Textbook of Diagnostic Microbiology 4th Edition Test Bank

Textbook of Diagnostic Microbiology 4th Edition Test Bank Sample Test 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 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 the cellular membrane of microbes. a. Quaternary ammonium compounds b. Heavy metals c. Chlorines d. Iodophors ANS: A Heavy metals are bacteriostatic. The mechanism by which chlorines kill microorganisms is the oxidative effects of hypochlorous acid. Iodophors kill through the action of periodic acid. Quaternary ammonium compounds are disinfectants that are cationic, surface-activated agents that disrupt the cellular membrane of microbes. REF: page 68 OBJ: Level 2 – Interpretation 29. This organization regulates chemical skin antiseptics. a. Environmental Protection Agency (EPA) b. Food and Drug Administration (FDA) c. Centers for Disease Control and Prevention (CDC) d. National Institutes of Health (NIH) ANS: B The Antimicrobial Division of the EPA regulates disinfectants. The CDC is the nation’s clearinghouse on infectious diseases. The NIH is a conglomerate of special federal agencies that award research grants to further knowledge in a particular area. The FDA regulates chemical skin antiseptics. REF: page 70 OBJ: Level 1 – Recall 30. The main goal of handwashing is to: a. Sterilize a person’s hand. b. Increase the risk of passing on pathogens. c. Eliminate transient florae. d. Disinfect a person’s hands. ANS: C A person’s hands are never sterile; therefore, the best handwashing scenario would be to cleanse the hands of transient florae. Sterilizing someone’s hands would also strip the hands of essential oils that would contribute to drying and cracking of the skin. Washing would eliminate most pathogens, thereby decreasing, not increasing, a person’s ability to transmit pathogens. Disinfection occurs when microorganisms are killed on inanimate objects. REF: page 71 OBJ: Level 1 – Recall 31. Routine handwashing in health care settings mandates washing at all the following times EXCEPT: a. In high-risk areas such as ICU and burn units b. On entering protective isolation units c. Before and after routine patient contact d. When gloves become soiled during a procedure or dressing change on the same patient. ANS: D Soiled gloves are changed during a procedure or dressing change on a single patient, but the hands are not washed until contact with that patient terminates. REF: page 71 OBJ: Level 1 – Recall 32. The purpose of surgical hand scrubs and waterless hand rubs is to: a. Eliminate the transient florae and most of the resident florae on the skin. b. Remove all physical dirt and some residential florae. c. Remove all resident florae. d. Remove all transient florae. ANS: A Surgical scrubs try to eliminate as much bacteria from the surgeon’s hand as possible. In case the surgeon’s glove is torn or punctured, very little bacteria will enter the surgical wound. So as much transient and resident florae as possible must be removed by the surgical hand scrubs and waterless hand rubs. REF: page 72 OBJ: Level 1 – Recall 33. The three types of alcohol used as an effective skin antiseptic include all the following EXCEPT: a. 60% to 95% ethanol b. Butyl alcohol c. 50% to 91.3% isopropyl alcohol d. n-Propyl alcohol ANS: B Federal regulations identify 60% to 95% ethanol and 50% to 91.3% isopropyl for use in the United States as an effective skin antiseptic. Europeans use n-propyl alcohol as a skin antiseptic. Butyl alcohol is not approved for use as a skin antiseptic. REF: page 72 OBJ: Level 1 – Recall 34. The most concentrated forms of ethanol and isopropyl alcohol are less bactericidal than the diluted forms of these alcohols. Why? a. No free radicals are present in solution to kill the bacteria. b. Only the dilutions can dissolve the lipopolysaccharide cell walls. c. Proteins are not denatured readily in the absence of water. d. Killing bacteria also requires the solution be heated, and it is difficult to heat concentrated alcohols because flammable. ANS: C Alcohols do not contain free radicals; their bacteriocidal action is based on denaturing proteins. Concentrated alcohols can dissolve the lipopolysaccharide cell wall, but killing the bacteria still relies on protein denaturation. These solutions do not have to be heated to exert their bactericidal effect. REF: page 67 OBJ: Level 2 – Interpretation 35. The most common iodophor used in the United States for preoperative skin preparation is: a. Calcium iodophor b. 95% ethanol and iodine c. Tincture of iodine d. Povidone iodine ANS: D Povidone iodine contains a low amount of free molecular iodine, reducing toxic effects, staining, and irritation. It also provides slow and continuous release of iodine. Tincture of iodine is not used as frequently. Ca iodophor and 95% ethanol and iodine are not used for preoperative surgical skin preparation. REF: page 68 OBJ: Level 1 – Recall 36. This topical antiseptic disrupts the microbial cell membrane and precipitates the cellular contents. a. Chlorhexidine gluconate b. Povidone-iodine c. 95% ethanol d. 60% isopropyl alcohol ANS: A Povidone iodine uses hypoiodonic acid and free iodine to disrupt the cell and eventually kill it. The bactericidal mechanism for alcohols is