TEST BANK FOR DIAGNOSTIC MICROBIOLOGY 4TH EDITION 61 PAGES

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 M ULTIPLE 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...

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