TESTBANK DIAGNOSTIC MICROBIOLOGY 4TH EDITION

TEXTBOOK OF DIAGNOSTIC MICROBIOLOGY 4TH EDITION TEST BANK Textbook of Diagnostic Microbiology 4th Edition Test Bank Textbook of Diagnostic Microbiology 4th Edition Test Bank To Purchase this Complete Test Bank with Answers Click the link Below nucleic acid. Bacteria and parasites are complete organisms that are killed by disinfection and sterilization, even in the spore and cyst stages. c. Bacteriostatic d. Bactericidal 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 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: 2. page 62 OBJ: Level 1 – Recall Organisms that are the most resistant to heat, chemicals, and radiation are: a. Parasites b. Prions c. Bacteria REF: d. Viruses 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 ANS: B b. Sterilizer 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 page 62 OBJ: Level 2 – Interpretation 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. b. Bacteriostatic c. Disinfection d. Bactericidalc. Antiseptic REF: d. Bactericidal 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. 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: ANS: D a. Temperature b. Contact time c. Biofilms REF: d. Humidity 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. 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. b. You would be wasting money by using too much disinfectant. c. The resulting solution would not kill mycobacteria. page 63 OBJ: 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. Level 1 – Recall 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. pages 62-63 OBJ: Level 1 – RecallREF: 9. d. The resulting solution would not kill parasites. a. A type of microorganism b. Temperature 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 REF: c. Hydrochloric acid 10. d. Water Disinfectants are usually used at this temperature. a. 50° to 100° C b. 0° to 10° C 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. c. 25° to 50° C d. 20° to 22° C page 64 OBJ: Level 1 – Recall c. Humidity d. Bioburden page 64 OBJ: Level 1 – Recall When killing microorganisms, you must take all the following into consideration EXCEPT: 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.b. Sterilization ANS: D c. Asepsis Disinfectants are usually used at room temperature (20° to 22° C). Too high or too low a temperature can actually inactivate a disinfectant. d. Filtration REF: 11. page 64 OBJ: Level 1 – Recall Using two disinfectants to clean an area may actually do more harm than good. Why? ANS: A 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. 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: 13. page 65 OBJ: Level 1 – Recall Autoclaves use this method to sterilize inanimate objects. a. Dry heat 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: 12. page 64 OBJ: Level 2 – Interpretation Pasteurization achieves _____. a. Disinfection ANS: B b. Heat under steam pressure c. Microwaves d. Infrared light raysPutting 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. c. Denature RNA d. REF: 14. page 65 OBJ: Level 1 – Recall 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 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. 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: 15. page 66 OBJ: Level 1 – Recall d. Use formaldehyde gas to clean the area. Alcohols use this mechanism to inactivate microorganisms. a. Denature proteins ANS: B b. Destroy DNA 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. b. Wipe down the work area with a 10% bleach solution. c. Wipe down the work area with a 50% alcohol solution. 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 Inhibit cell wall synthesisREF: 17. pages 67-68 OBJ: Level 3 – Synthesis c. There must be enough free iodine to kill the microorganisms. d. This increases contact time for adequate killing. 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 ANS: C b. 37% formalin c. Glutaraldehyde d. 90% alcohol 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. 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: 18. page 67 OBJ: Level 1 – Recall For the most effective microbial killing, all iodophors must be properly diluted because: a. They stain the skin if too concentrated. ANS: D b. This decreases contact time for adequate killing. 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. 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 actionREF: 20. page 68 OBJ: Level 1 – Recall d. Carbon dioxide 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 REF: d. Mercuric chloride 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 ANS: A b. To reduce the occurrence of hemolytic transfusion reactions 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. ANS: D a. Nitrous oxide b. Oxygen c. Ethylene oxide REF: page 71 OBJ: Level 1 – Recall 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. c. To reduce the need for antiseptics and disinfectants d. To reduce the spread of pathogenic bacteria from one individual to another page 70 OBJ: Level 1 – Recall 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.