denaturing proteins. The bactericidal mechanism for chlorhexidine gluconate is to disrupt the microbial cell membrane and precipitate the cellular contents. REF: page 69 OBJ: Level 2 – Interpretation 37. This compound is a diphenyl ether, and it exerts its bactericidal effects by disrupting the cell wall. It has good activity against gram-positive cocci, but poor activity against fungi. What is its name? a. 95% ethanol b. Triclosan c. Chlorhexidine gluconate d. Povidone iodine ANS: B 95% Ethanol denatures the cellular proteins. Chlorhexidine gluconate disrupts the cellular membrane and spills the cell’s contents. Povidone iodine kills the bacteria with free iodine and hypoiodonic acid. Finally, Triclosan is a diphenyl ether, and it exerts its bactericidal effects by disrupting the cell wall. REF: page 69 OBJ: Level 2 – Interpretation 38. Laboratory safety includes all the following areas EXCEPT: a. Radioactivity b. Chemical c. Isolation d. Fire ANS: C Isolation safety and precautions are usually practiced in conjunction with the patient on the floor or outpatient setting. In the laboratory, there are few patients, so safety focuses on areas like radioactivity, chemical safety, and fire safety. REF: page 75 OBJ: Level 1 – Recall 39. Why is laboratory-acquired infection an obvious hazard for personnel working in a microbiology lab? a. Microbiology personnel do not always adhere to safety practices. b. Safety practices are not applicable for the microbiology laboratory. c. In-service education is not provided for microbiology staff. d. Personnel deal with a variety of infections agents: viral, fungal, parasitic, and bacterial. ANS: D All specimens handled by laboratory techs are considered to be potentially infectious. Therefore if a person is careless, a laboratory-acquired infection can occur. Microbiology personnel should follow safety procedures for their own safety. Safety procedures do apply to the microbiology laboratory, and training is provided to each employee. REF: page 77 OBJ: Level 1 – Recall 40. The comprehensive safety program for the microbiology laboratory needs to fulfill all the following provision EXCEPT: a. It is specific to the hospital and does not need to conform to state, local, and federal regulations. b. It must address biologic hazards. c. It must teach correct techniques for lifting and moving heavy objects and patients (where applicable). d. It must describe the safe handling, storage, and disposal of chemicals. ANS: A The safety program must comply with federal and state regulations, hospital procedures, and good laboratory practice. It needs to address all safety hazards (fire, chemical, radiologic, and biologic) and be uniformly applied. Procedures need to be written, and employees need to take responsibility for keeping their workplace safe. REF: page 75 OBJ: Level 1 – Recall 41. Processing of patient specimens and handling of actively growing cultures of microorganisms puts an employee at risk of potential contact with the infectious agent through all the following routes EXCEPT: a. Mucous membranes b. Blood splashed onto intact skin c. Inhalation of aerosols d. Accidental ingestion ANS: B When working with specimens and culture plates, there is little chance of contracting an infection if blood is splashed onto intact skin. Infection—through the mucous membranes by rubbing eyes with contaminated hands, from inhaling aerosolized microorganisms, or by accidental ingestion—is possible when handling specimens and actively growing culture plates. REF: page 78 OBJ: Level 1 – Recall 42. All of the following organisms can typically cause infection from aerosolization of specimens EXCEPT: a. Mycobacterium tuberculosis b. Brucella spp. c. Staphylococcus aureus d. Francisella tularensis ANS: C Many reported cases of laboratory workers being infected with M. tuberculosis after being exposed to aerosols when processing sputum specimens fill the literature. Brucella and F. tularensis are very infectious organisms and several cases a year are reported of laboratory workers who contract the disease after processing culture specimens. Cases of S. aureus infection of laboratory workers occur often, but not usually through aerosol inhalation. REF: page 76 OBJ: Level 1 – Recall 43. The most common route of infection of laboratory workers with hepatitis B virus (HBV) and human immunodeficiency virus (HIV) is: a. Mucous membranes b. Inhalation c. Ingestion d. Needlestick ANS: D HBV and HIV are blood-borne pathogens that are transmitted through exposure to blood and body fluids. Although infection through the mucous membranes has occurred, the most common route of infection of health care workers is through needlesticks where the organisms are introduced into the bloodstream. REF: page 76 OBJ: Level 1 – Recall 44. What protective measures can a laboratory worker take when working with actively growing cultures to ensure that they do not become infected? a. Ensure that fungal cultures are sealed and worked in a biosafety cabinet. b. Wash their hands at the end of their shift. c. Handle specimens routinely, using extra care for HIV and HBV cultures. d. Take off bandages on fingers when reading plates. ANS: A Fungal cultures produce many infectious spores that can disseminate rapidly