Microbiology Unit 3 Flashcards
Sterilization
Destruction or removal of all viable microorganisms (including endospores and viruses); absolute
Decontamination
Removal of organic matter off surfaces (Ex. wiping off the counter after eating)
Disinfection
killing, inhibiting, or removal of pathogenic microorganisms
Disinfectants
used on inanimate objects
Sanitization
reduction of microbial population to levels deemed safe (based on public health standards)
Antisepsis
prevention of infection of living tissue (can be seen on the back of hand sanitizers)
Antiseptics (germicides)
chemical agents that kill or inhibit growth of microorganisms when applied to tissue
Chemotherapy
use of chemicals to kill or inhibit growth of microorganisms within host tissue
Moist Heat
method of destroying bacteria, fungi, and viruses; better penetration power because it uses water
Boiling
part of Moist Heat; will not always destroy endospores so does not necessarily sterilize
Pasteurization
part of Moist Heat; controlled heating at temperatures well below boiling; used for wine, milk, and other beverages
Which moist heat method kills pathogens present and slows spoilage?
pasteurization
Autoclave
part of Moist Heat; effective against all types of microbes (sterilization)
What temperature, in degrees Celsius, must be reached in an autoclave to effectively sterilize?
121
True or False: Autoclave time for endospores is the same as for vegetative cells.
False
Dry Heat Sterilization
less effective than moist heat sterilization; requires higher temperatures and longer exposure times; items subjected to 160-170 degrees C for 2 to 3 hours
Flaming
a method of dry heat sterilization (used in lab)
Freezing
stops microbial reproduction due to lack of liquid water; some microorganisms can die by ice crystal disruption of the cell membrane
What temperature is generally required for the freezing method?
-20 degrees C
Refrigeration
slows microbial growth and reproduction
What temperature is generally required for refrigeration (slowing of microbial growth and reproduction)?
4 degrees C
Ultraviolet (UV) Radiation
non-ionizing radiation; causes thymine dimers in DNA; has poor penetrating power and is limited to disinfection of surfaces, air, and water
Ionizing Radiation
beta, gamma, X-rays; penetrates deep into objects
Filtration
reduces microbial populations; sterilization of heat-sensitive solutions; uses membrane filter with defined pore size and also used for air
Antimicrobial agent
natural or synthetic chemical that kills or inhibits growth of microbes
-cidal
suffix indicating a chemical agent that kills pathogens and many-nonpathogens, but not necessarily endospores
-static
suffix indicating a chemical agent that inhibits growth
Minimal Inhibitory Concentration (MIC)
`lowest concentration of drug that inhibits growth of pathogen
Minimal Lethal Concentration (MLC)
lowest concentration of drug that kills pathogen
Dilution Susceptibility Test
used to detect the smallest amount of agent needed to inhibit the growth of a test organism and the broth from which a microbe cant be recovered
In the Dilution Susceptibility Test, which concentration is in the first two tubes with minimum turbidity?
MIC
In the Disk Diffusion Tests, what does the line between growth and no growth mean?
MIC
What are the factors influencing the effectiveness of an antimicrobial agent?
population size, population composition, concentration or intensity of the agent, duration of exposure, temperature, and local environment
Kirby-Bauer Method
used to determine the effectiveness of certain antimicrobials; relationship between zone diameter and degree of microbial resistance
Antigen
any molecule or substance that stimulates the immune system to make antibodies against it and activates immune memory
Vaccine
substance given to a host (usually by injection) that induces artificial active immunity (acts as an antigen, but doesn’t cause disease)
Vaccination/Immunization
inoculation of a host with a vaccine to stimulate protective immunity; sometimes a booster is required to enhance/restore protection
What is the spike protein on the SARS-CoV-2 virus?
an antigen
Covid-19 mRNA vaccine
made using mRNA that gives cells instructions on how to make the spike protein on the surface of the virus.
Covid-19 Viral Vector Vaccine
genetic material from COVID-19 virus is inserted into an unrelated, harmless virus.
Herd Immunity
resistance in a population to a pathogen (disease) as a result of the immunity of a large portion of the population
greater
the more highly infectious a pathogen, the ______ the proportion of immune individuals needed to prevent disease spread
Antimicrobial drugs
compounds used to treat disease by destroying or inhibiting the growth of pathogenic microbes within a host (in vivo)
semi-synthetics
chemically modified antibiotics
True
True or False: many antibiotics are discovered in soil.
