Emergency situations Flashcards

Question

what is Iodophors and how does it work?

Answer 1

Iodophors are used both as antiseptics and disinfectants. An iodophor is a combination of iodine and a solubilizing agent or carrier; the resulting complex provides a sustained-release reservoir of iodine and releases small amounts of free iodine in aqueous solution. Antiseptic iodophors are not suitable for use as hard-surface disinfectants because they contain significantly less free iodine than do those formulated as disinfectants. Wescodyne, Betadyne, Povidone-Iodine and other iodophors are commercially available Iodine-based disinfectants, which give good control when the manufacturer’s instructions for formulation and application are followed. Both bleach and iodophors should be made up in cold water in order to prevent breakdown of the disinfectant.

Answer 2

Phenolics are phenol (carbolic acid) derivatives. These biocides act through membrane damage and are effective against enveloped viruses, rickettsiae, fungi and vegetative bacteria. They also retain more activity in the presence of organic material than other disinfectants. Cresols, hexachlorophene, alkyl- and chloro derivatives and diphenyls are more active than phenol itself. Available commercial products are Lysol, Pine-Sol, Amphyl, O-syl, Tergisyl, Vesphene, L- Phase and Expose.

Answer 3

Strong mineral acids and alkalis have disinfectant properties proportional to the extent of their dissociation in solution. Some hydroxides are more effective than would be predicted from their values. In general acids are better disinfectants than alkalis. Mode of action is attributed to an increase of H+ and OH– species in solutions which interfere with certain microbial functions, however the total effect is not only dependent on pH alone. Weak organic acids are more potent than inorganic acids despite low dissociation rates in solution. Action is attributed to the disruption of 2° and 3° conformation of enzymes and structural proteins.

Answer 4

Soluble salts of mercury, silver lactate, mercuric chloride and mercurous chloride are efficient bactericidal agents. Silver nitrate and mercuric chloride are commonly used as 1:1000 aqueous solutions. Action is through attack on protein sulfhydryl groups and disruption of enzyme functions. Organic matter can reverse the disinfectant properties of mercurials. Caution: Please consult with EH&S’s Hazardous Materials group prior to using heavy metals because many of these must be disposed of as a hazardous waste. Specifically, disposal of elemental mercury and salts of mercury are very costly.

Answer 5

Alcohols work through the disruption of cellular membranes, solubilization of lipids, and denaturation of proteins by acting directly on S-H functional groups. Ethyl and isopropyl alcohols are the two most widely used alcohols for their biocidal activity. These alcohols are effective against lipid-containing viruses and a broad spectrum of bacterial species, but ineffective against spore-forming bacteria. They evaporate rapidly, which makes extended contact times difficult to achieve unless the items are immersed. The optimum bactericidal concentration for ethanol and isopropanol is in the range of 60% to 90% by volume. Their cidal activity drops sharply when diluted below 50% concentration. Absolute alcohol is also not very effective. They are used to clean instruments and wipe down interior of Biological Safety Cabinets and bottles, etc. to be put into Biological Safety Cabinets. Alcohols are generally regarded as being non-corrosive.

Answer 6

Always consult with the Autoclave Manufacturer and/or Operators Manual for proper temperature, pressure, and time because these may be different that what is specified in this document. Autoclaving at a temperature of 121oC (250○F), at 15 to 20 psi is one of the most convenient and effective means of sterilization available. The time is measured after the temperature of the material being sterilized reaches 121ºC (250ºF). Care must be taken to ensure that the steam can circulate around articles in order to provide even heat distribution. The success of the sterilization is very time-dependent in liquid media, with large volumes requiring longer periods of time to reach the effective temperature within the media itself. Additionally, there should be no void spaces in the load that could insulate against the steam – this condition could prevent the transference of heat to the vessels resulting in no sterilization of the contents. In dry loads small amounts of water should be included inside the autoclave bag to ensure sufficient moisture content within the load to allow for heat transference and distribution. Autoclave tape can be used for routine runs where glassware or sterile media are prepared before use.

Answer 7

Chemical indicators for steam autoclaving change colors after being exposed for a few minutes to normal autoclave operating temperatures of 121ºC (250ºF). Hence, chemical indicators can give a quick visual reference for heat penetration inside the autoclave. Chemical indicators should be positioned near the center of each load, and toward the bottom front of the autoclave.

Answer 8

Most chemical indicators can only be used to verify that your autoclave has reached normal operating temperatures for decontamination; they have no time factor. Chemical indicators alone are not designed to prove that organisms are actually killed during a decontamination cycle.

Answer 9

Tape indicators are adhesive backed paper tape with heat sensitive, chemical indicator markings. Commonly used heat sensitive markings include diagonal stripes (autoclave tape), and/or the word “sterile”. These markings only appear when the tape has been exposed for a few minutes to normal autoclave decontamination temperatures. Caution: Tape indicators can only be used to verify that your autoclave has reached normal operating temperatures for decontamination; they have no time factor. Tape indicators alone are not designed to verify that organisms are actually killed during a decontamination cycle.

Answer 10

Biological indicators are designed to demonstrate that an autoclave is capable of killing microorganisms. EH&S recommends the use of commercially available Bacillus stearothermophilus spores to monitor the effectiveness of steam autoclaves. Follow the manufacturer’s instructions for the spore test. This test must be performed at least every 90 days. Always post the results of the test on or near the autoclave – Date Performed; Test Result; Name of Person doing test.

Answer 11

Ovens operating at 160° – 170°C for periods of 2-4 hours are efficient for sterilizing glassware, or other non-porous heat conductive materials. It is unsatisfactory for organic and inorganic materials that can act as insulation and is also unsuitable for heat labile materials. Incineration is a very effective means of final sterilization and disposal, and is also used for “spot” sterilization of inoculating needles and loops as well as flaming glassware during microbiological culturing procedures. Care has to be exercised when flaming “charged” items, since this practice can release infectious micro-aerosols through spattering.

Answer 12

Ionizing radiation is not used for general laboratory sterilization, however ultraviolet radiation (U.V.) is used to control airborne microorganisms and environmental surface decontamination. Ultraviolet sources are used in biological safety cabinets for partial contamination control and should be turned on only when cabinets or enclosures are not in use. This form of control is extremely limited due to its poor penetrating power, susceptibility to air movement, requirement for long contact time periods, and has not been documented as an effective control method. The eyes and skin should not be exposed to direct or strongly reflecting UV radiation. Adequate eye and skin protection must be worn when working in an UV-irradiated area. Special safety glasses with side shields or goggles with solid side pieces should be worn. Skin protection is afforded by face shields, caps, gloves, gowns, etc.

Answer 13

From a practical point of view, formaldehyde, beta-propiolactone and ethylene oxide are not routinely used in laboratory sterilization practices. These sterilants are used in hospitals and commercial facilities where closed systems controlling temperature, humidity, and concentration are required to achieve sterilization using these agents.

Emergency situations Flashcards

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