via the ventilation system if a plate is opened on the bench in a laboratory. These cultures should always be handled in a biosafety cabinet. Bench techs should wash their hands frequently to ensure the number of pathogenic microorganisms on their hands is always low. All specimens should be handled as though they are HBV and HIV positive—with extreme care. Cuts on the hand should always be covered by finger cots or gloves. REF: page 78 OBJ: Level 1 – Recall 45. The laboratory exposure control plan should contain all the following EXCEPT: a. Engineer and work practice controls b. Review of control plan every 5 years c. Methods of compliance for Standard Precautions d. Guidelines for handling and disposal of regulated waste ANS: B The exposure control plan is mandated by the Occupational Safety and Health Administration (OSHA) to protect workers against blood-borne pathogens. This plan must be reviewed and updated annually. It must contain a determination of tasks and procedures that may result in an occupational hazard, a plan to investigate all exposure incidents and a plan to prevent these from reoccurring, methods of compliance for Standard Precautions, engineering and work practice controls, personal protective equipment, guidelines for ensuring that the work site is maintained in a clean and sanitary manner, guidelines for handling and disposal of regulated waste, and a training program for all employees (OSHA Bloodborne Standards). REF: page 75 OBJ: Level 1 – Recall 46. Universal/Standard Precautions require that: a. Only some body fluids be considered infectious and capable of transmitting disease b. Body fluids with visible blood be treated as noninfectious c. Blood and body fluids from all patients be considered infectious and capable of transmitting disease d. Urine and feces be considered noninfectious ANS: C Anything that comes from a patient is capable of transmitting disease. Blood and all body fluids, including secretions and excretions, except sweat, regardless of whether visible blood is present, are considered infectious. REF: pages 75-76 OBJ: Level 1 – Recall 47. Engineering controls and work practice controls to ensure Standard Precautions are followed include all the following EXCEPT: a. Eyewash stations b. The use of safety needles c. Plastic shield barriers d. Fire blankets ANS: D The Occupational Safety and Health Administration (OSHA) defines engineering controls as controls that isolate or remove the hazard from the workplace. Some examples of engineering controls are the use of closed tube sampling by laboratory equipment, the use of safety needles and single-use holders, eyewash stations, emergency showers, and plastic shield barriers. Ideally laboratories should have negative air pressure, access to the laboratory should be limited, and there should be a plan to prevent insect infestation. REF: page 76 OBJ: Level 1 – Recall 48. Standard Precautions do not address the following: a. Handwashing b. Gloves c. Lab coats d. Respirators ANS: D To ensure the guidelines required in Standard Precautions are followed within the laboratory, engineering controls and work practice controls are instituted, and employers must provide personal protective equipment. Respirators are not included in the items addressed by Standard Precautions because they are used in a Biosafety Level 3 laboratory. REF: page 75 OBJ: Level 1 – Recall 49. Work Practice Controls consist of all of the following EXCEPT: a. Ensuring written procedures are in place for a task b. Altering the manner in which a task is performed to reduce exposure to infectious agents c. Allowing workers to eat at the bench if it gets busy and they don’t have time to take a lunch break d. Reviewing the procedure manual annually ANS: C Work practice controls consist of altering the manner in which a task is performed to reduce the likelihood of exposure to infectious agents. This is accomplished by no mouth pipetting; no eating, drinking, or applying cosmetics in the laboratory; disinfecting workstations at the end of each shift and after any spill of infectious material; no recapping or breaking of contaminated needles; disposal of needles in an appropriate puncture-resistant container; performing procedures in a manner to minimize splashing and the generation of air droplets; placing specimens for transport in well- constructed containers with secure lids to prevent leakage of infectious materials; and frequent handwashing. REF: page 76 OBJ: Level 1 – Recall 50. All of the following are examples of personal protective equipment (PPE) EXCEPT: a. Gloves b. Lab coats c. Safety glasses d. Prescription glasses ANS: D PPE must be protective and appropriate. Blood and body fluids must not be able to penetrate the PPE material. Prescription glasses are not considered PPE because splashes of blood and body fluids can get to the eye by coming in around the sides, top, and bottom of the glasses. Safety glasses form a barrier where body fluids cannot come in around the sides, top, or bottom. REF: page 76 OBJ: Level 1 – Recall 51. Technicians are doing the morning chemistry run. Once they load the specimens onto the instrument, they remove their gloves to do paperwork in a clean area of the laboratory. What should the technicians do