Micro test 4 control of microbial Growth
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175 terms
Terms | Definitions |
|---|---|
 Ignatz Semmelweiz and Joseph Lister | first introduced the concept of microbial control |
| semmelweiz | required all personnel at the obstetrics ward in the Vienna General Hospital to wash their hands with chlorinated lime |
| lister | initiated aseptic surgery which included heat sterilization of surgical instruments and the application of phenol (carbolic acid) to wounds following surgery |
| microbial control | is needed to prevent the transmission of infection, contamination, and spoilage. -it does not always mean killing the microbes; the microbes could be inhibited or removed |
| sterilization | the process of destroying or removing all forms of microbial life on an object or in a material, including the destruction of endospores. NOT PRIONS |
| moist heat | 121ºC for 15 minutes at 15 PSI |
| moist heat; dry heat; ionizing radiation; gasses such as ethylene oxide | methods of sterilization |
| dry heat | 170ºC for 120 minutes |
| sterilization | is absolute, has no degrees |
| disinfection | the process of destroying vegetative pathogens, but not necessarily endospores or viruses |
| disinfectant | is usually a chemical applied to an object or a material; -tend to reduce or inhibit growth. -are usually a liquid chemical solution applied to a surface or to eliminate pathogens in water. ex: chlorination |
| antisepsis | refers to chemical disinfection of the skin, mucous membranes , or other living tissues; -term applied to the treatment of wounds |
| antiseptic | the chemical used in antisepsis treatment |
| germicide | chemical agent that rapidly kills microbes but not necessarily their endospores |
| bacteriocide; sporicide; fungicide; virucide; ameobicide | forms of germicide |
| sterilization; disinfection; germicide | terms related to destruction of organism |
| bacteriostasis; fungistasis; asepsis; degerming; sanitization | terms related to suppression of organisms |
| bacteriostasis | condition in which bacterial growth and multiplication are inhibited, but the bacteria are not killed; ex refrigiration |
| bacteriostatic | if ___ agent is removed, bacterial growth and multiplication may resume |
| bacteriostatic | many chemicals, such as dyes, are ___ |
| fungistasis | refers to the inhibition of fungal growth |
| asepsis | (without infection) refers to the absence of pathogens from an object or area |
| sepsis | bacterial contamination |
| aseptic techniques | designed to prevent the entry of pathogens into the body |
| air filtration; ultraviolet lights; personal masks, gloves, and gowns; instrument sterilization | factors in achieving asepsis |
| degerming | the removal of transient microbes from the skin by mechanical cleansing or by the use of an antiseptic. -alcohol swabs are often used on the skin before injection; -iodine-containing product are often used before surgery |
| sanitization | the reduction of pathogens to safe public health levels on eating utensils by mechanical cleansing or chemicals; -any chemicals must be compatible with safety and palatability of foods |
| most resistant microbes | general rule of disinfection is to try to kill the ____ that can be found on the object to be disinfected |
| constant rate | bacterial populations subjected to antimicrobial chemicals die at a ___ |
| number and species | the ___ of microrganims present will influence the effectiveness of the antimicrobial treatment |
| cold | ___ temp controls microbial growth |
| warm | biochemical reactions occur more rapidly at ___ temperatures |
| warm | disinfectant activity is enhance by ___ temp |
| positive; negative | gram ___ bacteria are generally more susceptible to disinfectants that gram ___ bacteria |
| negative; Pseudomonas | gram ___ bacteria, genus __ can even grow in some disinfectants and antiseptics |
| much smaller porins | the resistance of Pseudomonas to some disinfectants and antiseptics is probably related to ___ |
| opportunistic pathogens | microbes that do not ordinarily cause disease but become pathogenic in the absence of normal competitive flora, -as when antibiotics suppress he growth of other microbes |
| Mycobacterium | another group of nonendospore forming organism that exhibit greater than normal resistance to disinfectants |
