DLA1- Controlling Microbial Growth Flashcards
define sterile
free from bacteria or other microorganisms
compare sterilization vs commercial sterilization
- regular sterilization is short-term
- commercial sterilization is for long-term shelf lives of foods and other products
define disinfection and disinfectant
disinfection is the process of cleaning in order to remove or destroy bacteria with the use of a chemical/disinfectant
define antisepsis and antiseptic
antisepsis is the process of cleaning in order to remove or destroy disease causing microorganisms with the use of an antiseptic
define sanitization
process of reducing number of microorganisms in order to meet safety standards
define degerming
removal of pathogens from living tissues
Inert surfaces are treated with which of the following methods: physical, chemical, therapeutic antimicrobials
physical (non-ionizing radiation), chemical (disinfectants)
microbiology equipment is treated with which of the following methods: physical, chemical, therapeutic antimicrobials
physical (heat, UV, ethylene oxide), chemical (some disinfectants)
laboratory media are treated with which of the following methods: physical, chemical, therapeutic antimicrobials
physical (autoclave, filtration)
skin is treated with which of the following methods: physical, chemical, therapeutic antimicrobials
chemical (antiseptics), therapeutic antimicrobials (topical antimicrobials)
mucous membranes are treated with which of the following methods: physical, chemical, therapeutic antimicrobials
chemical (antiseptics), therapeutic antimicrobials (antimicrobials)
tissues/organs are treated with which of the following methods: physical, chemical, therapeutic antimicrobials
therapeutic antimicrobials (antimicrobials)
moist heat application in the process of sterilization is also known as…..
autoclaving
besides autoclaving, (1) and (2) can be used to achieve sterilization of equipment
1- ethylene oxide gas
2- radiation
describe the principle of autoclaving
proteins will coagulate as tertiary and secondary structures are destroyed
what are the settings required for sterilizing equipment via moist heat/autoclaving
steam at 2 atm at 121C for 15 mins
what are the settings required for sterilizing equipment via dry heat
objects exposed to 121C heat for 600 mins (121-171C for 1-6 hrs)
(moist/dry) heat penetrates more slowly
dry heat
the mechanism of action for dry heat sterilization is….
oxidation
boiling is used to destroy (1), but is ineffective in killing (2)
1- vegetative cells (most bacteria and fungi + could activate some viruses)
2- endospores
regular pasteurization process is as follows (1) and is used for (2)
1- 63C for 30 mins
2- milk, beer, fruit juices, wine, yogurt
HTST or flash sterilization process is as follows (1) and is used for (2)
(high temperature short time)
1- 72C for 15s
2- milk
Ultra high temperature sterilization process is as follows (1) and is used for (2)
1- 140C for 3s
2- milk and some juices
(note- no refrigeration required)
ionizing radiation uses (1- include λ) which used (2) as its mechanism of sterilization for the following products (3)
1- γ and X-rays (0.1-40 nm)
2- dislodges electrons from atoms to damage DNA and produce peroxides
3- heat or chemical sensitive objects (plastics, tissue grafts, fruits/veggies)
non-ionizing radiation uses (1- include λ) which used (2) as its mechanism of sterilization for the following products (3)
1- UV rays (50-400 nm)
2- absorbed by purines/pyrimidines –> forms pyrimidine dimers
3- some foods (nuts, spices)
ionizing or non-ionizing radiation penetrates better
ionizing (non-ionizing is limited to surface sterilization)
(1) are used to inhibit or kill microorganisms present on inert surfaces through the following non-specific mechanisms: (2)
1- disinfectants
2- damage cell membrane, denature proteins, inactivate enzymes
(combined with surfactant for better cleaning)
list the ideal disinfectant chracteristics
i- fast acting
ii- effective against all types of infectious agents
iii- inexpensive, easy to use/obtain
iv- no unpleasant smell
v- easy to prepare and stable when exposed to environment
Note- none have all these features
disinfectant effectiveness is measured through the following assays….
- use-dilution test
- filter paper disc method
quarternary ammonium compounds are used to clean (1) through (2) mechanism
1- surfaces and equipment
2- lipid solvent and protein denaturation
halogens are used to clean (1) through (2) mechanism
(Cl, I)
1- surfaces and equipment
2- oxidization
peroxygens are used to clean (1) through (2) mechanism
(H2O2)
1- surfaces and topical antiseptic
2- oxidization
alcohols are used to clean (1) through (2) mechanism
(EtOH, Iso-propyl alcohol)
1- surfaces, equipment, and topical antiseptic
2- lipid solvent and protein denaturation
___% of iso-propyl alcohol is used as disinfectant
60-70%, diluted with water
antiseptics are determined useful according to its (1) and (2)
applications include (3) and (4)
1- antimicrobial activity
2- toxicity to living tissues
3- reduce microorganisms from mucous membrane before surgery
4- remove microorganisms from skin before injection
inhibitors of peptidoglycans are used as antibiotics to block (1) and examples include (2)
1- cell wall formation (peptidoglycan cross-linking) in Growing bacteria
2- β-lactam antibiotics: penicillins, cephalosporins
antibiotic sensitivity testing is achieved through the following tests….
- Kirby-Bauer sensitivity testing (disk diffusion technique)
- broth dilution technique