after removing their gloves? a. Reposition the tubes in the racks. b. Take a break and eat a snack. c. Call any critical values. d. Wash their hands. ANS: D As soon as the gloves come off, the technicians must wash their hands to ensure that all potential pathogens are removed before the technicians touch inanimate objects in the clean area of the laboratory. REF: page 76 OBJ: Level 3 – Synthesis 52. The Biosafety Levels were categorized using all the following criteria EXCEPT: a. The bacterial load necessary to cause infection b. The organism’s ability to cause serious illness c. The organism’s mode of transmission d. Whether there is treatment available for an infection ANS: A The four Biosafety Levels were derived from categories of etiologic agents. These categories include the organism’s ability to cause serious illness, the organism’s mode of transmission, whether there is treatment available for infection, and whether there are any preventive measures, such as vaccines. Bacterial load was not a criterion. REF: page 78 OBJ: Level 1 – Recall 53. A Biosafety Level 1 (BSL-1) level of containment is used for organisms that: a. Cause 90% mortality of infected people b. Are well classified and not known to cause disease in healthy people c. Cause 90% morbidity of infected people d. Can be transmitted through aerosols ANS: B This is the lowest level of biosafety. These organisms pose a minimal threat to laboratory personnel and the environment. Lab work can be conducted on open bench tops. Employees should be trained in laboratory procedures and supervised by a scientist with training in microbiology. REF: page 79 OBJ: Level 1 – Recall 54. A Biosafety Level 2 (BSL-2) level of containment is used for organisms that: a. Can cause a catastrophe if released b. Usually cause 90% mortality in the population c. Create a moderate potential hazard for employees and the environment d. Do not cause significant harm to employees and the environment ANS: C These organisms pose a moderate hazard. Guidelines for laboratories that handle these agents include having a biosafety cabinet, limiting access to the laboratory when cultures are out, having employees receive immunizations for contact with possible pathogens, having an up-to-date biosafety manual, wearing personal protective equipment (PPE), and restricting use of sharp items to times when no alternative equipment can be used. REF: page 80 OBJ: Level 1 – Recall 55. Because Biosafety Level 3 (BSL-3) organisms have the potential for aerosol transmission, and diseases with these agents may have serious lethal consequences, all of the following guidelines apply to BSL-3 labs EXCEPT: a. BSL-3 labs should be separated from other parts of the building by an anteroom. b. BSL-3 labs should have restricted access with logbook documentation of personnel entering and exiting lab. c. BSL-3 labs should have solid ceiling and floor seams, and any seams must be sealed. d. BSL-3 labs should have positive air pressure. ANS: D BSL-3 labs must follow BSL-2 safety guidelines and must also have a Class II or III biologic safety cabinet; must ensure that employees wear appropriate personal protective equipment (PPE); should be separated from the other parts of the building by an anteroom; should have negative air pressure and the air from inside the lab should be directed outside without recirculation; should have ceilings and floors that are solid and any seams sealed; and must be constructed so that all parts of the lab can be easily cleaned and disinfected. BSL-4 labs should have restricted access. REF: page 80 OBJ: Level 1 – Recall 56. Biosafety Level 4 (BSL-4) organisms are dangerous, exotic, and pose an increased risk of aerosol-transmitted infections and life-threatening disease. Two examples of BSL-4 organisms are: a. Smallpox and Ebola b. St. Louis encephalitis virus and Coccidioides immitis c. Mycobacterium tuberculosis and Ebola d. Francisella tularensis and Ebola ANS: A St. Louis encephalitis virus, M. tuberculosis, and F. tularensis are all BSL-3 organisms. The only two BSL-4 organisms are smallpox and Ebola. REF: pages 80-81 OBJ: Level 1 – Recall 57. The Clinical Laboratory Standards Institute (CLSI) defines hazardous waste as: a. Those wastes that present an aerosol, infectious, or sharps danger to laboratory and hospital personnel b. Those substances that singly or in combination pose a significant present or potential threat or hazard to hu health c. Exotic and indigenous microorganisms and chemicals that present an infectious, explosive, corrosive, or irrit d. All the following classes of substances: microorganisms, toxic chemicals, electricity, fire, and blood-borne pa ANS: B All answers except answer b are incomplete. Answer b is the definition provided in the standard. REF: page 81 OBJ: Level 1 – Recall 58. The Occupational Safety and Health Administration (OSHA) requires laboratories to have this document to ensure that laboratory personnel have a thorough working knowledge of the hazards of the chemicals with which they work. a. Chemical Control Plan b. Standard Operating Procedures c. Chemical Hygiene Plan d. OSHA Compliance Plan ANS: C OSHA regulations require that employees compile a chemical hygiene plan that details the hazards of the chemicals