| actively growing | an ___ microorganism tends to be more susceptible to disinfectants than and older microbe |
| endospores | are more resistant to chemical agents and physical methods than vegetative cells |
| Clostridium botulinum | endospores of ___ can withstand boiling for several hours |
| organic matter and pH level | ___ frequently interfere with the actions of chemical control agents; ex; vomit, feces, pus, and food |
| alteration of membrane permeability; damage to proteins and nucleic acids; | actions of microbial control agents |
| alteration of Membrane Permeability | the susceptibility of the plasma membrane is due to its lipid and protein components; |
| altering its permeability | certain chemical control agents, such as quaternary ammonium compounds, damage the plasma membrane by |
| damage to Proteins and Nucleic acids | some microbial control agents damage cellular proteins by breaking hydrogen, covalent, and disulfide bonds, which are essential for the molecular structural and functional integrity; other agents interfere with DNA and RNA replication and protein synthesis |
| heat | is frequently used o eliminate microorganisms; it is economical and easily controlled |
| heat | kills microbes by denaturing their enzymes |
| thermal death point | the lowest temperature at which all bacteria in a liquid culture will be killed in 10 minutes |
| thermal death time | the length of time required to kill all bacteria in a liquid culture at a given temperature |
| decimal reduction time; DRT or D | the length of time in minutes, which 90% of a bacterial population will be killed at a given temperature |
| Dry heat sterilization | kills by oxidation effects |
| moist heat | kills more quickly because the water hastens the breaking of hydrogen bonds that hold proteins in their 3 dimensional structure |
| boiling or free flowing | type of moist heat sterilization which kills vegetative forms of bacterial pathogens, many viruses, and fungi and fungal spores within about 10 minute; |
| boiling or free flowing | type of moist heat sterilization which is used to sterilize dishes, basins, pitchers, and various equipment |
| boiling or free flowing | type of moist heat sterilization which is less effective against endospores and some viruses |
| autoclaving | types of moist heat sterilization (steam under pressure) is the most effective method of moist heat sterilization |
| 15; 121 ; 15 | autoclaving is effective at about ___ psi and ___ ºC will kill all organisms and their endospores in about ___ minutes or longer depending on the type and volume of material being sterilized |
| autoclaving | used to sterilize culture media, solutions, liens, utensils, dressings, equipment, and other items that can withstand temperature and pressure |
| vegetative forms of bacterial pathogens, many viruses, fungi and fungal spores | boiling or free flowing moist heat sterilization kills ___ within about 10 minute |
| pasteurization; 72; 15 | high-temperature, short-time (HTST) pasteurization is used on milk at ___ ºC for about ___ sec |
| ultra high temperature UHT; 140, 1 | milk that can be stored without refrigeration - sterilized by ultra high temperature treatment: ___ ºC for ___ sec |
| direct flaming | type of dry heat sterilization used to sterilize inoculating loops |
| incineration | burn to ashes; used to sterilize and dispose of contaminated paper cups, bags, and dressings |
| direct flaming; incineration | methods of dry heat sterilization |
| filtration | is the passage of a liquid or gas through a screen-like material with pores small enough to retain microorganisms |
| filtration | used to sterilize heat-sensitive materials such as some culture media, enzymes, vaccines, and antibiotic solutions |
| high-efficiency particulate air (HEPA) filter | ___ remove almost all microbe larger than about .3 um in diameter |
| cellulose esters or plastic polymers | membrane filters are composed of substances such as |
| .1 mm | membrane filter are about __ thick |
| .22um ; .45um ; .01um | pores of membrane filters include ___ and ___, intended for bacterial filtration and range down to ___, which will will retain viruses and even some large proteins molecules |
| heat; filtration; low temperature; dessication; osmotic pressure; radiation; nonionizing radiation | physical methods of microbial control |
| reproduce | most microbes do not ___ at ordinary refrigerator temperatures (0-7ºC) |
