Deck 22: Skin Infections

Question 1

The principal species of Staphylococcus found on the skin is

A) aureus.
B) acnes.
C) epidermidis.
D) pyogenes.
E) saprophyticus.

Answer 1

C

Question 2

The surface layer of the skin is the

A) cutaneous.
B) keratin.
C) epidermis.
D) dermis.
E) hypodermis.

Answer 2

C

Question 3

Which of the following is NOT true about diphtheroids?

A) They are part of the normal microbiota of the skin.
B) They are responsible for body odor.
C) They include Cutibacterium acnes.
D) They include Malassezia species.
E) These are all true.

Answer 3

D

Question 4

The preferred habitat of S. aureus is the

A) nasal chamber.
B) throat.
C) urethra.
D) bladder.
E) meninges.

Question 5

In many people, the growth of C. acnes within hair follicles leads to

A) eczema.
B) carbuncles.
C) boils.
D) acne.
E) all of these.

Question 6

Which is considered the most serious staphylococcal skin infection?

A) Tinea versicolor
B) Carbuncles
C) Folliculitis
D) Furuncles
E) Acne

Question 7

Which of the following is considered a function of the skin?

A) Regulation of body temperature
B) Prevention of fluid loss
C) Synthesis of vitamin D
D) Production of cytokines
E) All of the choices are correct.

Question 8

The member of the normal microbiota sometimes considered responsible for tinea versicolor is

A) Staphylococcus species.
B) diphtheroids.
C) Candida species.
D) Malassezia species.
E) Streptococcus species.

Question 9

The protein produced by S. aureus that interferes with phagocytosis is

A) M protein.
B) collagen.
C) protein A.
D) capsular protein.
E) flagellin.

Question 10

The antimicrobial aspect(s) of the skin is/are

A) dryness.
B) saltiness.
C) acidity.
D) toxicity.
E) All of the choices are correct.

Question 11

The Rickettsial disease that killed Howard Ricketts and Stanislaus Prowazek was

A) louse-borne typhus.
B) tick-borne typhus.
C) yellow fever.
D) bubonic plague.
E) unidentified.

Question 12

Which of the following is a fairly reliable method of characterizing strains of S. aureus?

A) Complement fixation
B) Protein fingerprint
C) Genome typing
D) LPS pattern
E) All of these

Question 13

The oily secretion that lubricates the hair follicles of the skin is

A) sebum.
B) eczema.
C) suder.
D) acnus.
E) mucus.

Question 14

Which of the following is an important function of the skin?

A) Hold muscle to bone
B) Manufacture blood cells
C) Produce antibodies
D) Control body temperature
E) All of the answer choices are correct.

Question 15

The secretions of the sweat and sebaceous glands provide ________ to the microbiota.

A) water
B) amino acids OR water
C) lipids AND amino acids
D) water, amino acids, AND lipids
E) sebum OR amino acids

Question 16

Which of the following organisms is not normally found on the skin?

A) Staphylococci
B) Diphtheroids
C) Candida species
D) Malassezia species
E) Staphylococci AND diphtheroids

Question 17

The bacteria that appear to maintain balance between the members of the normal microbiota and play a vital role in limiting colonization by pathogens are

A) staphylococci.
B) diphtheroids.
C) Candida spp.
D) Malassezia spp.
E) streptococci.

Question 18

Which of the following normal skin microbiota is a small yeast?

A) Staphylococci
B) Malassezia species
C) Diphtheroids
D) Candida species
E) Cutibacterium species

Question 19

A protein associated with a more virulent form of Staphylococcus is

A) leukocidin.
B) coagulase.
C) mannose.
D) streptokinase.
E) catalase.

Question 20

Which of the following may be added to normal media to make it more selective for staphylococci?

A) 7.5% salt
B) 0.5% HCl
C) 1.0% glucose
D) 5.0% mannose
E) 1.0% glucose AND 0.5% HCl

Question 21

Which of the following may aid Staphylococcus in resisting phagocytosis?

A) Leukocidin
B) Hemolysin
C) Granulation enzyme
D) Coagulase
E) Lipase

Question 22

Reactivation of chickenpox is called

A) shingles.
B) herpes zoster.
C) pneumonia.
D) exanthems.
E) shingles AND herpes zoster.

