OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections | 2022 LATEST UPDATE

T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 1 of 17 Chapter 21: Skin and Eye Infections * = Correct answer Multiple Choice 1. The top part of the skin, which is exposed to the environment, is called: A. adipose tissue B. the dermis C. the epidermis* D. the hypodermis Difficulty: Easy ASM Standard: N/A 2. Which bacterial genus is commonly associated with acne? A. Candida B. Clostridium C. Propionibacterium* D. Salmonella Difficulty: Easy ASM Standard: 23 3. Papillomas are also known as: A. comedones B. pustules C. urticaria D. warts* Difficulty: Easy ASM Standard: N/A 4. Tinea corporis is also known as: A. conjunctivitis B. ringworm* C. viral keratitis D. warts Difficulty: Easy ASM Standard: 23 5. The conjunctiva is the: A. boundary of the lens of the eye B. layer of mucus covering the eye C. layer of tissue surrounding the entire eye TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 2 of 17 D. mucous membranes of the eye* Difficulty: Easy ASM Standard: N/A 6. A deep lesion that develops from multiple boils is called a: A. carbuncle* B. furuncle C. macule D. pustule Difficulty: Easy ASM Standard: 23 7. Systemic symptoms are most likely to develop with a: A. carbuncle* B. comedo C. cyst D. pustule Difficulty: Easy ASM Standard: 23 8. Which of the following describes impetigo? A. a highly contagious infection caused by Staphylococcus aureus and Streptococcus pyogenes that causes vesicles, pustules, and bullae* B. a mild and self-limiting viral infection that can be caused by a wide range of infectious agents C. a noncontagious rash (not caused by an infectious agent) that spreads rapidly across the skin D. a systemic fungal infection caused by Candida spp. and other species that is difficult to treat Difficulty: Easy ASM Standard: 23 9. Which of the following is true of the normal skin microbiota? A. It does not change over time. B. It is always identical in all parts of the body. C. It varies between moist and dry areas only, but is consistent in areas of similar moisture content. D. It varies depending on microenvironment and is an important part of the nonspecific immune system.* Difficulty: Moderate ASM Standard: 23, 24 TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 3 of 17 10. One reason that the skin is inhospitable to microbes is that: A. It is moist and hypersaline, which prevents growth by most species of microbes. B. It is relatively lacking in salt and is hypotonic to bacteria. C. It is relatively moist and this inhibits their growth. D. The normal microbiota outcompetes other microbes and inhibits their growth.* Difficulty: Moderate ASM Standard: 23, 24 11. An important difference between sebaceous glands and sweat glands is that: A. Sebaceous glands are not typically associated with hair follicles, whereas sweat glands typically are associated with hair follicles. B. Sebaceous glands are tubular and sweat glands are coiled. C. Sweat glands are found fully within the dermis, whereas sebaceous glands are found fully within the epidermis. D. Sweat glands produce a watery fluid, whereas sebaceous glands produce lipid-rich sebum.* Difficulty: Moderate ASM Standard: N/A 12. How does sebum affect microbial growth on the skin? A. It dries out the skin, reducing the ability of microbes to grow where it is present. B. It may aid growth by providing nutrients but also has components that inhibit microbial growth.* C. It only aids microbial growth, providing a source of nutrition without generally having any harmful effects on microbes. D. It repels microbes and they cannot grow where it is present, making it an important part of the nonspecific immune response. Difficulty: Moderate ASM Standard: 23, 24 13. Sebum-rich areas of the skin, such as the back, generally harbor which of the following? A. highly mixed microbial populations, including a range of bacteria and fungi B. less diverse microbial populations than other regions* C. more diverse microbial populations than other regions D. varied microbial diversity that is difficult to predict compared with other skin regions Difficulty: Moderate ASM Standard: 23, 24 14. The normal skin microbiota primarily includes: A. bacteria and fungi only B. bacteria, fungi, and viruses* TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 4 of 17 C. bacteria only D. fungi only Difficulty: Moderate ASM Standard: 23, 24 15. The vitreous humor: A. has a microbiota similar to that of the conjunctiva B. has a rich bacterial microbiota, but no fungi C. has a variable and diverse microbial population D. has no normal microbiota* Difficulty: Moderate ASM Standard: 23, 24 16. What is one way you can distinguish between a Streptococcus and a Staphylococcus infection? A. Staphylococcus bacteria are gram negative, whereas Streptococcus bacteria are gram positive. B. Streptococcus bacteria are catalase positive, whereas Staphylococcus bacteria are catalase negative. C. Streptococcus bacteria grow on mannitol salt agar, whereas Staphylococcus bacteria do not. D. Under the microscope, Staphylococcus bacteria form clusters and Streptococcus bacteria do not.