| refrigeration | has a bacteriostatic effect; used to preserve food, drugs and cultures |
| deep-freezing; -50 - -95 ºC | is an effective method for preserving microbial cultures; accomplished between ___ temperatures |
| lyophilization | most effective method for long-term preservation of microbial cultures; water is removed by high vacuum at low temperature |
| dessication | •involves removing water from microbes; •microbes are not capable of growth capable of growth or reproduction, but can remain viable for years...primarily bacteriostatic; |
| gonorrhea bacterium | can withstand dryness for only about an hour |
| tuberculosis bacterium | can remain viable for months after dessication |
| viruses and endospores | can resist desiccation |
| osmotic pressure | •microbes in high concentration salts and sugars will lose water (plasmolysis); |
| molds and yeasts | are more capable of growing in materials with low moisture or high osmotic pressure than bacteria are |
| fruit and grain | are spoiled by molds rather than by bacteria |
| wavelength, intensity, duration | the effects of radiation depend on its ___, ___, and ___ |
| ionizing energy | gamma rays or high-energy electron beams have wavelenths less than 1nm and therefore , carry more energy |
| ionizing energy | are used to sterilize pharmaceuticals and disposable dental and medical supplies such as plastic syringes, gloves, suturing materials, and catheters |
| ionizing energy | not widespread in route sterilization; destroys the DNA |
| nonionizing radiation | has a longer wavelength than ionizing radiation, usually greater than 1 nm; |
| ultraviolet light | ex of nonioizing radiation |
| 260 nm | most effective UV wavelengths for killing microbes are about ___ |
| UV radiation | ued to control microbes in the air |
| UV or germicidal | ___ lamps are found in hospital rooms and cafeterias |
| UV light | used to sterilize vaccines, sera, toxins, waste water, and drinking water |
| UV light | has low penetrability and will not penetrate pater, glass, and textiles; can damage the eyes; prolonged exposure to UV light can cause burns and skin cancer |
| chemical agents | used to control microbes on living tissu and intimate objects |
| sterility | few chemical agents achieve ___ ; most of them reduce microbial populations to safe levels or remove vegetative forms of pathogens from objects |
| concentration | ___ of a disinfectant will affect it's action; should always be diluted exactly as suggested by the manufacturer |
| use-dilution test | current standard for evaluating effectiveness of disinfectant |
| Staphylococcus aureus (gram +), Salmonella typhi (gram - organism), Pseudomonas aeruginosa (gram - resistant to antimicrobials) | 3 organisms used in Use -dilution test for evaluating effectiveness of disinfectant |
| use-dilution test | -several test bacteria are added to a series of tubes containing increasingly strong concentrations of the test disinfectant; -tubes are incubated and growth or lack of it is recorded; -the more highly diluted the chemical can be and still be effective, the higher it's rating |
| disk-diffusion method | -a disk of filter paper is soaked with a chemical agnt and placed on the surface of an agar plate that has been inoculated with a test organism; -incubate and measure a clear zone representing the inhibition of growth (zone of inhibition) around the disk |
| phenol and phenolics | (carbolic acid) was the substance used by Joseph Lister in his operating room; |
| phenol and phenolics | seldom used today as an antiseptic or disinfectant because it irritates the skin and has a disagreeable odor |
| 1% | in concentrations above ___, phenol has an antibacterial effect |
| phenolics | derivatives of phenol that has been chemically altered to reduce it's irritating qualities |
| phenolics | suitable agents for disinfecting pus, saliva, and feces |
| halogens; chlorines | the addition of ___ such as ___ to phenolics usually increases their antimicrobial activity |
| cresols | one of the most frequently used phenolics is from coal tar; very good surface disinfectant |
| cresol O-phenylphenol | the ___ is the main ingredient in Lysol |
| hexachlorophene; pHisoHex | another phenolic, consists of 2 molecules of phenol and was an ingredient of ___, a prescription lotion used for surgical and hospital microbial control |
