BYU General Microbiology Chapter 6 – Dr. Robison – Flashcards
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| Sterilization |
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| The Complete absence of life |
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| Disinfection |
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| Destruction of vegetative pathogens; usually inanimate objects |
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| -cides |
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| agents which kill |
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| -static |
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| agents which prevent growth |
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| Sepsis |
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| bacterial contamination and Growth |
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| Antiseptic |
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| Agent which destroys vegetative pathogens |
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| Sanitation |
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| Lowering bacterial counts to safe public health levels- broad, ambiguous |
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| Type of Heat: Steam Autoclave |
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| Moist heat under pressure: 121 C for 20 min |
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| Types of Heat: pasteurization |
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| Moist heat not under pressure: 63 C for 30 min or 72 C for 15 sec |
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| Types of Heat: oven |
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| Dry heat: 170 C for 2 hrs |
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| Types of Heat: Chemiclave |
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| Heat and chemical vapor: 132 C for 20 min using 15 psi of alcohol/formaldehyde vapor |
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| 2 basic ways that antimicrobial agents work |
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| alteration of cell walls or cytoplasmic membranes, interference w/protein and nucleic acid structures |
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| critical instruments |
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| sterile: penetrates body |
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| semi-critical instruments |
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| pathogen free: in a colonoscopy, microbes are already there |
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| non-critical instruments |
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| asceptic: on skin, ex. stethoscope |
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| order of most resistant microbes to most susceptable |
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| Prions Coccidia Spores big gap Mycobacteria cysts non-enveloped viruses trophozoites non-sporulating gram - bacteria fungi large non-enveloped viruses non-sporulating gram positive bacteria enveloped viruses |
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| AOAC use-dilution test |
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| the best method for evaluating disinfectants and antiseptics use Staph aureus, pseudomonas aureginosa and salmonella cholerasusis |
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| physical methods of microbial control |
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| exposure to heat extremes exposure to cold extremes desiccation (remove moisture) filtration osmotic pressure radiation |
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| heat related methods do what to cells? |
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| denature proteins interfere with integrity of cytoplasmic membrane, cell wall disrupt nucleic acids |
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| 4 methods of microbial control using moist heat |
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| boiling autoclaving Pasteurization Ultrahigh-Temperature Sterilization |
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| moist or dry heat more effective? |
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| moist heat |
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| Can boiling sterilize? if not, what survives boiling? |
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| no. endospores, protozoan cysts, prions |
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| autoclave conditions |
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| 121 C, 15 psi, 15 min |
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| Is pasteurization sterilization? |
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| no: heat tolerant and heat-loving microbes survive, but these normally aren't pathogenic and don't cause spoilage. |
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| incineration |
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| sub group of dry heat, ultimate means of sterilization |
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| differences between dry heat and moist heat |
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| dry heat: used when moist heat woud ruin materials and requires higher temps for longer time than moist heat (106 C for 2 hrs of 171 C for 1 hr. |
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| refrigeration |
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| slows growth of most pathogens (not psychrophiles) |
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| freezing |
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| halts growth of most pathogens (not psychrophiles), slow freezing is more effective that quick freezing, no liquid water available |
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| desiccation |
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| drying inhibits growth due to removal of water |
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| lypholozation |
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| freeze-drying, used for long term preservation of cultures- it prevents formation of damaging ice crystals |
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| osmotic pressure |
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| high concentrations of soutes inhibit growth through desiccation, fungi survive it best |
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| Ionizing radiation |
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| wavelengths < 1 nm. ex: electron beams, gamma rays, X-rays. Create ions by ejection electrons from atoms they strike, ions break DNA, can be used to sterilize |
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| Electron beams |
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| effective at killing but do not penetrate well. |
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| gamma rays |
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| penetrate well but takes hours to kill microbes |
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| X-rays |
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| take too much time to be practical for growth control |
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| nonionizing radiation |
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| wavelengths > 1 nm, UV mutates DNA, disinfects air, transparent fluids, and surfaces of object |
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| phenols and phenolics |
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| chemical method. intermediate to low level disinfectant. denatures proteins and disrupts cell membranes. effective in presence of organic matter. remain activated for long periods of time, commonly used in health care settings, labs, and homes, have a bad odor |
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| what percent of ethyl alcohol is good on organic material? |
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| 75% |
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| Alcohol |
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| chemical method. inermediate-level disinfectant, denatures proteins and disrupts cytoplasmic membrane, evaporates rapidly, good surface disinfectant, rapid, works against almost every vegetative |
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| Halogens |
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| intermediate-level disinfectant damage enzymes by oxidation or denaturing them, ex: iodine, chlorine, chloramine, bromine, bleach |
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| Oxidizing agents |
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| ex: peroxides, ozone, peracetic acid high level disinfectants |
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| hydrogen peroxide |
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| can sterilize and disinfect can't use on open wounds bc catalase neutralizes |
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| ozone |
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| treats drinking water |
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| peracetic acid |
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| effective sporicide: used to sterilize equipment |
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| Surfactants |
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| reduce surface tension of solvents to make them more effective at dissolving solutes ex: soaps, detergents, quats |
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| soaps |
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| have hydrophilic and hydrophobic ends; good degerming agents, not antimicrobial |
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| detergents |
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| positively charged organic surfactants |
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| quats |
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| low level disinfectant colorless, tasteless, harmless to humans, antimicrobial |
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| heavy metals |
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| low-level bacteriaostatic/ fungistatic agents ions that alter shape of proteins ex: use in babies' eyes 1% silver nitrate -> no blindness from N. gonorrhoeae use copper to prevent algae growth Thimerosal used to preserve vaccines |
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| Aldehydes |
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| have -CHO terminal group denatures proteins and inactivates nucleic acids ex: Gluteraldehyde, Formalin |
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| Gluteraldehyde |
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| disinfects (short exposure), sterilizes (long esposure) |
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| Formalin |
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| used in embalming, and disinfecting rooms and instruments |
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| Gaseous Agents |
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| used in closed chambers to sterilize them denatures proteins and DNA can be hazardous to ppl |
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| development of resistat microbes |
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| no data behind avoiding antimicrobial agents |
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| Microbes in Air |
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| how long they stay in the air depends on particles they're riding barrier HEPA filters air sampling: anderson sampler is similar to human lungs |
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| what kind of masks are better? |
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| tie-on filter over pre-formed cup |
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| best antimicrobial handwash |
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| 4% chlorhexidine |
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| best countertop disinfectant |
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| 70-80% ethanol |
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| best thing to mop floor with |
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| substituted phenols |
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| best thing to disinfect semicritical instruments |
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| 2-3.2% glutaraldehyde |
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| best thing to sterilize plastics |
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| gamma irradiation |
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| best thing to sterilize scopes |
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| H2O2 gas plasma |