Selective toxicity
ability of drug to kill or inhibit pathogen while damaging the host as little as possible
Therapeutic (effective) dose
drug level required for clinical treatment
toxic dose
drug level at which drug becomes too toxic for patient (produces side effects)
therapeutic index
ratio of toxic dose to therapeutic dose; the larger it is, the better
narrow-spectrum drugs
attack only a few different pathogens
broad-spectrum drugs
attack many different pathogens
cidal agent
agent that kills microbes
static agent
agent that inhibits growth of microbes
side effects
undesirable effects of drugs on host cells
growth factor analogs
structurally similar to an essential growth factor; disrupt cell metabolism
Isoniazid
narrow spectrum growth factor analog; cidal if actively growing, static if dormant; treats tuberculosis
Quinolones
interfere with bacterial DNA gyrase; prevent DNA packaging
Ciprofloxacin
narrow spectrum growth factor analog; cidal
Growth factor analogs and quinolones
Which groups are synthetic antimicrobial drugs?
Macrolides
target the 50S ribosomal subunit
Tetracyclines
target the 30S ribosomal subunit
Lipid biosynthesis disruptor
targets fatty acid biosynthesis
Erythromycin
broad spectrum macrolide; static
Tetracycline
broad spectrum tetracycline; static; can treat acne
Platensimycin
broad spectrum lipid biosynthesis disruptor; static; effective against MRSA and VRE
Macrolides, Tetracyclines, and Lipid Biosynthesis Disruptors
Which groups are antibiotics from Bacteria?
Beta-Lactam antibiotics from fungi
include penicillins and cephalosporins; target cell wall synthesis ; effective primarily against gram-positive bacteria; cidal against actively growing cells
Penicillin is produced by what group of microbes?
Fungi
Penicillin mechanism of action
cidal; inhibit transpeptidation enzymes involved in cross-linking the polysaccharide chains of peptidoglycan; activate cell wall lytic enzymes
Antimicrobial drug resistance
acquired ability of a microorganism to resist the effects of a chemotherapeutic agent to which it is normally sensitive
Using antimicrobials does not ______ resistance but _______ for those that are resistant
cause; selects
Four mechanisms of bacterial resistance
target modification, preventing entrance, inactivation and effex pumps
Origin of drug resistance
natural immunity genes, spontaneous mutations, location of resistance genes
transmission of drug resistance
horizontal gene transfer (transformation, conjugation, transduction)
Methods of preventing emergence of drug resistance
give drug in high concentrations to destroy susceptible, use antimicrobials only when necessary, take full course of antimicrobial, use narrow spectrum antimicrobials, give combination of unrelated drugs
Any change in appearance, smell, or taste of a food that makes it unpalatable to the consumer, may be safe to eat
food spoilage
Food composition and spoilage for carbohydrates
mold predominates, degrades food by hydrolysis, ergotism (disease caused by Claviceps purpurea toxins)
food composition and spoilage for proteins or fats
bacterial growth predominates, putrefication (anaerobic breakdown of proteins, foul-smelling amine compounds)
List of intrinsic factors for food spoilage
pH, presence and availability of water, oxidation-reduction potential, physical structure, antimicrobial substances
pH for food spoilage
low pH favors yeast and mold
presence and availability of water for food spoilage
lower water activity inhibits microbial growth
oxidation-reduction potential for food spoilage
lower redox (less oxygen) favors growth of anaerobic bacteria
physical structure for food spoilage
grinding and mixing promotes microbial growth
antimicrobial substances for food spoilage
coumarins, lysozyme, allicin, etc.
list of extrinsic factors for food spoilage
temperature, relative humidity, atmosphere
temperature for food spoilage
lower temperatures retard microbial growth
relative humidity for food spoilage
higher levels of humidity promote microbial growth
atmosphere for food spoilage
oxygen promotes growth
Modified Atmosphere Packaging (MAP)
use of shrink wrap and vacuum technologies to package food in controlled atmospheres
temperature to know for refrigeration in food preservation
4 degrees C
temperature to know for freezing in food preservation
-20 degrees C
What is the danger zone for food preservation
5-60 degrees C
What are high temperature methods for food preservation?
cooking and holding at high temperatures, canning, pasteurization