* Difficulty: Moderate ASM Standard: 23 17. Individuals who wear contact lenses are at particular risk of developing which of the following? A. acute bacterial conjunctivitis B. blepharitis C. herpes simplex virus 1 lesions D. keratitis* Difficulty: Moderate ASM Standard: 23 18. Neonatal conjunctivitis is commonly treated with which of the following? A. chloramphenicol B. erythromycin* C. fluoroquinolones D. penicillin Difficulty: Moderate TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 5 of 17 ASM Standard: 14, 23 19. What does it mean to say that HSV-1 is often latent? A. It is always present in infected individuals, but lesions may be small or hidden. B. It is normally difficult to detect even when causing an active infection, unless appropriate screening tests are conducted. C. It undergoes cycles of rapid growth and slower growth, affecting the symptoms that can be observed. D. It undergoes periods of inactivity when it resides in trigeminal nerve ganglia and does not cause symptoms.* Difficulty: Moderate ASM Standard: 10, 23 20. To reduce transmission risk and symptoms, HSV-1 is often treated with which of the following? A. azithromycin B. fluoroquinolones C. itraconazole D. valacyclovir* Difficulty: Moderate ASM Standard: 14, 23 21. The relatively mild viral disease usually caused by human herpesvirus-6, or sometimes human herpesvirus-7, is better known as: A. chicken pox B. fifth disease C. measles D. roseola* Difficulty: Moderate ASM Standard: 23 22. Fifth disease is normally: A. allowed to resolve without treatment* B. prevented through vaccination C. treated intensively with intravenous antibiotics D. treated with topical antibiotic ointments Difficulty: Moderate ASM Standard: 14, 23 23. Tineas are commonly caused by which of the following? A. bacteria such as Staphylococcus and Streptococcus B. human papillomaviruses, especially strains 16 and 18 TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 6 of 17 C. parasites such as helminths D. Trichophyton, Epidermophyton, and Microsporum fungi* Difficulty: Moderate ASM Standard: 23 24. Acanthamoeba keratitis is generally treated with which of the following? A. cephalosporins and fluoroquinolones B. chlorhexidine, azoles, and polyhexmamethylene biguanide* C. intravenous vancomycin administered in a hospital D. penicillins and related antibiotics Difficulty: Moderate ASM Standard: 23 25. Deerflies spread which of the following? A. Acanthamoeba B. the loa loa worm* C. the varicella-zoster virus D. staphylococcal bacteria Difficulty: Moderate ASM Standard: 23 26. Albendazole is a medication that affects the ability of organisms to use tubulin to synthesize microtubules. Although it has other uses, from this information, what can you tell about the type of infection it is used for? A. It is probably used to treat bacterial infections because bacteria use tubulin within their cell walls. B. It is probably used to treat many varied infections because tubulin is present in all cells. C. It is probably used to treat parasitic infections such as those caused by helminths because they are eukaryotes.* D. It is probably used to treat viral infections because viruses require tubulin to replicate. Difficulty: Difficult ASM Standard: 9, 14, 23 27. The skin is an effective barrier against many pathogens. All the following describe ways that pathogens penetrate the skin except for which one? A. Bacteria on the surface of the skin often gradually consume the epidermis and dermis, creating a pathway to deeper parts of the body.