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Define sterilization
the destruction of all life forms
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Define disinfection
the elimination of microorganisms from inanimate objects/surfaces
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Define decontamination
the treatment of an object or inanimate surface to make it safe to handle
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Define disinfectant
used to disinfect inanimate objects/surfaces but is generally too toxic to use on human tissues
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Define antiseptic
used to kill or inhibit the growth of microbes but is safe to use on human tissue
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Define sanitizer
used to reduce, but not eliminate, microbial numbers to a safe level
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Why are chemical agents usually unreliable for sterilization?
because they work slowly on viruses, endospores, and bacteria w/an acid-fast cell wall
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List 5 factors that may influence the antimicrobial action of disinfectants, antiseptics, and sanitizers
- concentration of the chemical agent
- temperature at which the agent is being used (lower the temp, the longer it takes to disinfect)
- the kinds of microorganisms (endospores, acid-fast bacteria are harder to eliminate)
- the number of microorganisms present (the more there are, the harder to eliminate them)
- the nature of the material bearing the microorganisms (dirt and other things may interfere w some agents)
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Describe two ways disinfectants/antiseptics/sanitizers work
- they can damage the lipids/proteins of the semipermeable cytoplasmic membrane -> resulting in leakage of cellular materials
- they can denature microbial enzymes and other proteins, which blocks metabolism and kills the cell
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Name one chemical agent that is reliable for sterilization
- aldehyde
- ethylene oxide gas
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State why the results of an in vitro test may not apply to in vivo situations
because in vitro does not show the same conditions under which it will be used
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Define transient flora and resident flora
- transient - microorganisms you pick up from what you have been handling
- resident - normal flora of the skin
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Define antibiotic
substances produces as metabolic products of one microorganism which inhibit or kill other microorganisms
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Define antimicrobial chemotherapeutic chemical
chemicals synthesized in the laboratory which can be used therapeutically on microorganisms
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Define narrow spectrum antibiotic
effective against just gram positive or just gram negative bacteria
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Define broad-spectrum antibiotic
effective against a variety of both gram-neg and gram-pos
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Describe 4 different major modes of action of antimicrobial chemotherapeutic chemicals and give 3 examples of drugs fitting each mode of action
- inhibit peptidoglycan synthesis (penicillin, cephalosporins, carbapenems, bacitracin)
- inhibit synthesis of acid-fast cell wall (INH, ehatmbutol)
- alter the cytoplasmic membrane (polymyxins, daptomycin, pyrazinamide, nystatin)
- inhibit protein synthesis (rifampin, aminoglycosides, tetracyclines, macrolides)
- interfere with DNA synthesis (quinolones, sulfonamides, metronidazole)
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Define protozoan
- unicellular eukaryotic microorganisms
- belong to kingdom protista
- reproduce asexually by fission, budding, or schizogony
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Define trophozoite
- the vegetative form of a protozoan
- motile, feeding, reproducing form
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Define cyst
a protective form that enables them to survive harsh environments
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State how the following disease is transmitted and diagnosed -- amoebic dysentery
- by fecal oral route
- look for cysts of E. hystolica in a fecal smear
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State how the following disease is transmitted and diagnosed -- african sleeping sickness
- by the bite of an infected tsetse fly
- look for Trypanosoma in the blood, in aspirated fluid from lypmh nodes, or in spinal fluid
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State how the following disease is transmitted and diagnosed -- giardiasis
- transmitted by fecal-oral route
- look for cysts of G. intestinalis in fecal smears
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State how the following disease is transmitted and diagnosed -- genitourinary trichomoniasis
- by venereal contact
- look for T. vaginalis trophozoites in vaginal discharge and urine
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State how the following disease is transmitted and diagnosed -- balantidiasis
- by fecal-oral route
- look for B. coli in fecal smear
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State how the following disease is transmitted and diagnosed -- malaria
- by infected female Anopheles mosquito
- look for parasite in infected red blood vells
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State how the following disease is transmitted and diagnosed -- toxoplasmosis
- by ingesting raw meat of an infected mammal or ingesting cysts of T. gondii from cat feces
- serologically test and grow the organism in cell culture
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What organism is this + what disease is it associated with?
- entamoeba histolytica
- causes amoebic dysentery
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What organism is this + what disease is it associated with?
- Trypanosoma gambiense
- causes african sleeping sickness
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What organism is this + what disease is it associated with?
- Giardia lamblia
- causes giardiasis
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What organism is this + what disease is it associated with?
- Trichomonas vaginalis
- causes genitourinary trichomonas
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What organism is this + what disease is it associated with?
- Balantidium coli
- causes balantidiasis
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What organism is this + what disease is it associated with?
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Define helminth
a parasitic worm
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Define ova
female reproductive cells
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Define hermaphroditic
having both male and female reproductive organs
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List 3 classes of parasitic helminth and state the common name for each class
- nematodes - roundworms
- cestodes - tapeworms
- trematodes - flukes
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State how ascariasis is transmitted to humans
by ingesting water or food contaminated with feces that contains Ascaris ova or from fingers contaminated with polluted soil
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State how pinworms are transmitted to humans
- inhaling/ingesting eggs
- or transfer of ova to mouth from fecally-contaminated fingers
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State how trichonosis is transmitted to humans
by eating poorly cooked infected pork
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State how tapeworms are transmitted to humans
by eating poorly cooked infected beef/pork/fish containing cysticerci
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State how flukes are transmitted to humans
by ingesting poorly cooked fish, crayfish, crabs, snails, or water vegetables infested with flukes
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What is this?
Ascaris ova
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What is this?
a roundworm
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What is this?
pinworm ova
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What is this?
Trichinella in muscle tissue
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What is this?
tapeworms
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What is this?
scolex of a tapeworm
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what is this?
a fluke (trematode)
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Define static
inhibits the growth of microorganisms
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Define cidal
kills microorganisms and viruses
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State why moist or dry heat is more effective in controlling microorganisms and why
moist -> because of its ability to penetrate microbial cells
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State two methods of applying moist heat
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Briefly describe the process of autoclaving (pressure, time, temp)
- employs steam under pressure
- temperature to noil is 121 degrees celsius
- generally 15-45 min
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State whether or not boiling is an effective means of sterilization + why
- no because certain viruses and endospores can survive boiling for long periods of time
- so it is not very effective for killing all life forms
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State two methods of dry heat
- hot air sterilization
- incineration
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Define pasteurization
- the mild heating of milk and other materials to kill particular spoilage organisms or pathogens
- does not kill all organisms
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State whether low temperature has a static or cidal effect on microorganisms + why
static effect because it inhibits microbial growth by slowing down microbial metabolism
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State how the wavelength and the length of exposure influence the bacteriocidal effect of UV light
- the longer the exposure the greater the cidal activity
- most cidal wavelengths lie in 260 - 270 nm
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Describe how UV light kills microorganisms
it causes the formation of thymine-thymine dimers, which ultimately leads to mutations
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Describe how ionizing radiation kills microorganisms and state several common applications
- it disrupts DNA molecules and proteins
- applications - used to sterilize medical supplies, slow down spoilage of food
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State the concept behind sterilizing solutions with micropore membrane filters
they have holes large enough to all the fluid to pass through but small enough to prevent the passage of microbes
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