Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
64 Cards in this Set
- Front
- Back
|
Clean
|
free of dirt
|
|
|
disinfect
|
a process whereby the number of pathogenic microbes is reduced; generally vegetative cells are killed but spores & resistant cells may survive
|
|
|
disinfectants
|
generally used on inanimate objects, destroy pathogens
|
|
|
antispetic
|
agent used on living tissue to kill or inhibit the growth of pathogens
|
|
|
sanitizer
|
agent that both disinfects & cleans
|
|
|
sterilization
|
process whereby all microbes have been killed ... free of life ... includes spores and resistant structures
|
|
|
-static
|
refers to inhibiting growth of a microbe
|
|
|
-cide
|
refers to killing
|
|
|
bacteriostatic
|
inhibits growth of bacteria
|
|
|
bacteriocidal
|
kills bacteria
|
|
|
Conditions that influence how antimicrobic will work
|
Population size
Population composition Concentration or intensity of an antimicrobial agent Duration of exposure Temperature Local environment |
|
|
Methods of evaluating chemical antimicrobics
|
Phenol Coefficient
Filter Paper Method The Use-Dilution Method |
|
|
Phenol Coefficient
|
Ratio of lowest dilution of an agent that kills the test microbes TO lowest dilution in which phenol has the same activity.
Dilution in which cells are killed in 10min but still alive after 5 min is used to calculate PC |
|
|
Filter Paper Method
|
Disks soaked in agent laid on agar plate seeded w/ organism, after incubate measure zone of inhibition
|
|
|
Influences size of zone of inhibition
|
nature of agent
diffusibility of agent concentration of agent test organism |
|
|
Use-Dilution Method
|
if microbial growth present agent was ineffective
satisfactory use-dilution is 95% confidence level of killing (100% would be sterilized) |
|
|
Phenol Coefficient control organism
|
Staphylococcus aureus
Salmonella typhi |
|
|
Use-Dilution Method control organism
|
Staphylococcus aureus
Salmonella typhi Pseudomonas aeruginosa |
|
|
AOAC
|
Use-Dilution Method
|
|
|
Pseudomonas
|
blue green pus former
opportunist problem for burn patients resistant to lots of antibotics |
|
|
Mechanisms of Action of Chemical Agents
|
denature proteins
affect membranes react with other cell parts viruses - disrupt envelop; destroy nucleic acid or protein |
|
|
Chemical Disinfectants
|
Detergents
heavy Metals Halogens Phenols Peroxides Alkylating Agents Dyes |
|
|
Detergents
|
contain hydrophilic & hydrophobic ends allows emulsification
catonic detergents disrupt membranes & denature proteins many are quaternary ammonium (quats) used for food utensils & skin antiseptics |
|
|
Heavy Metals
|
bacteriostatic agents
1% Silver nitrate used as eyewash in infants eyes - replaced w/ erythromycin because of Chlamydia Selenium sulfide used in dandruff shampoos |
|
|
Halogens
|
effective in killing bacteria & inactivating viruses but don't kill spores
oxidize proteins, disrupt membranes, inactivate enzymes ex - chlorine (1:10 dilution of bleach) iodine (too toxic to skin) |
|
|
Alcohols
|
Disinfectant
denatures proteins & dissolves lipids higher concentration not better - evaporates too fast |
|
|
Ethyl Alcohol
|
drink
|
|
|
Isopropyl
|
use on cuts
|
|
|
Ethanol
|
use in lab
|
|
|
Advantages of Phenols
|
tuberculocidal
effective in presences of organic material remains active on surface long after application |
|
|
Lysol
|
Othophenylphenal
|
|
|
Hexachlorophene
|
Phenol
Phisohex used on skin to limit Staph but is absorbed - toxic to babies |
|
|
Chlorohexiden
|
Phenol
Hibiclens good cause not absorbed into skin - limits Staph |
|
|
Peroxides
|
Hydrogen Peroxide - during generation of O2 gas the superoxide radical is formed, inactivates proteins & disrupts membranes
|
|
|
Alkylating Agents
|
All Steralize
Formaldehyde Formalin 2% alkaline gluteraldeyde (Cidex) Ethylene Oxide |
|
|
Formaldehyde
|
very toxic
|
|
|
Formalin
|
35% formaldehyde
still very toxic |
|
|
Cidex
|
Alkylating Agent
glutaraldehyde cold sterilant - kills everything used on endoscopy equipment |
|
|
Ethylene oxide
|
alkylating agent
gas sterilizing agent great for heat sensitive items highly explosive & carcenigenic great for catheters, IV lines, needles, band aids |
|
|
Dyes
|
Gentian violet
inhibits microbe growth |
|
|
Uses for Gentian violet
|
impetago - caused by Staph or Strep
Trichomonas Candida albicans topical infections Triple dye used for umbilical cord |
|
|
Physical Methods of Control
|
Heat - moist & dry
Autoclaving Pasteurization Refrigeration Raditation X-ray Microwave |
|
|
Filtration
|
membrane filters - used to decontaminate heat labile liquids
High-efficiency particulate air (HEPA) filter |
|
|
Membrane filter pore size for bacteria
|
0.4 micrometers
|
|
|
Pore size for HEPA filter
|
0.3 micrometers
|
|
|
Moist Heat
|
boiling common disinfectant - all but endospores killed in 10 minutes
|
|
|
Thermal Death Point
|
lowest temperature organism killed in 10 minutes
|
|
|
Thermal Death Time
|
time it takes to kill organism at given temperature
|
|
|
decimal reduction time
|
time it takes to kill 90% of microbes in sample at specific temperature
|
|
|
Autoclaving
|
steam under pressure - under pressure steam temperature can exceed 100 C
|
|
|
Autoclave to sterilize culture media
|
15 minutes @ 121 C and 15 psi
|
|
|
Pasteurize
|
disinfect ... not sterilize
63 C for 30 minutes |
|
|
Flash pasteurize
|
72 C for 15 sec then rapidly cool
|
|
|
Ultrahigh Temp ...
|
sterilizes, 130 - 140 C for 1-3 sec
|
|
|
Pathogens in raw milk
|
Salmonella
Listeria Mycobacterium Brucella |
|
|
Dry Heat
|
sterilizes
oven: 160 - 170 C for 2-3 hrs kills Clostridium + spores incineration: flaming needles in lab |
|
|
Refrigeration
|
Storage @ 5 C only inhibits growth
|
|
|
Freezing
|
-70 C freezers can be used yet often need glycerol to protect membranes from ice crystals
|
|
|
Freeze Drying
|
lyophilization
drying from frozen state best long term storage for bacterial cultures |
|
|
Radiation
|
UV Light
X-rays Microwaves |
|
|
UV Light
|
non-ionizing radiation - formation of thymine dimers
used for air & surface DISINFECTION |
|
|
X-Ray
|
ionizing radiation - causes breakdown in DNA sugar phosphate backbone
used for perishable meats not residual radiation left on food |
|
|
Microwave
|
not good for killing - heats unevenly
mechanism is boiling of water to increase heat in area endospores lack water |
|
|
MikroClave
|
microwave under pressure
designed to heat culture medium to a sterilizing temp in 6.5 min |