* B. Helminths may burrow into the skin, creating their own paths to deeper tissues. C. Microbes may enter the body through skin that has been damaged, allowing them to reach deeper tissues. D. The loa loa worm enters the bloodstream through the bite of the deerflies that carry it. TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 7 of 17 Difficulty: Difficult ASM Standard: 23 28. The most common subcutaneous mycosis in temperate regions, sporotrichosis, is usually treated with: A. azithromycin B. itraconazole* C. penicillin D. tetracycline Difficulty: Difficult ASM Standard: 14, 23 29. Candidiasis is common and often mild. Of the patients below, which would most likely be an appropriate candidate for preventive or long-term treatment for candidiasis? A. a patient undergoing treatment for cancer who has a history of candidiasis* B. a patient who has been in remission from cancer for 2 years C. a patient with a history of repeated cases of mild cutaneous candidiasis D. a patient with newly diagnosed cutaneous candidiasis who has not previously been diagnosed with this infection Difficulty: Difficult ASM Standard: 14, 23 30. Why is a wet mount of a KOH preparation often used to diagnose tineas? A. KOH dissolves the fungal cells, allowing their internal structures to be viewed. B. KOH helps dissolve the keratin in the tissues, which better reveals the fungal structures.* C. KOH is necessary to fully spread the sample on the slide. D. KOH stains the tissue, making fungi more visible. Difficulty: Difficult ASM Standard: 23 31. Which of the following is not true of biofilms? A. Biofilms often form in wounds and are associated with medical devices such as prosthetic joints and catheters. B. Cells in biofilms are generally more resistant to antibiotic treatment. C. Nutrients are equally distributed throughout a biofilm, so all the cells are healthy and resistant.* D. The biofilm matrix helps attach cells to a surface. Difficulty: Difficult ASM Standard: 14, 23 32. Biofilms are commonly considered bacterial structures. Are biofilms always bacterial? A. No, biofilms may occasionally consist of viruses instead of bacteria. TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 8 of 17 B. No, fungi (including medically important fungi) may also form biofilms.* C. Yes, each biofilm consists of a monoculture of one species of bacterium. D. Yes, each biofilm consists of one or more bacterial species with no other species. Difficulty: Difficult ASM Standard: 9, 21, 23 33. Blackheads differ from whiteheads because whiteheads are covered by skin, whereas blackheads are open to the air. What causes the dark coloration? A. Lipids within the sebum react with air, resulting in chemical oxidation and the formation of the black color.* B. Sebum is always a dark color, but it is more concentrated in blackheads and is visible because there is no skin covering it. C. The dead cells turn black as they die. D. The sebum, dead cells, and lipids within the pore are naturally dark. Difficulty: Difficult ASM Standard: N/A True/False 34. Biofilms make the treatment of skin infections more difficult. Answer: True Difficulty: Easy ASM Standard: 21, 23 35. Herpes simplex virus 1 only causes lesions on and around the mouth. Answer: False Difficulty: Easy ASM Standard: 23 36. Keratitis is always caused by Acanthamoeba. Answer: False Difficulty: Moderate ASM Standard: 23 37. The immune system is often able to clear warts without medical treatment. Answer: True Difficulty: Moderate ASM Standard: 23 TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 9 of 17 38. Herpes simplex virus 1 is relatively uncommon; it is estimated that about 3% of individuals in the United States have been infected. Answer: False Difficulty: Moderate ASM Standard: 23 39. Blackhead pimples are comedones that are covered by skin. Answer: False Difficulty: Moderate ASM Standard: 23 40. Isotretinoin is used to treat acne, but only in severe cases because of potentially severe side effects. Answer: True Difficulty: Difficult ASM Standard: 14 41. Bacillus anthracis uses a capsule to help evade the immune response. Answer: True Difficulty: Difficult ASM Standard: 8, 23 Matching 42. Match each type of lesion with the best illustration. TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 10 of 17 (Credit “iii”: modification of work by Bruce Blaus) Answers: A. iii., B. ii., C. iv., D. i. Difficulty: Easy ASM Standard: N/A 43. Match each eye infection with the causative agent. A. acute hemorrhagic conjunctivitis i. viral (e.g., adenovirus) or caused by environmental irritants B. acute ulcerative blepharitis ii. viral (Picornaviridae) C. follicular conjunctivitis iii. viral (e.g., herpes simplex or varicella zoster) or bacterial (e.g., Staphylococcus) D. papillary conjunctivitis iv. environmental irritants and allergens Answers: A. ii., B. iii., C. i., D. iv. Difficulty: Moderate ASM Standard: 23 44. Match each infection with the most likely causative agent. A. acne i. Pseudomonas aeruginosa B. cellulitis ii. Propionibacterium acnes C. otitis externa iii. Streptococcus pyogenes TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 11 of 17 D. tinea corporis iv. Trichophyton, Epidermophyton, or Microsporum Answers: A. ii., B. iii., C. i., D. iv. Difficulty: Moderate ASM Standard: 23 45. Match each infection with