used in the workplace. This plan must also contain a provision for hazardous communication training. REF: page 82 OBJ: Level 1 – Recall 59. A Material Safety Data Sheet (MSDS) contains all the following information EXCEPT: a. The nature of a chemical (flammable, toxic, carcinogen) b. General characteristics c. Precautions when using a chemical d. Classification of a chemical (acid, base, protein) ANS: D MSDSs document the nature of a chemical (flammable, toxic, carcinogen), general characteristics, precautions to take in using a chemical, emergency information, spill cleanup procedure, and disposal recommendations. REF: page 83 OBJ: Level 1 – Recall 60. If a laboratory uses hazardous chemicals, it must: a. Keep a chemical inventory and Material Safety Data Sheets (MSDSs) on hand. b. Keep chemicals in a special corrosive cabinet. c. Keep chemicals in a special locking cabinet. d. Post chemical names and locations on the door of the laboratory. ANS: A A lab must maintain a current inventory of hazardous chemicals, and the MSDSs for those particular chemicals according to 29 CFR Part 1910, Subpart2, Toxic and Hazardous Substances (OSHA). REF: page 83 OBJ: Level 1 – Recall 61. Laboratory Safety for Hazardous Chemicals includes: a. Restricting use of these chemicals to specific individuals b. Using fume hoods to prevent inhalation of fumes c. Locking chemicals in one specific “corrosives” cabinet d. Providing biohazard training to affected individuals ANS: B Lab safety for hazardous chemicals includes using fume hoods to prevent inhalation of fumes, personal protective devices (fume masks, gloves, aprons, and eyewear), acid and flammable spill kits, and warning signs in appropriate places announcing the hazardous chemical. REF: page 83 OBJ: Level 1 – Recall 62. Most institutions use the RACE acronym to respond to a fire emergency. RACE stands for a. Race, Alert, Cite, Evacuate b. Run, Avoid, Call, Emergency c. Rescue, Alarm, Contain, Extinguish d. Retrieve, Announce, Close, Exit ANS: C RACE stands for Rescue (remove anyone who is in danger), Alarm (know where the nearest fire pull box or alarm station is located and know the number to call to report the fire), Contain (close doors to contain fire and smoke), and Extinguish (use the properly rated fire extinguisher on small fires). REF: page 83 OBJ: Level 1 – Recall 63. To ensure the electrical safety of laboratory personnel, the College of American Pathologists (CAP) requires these checks annually. a. Leakage and AC check b. Electrical cords and cycle check c. Grounding and cycle check d. Electrical grounding and leakage checks ANS: D CAP requires electrical grounding and leakage checks annually. It is also recommended that you check all electrical cords for fraying and grounded plugs. REF: page 89 OBJ: Level 1 – Recall 64. The best way to care for your back is to prevent back injuries. All of the following are some ways to prevent back injuries EXCEPT: a. Carefully lifting heavy objects overhead b. Using good posture c. Using the legs to lift, not the back d. Asking for assistance when a load is too heavy ANS: A Carrying heavy trays of culture plates, lifting heavy loads in and out of autoclaves, and sitting or standing improperly can all contribute to back stress injuries. Using good posture, using the legs to lift (not the back), asking for assistance when a load is too heavy, and staying physically fit all help prevent back injuries. REF: page 89 OBJ: Level 1 – Recall 65. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) requires the following safety training to be documented in an employee’s record EXCEPT: a. Proper storage of gases b. Biosafety level training c. Blood-borne pathogen training d. Hazardous materials management ANS: B Biosafety level training is not required by JCAHO because this training is laboratory specific. The remaining training applies to all employees in a hospital. REF: page 89 OBJ: Level 1 – Recall 66. Three levels of laboratories outlined in the Laboratory Response Network (LRN) include all the following EXCEPT: a. Sentinel b. Reference c. First responder d. National responder ANS: C The Centers for Disease Control and Prevention (CDC) developed the LRN in 1999 so that laboratories could respond quickly and effectively to a bioterrorism event. The three levels of laboratories contained in this document include sentinel, reference, and national responder. REF: page 90 OBJ: Level 1 – Recall 67. In the Laboratory Response Network (LRN) program, hospital-based microbiology laboratories are classified as this type of laboratory. a. Reference b. National c. Primary d. Sentinel ANS: D There are only 100 reference laboratories in the Unites States and two national laboratories (CDC and the United States Army Medical Research Institute for Infectious Disease [USAMRIID]). The remaining hospital laboratories are designated as sentinel laboratories. REF: page 90 OBJ: Level 1 – Recall 68. Category A bioterrorism agents: a. Pose the highest threat because they are easily transmitted and highly infectious b. Have moderate morbidity and low mortality and are not easily transmitted c. Are emerging pathogens d. Are enteric pathogens ANS: A Category B bioterrorism agents have moderate morbidity and low mortality and are