Exam 3 review Flashcards
Fomite(s)
Any inanimate object that, when contaminated with or exposed to infectious agents can transfer disease to a new host
Boiling Heat Method
Exposure of materials in boiling water for 30+ minutes will kill most non spore forming pathogens
How does it act upon the Microbe:
Denatures proteins and alters cell membrane
*Will quickly recontaminate items as soon as removed from boiling water
Used in:
Drinking, making ice, making jello, brushing teeth, giving pet water to drink
Filtration
Physical control method
Strain fluid or air through a porous membrane to physically remove microbes
How does it act upon the microbe:
Physical separation, not destroying the microbe
Used in:
Filters in HEPA that provide a flow of sterile air to hospital rooms and sterile rooms
Microbial control Methods
- Physical (Heat - Dry vs Moist, Filtration, Desiccation, Radiation, Cold)
- Chemical
-Chemotherapeutic Drugs (Antibiotics in Ch. 12)
-Biocides (Halogens, Phenolics, Alkylating Agents, Alcohols, Peroxygens, surfactants, Heavy Metals)
Microbial control Methods
- Physical (Heat - Dry vs Moist, Filtration, Desiccation, Radiation, Cold)
- Chemical
-Chemotherapeutic Drugs (Antibiotics in Ch. 12)
-Biocides (Halogens, Phenolics, Alkylating Agents, Alcohols, Peroxygens, surfactants, Heavy Metals)
Contaminant
Microbes present that are undesirable or unwanted
Resistance of microbes
Highest resistance (Prions and Bacterial endospores)
Moderate resistance (Protozoan Cysts, naked viruses, Bacteria with no endospores but resistant walls)
Least resistance (Most bacterial vegetative cells, fungal spores and hyphae, Protozoan trophozoites, Enveloped viruses, Yeasts)
Anthrax spores
It forms a protective layer called endospore by which it can remain inactive for many years and, under suitable environmental conditions, can revive and become infective. Because of endospore resistance, Anthrax spores are a bioterroism agent.
Endospore formation
- Vegetative cell that is metabolically active and growing
- Certain environmental conditions trigger
- Sporulating cell forms
- Mature endospore forms
- Endospore breaks dormancy and revitalizes cell in a process called germination
Microbial death is defined as…
Loss of reproductive capacity
Microbial death value
Describes the effectiveness of a particular agent or process often plotted as semilog functions
The amount of time it takes for a protocol to diminish the microbe is called the D value
Disinfection
Process or agent that destroys most microbes
Sterilization
All microbes are killed
Antisepsis
The use of chemicals on skin or human tissues to inhibit or eliminate microbial growth, but is NOT equal to sterilization
(safe and non toxic to humans)
Sanitization
Cleansing technique to remove debris, soil, toxins and in the process prevent future growth of microbes
Static
Stasis or same
Halts the growth but doesn’t kill
Cidal
Carcass still there
Lytic
Break open or explode, carcasses no longer there
Germ + icide = Germicide
An agent that kills pathogenic or “Germ” microorganisms. Can be used on nonliving materials or on living tissue.
Which is more effective Moist or Dry heat?
Moist heat
Pastuerization
The use of elevated heat for a long time (more than 30 min) to reduce microbial loan and destroy pathogens, followed by rapid cooling to minimize damage to food or liquid
Mode of Action:
Denatures proteins and alters cell membrane
Autoclaves
An enclosed metal chamber with an airtight door and racks to hold materials. Uses a combination of high pressure and high steam temps to sterilize objects
Mode of action:
Denatures and alters cell membrane
*Sporicidal
Incineration
Use of a flame or electric heating coil to ignite and reduce microbes to ashes and gas
Mode of action:
Destroy by burning
Ovens
Heated to 180 C for 2 to 4 hours
Mode of Action:
Dehydration (water loss), denatures protein and alters membranes
Food poisoning
Disease caused by ingesting contaminated food
Food Intoxication
Exoproducts produced by microbes caused disease
Food Infection
Microbe itself cause disease (Salmonella)
Cold
Put sample or item in refrigerator or in freezer
Mode of Action:
Inhibits metabolism (slows or arrests cell division), freezing may lyse cells
Dessication.
Dry out the sample (use a salt or heat)
Mode of action: Water is essential for metabolism and survival
*Not effective and not sporicidal
Radiation
Defined as the energy emitted from atomic activities and dispersed at high velocity through matter or space.
Ionizing Radiation
consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them
Mode of action:
Strong enough to pass into the cell where it alters molecular structures and damages cell components. Introduces double-stranded breaks in DNA.
*High penetrating power but sporicidal
Non Ionizing radiation
Shine or expose the sample with UV or Sunlight.
Mode of Action:
Introduces thymine dimers leading to DNA mutations.
*Low penetrating power but sporicidal
Halogens
Cheap and effective disinfectants and antiseptics because they are microbicidal and not just micro bistatic.
Mode of action:
Oxidation and breaks down proteins, damages DNA, RNA and fatty acids.
Ex:
Used in Surgeries or other procedures requiring a sterile environment.
Bleach (Sodium Hypochlorite)
Wipe down lab benches and surfaces
Phenolics
Phenol consists of a benzene ring with an OH (hydroxyl) group
Mode of Action:
Inhibit microbial growth by denaturing proteins and disrupting membranes.