the most likely treatment. A. acne (moderate) i. erythromycin, clindamycin, and others B. erysipelas ii. intravenous antibiotics, debridement, and sometimes amputation C. necrotizing fasciitis iii. antibiotics, especially penicillin D. Pseudomonas aeruginosa wound infections iv. polymyxin B, fluoroquinolones, gentamicin, and others Answers: A. i., B. iii., C. ii., D. iv. Difficulty: Moderate ASM Standard: 9, 14, 23 46. Match the fungal infection with its location. A. tinea capitis i. the body B. tinea corporis ii. the genital region C. tinea cruris iii. nails D. tinea unguium iv. the head Answers: A. iv., B. i., C. ii., D. iii. Difficulty: Moderate ASM Standard: 23 47. Match the infection with a common treatment. A. Acanthamoeba keratitis i. terbinafine, miconazole, clotrimazole, oral griseofulvin B. loiasis ii. itraconazole C. sporotrichosis iii. diethylcarbamazine, albendazole D. tinea capitis iv. polyhexamethylene biguanide, chlorhexidine, azoles Answers: A. iv., B. iii., C. ii., D. i. Difficulty: Difficult ASM Standard: 14, 23 Fill in the Blank 48. ________ is the term for inflammation of the cornea of the eye. Answer: Keratitis Difficulty: Easy ASM Standard: 23 49. ________ conjunctivitis is caused by bacteria. TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 12 of 17 Answer: Acute purulent Difficulty: Easy ASM Standard: 23 50. Tears travel from the lacrimal sac to the inner nose via the ________. Answer: nasolacrimal duct Difficulty: Moderate ASM Standard: 51. Microbes found on the skin may be part of the long-term normal microbiota or they may be ________ microbes. Answer: transient Difficulty: Moderate ASM Standard: 23, 24 52. When the nasolacrimal duct becomes blocked, the lacrimal sac may become inflamed in a condition called ________. Answer: dacryocystitis Difficulty: Moderate ASM Standard: 23 53. A microbe that is part of the normal human skin microbiota, less virulent than Staphlococcus aureus, and a major cause of nosocomial infections and infections associated with medical devices is ________. Answer: Staphylococcus epidermidis Difficulty: Moderate ASM Standard: 23, 24 54. ________ is a streptococcal cell wall protein that is an important virulence factor. Answer: M protein Difficulty: Moderate ASM Standard: 8, 23 55. Individuals infected with the loa loa parasite may develop ________, which are areas of allergic inflammation. Answer: Calabar swellings Difficulty: Moderate ASM Standard: 23 TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 13 of 17 56. Aspergillosis can cause formation of distinctive structures called ________. Answer: eschars Difficulty: Difficult ASM Standard: 23 57. Intertrigo and oral thrush can be caused by ________. Answer: Candida spp. Difficulty: Difficult ASM Standard: 23 Short Answer 58. Why are individuals with contact lenses at greater risk of developing Acanthamoeba keratitis infection? Sample Answer: The area between the contact lens and the cornea of the eye is suitable for Acanthamoeba to grow. Difficulty: Easy ASM Standard: 23 59. Which regions of skin have the least most microbial diversity and why? Sample Answer: Regions with higher amounts of sebum are associated with lower diversity because chemicals in sebum inhibit growth. [Students may also answer that microbes are most abundant and diverse in moist regions of the skin because other areas are too dry for extensive microbial growth, but this is not specifically addressed in the chapter]. Difficulty: Easy ASM Standard: 23, 24 60. What general groups of microbes are found on the skin, making up the normal microbiota? Sample Answer: Bacteria, fungi, and viruses are most commonly found in the normal microbiota. Difficulty: Easy ASM Standard: 23, 24 61. How could someone reduce their risk of developing Acanthamoeba keratitis? Sample Answer: To reduce the risk of Acanthamoeba keratitis, someone could either avoid using contact lenses or practice careful contact lens hygiene. Difficulty: Easy ASM Standard: 14, 23 62. What are some factors that make the skin an effective barrier? TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 14 of 17 Sample Answer: The skin is relatively dry and salty, with secretions that inhibit microbial growth. Additionally, the normal microbiota competes with other microbes and makes it more difficult for them to become established. The normal microbiota also produces substances that inhibit the growth of other microbes. Difficulty: Moderate ASM Standard: 23, 24 63. What are some ways that a person can reduce their risk of developing ringworm? Sample Answer: The fungi that cause ringworm thrive in dark, moist environments; therefore, it is important to practice good