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Sterilization
Destroying all forms of microbial life
Disinfection
Destroying pathogens and growing cells but not necessarily spores
Germicide
A chemical that quickly kills microbes but not necessarily spores
Bactericide
Kills bacteria
Fungicide
Kills fungi
Virucide
Kills viruses
Bacteriostasis
Inhibits bacterial growth, doesn’t kill cells
Antiseptics
Antimicrobial chemicals that are non toxic enough to use of body surfaces
Asepsis
The absence of pathogens from an object or area
Degerming
The temporary removal of microbes
Sanitizing
Reducing pathogens to safe levels for the general public
Bio safety level 1
Sterile techniques for microbes that don’t cause disease in healthy people
Bio safety level 2
Moderate risk microbes, lab coats, eye and face protection, doors that automatically close
Bio safety level 3
For pathogens that cause serious or possibly fatal disease, hoods, controlled airflow, double door entry
Bio safety level 4
Deadly pathogens, sophisticated body suits, hoods, decontamination chambers, controlled airflow, separate building or restricted section
Opportunistic pathogen
Causes disease under unusual conditions
Most common method to kill microbes
Thermal death point
The lowest temperature required to kill all the microbes in 10 minutes
Thermal death time
The minimum time needed to kill all the microbes at a given temperature
Decimal reduction time
The time required for 90% to be killed at a certain temperature
Critical risk for transmitting infectious agents
Comes into direct contact with body tissues, so they must be sterile
Semicritical risk for transmitting infectious agents
Contact mucous membranes but don’t penetrate body tissue, should be free of microbes but can contain a few spores
Noncritical risk for transmitting infectious agents
Contact broken skin so no standard germicidal procedures
Moist heat
Kills quicker than dry heat because water breaks bonds
Autoclave
Applies steam, heat, and pressure to tools
Pasteurizing
63 degrees c for 30 minutes fir 72 degrees c for 15 seconds
Dry heat sterilization
Direct flame or incineration
Filtration
Passing through small pores that don’t allow microbes
Effect of freezing on bacteria
Slow freezing form ice crystals that pierce the membrane of cells and damage them
Desiccation
Drying out
Ionizing radiation
Short wavelength high energy
Non ionizing radiation
Long wavelength such as UV light; they damage the DNA or heat the water inside cells
Alcohols
Kill bacteria and fungi, but not spores or virus; Disrupts, membranes and proteins
Aldehydes
Inactive proteins; kill bacteria and viruses and minutes, but kills spores in a few hours
Chlorhexidine
Damages the micro cell membrane, but not spores
Ethylene oxide
A gas denatures proteins; kills all microbes and spores, can cause cancer
Halogens
React with water to form acids also damage; amino acids and fatty acids and kills bacteria, fungi, spores, and some viruses
Metal compounds
High atomic weight elements, such as Ag, Hg, Cu, Zn, Pb; damage proteins and have variable effects on microbes
Ozone peroxide
Produces toxic oxygen molecules that kills microbes and some spores
Phenol
Damages, cell membranes, and proteins; kills mostly everything (lysol)
Benzalkonium chloride
Positively charged detergent changes, cell permeability, and causes cytoplasm to leak; affective against fungi amoebas and viruses
Phenol coefficient
Compare the affects of a test chemical against phenol
Use dilution test
Bacteria are added to serial dilutions of a chemical, the amount of growth is observed
Filter paper test
A piece of filter paper soaked with the chemical is placed on top of growing bacteria in a petri plate and the zone of inhibition is measured
Methods to slow microbial growth in perishable products
Freeze drying
Sugar and salt to draw water out of bacteria and kill it
Refrigeration and freezing
Benzoic acids, nitrates, and nitrites inhibit bacteria in processed meat
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