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Microbio Report 5
The Control of Microbial Growth
| Question | Answer |
|---|---|
| removal or destruction of all living microorganisms, done by steam under pressure or sterilizing gas (ethylene oxide) | STERILIZATION |
| - the most common method for killing microbes ■ even the most resistant forms - including endospores | ENDOSPHORES |
| sterilizing agent. Liquids/ gases can be sterilized. | STERILANT |
| limited heat treatment. ■ used by canned foods with only enough heat to destroy the endospores of Clostridium botulinum, which produces a deadly toxin. | COMMERCIAL STERILIZATION |
| directed at destroying vegetative (non-endospore-forming) pathogens on inanimate objects ○ not similar to complete sterility | DISINFECTION |
| chemicals applied in disinfection - Lysol. ○ can be physical methods (ultraviolet radiation, boiling water, or steam). | DISINFECTANT |
| term used when disinfection is directed at living tissue | ANTISEPSIS |
| almost always chemical used in antisepsis - Betadine. | ANTISEPTIC |
| mechanical removal (instead of killing) of most of the microbes in a limited area. ○ alcohol swabbing of a skin site before receiving an injection | DEGERMING |
| high-temperature washing or washing in a sink followed by a dip in a chemical disinfectant. ○ intended to lower microbial counts to safe public health levels and minimize the chances of disease transmission. | SANITIZATION |
| indicates bacterial contamination | SEPSIS |
| absence of significant contamination | ASEPSIS |
| area is free of pathogens | ASEPTIC |
| - important in surgery to minimize contamination from the instruments, operating personnel, and the patient. | ASEPTIC TECHNIQUE |
| use of chemical agents to kill or inhibit the growth of microorganisms within host tissue | CHEMOTHERAPHY |
| cause outright death of microbes, attaches a suffix? | -cide |
| - kills microorganisms - kills fungi - inactivates viruses. | biocide/germicide, fungicide, virucide |
| stop or steady) only inhibits growth and multiplication of bacteria, attaches a suffix? | stat or stasis |
| TRUE OR FALSE. bacterial populations usually die at a constant rate when they are heated/treated with antimicrobial chemicals. | TRUE |
| it is necessary to graph bacterial populations effectively | LOGARITHMIC NUMBERS |
| Enumerate the Factors Influencing the Effectiveness of Antimicrobial Treatments (4) | NUMBER OF MICROBES, ENVIRONMENTAL INFLUENCES, TIME OF EXPOSURE, MICROBIAL CHARACTERISTICS |
| more microbes there are to begin with, the longer it takes to eliminate the entire population. | NUMBER OF MICROBES |
| due to temperature-dependent chemical reactions, most disinfectants work somewhat better in warm solutions. | ENVIRONMENTAL INFLUENCES |
| chemical antimicrobials often require extended exposure to affect more resistant microbes or endospores. | TIME OF EXPOSURE |
| impact the choice of chemical and physical control methods. | MICROBIAL CHARACTERSITICS |
| - sometimes called “little bags of enzymes” | BACTERIA |
| bonds are susceptible to breakage by heat/chemicals ● damage to nucleic acids DNA and RNA by heat, radiation, or chemicals is frequently lethal as these cells can no longer replicate nor carry out normal metabolic functions (synthesis of enzymes) | DENATURATION |
| Enumerate the Physical Methods in killing or controlling microbial growth (7) | Heat, Filtration, Low Temperatures/ Cold, High Pressure, Desiccation, Osmotic Pressure, Radiation |
| killing microorganisms by denaturing their enzymes | HEAT |
| Lowest temperature at which all the microbes in a certain liquid suspension will be killed in 10 mins | THERMAL DEATH POINT |
| minimal length of time for all bacteria in a particular liquid culture to be killed at a given temperature | THERMAL DEATH TIME |
| me (in minutes) in which 90% of the population of bacteria at a given temperature will be killed | DECIMAL REDUCTION TIME or D value |
| kills organisms primarily by coagulating proteins (denaturation), e.g. fry eggs | MOIST HEAT STRERELIZATION |
| kills vegetative forms of bacterial pathogens ● many viruses, fungi and their spores within 10 minutes, or usually much faster. ● endospores and some viruses not destroyed quickly | BOILING |
| higher temperatures required for reliable sterilization are achieved by steam under pressure ■ the higher the pressure, the higher the temperature | AUTOCLAVING |
| mild heating to kill microbes or lower microbial numbers introduced by Louis Pasteur | PASTEURIZATION |
| routinely used by dairy industry to determine if products have been pasteurized, an enzyme that is naturally present in milk | PHOPHATASE TEST |