hygiene in places such as locker rooms and public showers. Wearing appropriate shoes and keeping skin and clothes dry are helpful. Good overall health also helps prevent infection. Difficulty: Moderate ASM Standard: 14, 23 64. What are some eye conditions that can be caused by environmental irritants? Sample Answer: Some examples of eye conditions that can be caused by environmental irritants are follicular conjunctivitis, keratitis, nonulcerative blepharitis, and papillary conjunctivitis. Difficulty: Moderate ASM Standard: N/A 65. What is the usual treatment for someone with a suspected staphylococcal infection of the skin? Sample Answer: Because MRSA has become so common, it is often assumed that the pathogen is resistant even before testing for antibiotic susceptibility. Ideally, antibiotic susceptibility testing would be used to select the best antibiotic in each case. However, treatment is normally started with TMP/SMZ, a tetracycline, clindamycin, or a linezolid, because MRSA is generally susceptible to those. Difficulty: Moderate ASM Standard: 14, 23 66. What is a common way that Staphylococcus aureus and S. epidermidis are distinguished by culture methods? Sample Answer: Because S. aureus is coagulase positive and S. epidermidis is coagulase negative, they can be distinguished using passive agglutination testing (although this does not definitively identify the species). They can also be cultured on mannitol salt agar, which distinguishes coagulase-positive species that ferment mannitol from coagulase-negative species that do not. Difficulty: Moderate ASM Standard: 23, 34, 36 TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 15 of 17 67. How do tinea corporis, tinea capitis, tinea pedis, tinea barbae, tinea cruris, and tinea unguium differ? Sample Answer: They are caused by the same species of fungi and distinguished by their location on the body. Tinea corporis is found on the body, tinea capitis is found on the head (primarily the scalp), tinea pedis is found on the feet, tinea barbae is found in beards, tinea cruris is found in the genital region (groin), and tinea unguium is found in nails. Difficulty: Moderate ASM Standard: 23 68. What is another term for onychomycosis? Sample Answer: Onychomycosis is also known as tinea unguium. Difficulty: Moderate ASM Standard: 23 69. What symptoms commonly characterize a Candida infection of a fingernail? Sample Answer: The nail may become unusually hard and develop a yellow coloration. Difficulty: Moderate ASM Standard: 23 70. What medications can be used for long-term treatment of Candida infections in immunocompromised patients? Sample Answer: Ketoconazole and itraconazole are most commonly used for long-term treatment of Candida infections. Difficulty: Difficult ASM Standard: 14, 23 71. Why is it common to leave some viral infections, such as roseola, fifth disease, and viral conjunctivitis, untreated? Sample Answer: Some viral infections can become serious and require treatment. However, many viral infections are sufficiently mild that treatment is not necessary. Treatment may sometimes be used, even if the condition cannot be cured, to reduce the risk of transmission and severity of symptoms. Immunocompromised individuals may benefit from treatment not necessary for those with healthy immune systems. Difficulty: Difficult ASM Standard: 14, 23 72. What are the best ways to reduce the risk of viral infections of the eyes and skin? Sample Answer: Most viral infections of the eyes and skin are primarily spread by contact with infected individuals or their secretions (e.g., respiratory discharge). Good hygiene and avoidance of close contact with infected individuals reduces the risk of transmission. TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 16 of 17 Individuals with long-term viral skin infections, such as herpes simplex virus infections, can take antiviral medications to reduce the risk of transmitting the virus. Difficulty: Difficult ASM Standard: 14, 23 Brief Essay Essay Question Rubric RATING Failing Below Average Competent Advanced Criteria for evaluation Answer does not provide an argument. Answer contains inaccuracies. Writing is poor and contains numerous grammatical mistakes and misspellings. Answer fails to provide examples to support an argument. Writing is poor and grammatical errors are common. Answer is somewhat incoherent. Answer provides an argument with one or two examples that support it. Writing is acceptable for the college level but may contain one or two grammatical mistakes or misspellings. Answer clearly provides an argument with two or more excellent examples that support it; student makes the argument clearly and eloquently. Answer is well organized and free of grammatical errors and misspellings. POINT VALUE 0 1 2 3 Assume rating/grading scale for the question ranges from 0 to 3 points. 