the removal of all microbes
an environment or procedure free from contamination
the use of chemical or physical agents to kill or inhibit the frowth of microorganisms
the removal of microbes from a surface by mechanical means
- deisinfection of places or things used by the public
- used to reduce the # of pathogens to meet accepted public health standards
sing heat to kill pahtogens
disinfecting on skin (like using alcohol wipe) and in tissue
define what the ending cide/cidal means
kills bacteria or organism
define the ending static/stasis means
defn microbial death
is difficult to determine, so there are special reuirements to define microbial death
what are factors that affect the rate of microbial death?
- the greater the # of organisms, the longer it will take to kill all of them.
- duration of exposure-
- can vary depending on the accessibility of the agen to the organism as well as the microbe in q.
- temperature- lower the temp at which the microbes are treated, the longer it will take to kill all of them
- endospore formation-
- endospores are resistent to many of the agents routinely used to inhibit microbial growth
what are the four targets of antimicrobial agents?
- integrity of cell wall
- integrity of the cell membrane
- the shape & function of proteins
- induce mutations and halt proteins synthesis of nucleic acids
what does radiation damage do to DNA?
- can interfere w/ DNA & RNA function
- -irradiation w/ gamma rays, UV radiation & x-rays causes mutations
- -these can result in permanent inaactivation of nucleic acids
what are the 3 major roles for controlling microbial growth?
- mechanical removal
describe the methods for controlling microbial growth
what 3 factors do you need to consider when evaluating the effectiveness of disinfectants& antiseptics?
The effects of chemical agents varies with?
- length of exposure
- amount of contaminating organic material
how do the potency of disinfects & antiseptics differ for chemicals & alcohol?
- for most chemical agents, increasing cncentration, increase its potency
- not true of alcohol; as concentration increases killing is hindered; must have some water (makes for better penetration & determination of proteins)
what are the tests used to evaluate disinfectents & antiseptics?
- comparison of the agent w/ phenol coefficient
- disk method
- use dilution method
explain the disk method.
- uses tiny disks of filter paper soaked in the agent
- an agar plate is inoculated & the disks are placed at various positions
- inhibition of growth around the disk is called the zone of inhibition (sizes of the zone are not comparable, sizes may reflect differences in concentration & dffusion rates)
name the 8 major categories of chemical agents.
- phenol and phenolic compounds
- oxidizing agents
- heavy metals
- gaseous agents
describe the types of chemical agents
explain the types of physical methods