| hexachlorophene | especially effective as a bacteriostatic agent against gram + staphylococciand streptococci |
| hexachlorophene | in 1972, it was found that excessive use of ___ can lead to neurological damage; thus a prescription is required to purchase 3% or stronger solution |
| injuring plasma membranes; inactivating enzymes; denaturing proteins | phenolics and phenol exer antimicrobial activities by: |
| chlorhexidine | used for disinfection of skin and mucous membranes; combined with a detergent or alcohol for surgical hand scrubs and preoperative skin preparation |
| plasma membranes; blocking an enzyme needed for lipid synthesis | mechanism of action of chlorhexidine - damages ___ by ___ |
| chlorhexidine | effective against many vegetative gram+ and gram - bacteria; is nontoxic (low toxicity) on the skin; persistent-effective for 6 hrs |
| halogens | ___ such as iodine and chlorine are used alone or as components of inorganic or organic solutions as chemical disinfectants |
| iodine | halogen effective against all kinds of bacteria, many endospores, various fungi, and some viruses; -main use as skin disinfectants and wound treatment |
| combines with tyrosine (a.a.) | mechanism of action of iodine: ___ and thus inhibits protein function |
| tincture | ___ of iodine: iodine solution in aqueous alcohol |
| iodophor | a combination of iodine and an organic molecule, usually a detergent in which the iodine is released slowly |
| betadine and isodine | examples of iodophor |
| chlorine | halogen, can be used as a gas or in combination with other chemicals ; germicidal action is caused by the hypochlorous acid (HOCl) that forms when chlorine is added to water |
| hypochlorous acid | germicidal action of chlorine is caused by ___ that forms when chlorine is added to water |
| hypochlorous acid (HOCl) | strong oxidizing agent that prevents fx of much of the cellular enzymes |
| hypochlorous acid | most effective form of chlorine because it is neutral in electrical charge and it diffuses rapidly through the cell wall |
| Calcium hypochlorite (Ca(OCl)2) | used to disinfect dairies, barns, slaughterhouses, and restaurant's eating utensils |
| Sodium hypochlorite (NaOCl) | used as a household disinfectant and as a bleach (Chlorox), as a disinfectant in dairies, food processing establishments, and hemodialysis systems |
| 2 drops; 4 drops | can use ___ of bleach/liter of water, ___ / liter if water is cloudy, to render water safe for drinking under emergency conditions; -let chlorinated waster sit for 30 minutes before using |
| chloramines | consist of chlorine and ammonia; used as disinfectants, antiseptics, or sanitizing agents; very stable compounds that release chlorine over long periods of time; relatively effective in organic matter; |
| chloramines | used to sanitize glassware and eating utensils and to treat dairy and food manufacturing equipment; toxic to aquarium fish |
| chlorine gas | used to disinfect water |
| alcohols | effectively kill bacteria and fungi but not endospores and nonenveloped viruses |
| alcohol | ___ mechanism of action: protein denaturation, disruption of membranes and dissolve many lipids including the lipid components of enveloped viruses |
| alcohol | advantage of ___, evaporates rapidly and leaves no residue |
| alcohol | unsatisfactory disinfectants when applied to woulds because they cause coagulation of a layer of protein under which the bacteria continue to grow |
| 70%, 60-95% | recommended optimum concentration of ethanol is ___: ___ seem to kill as quickly |
| isopropanol (rubbing alcohol) | ___ is slightly superior to ethanol as an antiseptic and disinfectant |
| silver,mercury, and copper | these heavy metals can be germicidal or antiseptic |
| oligodynamic action | the ability of very small amounts of heavy metals, especially silver and copper to exert antimicrobial activity |
| sulfhydryl group (-SH) | when metals combine with the ___ , on cellular proteins, denaturation results |
| 1% silver nitrate | ___ solution (heavy metal) is antiseptic. few drops are put into newborns' eyes to guard against a gonococcal infection of the eyes |
| inorganic mercuric chloride | heavy metal; probably has been in use the longest. effect is primarily bacteriostatic |
| copper sulfate | used chiefly to destroy green algae that grows in reservoirs, swimming pools, and fish tanks; -concentration one part per million |
| zinc chloride | common ingredient in mouthwash |