not easily transmitted. Category C bioterrorism agents are emerging pathogens. Enteric pathogens are usually considered gram-negative rods. REF: page 90 OBJ: Level 1 – Recall 69. Once bioterrorism is suspected, a sentinel laboratory should perform all culture manipulation using these safety guidelines. a. BSL-2 b. BSL-3 c. BSL-4 d. BSL-1 ANS: B All manipulations should be handled using Biosafety Level 3 (BSL-3) guidelines, and all work should be done in a Class II or III biologic safety cabinet. As soon as possible after a sample has been identified as a potential bioterrorism agent, it should be referred to the appropriate Laboratory Response Network (LRN) Reference laboratory. REF: page 90 OBJ: Level 1 – Recall Mahon: Textbook of Diagnostic Microbiology, 4th Edition Chapter 07: Microscopic Examination of Infected Materials Test Bank MULTIPLE CHOICE 1. Culture results: a. Confirm the correctness of the therapeutic choices already made and implemented b. Help the physician select an antibiotic for treatment c. Must be confirmed before initiating antibiotic treatment for a patient d. Help confirm the patient’s high white blood count ANS: A In more than 88% of the instances, the physician has a correct idea about the diagnosis after taking a patient’s history and performing a physical examination. The physician is greatly pressured to begin immediate treatment of symptomatic patients. The ability of the laboratory to respond to the physician in a timely manner with useful results is key to keeping the treatment moving in the correct direction or changing the direction of treatment if the physician’s presumptive diagnosis proves incorrect. REF: page 127 OBJ: Level 1 – Recall 2. When using a swab to make a smear: a. It is okay to use the swab after it has been used to inoculate culture media. b. Ensure the swab has not been used to inoculate culture media first. c. Rub the swab back and forth on the glass slide to smear the specimen for easier viewing. d. Dip the swab in thioglycollate broth for easier smearing on the slide. ANS: B Smears should not be prepared from a swab after it has been used to inoculate culture media. Ideally, if the sample can be collected only on swabs, two swabs are submitted. Smears from swabs are prepared by rolling the swab back and forth over the glass slide. The swab should never be rubbed back and forth across the slide, because important material on the opposite side of the swab might not be deposited and smear elements could be broken up. Dipping the swab in the liquid would remove much of the material to be stained. REF: page 127 OBJ: Level 1 – Recall 3. All of the following steps should be used to prepare a smear from thick, granular, or mucoid materials EXCEPT: a. Place a portion of the sample on the labeled slide, and press a second slide onto the sample to flatten or cru components. b. Once the material is flattened and sufficiently thinned, pull the glass slides smoothly away from each other to produce two smears. c. Take an additional swab and rub it back and forth on the two glass slides to ensure the material is thin enou read once it is stained. d. If the material is still too thick, repeat the first three steps with another (third) glass slide. ANS: C Once the material is flattened between the two slides and the glass slide is pulled away to make two smears, you never put a swab on the specimen to spread it out. If it is still too thick, then an additional slide is used to flatten the material out and another pull slide is made. This slide should be adequate to stain and read. REF: page 128 OBJ: Level 1 – Recall 4. When making slides of thin materials such as urine and cerebrospinal fluid (CSF): a. Spread the material once, let the specimen dry, then spread another layer on top to ensure enough specime stain. b. Use the two-slide pull method to ensure evenly distributed material over the slides. c. Dip a swab into the specimen, then roll the swab over the glass slide to ensure adequate coverage for staini d. Mark the area of the sample drop on the reverse side with a wax pencil, then place a drop of the specimen i marked area. ANS: D Thin materials such as urine and CSF are difficult to view on a glass slide. Marking the underneath area with a wax pencil will allow the tech to know exactly where the sample was placed. This may be helpful after staining the specimen. Never spread two layers of a specimen on a slide. A drop on a slide contains enough material to be stained and visualized. The two-slide pull method is for thick specimens, not thin. Never use a swab to apply a specimen when there is enough fluid to be dropped onto a slide. REF: page 128 OBJ: Level 1 – Recall 5. A cytocentrifuge is an excellent method for preparing nonviscous fluids because: a. It deposits cellular elements and microorganisms from the specimen onto the surface of a glass slide as a monolayer. b. It concentrates the protein evenly throughout the slide surface. c. The sediment is mixed with 70% albumin before spreading it on the surface of a slide. d. The cytocentrifuge not only spreads the specimen over the surface of a slide but also stains the specimen. ANS: A The cytocentrifuge is a centrifuge that deposits a uniform layer of the specimen onto a glass slide. It does not