Exam (elaborations) TEST BANK FOR DIAGNOSTIC MICROBIOLOGY 4TH EDITION

TEST BANK FOR DIAGNOSTIC MICROBIOLOGY 4TH EDITION Mahon: Textbook of Diagnostic Microbiology, 4th Edition Chapter 04: Control of Microorganisms Test Bank MULTIPLE CHOICE 1. The chemical or physical method that destroys all forms of life is called: a. Sterilization Textbook of Diagnostic Microbiology 4th Edition Test Bank b. Disinfection c. Bacteriostatic d. Bactericidal ANS: A Sterilization is the destruction of all forms of life, including bacterial spores. Disinfection is a process that eliminates a defined scope of microorganisms, including, in some cases, spores. Bacteriostatic inhibits the growth of microorganisms. Bactericidal kills bacteria. REF: page 62 OBJ: Level 1 – Recall 2. Organisms that are the most resistant to heat, chemicals, and radiation are: a. Parasites b. Prions c. Bacteria d. Viruses ANS: B Prions are naked pieces of protein, so they are harder to kill than any other organism. Viruses usually contain a nucleic acid, and all the mentioned forms of killing can effectively disrupt their nucleic acid. Bacteria and parasites are complete organisms that are killed by disinfection and sterilization, even in the spore and cyst stages. REF: page 63 OBJ: Level 1 – Recall 3. After using the phone, the laboratory tech sprayed the receiver with a chemical spray. This process will kill a defined scope of microorganisms. What is this process called? a. Sterilization b. Bacteriostatic c. Disinfection d. Bactericidal ANS: C Sterilization kills all organisms and spores at a site. Bacteriostatic and bactericidal are adjectives that describe the particular action of chemical agents: to inhibit bacterial growth or kill bacteria. Disinfection kills a defined scope of microorganisms. REF: page 62 OBJ: Level 2 – Interpretation 4. Before performing a phlebotomy, the phlebotomist will clean the area on a patient’s arm with a substance before inserting the needle. This substance is called a(n): a. Disinfectant b. Sterilizer c. Antiseptic d. Bactericidal ANS: C A disinfectant is a chemical agent used to kill microorganisms on an inanimate object. To sterilize is to kill all life; skin will still have organisms growing after wiping. Bactericidal is the process of killing bacteria. An antiseptic is a substance applied to the skin for the purpose of eliminating or reducing the number of bacteria present. REF: page 62 OBJ: Level 2 – Interpretation 5. All the following factors play a significant role in the selection and implementation of the appropriate method of disinfection EXCEPT: a. Temperature b. Contact time c. Biofilms d. Humidity ANS: D Temperature, contact time, and biofilms all play a role in selection and implementation of the appropriate method of disinfection. Humidity is not important when attempting to disinfect or kill organisms. REF: pages 62-63 OBJ: Level 1 – Recall 6. When eliminating organisms from inanimate objects, higher numbers of organisms require longer exposure times because: a. All disinfecting agents are not alike and some require shorter times. b. The chemical composition of the disinfecting agent varies. c. Disinfecting agents containing carbon tetrachloride require longer times to act. d. It takes longer to eliminate 99% of microorganisms. ANS: D When there are higher numbers of microorganisms, it takes longer to kill 99% of microorganisms present. Although disinfectants are different, it still takes longer to kill more organisms. The chemical composition of a disinfecting agent may affect the time required to kill microorganisms, but microbial load is a determining factor. REF: page 63 OBJ: Level 1 – Recall 7. When using disinfectants, it is important to follow the manufacturer’s instructions for diluting the product because if it is not diluted properly: a. There may not be enough free chemicals to kill the organisms. b. You would be wasting money by using too much disinfectant. c. The resulting solution would not kill mycobacteria. d. The resulting solution would not kill parasites. ANS: A The manufacturer tests disinfectants at a particular dilution, and this is the dilution needed for optimum performance of the disinfectant. If the manufacturer’s instructions are not followed, optimum effectiveness cannot be guaranteed. REF: page 63 OBJ: Level 1 – Recall 8. If this is present on a surface to be disinfected, it can shield microorganisms from the disinfectant or inactivate the disinfectant. What is this substance? a. Bleach (sodium hypochlorite) b. Organic material c. Hydrochloric acid d. Water ANS: B Bleach, hydrochloric acid, and water can counteract another disinfectant, but they cannot shield microorganisms from a disinfectant. Organic matter (e.g., blood, pus) can keep the disinfectant from reaching and killing the microorganism. REF: page 64 OBJ: Level 1 – Recall 9. When killing microorganisms, you must take all the following into consideration EXCEPT: a. A type of microorganism b. Temperature c. Humidity d. Bioburden ANS: C The type of microorganism (bacteria, mycobacteria, parasite, etc.), the temperature, and the bioburden (the number of bacteria) must be taken into consideration when decided how to best kill microorganisms. The humidity plays no role in the killing of microorganisms. REF: page 64 OBJ: Level 1 – Recall 10. Disinfectants are usually used at this temperature. a. 50° to 100° C b. 0° to 10° C c. 25° to 50° C d. 20° to 22° C ANS: D