*Low to intermediate effectiveness (Not sporicidal)
*Can cause irritations on skin and possible toxicity of phenolics makes them a questionable choice as antiseptics
Alcohols
Mode of Action:
Work by rapidly denaturing proteins (which inhibits cell metabolism) and by disrupting membranes (which leads to cell lysis)
*Not sporicidal, dry quickly and may cause skin irritation because it dehydrates the skin
*Safe as antiseptic
Aldehydes
An organic compound containing Aldehyde functional groups
H-C-O
Mode of action:
Kill by alkylating protein and DNA
Peroxygens
Compounds containing an oxygen-oxygen bond
Mode of Action:
Produce highly reactive hydroxyl free radicals that damage protein and DNA while also decomposing to O2 gas- toxic to anaerobes.
*Antiseptic at low conc. and strong solutions are sporicidal
Gases-Ethylene oxide (ETO)
Processing inanimate substances with chemical vapors, gases and aerosols provide a versatile alternative to heat or liquid chemicals
Ex:
Sterilize and disinfect plastics and prepackaged devices, foods
*Sporicidal but take several hours and have damaging side effects
Soaps and detergents
Polar molecules, and surfactants, mechanically remove soil and grease-containing microbes.
Mode of Action:
Surfactants insert in the lipid bilayer and disrupt it to create abnormal channels that alter permeability and cause leakages.
Used in sanitization
*Weak micro biocide and not sporicidal
preservatives
edible, nontoxic to humans
Mode of action: Often weak acids (vinegar) that disrupt membrane functions, also solutes like salt and sugars that produce conditions of high osmolarity
Microbial load
the number of microbes
Genetics
The study of genes and genomes, and their role in the biology of an organism
Genome
Instructions or blueprint for cell to survive different environmental conditions
Genotype
The specific sequence of DNA bases encoded into the genome
Phenotype
The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment
Gene
units that makeup the genome
DNA
contains a deoxyribose sugar and base pairs ACGT
RNA
contains a ribose sugar and base pairs ACGU
DNA polymerase
enzyme that synthesized new DNA strand in the 5’ to 3’ direction
Replication
- Initiation at the origin
- Replisome copies DNA strand
- Elongation
- Termination of replication
- Separation
Leading strand
goes in a straight shot when copying
Lagging strand
goes in short segments that are later ligated together using an enzyme called ligase
Gene expression
Transcribing the DNA into SSRNA
Template strand
part of the DNA genome that is transcribed sigma factors (proteins) brings RNA polymerase to the correct promoter
messenger RNA
A transcribed version of a structural gene or genes in DNA, copy of the DNA gene but in RNA
ribosomal RNA
Contributes to the structure and function of ribosomes: reading the mRNA code, facilitating its interaction with tRNA and producing proteins
transfer RNA
Responsible for recognizing the correct codon and bringing the correct amino acid to the ribosome during translation
Anticodon
binds to the codon
Shine-Dalgarno site
Ribosome binding site
Operons
Multiple genes encoded on one mRNA transcript
Base triplet
3 bases
Codon
Base triple 1 codon for 1 amino acid. There is degeneracy of the code
Retrovirus genetics
Undergoes reverse transcription. Starts with endocytosis and ends with assembly and release
Oncogene
Gene that has the potential to cause cancer
Gene regulation
general control, processes, ensure protein/genes are expressed when needed
Negative regulation
Turn off expression, makes less of gene product
Positive regulation
Turn on gene expression, makes more of gene product
Transduction
Transfer by viral delivery
Conjugation
Plasmid transfer
Transformation
cell takes on extracellular genetic material
recombination
rearrangement of DNA sequence during replication
Mutation
Change in “wild type” or normal chromosomal genome composition
Wild type
Found in most organisms and is considered the “normal” sequence
Missense
Causes a different amino acid to be incorporated into a protein.
silent
A change in the DNA sequence codon that still results in the same protein
nonsense
Converts a codon to a stop codon resulting in a premature termination of protein synthesis
Insertion
Addition of a letter into a sequence (Frameshift mutation)
Deletion
Removal of a letter which causes a change in the sequence (Frameshift mutation)
Linezolid
Binds 50s large subunit to prevent translation initiation complex formation
retrovirus
any of a family of RNA viruses that have an enzyme (reverse transcriptase) capable of making a complementary DNA copy of the viral RNA, which then is integrated into a host cell’s DNA
Chemotherapeutic drug
Any chemical used in the treatment, relief or prophylaxis of a disease.
Prophylaxis
Use of a drug to prevent the potential for infection in a person at risk.
EX: dental cleanings or vaccine
Antimicrobial Therapy
The use of chemotherapeutic drugs to control infection
Antimicrobials
All-inclusive term for any antimicrobial drug regardless or its origin
Antibiotics
Substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms
Natural productd
Compound or substrate produced by a living organism
Semisynthetic drugs
Drugs that are chemically modified in the laboratory after being isolated from natural sources.
Synthetic drugs
Antimicrobial compounds synthesized entirely in the laboratory through chemical reactions
Narrow spectrum
Antimicrobials effective against a limited array of microbial types; for example, a drug effective mainly on gram-positive bacteria
Broad spectrum
Antimicrobials are effective against a wide variety of microbial types; for example, a drug effective against both gram-positive and gram-negative bacteria
Mechanism of action for Penicillin
Inhibit cell wall synthesis
Subunits produced by peptidoglycan in the cytoplasm are added to the cell wall which inhibits cell wall synthesis