| most commonly used milk pasteurization method today ● at least 72 degrees Celsius for only 15 seconds which kills pathogens and lowers bacterial counts so the milk keeps well under refrigeration | HIGH-TEMPERATURE SHORT-TIME PASTEURATION |
| ultra high temperature (UHT) treatments ● another method to treat milk for it to be stored for several months without refrigeration | STERILIZATION |
| Enumerate the Methods under moist heat sterilization (4) | Boiling, Sterilization, Pasteurization, Autoclaving |
| kills microbes by effects of oxidation | DRY HEAT STERILIZATION |
| one of the simplest methods of dry heat sterilization ■ used when sterilizing inoculating loops in the laboratory | FLAMING |
| sterilize and dispose of contaminated paper cups, bags, and dressings | INCINERATION |
| items places in oven at about 170 degrees Celsius for 2 hours | HOT AIR STERILIZATION |
| Enumerate the Methods under Dry Heat Sterilization (3) | Flaming, Incineration, Hot Air Sterilization |
| separation of bacteria from suspending liquid ● removes microbes by passage of a liquid or gas through a screen-like material ● used to sterilize heat-sensitive materials | FILTERING |
| remove almost all microbes larger than 0.3 micrometer diameter | High-Efficiency Particulate Air (HEPA) filter |
| cellulose esters or plastic polymers | MEMBRANE FILTERS |
| metabolic rate of most microbes is so reduced that they cannot reproduce or synthesize toxins | LOW TEMPERATURES / COLD |
| decreased chemical reactions and possible changes in proteins ○ bacteriostatic effects, except psychrotrophs | REFRIGERATION |
| more harmful to bacteria, ice crystals form and grow to disrupt cellular and molecular structure of bacteria. | SLOW FREEZING |
| alteration of molecular structure of proteins and carbohydrates ● preserves colors, flavors, nutrient values of fruit juices | HIGH PRESSURE |
| disruption of metabolism ● Involves removing water from microbes; primarily bacteriostatic. ● resistance of vegetative cells to desiccation varies with the species and the organism’s environment | DESSICATION |
| use of high concentrations of salts and sugars to preserve food | OSMOTIC PRESSURE |
| results in loss of water from microbial cells | PLASMOLYSIS |
| destruction of DNA ○ shorter wavelength ■ less than about 1 nm ■ carries much more energy | IONIZING RADIATION |
| emitted by certain radioactive elements such as cobalt ■ electron beams produced by accelerating electrons to high energies in special machines ■ penetrate deeply but may require hours to sterilize large masses | GAMMA RAYS |
| produced by machines in a manner similar to the production of electron beams | XRAYS |
| forms from ionization of water ■ kill organisms by reacting with organic cellular components, especially DNA | HIGHLY REACTIVE HYDROXYL RADICALS |
| damage to DNA ○ longer wavelength ■ greater than 1 nm | NONIONIZING RADIATION |
| List the radiations under Ionizing Radiation | GAMMA RAYS and XRAYS |
| causes thymine dimers ● inhibit correct DNA replication ■ 260 nm ● most effective biocidal wavelength ● absorbed by cellular DNA ■ disinfect vaccine and other medical products | UV LIGHT |
| 470 nm ● kills methicillin-resistant Staphylococcus aureus in lab cultures ● practical treatment for skin infections | VISSIBLE BLUE LIGHT |
| Nonionizing Radiations (2) | UV LIGHT and VISSIBLE BLUE LIGHT |
| natural or synthetic chemical that kills or inhibits microbial growth | ANTIMICROBIAL AGENT |
| used in teaching laboratories to evaluate the efficacy of a chemical agent. | DISK-DIFFUSION METHOD |
| clear zone presenting inhibition of growth if chemical is effective (after incubation) ● disks containing antibiotics are commercially available and used to determine microbial susceptibility to antibiotics. | ZONE OF INHIBITION |
| List Types of Disinfectants (4) | PHENOLS, BISPHENOLS, BIGUANIDES, TERPENES / ESSENTIAL OIL |
| derivatives of phenol chemically altered ● reduce irritating qualities ● increase antibacterial activity in combination with a soap or detergent ● injure lipid-containing plasma membrane ● suitable agents for disinfecting pus, saliva, and feces. | PHENOLICS |
| one of most frequently used group of chemicals ● derived from coal tar ● O-phenylphenol - main formula of Lysol ● very good surface disinfectants | CRESOLS |
| derivatives of phenol ○ two phenolic groups connected by a bridge (bis indicates two) | BISPHENOLS |
| - ingredient widely used in antibacterial soaps, toothpaste, and plastic kitchenware. | TRICLOSAN |