Disinfectants are usually used at room temperature (20° to 22° C). Too high or too low a temperature can actually inactivate a disinfectant. REF: page 64 OBJ: Level 1 – Recall 11. Using two disinfectants to clean an area may actually do more harm than good. Why? a. Two disinfectants may increase the amount of corrosion that occurs on a surface. b. Two disinfectants may cause an adverse chemical reaction where a poisonous gas may be released. c. When used together, two disinfectants may combine to sterilize a site instead of just disinfecting it. d. Two disinfectants may inactivate one another’s activity against microorganisms. ANS: D In many disinfectants, free ions are responsible for the killing activity of the solution. If two solutions are mixed and one binds the free ions in the other solution, the microbial killing ability terminates. REF: page 64 OBJ: Level 2 – Interpretation 12. Pasteurization achieves _____. a. Disinfection b. Sterilization c. Asepsis d. Filtration ANS: A Pasteurization kills foodborne pathogens, but not microbial spores present in a liquid. Because sterilization is killing of all microorganisms plus spores and cysts, pasteurization only disinfects. Asepsis describes no bacteria present. Filtration describes another method of disinfection where microorganisms are removed from a liquid by a physical device—a filter. REF: page 65 OBJ: Level 1 – Recall 13. Autoclaves use this method to sterilize inanimate objects. a. Dry heat b. Heat under steam pressure c. Microwaves d. Infrared light rays ANS: B Putting steam under 1 atmosphere of pressure achieves a temperature of 121° C. This temperature and this pressure will kill all microorganisms except prions. Dry heat will not kill spores or cysts. Microwaves and infrared light rays are not used for sterilization or disinfecting objects. REF: page 65 OBJ: Level 1 – Recall 14. Chemosterilizers exert their killing effect through all the following mechanisms EXCEPT: a. Denaturation of cellular proteins b. Damage of RNA and DNA c. Inactivating enzyme substrates d. Reactions with components of the cytoplasmic membrane ANS: C If a chemical can denature proteins that are used by the cell, damage RNA or DNA, or react with components of the cell membrane, they can damage the cell. Inactivating an enzyme substrate may or may not have an effect on cellular function. REF: page 66 OBJ: Level 1 – Recall 15. Alcohols use this mechanism to inactivate microorganisms. a. Denature proteins b. Destroy DNA c. Denature RNA d. Inhibit cell wall synthesis ANS: A Alcohols do not have the capability to destroy DNA, denature RNA, or inhibit cell wall synthesis. Instead, they disrupt the tertiary and quaternary structure of the cell wall proteins to destroy microorganisms. REF: page 67 OBJ: Level 1 – Recall 16. A laboratory technician is working with tissue infected with Mycobacterium tuberculosis that has been preserved in formalin for a couple years. After dissecting the tissue, how should the worker sterilize the work area? a. Wipe down the work area with a 37% formalin solution. b. Wipe down the work area with a 10% bleach solution. c. Wipe down the work area with a 50% alcohol solution. d. Use formaldehyde gas to clean the area. ANS: B 1. tuberculosis can survive for years in formalized specimens. A powerful sterilizer is needed to sterilize this area, and that is 10% bleach. Alcohol is not a sterilizer but rather an antiseptic. Formaldehyde gas is used to disinfect biosafety hoods, but it is not a sterilizer. REF: pages 67-68 OBJ: Level 3 – Synthesis 17. The tech needs to sterilize a piece of equipment that cannot be autoclaved or gas sterilized because the equipment contains lenses, metal, and rubber components. What solution should be used to sterilize this piece of equipment? a. 10% bleach b. 37% formalin c. Glutaraldehyde d. 90% alcohol ANS: C 10% bleach cannot be used because it is a corrosive and can corrode metal; 37% formalin cannot be used because it is a carcinogen, and the Occupational Safety and Health Administration (OSHA) does not recommend it for routine sterilizing or disinfecting; 90% alcohol can be corrosive, but it is also inactivated with any organic material that may be present on the instrument. Glutaraldehyde is the sterilant of choice because it is not inactivated by organic material, and it can kill both microbes and spores, depending on contact time. REF: page 67 OBJ: Level 1 – Recall 18. For the most effective microbial killing, all iodophors must be properly diluted because: a. They stain the skin if too concentrated. b. This decreases contact time for adequate killing. c. There must be enough free iodine to kill the microorganisms. d. This increases contact time for adequate killing. ANS: C When iodophors are used as skin preparations, contact time is essential for killing microorganisms. Contact time does not depend on dilution. Iodophors are considered nonstaining. The reason for diluting iodophors properly is that the dilution ratio is important to ensure there is enough free iodine to kill microorganisms. REF: page 68 OBJ: Level 1 – Recall 19. Even though hypochlorites are inexpensive and have a broad range of microbes that they kill, they are not used as sterilants because of: a. The corrosive nature of the compound b. The activation required by organic matter c. Short exposure time for sporicidal action d. Long exposure time for sporicidal action ANS: D Hypochlorites