Human Micro Exam 4
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The presence of a toxin or pathogenic organism in blood and tissue
- The removal of all microorganisms, including endospores
- exception being prions
done by steam under pressure, sterilizing gas (ethylene oxide)
A substance capable of killing microorganisms
Any treatment used on inanimate objects to kill or inhibit the growth of microorganisms; a chemical used is called a disinfectant.
Thermal Death Point (TDP)
The lowest temperature required to kill all the bacteria in a liquid culture in 10 minutes.
Thermal Death Time (TDT)
The minimum length of time required to kill all bacteria in a liquid culture at a given temperature.
The absence of contamination by unwanted organisms
A treatment capable of inhibiting bacterial growth without killing the bacteria
A state in which bacterial growth is inhibited without the bacteria being killed
The removal of water
Tolfnaftate (other antifungal drug)
- 1. Antifungal drug
- 2. Unknown mode of action
- 3. Used to treat athlete's foot
- 1. Antifungal drug
- 2. Inhibits plasma membrane synthesis
- 1. Inhibbits mRNA
- 2. Used to treat tuberculosis
- 1. Inhibits protein synthesis (amino acids are prevented from growing into polypeptide chains)
- 2. Don't penetrate well into intact mammalian cells
- 3. Small amounts enter host cells = rickettsias and chlamydias are sensitive to tetrabycline
- 4. Are effective on G+ and G- bacteria
- Three commonly used: Oxytetracycline (terramycin), chlortetracycline (Aureomycin), and Tetracycline
Common uses for tetracycline
- urinary tract infections
- mycoplasmal pnuemonia
Adverse reactions to tetracycline
- discoloration of teeth in children
- liver damage in pregnant women
- added to animal feed can result in human health problems
- 1. Inhibits RNA synthesis of cell wall components and protein
- 2. Used against systemic fungal infections
- 3. Agent inhibiting nucleic acids
- Broad spectrum; combination is widely used
- Inhibits synthesis if essential metabolites
- 1. Destroys plasma membrane
- 2. Topical use against G- bacteria
1. Inhibits protein synthesis pg. 555
- 1. Inhibits cell wall synthesis
- 2. Natural penicillin
- 3. Used against G+ bacteria
- 4. Requires injection
1. Used against systemic fungal infections
narrow spectrum of microbial activity
- narrow range of different microbial types they affect
- example: Penicillin G affects gram-positive bacteria but very few gram-negative bacteria.
a substance produced by microorganisms that in small amounts inhibits another microorganism.
more than half of antibiotics are produced by what species?
- a term that is applied to growth of a target pathogen that has developed resistance to the antibiotic.
- Antibiotic resistant strain replaces the original sensitive strain and the infection continues.
Gram positive rods:
Bacillus subtilis and Paenbacillus polymyxa
Antibiotic: Bacitracin and Polymycin
- S. nodus - Amphotericin
- S. venezuelae - Chloramphenicol
- S. aureifaciens - Chlortetracycline and tetracycline
- Cephalosporium - Cephalothin
- Penicillium griseofulvum - Griseofulvin
- Penicillium chrysogenum - Penicillin
- The property of of some antimicrobial agents to be toxic for a microorganism and nontoxic for the host.
- Eukaryotic vs Prokaryotic. Eukaryotic have cell wall and other developed characteristics that make them different from prokaryotic bacteria...
- This is why antibiotics don't work well of fungus, protozoan or helminth their cellular level closely resembles human cells.
- hard to treat
- within the host cell
- genetic information of virus is directing the himan cell to make viruses rather than synthesize normal cellular materials.
limited heat tx to destroy endospores of C. botulinum
- destruction of vegetative pathogens
- uses physical or chemical methods.
- Destruction of vegetative pathogens living on tissue.
- Treatment almost always by chemical antimicrobials
- removal of microbes from a limited area, such as the skin around an injection site
- chemical- alcohol swab
- tx intended to lower microbial counts on eating and drinking utensils to safe and public levels
- done using high pressure washing or by dipping into a chemical disinfectant.
Effectiveness of microbial treatment influenced by
- 1. number of microbes ( the more microbes the longer it takes)
- 2. Environmental influences (organic matter present influences the selection of disinfectants) disinfectants work better under warm conditions. Heat is also measurably more effective under acidic conditions.
- 3. Time exposure- Chemical antimicrobials work better with longer exposure.
- 4. Microbial characteristics- different characteristics effect the choice of physical and chemical contro methods.
Would a chemical microbial control agent that affects plasma membranes affect humans?
A microbial agent that targets the plasma membrane of the microorganism would not be advised because humans also have a plasma membrane. For this reason, it is important to develop a microbial agent that targets components of the microorganism that are not present in the host cell. For example, penicillin is an antibiotic that targets the cell well. Since the cell wall is not present in human cells, penicillin causes no damage to the host cell.
Why would a can of pork take longer to sterilize at a given temperature than a can of soup that also contained pieces of pork?
Solid foods heat unevenly because of the uneven distribution of moisture.
What is the connection between the killing effect of radiation and hydroxyl radical forms of oxygen?
These radicals are produced from ionizing radiation that take electrons from other molecules.
anything applied to skin to disinfect, such as betadine
Phenols- Ethylene oxides
- most common canned
- Freeze drying
Decimal reduction time (heat resistance)
Time in minutes in which 90% of population of bacteria will be killed at a given temperature.
Moist heat sterlization
- kills microorganisms by denaturing proteins
- breakage of hydrogen bonds
preferred method of heating sterilzation unless material can be damaged by heat and moisture.
- The higher the pressure the higher the temperature
- 100*C at 1 atmosph. abovve sea level =15lbs of pressure per square in (psi)
- 15psi (121*C)= will kill all organisms but prions.
- Used to sterilize culture media, instruments, dressing, I.V. equipment ect...if it can stand high temps and pressure.
kills by oxidation effects
Ionizing- ionization of waterwhich forms highly reactive hydroxyl radicals
nonionizing- UV light
- kills bacteria and fungi, but not endospores
- method of action is protein denaturation
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