| broad spectrum of activity primarily affecting bacterial cell membranes ○ especially effective against gram-positive bacteria, also gram-negative bacteria except most pseudomonads. | BIGUANIDES |
| more rapid in its action than chlorhexidine. ■ expected to replace povidone-iodine (betadine) in many applications | ALEXIDINE |
| mixture of hydrocarbons extracted from plants - peppermint oil, pine oil, orange oil. ○ used for centuries in traditional medicine and for preserving food. ○ not toxic, pleasant odor, biodegradable ○ similar to phenolics | TERPENES / ESSENTIAL OILS |
| - one of the oldest and most effective antiseptics. ■ impairs protein synthesis and alters cell membranes ■ available as tincture (solution in aqueous alcohol) and as iodophor | IODINE |
| another widely used disinfectant (gas) or in combination with other chemicals ■ germicidal action caused by the hypochlorous acid (HOCl) | CHLORINE |
| organic compound that contains hydroxyl (-OH) group attached to a carbon atom. ○ evaporates quickly with effective antimicrobial properties used in healthcare settings, where quick disinfection is essential. ○ potent antiseptic and disinfectant | ALCOHOLS |
| most commonly used disinfectants ● sanitizing hands to disinfecting surfaces and medical instruments. ■ best at 70% concentration | ETHANOL and ISOPROPYL |
| esser potential as an antimicrobial agent compared to its aqueous form since water is an essential element for denaturation. | PURE ETHANOL |
| long history of use as disinfectants ● broad spectrum of activity primarily bacteriostatic ● now limited due to toxicity and ineffectiveness in organic matter. | MERCURIC CHLORIDE |
| True or False. The time it takes to kill a microbial population is proportional to the number of microbes. | TRUE |
| Silver, mercury, copper, and zinc exert their antimicrobial action through _______. When heavy metal ions combine with sulfhydryl (—SH) groups, proteins are denatured. | OLIGODYNAMIC ACTION |
| are cationic detergents attached to NH4 + that disrupt plasma membranes. | QUATS |
| are antibiotics used to preserve foods, especially cheese. | NISIN and NATAMYCIN |
| _______such as formaldehyde and glutaraldehyde are among the most effective chemical disinfectants. They exert their antimicrobial effect by inactivating proteins. | ALDEHYDES |
| it is the gas most frequently used for sterilization. It penetrates most materials and kills all microorganisms by protein denaturation. | ETHYLINE OXIDE |
| _________ Bacteria are generally more resistant than___________ bacteria to disinfectants and antiseptics. | GRAM-NEGATIVE, GRAM-POSITIVE BACTERIA |
| __________viruses are generally more resistant than _________ viruses to disinfectants and antiseptics. | NONENVELOPED, ENVELOPED |
| A microbes that is resistant to disinfection and autoclaving. | PRIONS |
| openings that are highly selective of molecules that they permit to enter the cell which makes gram-negatives resistant to many antibiotics | PORINS |
| True or False. Mycobacteria, endospores, and protozoan cysts and oocysts are not resistant to disinfectants and antiseptics. | FALSE |
| short-lived gas usually manufactured at the place of use ■ used to fumigate enclosed building areas contaminated with endospores of anthrax ■ more stable in aqueous solution | CHLORINE DIOXIDE |
| fourth state of matter ○ gas is excited by an electromagnetic field | PLASMA |
| combines chemical and physical methods ○ carbon dioxide is compressed into a “supercritical” state | SUPERFICIAL FLUIDS |
| group of oxidizing agents that includes hydrogen peroxide and peracetic acid. | PEROXYGEN |
| antiseptic found in many household medicine cabinets and in hospital supply rooms. ■ not a good antiseptic for open wounds. | HYDROGEN PEROXIDE |
| one of the most effective liquid chemical sporicides available ■ used as a sterilant ■ action is similar to hydrogen peroxide | PERACETIC ACID |
| ■ highly reactive form of oxygen ● generated by passing oxygen through high-voltage electrical discharges ■ responsible for fresh air odor after a lightning storm ■ supplement chlorine in the disinfection of wate | OZONE |
| once used extensively to preserve biological specimens and inactivate bacteria and viruses in vaccines. | FORMALIN |
| reduce surface tension among molecules of liquid ● disrupting microbial cell membranes, easier to remove microbes during cleaning | SURFACTANTS |
| often used in food processing industries and healthcare settings ○ acidic in nature, odorless, nontoxic, noncorrosive, and fast acting | ACID-ANIONIC SANITIZERS |
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