| zinc oxide | used as an antifungal agent in paints |
| surface-active agents or surfactants | decreases surface tension among molecules of a liquid ; includes soaps and detergents; |
| surface-active agents or surfactants | fx in mechanical removal of microbes through scrubbing (degerming) |
| Triclocarban | sufactants may contain ___ which inhibits gram + bacteria |
| acid-anionic surface-active sanitizers | surfactants that are important in cleaning dairy industry's utensils and equipment; -act on wide spectrum of microbes, including thermoduric bacteria; -nontoxic, noncorrosive, and fast - acting |
| quaternary ammonium compounds | are cationic detergents; are modifications of the 4 valance ammonium ion NH4+ |
| quaternary ammonium compounds | •strongly bactericidal against gram _ bacteria; they are less strong against gram - bacteria; •are also fungicidal, amoebicidal and virucidal against enveloped viruses; -mechanism of action unknown, probably affect the plasma membrane |
| endospores or tuberculosis bacteria | quaternary ammonium compounds do not kill __ but they are bacteriostatic |
| Pseudomonas | __ species not only survive in quats, but actively grow in them |
| organic acids and derivatives | used as preservatives to control mold growth; mechanism of action: inhibits enzymatic and metabolic activity |
| sorbic acid; potassium sorbate | ___ (or its salt, ____ ) is used to inhibit mold growth in acidic foods such as cheese |
| benzoic acid; sodium benzoate | ___ , or its salt ___, is an antifungal and is effective at low pH levels and is used in soft drinks and other acidic foods |
| parabens; methylparaben; propylparben | ___ such as ___ and ___ are used to inhibit mold growth in liquid cosmetics and shampoos; -derivatives of benzoic acid, but work at neutral pH |
| Calcium propionate | prevents mold growth in bread; |
| aldehydes | mech of action: inactivate proteins by forming covalent crosslinks with a number of organic functional groups of protains |
| formaldehyde and glutaraldehyde | example of aldehydes |
| formaldehyde gas | in an excellent disinfectant; -more commonly used as formalin, a 37% aqueous solution of ___ |
| formalin | was used to preserve biological specimens, embalm corpses, and inactivate bacteria and viruses in vaccines; spporicidal at high concentrations; |
| formaldehyde | is tissue irritating, has poor penetration, slow action, unpleasant odor, and leaves a white residue on treated materials; is carcinogenic |
| glutaraldehyde | less irritating and more pleasant to handle than formaldehyde; -used to sterilize hospital instruments, including respiratory therapy equipment; -2% solution (Cidex) is bactericidal, tuerculocidal, virucidal in 10 minutes and sporicidal in 3-10 hours |
| Cidex | 2% solution of glutaraldehyde that is bactericidal, tuerculocidal, virucidal in 10 minutes and sporicidal in 3-10 hours |
| gaseous sterilants | chemicals that sterilize in a closed chamber; -depends on denaturation of proteins and involves replacement of labile hydrogen in the proteins with alkyl groups such as -CH2CH2OH |
| ethylene oxide | •example of gaseous sterilants; •kills all microbes and endospores; •toxic and explosive in its pure form so it is usually mixed with CO2 or nitrogen; •although exposure time is from 4-18 hours, it is highly penetrative |
| gaseous sterilants | excellent sterilants for objects that would be destroyed by heat; used widely to sterilize medical supplies and equipments |
| oxidizing agents | exert antimicrobial activity by oxidizing cellular components of treated microbes |
| ozone (O3); hydrogen peroxide (H2O2); zinc peroxide; benzoyl peroxide | examples of oxidizing agents |
| ozone | highly reactive form of oxygen generated by high voltage electrical discharge |
| hydrogen peroxide | poor antiseptic for open wounds because it is quickly broken down to water and gaseous O2 by catalase, which is present in human cells; -effective disinfectent when used to disinfect inanimate objects; -can be sporicidal |
| zinc peroxide and hydrogen peroxide | used in irrigation of deep wounds where the release of oxygen inhibits the growth of anaerobic bacteria; |
| benzoyl peroxide | also useful in the treatment of wounds infected by anaerobic pathogens; used also to treat acne which is caused by anaerobic bacteria |
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