CPA #15 Questions Flashcards
(36 cards)
explain: hygiene hypothesis
exposure to everything can reduce infections; fewer childhood illnesses and increased personal hygiene have reduced children’s exposure to microbes so that when they do, the immune system overreacts and causes allergies
what infectious agent does sterilization not apply to?
prions; standard sterilization techniques do not destroy them
is commercially canned food free of microbes?
no; the commercial sterilization technique does not kill hyperthermophilic microbes because they do not cause disease and do not cause food to spoil at normal temp
define: degerming
removal of microbes from a surface by scrubbing, such as when you wash your hands; the action of scrubbing is more important than the chemicals
define: -stasis/-static
chemical agent that inhibits microbial growth/metabolism, but does not kill them
define: -cide/-cidal
refer to agents that destroy or permanently inactivate microbe
what are the two categories of antimicrobials?
- those that disrupt the integrity of cells by adversely altering their cell walls or cytoplasmic membranes
- those that interrupt cellular metabolism and reproduction by interfering with the structures of proteins and nucleic acids
what are the 3 characteristics of ideal antimicrobials?
inexpensive, fast-acting, stable during storage
what are the 3 factors when selecting a microbial control method?
- relative susceptibility of microbes
- environmental conditions
- site to be treated
define: high-level germicide
kill all pathogens (excluding prions), including bacterial endospores; healthcare professionals use them to sterilize invasive instruments
define: intermediate-level germicide
kill fungal spores, protozoan cysts, viruses, and pathogenic bacteria, but not endospores
define: low-level germicides
eliminate vegetative bacteria, fungi, protozoa, and some viruses; used to disinfect items that contact only the skin of patients (furniture, electrodes)
what agency established the biosafety levels?
Center for Disease Control and Prevention (CDC)
define: biosafety level-I (BSL-I)
suitible for handling microbes, such as E. coli, not known to cause disease in healthy humans; precautions are minimal; include hand-washing with antibacterial soap and disinfecting surfaces
define: BSL-II
designed for handling moderately hazardous agents, such as hepatitis and influenza viruses, methicillin-resistant S. aureus; precautions taken with contaminated sharps and aerosol producing procedures
define: BSL-III
all manipulations be done inside safety cabinets with HEPA filters; TB, yellow fever, Rocky Mountain Spotted Fever, anthrax
define: BSL-IV
“space suits”; separate buildings for testing; fatal diseases; ebola, smallpox, lassa fever viruses
why is heat used for microbial control?
high temps denature proteins, interfere with integrity of cytoplasmic membrane/cell walls, and disrupt the function of nucleic acids
define: moist heat
commonly used to disinfect, sanitize, sterilize, pasteurize; more effective than dry heat because water is a better conductor of heat than air
define: autoclave
pressure chamber; pipes introduce and evacuate steam; valves remove air and control pressure
define: pasteurization
thermoduric and thermophilic prokaryotes survive; combination of time and temperature, varies by product;
how is cold used to control microbial growth?
halts/slows down growth for mesophiles
does freezing eliminate bacteria?
no, because it just slows down the metabolism, does nothing to inactivate the pathogen
define: desiccation
aka drying; preserves foods such as fruits, beans, grains, etc; inhibits growth because metabolism requires liquid water