concentrate protein, nor does it mix the specimen with 70% albumin. The sediment is fixed and decontaminated in 70% alcohol for 5 minutes. The cytocentrifuge is only a centrifuge—it is not a stainer and does not stain the slide. REF: page 128 OBJ: Level 1 – Recall 6. The purpose of a simple stain is to: a. Color specific components of specific elements. b. Color the forms and shapes present. c. Specifically identify an organism. d. Identify the types of DNA and RNA present in the nucleus of a cell. ANS: B Simple stains identify colors and forms. Differential stains color specific components of those elements present. DNA probe-mediated stains are directed specifically at an organism’s identification. REF: page 129 OBJ: Level 1 – Recall 7. In the microbiology laboratory, this instrument is routinely used to examine smears for structures that are too small to be seen with the unaided eye. a. Cytocentrifuge b. Thermal cycler c. Compound microscope d. Electron microscope ANS: C A cytocentrifuge makes monolayer smears from specimens. A thermal cycler carries out DNA amplification. An electron microscope is a specialized piece of equipment available in some laboratories for viewing special specimens. A compound light microscope is routinely used in the microbiology laboratory for viewing specimens and bacterial colonies. REF: pages 130, 132 OBJ: Level 1 – Recall 8. A tech is working the night shift and receives a CSF specimen on an infant. The tech makes a Gram stain of the spinal fluid then reads the smear under the microscope. The report the tech sends to the physician reads as follows: “gram-negative bacillus, small and pleomorphic.” What bacteria are being implied as the infecting agent? a. Escherichia coli b. Legionella pneumophila c. Staphylococcus aureus d. Haemophilus influenzae ANS: D Microorganisms can be described in such a way that, based on prevalence, the description implies the identification of the organism. A gram-negative bacillus, small and pleomorphic, brings to mind a miscellaneous gram-negative bacillus. Because it is in the spinal fluid of an infant where H. influenzae is known to cause meningitis, the physician would base his or her treatment upon this fact. REF: page 134 OBJ: Level 3 – Synthesis 9. A patient comes to the emergency department with a productive cough, shortness of breath, and a fever of 102° F. The patient is diagnosed with pneumonia. What organism commonly encountered in the microbiology laboratory can cause this disease? a. Streptococcus pneumoniae b. Staphylococcus aureus c. Escherichia coli d. Haemophilus influenzae ANS: A Several common organisms are encountered in the microbiology laboratory. Infections caused by common single species, or by classic infectious agents, include Str. pneumoniae pneumonia, Sta. aureus abscesses or pyodermas, H. influenzae tracheobronchitis or meningitis in infants, Clostridium perfringens gas gangrene, Nocardia spp. lung abscesses, and gonococcal urethritis. REF: page 134 OBJ: Level 3 – Synthesis 10. What is the most common causative agent of urethritis? a. Staphylococcus aureus b. Neisseria gonorrhea c. Clostridium perfringens d. Haemophilus influenzae ANS: B Several common organisms are encountered in the microbiology laboratory. Infections caused by common single species, or by classic infectious agents, include Streptococcus pneumoniae pneumonia, Sta. aureus abscesses or pyodermas, H. influenzae tracheobronchitis or meningitis in infants, C. perfringens gas gangrene, Nocardia spp. lung abscesses, and gonococcal urethritis. REF: page 134 OBJ: Level 2 – Interpretation 11. What is the most common causative agent of gas gangrene? a. Staphylococcus aureus b. Neisseria gonorrhea c. Clostridium perfringens d. Haemophilus influenzae ANS: C Several common organisms are encountered in the microbiology laboratory. Infections caused by common single species, or by classic infectious agents, include Streptococcus pneumoniae pneumonia, Sta. aureus abscesses or pyodermas, H. influenzae tracheobronchitis or meningitis in infants, C. perfringens gas gangrene, Nocardia spp. lung abscesses, and gonococcal urethritis. REF: page 134 OBJ: Level 2 – Interpretation 12. What is the most common causative agent of pyoderma? a. Staphylococcus aureus b. Neisseria gonorrhea c. Clostridium perfringens d. Haemophilus influenzae ANS: A Several common organisms are encountered in the microbiology laboratory. Infections caused by common single species, or by classic infectious agents, include Streptococcus pneumoniae pneumonia, Staphylococcus aureus abscesses or pyodermas, H. influenzae tracheobronchitis or meningitis in infants, C. perfringens gas gangrene, Nocardia spp. lung abscesses, and gonococcal urethritis. REF: page 134 OBJ: Level 2 – Interpretation 13. Polymicrobial presentations in smears require more interpretation and must take into account all the following EXCEPT: a. Smear background b. Morphology of the organisms c. Anatomic location of the suspected infection d. Method used to make the smear ANS: D Polymicrobial presentations in smears require more interpretation and must take into account smear background, the morphology of the organisms, and the anatomic location of the suspected infection, as well as accompanying clinical