MICRO CHAPTER 21 QUESTIONS/ANSWERS

Herpes simplex virus 1 is relatively uncommon; it is estimated that about 3% of individuals in the United States have been infected.

Answer: False

Herpes simplex virus 1 only causes lesions on and around the mouth.

Answer: False

Keratitis is always caused by Acanthamoeba.

Answer: False

________ is the term for inflammation of the cornea of the eye.

Answer: Keratitis

________ is a streptococcal cell wall protein that is an important virulence factor.

Answer: M protein

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

Bacillus anthracis uses a capsule to help evade the immune response.

Answer: True

Biofilms make the treatment of skin infections more difficult.

Answer: True

Isotretinoin is used to treat acne, but only in severe cases because of potentially severe side effects.

Answer: True

The immune system is often able to clear warts without medical treatment.

Answer: True

When the nasolacrimal duct becomes blocked, the lacrimal sac may become inflamed in a condition called ________.

Answer: dacryocystitis

Aspergillosis can cause formation of distinctive structures called ________.

Answer: eschars

Tears travel from the lacrimal sac to the inner nose via the ________.

Answer: nasolacrimal duct

Microbes found on the skin may be part of the long-term normal microbiota or they may be ________ microbes.

Answer: transient

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.

B. It may aid growth by providing nutrients but also has components that inhibit microbial growth.*

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.

B. KOH helps dissolve the keratin in the tissues, which better reveals the fungal structures.*

Individuals infected with the loa loa parasite may develop ________, which are areas of allergic inflammation.

Answer: Calabar swellings

Intertrigo and oral thrush can be caused by ________.

Answer: Candida spp.

Blackhead pimples are comedones that are covered by skin.

Answer: False

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.

A. Bacteria on the surface of the skin often gradually consume the epidermis and dermis, creating a pathway to deeper parts of the body.*

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.

A. Lipids within the sebum react with air, resulting in chemical oxidation and the formation of the black color.*

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

A. a highly contagious infection caused by Staphylococcus aureus and Streptococcus pyogenes that causes vesicles, pustules, and bullae*

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

A. a patient undergoing treatment for cancer who has a history of candidiasis*

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

A. allowed to resolve without treatment*

A deep lesion that develops from multiple boils is called a: A. carbuncle B. furuncle C. macule D. pustule

A. carbuncle*

Systemic symptoms are most likely to develop with a: A. carbuncle B. comedo C. cyst D. pustule

A. carbuncle*

________ conjunctivitis is caused by bacteria.

Answer: Acute purulent

Biofilms are commonly considered bacterial structures. Are biofilms always bacterial? A. No, biofilms may occasionally consist of viruses instead of bacteria. 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.

B. No, fungi (including medically important fungi) may also form biofilms.*

The normal skin microbiota primarily includes: A. bacteria and fungi only B. bacteria, fungi, and viruses C. bacteria only D. fungi only

B. bacteria, fungi, and viruses*

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

B. chlorhexidine, azoles, and polyhexmamethylene biguanide*

Neonatal conjunctivitis is commonly treated with which of the following? A. chloramphenicol B. erythromycin C. fluoroquinolones D. penicillin

B. erythromycin*

The most common subcutaneous mycosis in temperate regions, sporotrichosis, is usually treated with: A. azithromycin B. itraconazole C. penicillin D. tetracycline

B. itraconazole*

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

B. less diverse microbial populations than other regions*

Tinea corporis is also known as: A. conjunctivitis B. ringworm C. viral keratitis D. warts

B. ringworm*

Deerflies spread which of the following? A. Acanthamoeba B. the loa loa worm C. the varicella-zoster virus D. staphylococcal bacteria

B. the loa loa worm*

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.

C. It is probably used to treat parasitic infections such as those caused by helminths because they are eukaryotes.*

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.

C. Nutrients are equally distributed throughout a biofilm, so all the cells are healthy and resistant.*

Which bacterial genus is commonly associated with acne? A. Candida B. Clostridium C. Propionibacterium D. Salmonella

C. Propionibacterium*

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

C. the epidermis*

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.

D. It undergoes periods of inactivity when it resides in trigeminal nerve ganglia and does not cause symptoms.*

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.

D. It varies depending on microenvironment and is an important part of the nonspecific immune system.*

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.

D. Sweat glands produce a watery fluid, whereas sebaceous glands produce lipid-rich sebum.*

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.

D. The normal microbiota outcompetes other microbes and inhibits their growth.*

Tineas are commonly caused by which of the following? A. bacteria such as Staphylococcus and Streptococcus B. human papillomaviruses, especially strains 16 and 18 C. parasites such as helminths D. Trichophyton, Epidermophyton, and Microsporum fungi

D. Trichophyton, Epidermophyton, and Microsporum fungi*

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.

D. Under the microscope, Staphylococcus bacteria form clusters and Streptococcus bacteria do not.*

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

D. has no normal microbiota*

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

D. keratitis*

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 D. mucous membranes of the eye

D. mucous membranes of the eye*

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

D. roseola*

To reduce transmission risk and symptoms, HSV-1 is often treated with which of the following? A. azithromycin B. fluoroquinolones C. itraconazole D. valacyclovir

D. valacyclovir*

Papillomas are also known as: A. comedones B. pustules C. urticaria D. warts

D. warts*