegetative pathogens on living tissue. (Ex: skin preparation before surgery)
What is antisepsis?
The lowest temperature at which all cells in a culture are killed within 10 minutes.
What is thermal death point (TDP)?
Joseph Lister was the first to use this. These agents disrupt membranes and denature proteins. Lysol, a common surface disinfectant, has this as its active ingredient. They are found in mouthwash, toothpaste, and antibacterial soaps.
What are phenols and phenolics?
Effective against many bacteria but not against endospores or nonenveloped viruses.
What is alcohols (ethanol, isopropanol)?
Inactivate or denature proteins. Glutaraldehyde (Cidex) is a very effective antimicrobial agent.
What is aldehydes (glutaraldehyde, formaldehyde)?
The inhibition of microbial growth and multiplication, without killing. (Ex: refrigeration of food)
What is bacteriostatis?
The time in minutes required to kill 90% of a microbial population at a given temperature. (Canned Goods)
What is the decimal reduction time (DRT)?
Organic Acids (Sorbic, Benzoic): Inhibit mold and bacteria in foods and cosmetics.
Nitrite: Prevents endospore germination in meat products.
Antibiotics (Nisin, Natamycin): Prevent spoilage of cheese.
What are chemical food preservatives?
Disrupts plasma membranes. It is bacteriocidal and effective against certain enveloped viruses but resistant to mycobacteria, endospores, and cysts. It is a common component of skin antiseptics and surgical scrubs.
What is biguanides (chlorhexidine)?
Prevents metabolism by depriving microbes of water, a common method for food preservation.
What is desiccation?