symptoms. Polymicrobial infections usually arise from displaced normal or altered florae, and culture will yield the same species that can be isolated in culture from uninfected but contaminated specimens. The method used to make the smear has no bearing on smear interpretation. REF: page 134 OBJ: Level 2 – Interpretation 14. Commonly encountered polymicrobial infections are: a. Perirectal abscesses b. Indwelling catheter infections c. Infant meningitis d. Food poisoning ANS: A The rectal area contains a lot of different types of normal bacteria called fecal florae. These bacteria can invade infected tissue once the body’s defenses are lowered. Indwelling catheter infections are a colonization, not usually caused by skin florae. Infant meningitis and food poisoning are usually single-organism infections that are not caused by normal florae. REF: page 134 OBJ: Level 1 – Recall 15. When a laboratory professional examines a specimen smear, he or she should be looking for all of the following EXCEPT: a. Squamous epithelial cells b. Mucus c. Bacteria without the cells of inflammation d. Debris ANS: B Squamous epithelial cells, bacteria without the cells of inflammation, food, or other debris on a smear may indicate contamination by normal (resident) microbial florae. Mucus is a common lubricant of the mucous membranes and may be found in acceptable (not contaminated) as well as unacceptable (contaminated) specimens. REF: pages 134-136 OBJ: Level 1 – Recall 16. A specimen that is spread on a smear and appears to have a homogenous constitution is said to: a. Be clumped at different areas on the slide b. Contain pathogens only in one visual field c. Have material spread evenly throughout the slide d. Contain normal florae ANS: C Specimens can be homogenous or heterogenous and may contain pathogens evenly distributed throughout the specimen or limited to one visual field. Homogenous is said to have an even consistency throughout. REF: page 134 OBJ: Level 1 – Recall 17. Why should laboratory professionals look for contamination of a specimen by normal microbial florae? a. Contaminated specimens will have much amorphous debris that also goes with them. b. Normal florae always preclude the possibility of a pathogen infecting the area where they reside. c. The normal florae will be found in clumps, and any pathogenic bacteria will be found with the normal florae. d. Contamination of specimens with normal florae that are not collected from sterile sites diminishes the value culture studies. ANS: D Normal florae can indicate contamination of a culture. If there is contamination of a culture, the pathogenic organism may be close to impossible to identify in that culture. The normal florae may also overgrow the culture and kill the pathogen. REF: page 134 OBJ: Level 2 – Interpretation 18. Why should the laboratory professional look for unexpected structures in smears? a. Large granules, grains, or fungal forms, such as spherules or fungal mats, can best be recognized at low po give the tech and the physician an insight to the infectious process occurring at that site. b. Small numbers of organisms in samples from sterile sites must be seriously considered. c. The inflammatory cells that do migrate into the area of the infection can be lysed, and patients with leukopen also have fewer inflammatory cells within their inflammatory debris. d. Debris is characteristic of particular organisms. ANS: A Curschmann’s spiral is most often confused with parasitic larvae, which can also be found in sputum through use of low-power magnification. Some distinguishing structures, such as granules or fungal mats, give the tech a hint into what types of pathogens are present in the specimen. REF: page 134 OBJ: Level 2 – Interpretation 19. When examining specimen smears for pathogenic bacteria, this is important to note. a. Wright’s stain reaction b. Intracellular and extracellular forms c. Details of the microbe’s nuclear structure d. The amount of fecal material on the slide ANS: B Intracellular and extracellular forms are important to note because they point to definite processes in the infection. If the white blood cells are alive and phagocytic, they would engulf the bacteria causing the infection. This can be easily observed under oil immersion on a slide. Most of the time, bacteriologic smears are not stained with Wright’s stain, unless a blood-borne parasite or pathogen is being sought. Unfortunately, details of the microbe’s nuclear structure are not visible under bright light microscopy, but only electron microscopy. Fecal material will only be present in fecal smears. REF: page 136 OBJ: Level 1 – Recall 20. Because cell wall–damaged bacteria, antibiotic-treated bacteria, or dead bacteria may appear falsely gram-negative, what are “critical cocharacteristics”? a. Color and cell wall composition b. Growth characteristics c. Shape and size d. Size and color ANS: C When bacteria die, their Gram-staining characteristics are different than a living organism. For example, when Streptococcus pneumoniae dies, it can appear to be gram-negative, lancet-shaped diplococci. Normally S. pneumoniae is a gram-positive, lancet-shaped diplococci. One cannot always rely on color, but the size and shape of bacteria will always be the same.