require a long exposure time to kill spores, and they are inactivated by organic material present on an object. They are not used as a disinfectant because they are corrosive. REF: page 68 OBJ: Level 1 – Recall 20. Disinfectants containing heavy metal compounds have been replaced as disinfectants, except for _____, which is still used as a prophylactic treatment in newborns to prevent gonococcal conjunctivitis. a. Silver nitrate b. Copper sulfate c. Ammonium nitrate d. Mercuric chloride ANS: A Mercuric chloride is a preservative used in parasitology. Copper sulfate is used to estimate the amount of hemoglobin in a drop of blood. Ammonium nitrate is used as a component of gunpowder. Silver nitrate is indeed used to swab the eyes of newborns to protect them from gonococcal conjunctivitis. REF: page 69 OBJ: Level 1 – Recall 21. Many materials in hospitals that must be sterilized cannot withstand steam sterilization. Gas sterilization is used instead, using this gas. a. Nitrous oxide b. Oxygen c. Ethylene oxide d. Carbon dioxide ANS: C Nitrous oxide, oxygen, and carbon dioxide are all gases, but they do not kill microbes or their spores. Ethylene oxide is usually mixed with nitrogen or carbon dioxide before use because it is explosive in its pure form. It is used in hospitals and in the manufacturing industry for sterilizing thermoplastic products. REF: page 70 OBJ: Level 1 – Recall 22. Why should health care workers wash their hands after coming into contact with a patient? a. To reduce the amount of red blood cells transmitted from one patient to the next b. To reduce the occurrence of hemolytic transfusion reactions c. To reduce the need for antiseptics and disinfectants d. To reduce the spread of pathogenic bacteria from one individual to another ANS: D Any pathogenic bacteria present on the hands of one individual will be passed on to the next individual unless the hands are washed to remove the pathogens. Hands visibly contaminated with red blood cells are always washed after becoming soiled. Hemolytic transfusion reactions are caused by the intravenous administration of red blood cells. Antiseptics and disinfectants will always be needed to cleanse skin and inanimate objects to free them of pathogenic bacteria. REF: page 71 OBJ: Level 1 – Recall 23. High-level disinfectants are active against all the following EXCEPT: a. Parasites b. Spores c. Fungi d. Tubercle bacilli ANS: A High-level disinfectants are active against vegetative cells, tubercle bacilli, spores, fungi, and viruses. These disinfectants have no activity against parasites. REF: page 64 OBJ: Level 1 – Recall 24. This agency regulates the use, sale, and distribution of antimicrobial pesticide products for certain inanimate, hard, nonporous surfaces, or incorporated into substances under the pesticide law. a. Antimicrobial Division of Environmental Protection Agency (EPA) b. Centers for Disease Control and Prevention (CDC) c. U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID) d. U.S. Food and Drug Administration (FDA) ANS: A The CDC acts as a clearinghouse for information of medically important bacteria and houses one of two Biosafety Level 4 laboratories. The other Biosafety Level 4 laboratory is found at the Army infectious disease research facility, USAMRIID. The FDA regulates substances that are put into the body. The Antimicrobial Division of the EPA regulates the use of antimicrobials on inanimate, nonporous surfaces. REF: page 70 OBJ: Level 1 – Recall 25. The disinfectant label should indicate several highlighted points important in selecting the appropriate agents for designated use, including all the following EXCEPT: a. Level of biocidal action b. Alcohol content c. The nature of microbial contamination d. Structure and design of an item to be disinfected ANS: B The label of a disinfectant should include the structure and design of an item, active ingredient of chemical, pH, hardness of water, exposure time, extent of precleaning, biocidal action, nature of microbial contamination, requirements of chemical agents, kill time, composition of items to be disinfected, and method of application. REF: pages 70-71 OBJ: Level 2 – Interpretation 26. These two alcohols are effective in killing hepatitis B virus (HBV). a. 50% isopropyl and 50% butanol b. 95% propanol and 70% ethanol c. 70% isopropyl and 95% ethanol d. 70% pentanol and 70% isopropyl ANS: C The only two alcohols used in U.S. hospitals that kill HBV are 70% isopropyl and 95% ethanol. REF: page 67 OBJ: Level 1 – Recall 27. This chemical is a saturated 5-carbon dialdehyde that has broad-spectrum activity, rapid killing action, and remains active in the presence of organic matter. a. Formalin b. Formaldehyde c. Haloaldehyde d. Glutaraldehyde ANS: D Formalin is designated as a carcinogen by the Occupational Safety and Health Administration (OSHA), and worker exposure limits have been set. These adverse effects limit its usefulness. Formaldehyde is a gas that is usually known as formalin. Haloaldehyde is not used as a disinfectant. Glutaraldehyde is a good killing agent because it has broad-spectrum activity, rapid killing action, remains active in the presence of organic matter, and can be used on sensitive equipment. REF: page 67 OBJ: Level 2 – Interpretation 28. These disinfectants are cationic, surface-activated agents that work by reducing the surface tension of molecules in a liquid, resulting in the disruption of