Aerobe Test Clinical Microbiology – Flashcards
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Unlock answers| Sterilization |
| The killing or removal of all microorganisms in a material or on an object |
| Disenfection |
| The reduction of the number of pathogenic microorganisms to the point where they pose no danger or to inhibit their growth |
| Antiseptic |
| A chemical agent that can be safely used externally on living tissue to destroy microorganisms or to inhibit their growth |
| Disenfectant |
| a chemical agent used on inanimate objects to destroy microorganism.most do not kill spores |
| Sanitizer |
| A chemical agent, used typically on food handling equipment to reduce bacterial numbers so as to meet public health standards |
| Bacteriostatic agent |
| An agent that inhibs the growth of bacteria |
| Germicide |
| an agent capable of killing microbes rapidly, some effectively kill the microbe, while others only inhibit growth |
| Bactericide |
| an agent that kills bacterdia. most do not kill spores |
| Viricide |
| An agent that inactivates viruses |
| Fungicide |
| An agent that kills fungi |
| Sporocide |
| An agent that kills bacterial endospores and fungal spores. |
| Denaturing proteins |
big mechanism in the how chemical agents work. Destroys the proteins tertiary shape-non covalent bonds are being broken
ex: fried egg-the protein is permenantly denatured warmed milk-the protein can be reconfigured, only temporary denaturation |
| Surfactant |
membran alteration-allows penetration by reducing the surface tension
ex: greasy skillet- soap (surfactant) binds to the grease and disoldges it
surfactant binds to a cell and the cell dies |
| Effective Chemical Agents |
Heavy metal Alochols Phenol compounds (lysol) Oxidizing agent (Hydrogen peroxide) Soaps and detergents Halogentated Compounds (iodine) |
| Physical Agents |
Heat Autoclave Pasterurization Filtration Radiation |
| Heat |
Moist-boiling (more effective-penetrates better) Dry- flame
One of the most popular ways to destroy microbes
Exposure to boiling water for 10 mins is sufficient to destroy vegetative cells and eukaryotic spores. |
| Autoclave |
moist heat+pressure kills spores
all air must be removed from the chamber-pressure is needed to break the spores. |
| pasteurization |
invented by pasteur to destroy microbes that caused wine to sour-does not acheive sterility. kills salmonella and mycobacterium flash method-heated at high temp/short time holding method- heated at lower temp/longer time |
| UV radiation |
| quite lethal in destroying microbes, but will not penetrate through glass, water or dirt films |
Ionizing radiation
|
excellent sterilizing agent because of its ability to penetrate deep into objects
-electrons are released from the atoms creating ions
will destroy bacterial endospores and both prokaryotic and eukaryotic vegatative cells |
| Filtration |
can be used to sterilize substances that are destroyed by heat (drugs, serum vitamins, sucrose)
helpful in making vaccines |
| Antibiotics |
anything bacteria produce that will kill or inhibit another organism -anything of microbial origin |
| Synthetic drugs |
| from the minds of chemists-derived from parts of antibiotics from organisms |
| Selective Toxicty |
| ability to targe a particular organism or group of organisms without harming the host-knowing the difference from good and bad |
| Narrow Spectrum of activity |
| targets a single organism |
Summary of targets
-works in five ways |
1. Inhibition of cell wall synthesis 2. Disruption of cell membrane function 3. Inhibition of protein synthesis 4. Inhibiton of nucleic acid synthesis 5. Action as antimetabolites |
| Penicillin |
beta lactem ring binds to enzymes involved in make the cross link in the cell wall-weakening the cell wall, the pressure on the inside of the cell is enough to destroy the cell. |
| Side effects |
toxicty allergy disruption of microflora |
| Chemotherapeutic index |
| max tolerable dose/min amount needed to kill an organism |
| Chromosomal drug resistance |
a gene has mutated and has an altered protein, the antibiotic doesnt recognize the protein
(specific resistance) |
| Plasmid borne drug resistance |
a single plasmid may carry the resistance gene for many products. plasmids are scattered all throughout the cytoplasm much more worrysome |
| Limiting drug resistance |
-effective drug concentrations (improper dosages) -restricting drug prescriptions (many prescriptions are given unnecessarily) |
| Disk Diffusion Method |
great 1st step in determining microbial sensitivites. place disks of antibiotics into culture. done most often, but takes time. culture could be classified as sensitive, intermediate or resistant. |
| Dilution Method |
| finds the minimum amount of antibiotic needed to inhibit growth. Place dilutions of antibiotics into broth cultures. |
| Serum killing power |
| anaylyzes antibiotic resistance-kirby bauer method |
| Ideal antimicrobial attributes |
Solubility Selective Toxicity Stable toxicity level Allergenicity Tissue Stability Resistance Aquisition Shelf life Cost |
| Cell Wall targets |
Penicllins Cephalosporins = all have the beta lactem rings |
| Cell membrane targets |
| polymyxins-most come from Bacillus sp. |
| Protein synthesis inhibition |
| most of these products are purifed from Streptomyces sp. |
| Antimetabolites |
| interfere with metabolic pathways-inhibit normal metabolism |
| Molecular Mimicry-Folic acid synthesis |
biosynthetic pathway sulfa drugs mimic the intermediate in the production of folic acid-then stops production
tricks the cell into thinking it has the specifc part it needs but then stops-meaning the cell is missing that vital part to surive so it dies off.