73. Staphylococcus epidermidis is a common resident on human skin, contributing to the normal microbiota. Explain why it is still an important concern as a source of infection. Answer: Student answers will vary but should include components of the following. Staphylococcus epidermidis on the skin is normally harmless. However, it is an opportunistic pathogen and can cause serious infections when it enters the body. It is a particular problem associated with medical procedures, during which it may be accidentally introduced deeper into the body. It may also be introduced into the body on medical devices. Difficulty: Moderate ASM Standard: 23, 24 74. A patient in the hospital develops a serious infection after surgery. How could you distinguish between an infection caused by a Staphylococcus species and one caused by a Streptococcus species? If the infection is caused by a Staphylococcus species, then how could you determine whether it was caused by S. aureus or S. epidermidis? Answer: Student answers will vary but should include components of the following. Species of Staphylococcus and Streptococcus can most easily be distinguished under the microscope because of differences in their morphologies. Staphylococcus forms distinctive grape-like clusters, whereas Streptococcus forms chains. The bacteria can also be cultured; Staphylococcus has a distinctive opaque white to cream coloration when grown on blood TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER T E S T B A N K S E L L E R . C O M OpenStax Microbiology Test Bank Chapter 21: Skin and Eye Infections Page 17 of 17 agar. A catalase test can be used because Staphylococcus is catalase positive, whereas Streptococcus is catalase negative. To distinguish between S. aureus and S. epidermidis, passive agglutination testing can be used, although this does not definitively identify the species): S. aureus is coagulase positive and S. epidermidis is coagulase negative. These bacteria can also be cultured on mannitol salt agar, which distinguishes coagulase-positive species that ferment mannitol from coagulase-negative species that do not. Because species in both genera are gram-positive cocci, Gram staining is not sufficient to distinguish them. Difficulty: Moderate ASM Standard: 6, 23, 32, 34, 36 75. Explain the pros and cons of screening hospital patients and workers for MRSA to reduce its spread in hospitals. How could these programs be improved? Answer: Student answers will vary but should include the following. Screening identifies individuals with MRSA, but many people are asymptomatic and may not want treatment. Additionally, decolonization procedures could increase the risk of resistance to treatment. The data on the efficacy of these programs are mixed and the protocols used vary greatly. Students should discuss the roles of individual preferences in screening and treatment, as well as possible options to strengthen these programs, such as studying standardized protocols. Students may also mention other approaches to reduce the risk of crosscontamination, such as checklists to improve compliance with handwashing and other hygiene protocols. This topic is discussed in detail in the Eye on Ethics box on page 917. Difficulty: Difficult ASM Standard: 14, 23, 31 76. There is a vaccination available for anthrax, but it is only approved for use in those who are at high risk. Why do you think the vaccine is not more widely available? What are the pros and cons of this approach? Could improvements be made? Answer: Student answers will vary but should include components of the following. The anthrax vaccine requires an initial series of five intramuscular injections over the course of 18 months, then annual booster vaccinations. It is difficult to encourage people to have regular vaccinations, especially on such a frequent schedule, so having widespread vaccination with a relatively difficult vaccine may not be realistic. Additionally, the risk of exposure is so low for most people that it would be an unnecessary effort. The book mentions that postexposure vaccination could potentially be offered to people. If there were a sufficiently increased risk of anthrax exposure, then increased research into postexposure treatment would probably more effective than attempting a widespread vaccination program. Difficulty: Difficult ASM Standard: 14, 23, 31 This file is copyright 2017, Rice University. All rights reserved. TESTBANKSELLER.COM TESTBANKSELLER.COM #1 TEST BANKS WHOLESALER