|
| Metagenomics |
| technique used to examine dna from cells you cant grow in a lab |
| Pathogenicty |
| ability of an organism to cause disease |
| Pathogenic microbiolgy |
| concernce with organsims causing diseases |
| Normal Flora |
beneficial those organisms that we always have occupies sites on our bodies so the bad bacteria cant bind |
| Resident flora |
| with us all the time |
| Transient flora |
may colonize for a few weeks, and then leaves
|
| Opportunistic infection |
bacterium that is usually apart of our normal flora and usually causes no harm. however if our body is compromised it can cause disease
candida albicans-yeast infections due to low number of lactobacillus. |
| Infection |
| growth of microbes in tissue, may or may not cause harm |
| Infectious disease |
| causes damage |
| Communicable disease |
| transmitted from person to person |
| Non-communicable disease |
| transmitted from object to person |
| Resevoir |
| describes where an organism lives. every organism has a resevoir and the resevoir must be able to withstand that organism |
| Carrier |
| houses an organism |
| Healthy carrier |
| no s/s of disease ever present |
| incubatory carrier |
| initial stages of disease, before s/s are noticed |
| Convalescent Carriers |
| had the disease, recoverd, no s/s, but will continue to shed the organism-could still be contagious |
| Latent infections |
doesnt follow the normal progression, organism may be carried for year before symptoms appear -cold sores -leprocy -tuberculosis |
| How the organism causes disease |
-organism must get into the body, bind and replicate -organism goes thru and incubation period -clinical symptoms begin to show up -recovery period |
| Ways bacteria cause disease |
Invasivion Toxin production |
| Toxin |
| molecule released by the cell |
Endotoxin
|
(LPS) only produced by gram (-) bacteria when bacteria are lysed, endotoxin is released which causes a spike in fever |
| Exotoxin |
very broad-many different types, but each kind has a specific mode of action (neurotoxins, enterotoxins)
gram (-) bacteria has endotoxins and exotoxins |
| Toxoid |
chemically inactivated version of an exotoxin, still recognized by the body-body can build and immunity against it---used in vaccines
impossible to make toxoid out of endotoxin |
Non-specific (innate) immunity
|
what we're born with requires no previous exposure to organism ; ex; lysozyme, skin, cilia, phagocytosis |
Complement proteins ; |
form of innate immunity ~20 proteins binds to surface of cell and punches holes in the suface |
| Opsonin |
puts a red flag on the cell to enhance the ability of the phagocytes to recognize the intruder ; is considered to be a specific and a non specific form of immunity |
| Antibody |
molecule that recognizes an antigen made by a b-cell |
| Antigen |
| foreign molecule that elicts an immune response |
| Specific Immunity |
requires previous exposure ; includes b and t cells |
| b-cells |
| recognizes intruder and makes an antibody for it |
| t-cells |
responsible for cell-mediated immunity useful for organisms that invade cells |
| anti-codon |
| series of any thre nucleotides on tRNA that binds to the codon on the mRNA |
| Start Codon |
| AUG-methionine |
| Stop Codons |
| UAA UGA UAG |
| Wobble position |
3rd position in a codon it doesnt usually matter what nucelic acid is in this spot because it will still attract the same tRNA and code the same amino acid ; |
| Inosine |
can bind w/ A,C,G, and T lacks base pairing rules |
| Translation |
initiation elongation termination |
Initiation ; |
30s ribosome binds to rbs the first tRNA binds 50s ribosome binds p, a, and e site are now present |
| Elongation |
for elongation to occur, the a site must be empty incoming tRNA's enter thru the empty a site |
| Translocation |
| shifting of the entire ribosome down one codon |
| Termination |
starts when the a site is over a stop codon there is nothing to bind to, so the polypeptide chain gets released by release factors and the ribosome detaches from the mRNA and tRNA |
| Transcriptional Control |
form of gene regulation if the gene is needed the repressor falls off if a gene is on, you make the protein, if its off, you dont |