Question 23

The main vector(s) of Rocky Mountain spotted fever in the western United States is/are ________.

A) ticks
B) bats AND humans
C) humans
D) mosquitoes AND ticks
E) fleas AND mites

Question 24

The childhood disease that damages the body defenses and is frequently complicated by secondary infections involving mostly Gram-positive cocci is

A) German measles.
B) measles.
C) mumps.
D) chickenpox.
E) shingles.

Question 25

In addition to S. aureus, impetigo may also involve

A) M. luteus.
B) S. pyogenes.
C) S. epidermidis.
D) Pseudomonas species.
E) Cutibacterium species.

Question 26

A common viral rash of childhood with the popular name chickenpox is also known as

A) bariola.
B) rubella.
C) rubeola.
D) varicella-zoster.
E) salmonella.

Question 27

Many childhood diseases caused by viral infections of the upper respiratory tract can usually be diagnosed by

A) inspection of the rash.
B) the type of cough.
C) the type of fever.
D) the incubation period.
E) the gender of the patient.

Question 28

Which is true of MRSA strains?

A) They are all resistant to vancomycin.
B) They carry the R plasmid AND they are all resistant to vancomycin.
C) They may be susceptible to linezolid.
D) The carry the R plasmid AND they may be susceptible to linezolid.
E) The carry the F plasmid AND they may be susceptible to linezolid.

Question 29

Which of the following is an obligate intracellular parasite?

A) Micrococcus luteus
B) Streptococcus pyogenes
C) Rickettsia rickettsii
D) Pseudomonas aeruginosa
E) Staphylococcus epidermidis

Question 30

The varicella-zoster virus is a member of which virus family?

A) Paramyxoviridae
B) Herpesviridae
C) Togaviridae
D) Papillomaviridae
E) Retroviridae

Question 31

After being bitten by an infected tick, transfer of the rickettsial organism occurs

A) within 4-10 hours.
B) within 20 minutes.
C) within 5 minutes.
D) immediately.
E) after 7 days.

Question 32

The S. aureus product that causes scalded skin syndrome is

A) exfoliation toxin.
B) lipases.
C) leukocidins.
D) protein M.
E) peeling toxin.

Question 33

Rubella, rubeola, and varicella-zoster are all only acquired via

A) the gastrointestinal route.
B) the respiratory route.
C) wounds.
D) blood transfusions.
E) arthropods.

Question 34

A frequent complication of scalded skin syndrome is

A) a bacterial secondary infection.
B) secondary viral infections.
C) dehydration.
D) dehydration and a secondary bacterial infection.
E) toxemia.

Question 35

Which of the following virulence factors used by Staphylococcus puts holes in host cells?

A) Protein A
B) Alpha toxin
C) Leukocidin
D) Clumping factor
E) Membrane attack complex

Question 36

S. aureus clumping factor

A) causes fibrinogen to clump together.
B) causes bacteria to clump together in plasma.
C) reacts with prothrombin.
D) produces staphylothrombin.
E) causes phagocytes to clump bacteria.

Question 37

In which of the following does a rash start on the palms and soles and progress toward the trunk?

A) Epidemic typhus
B) Typhoid
C) Measles
D) Impetigo
E) Rocky Mountain spotted fever

Question 38

In S. pyogenes, which of the following interferes with phagocytosis?

A) M protein
B) Protein A
C) Collagen
D) Pilin
E) Peptidoglycan

Question 39

The rubeola virus contains

A) single-stranded DNA.
B) double-stranded DNA.
C) single-stranded RNA.
D) double-stranded RNA.
E) single-stranded RNA OR double-stranded RNA.

Question 40

Rocky Mountain spotted fever is an example of a(n)

A) animalosis.
B) tickonosis.
C) plantonosis.
D) zoonosis.
E) aviosis.

Question 41

Who would have larger numbers of bacteria living on the surface of their skin-a person living in the tropics or in the desert, and why?

A) The tropics would provide more shade, so the surface of the skin wouldn't be exposed to high levels of ultraviolet radiation. This would protect the bacteria on the skin, and they would have higher numbers due to this shading effect.
B) The very low humidity of the desert would lead to rapid evaporation of sweat and sebum from an individual's skin. Bacteria need these secretions for a nutrient source. Without them, bacteria would be found in much lower numbers on the skin of a person in the desert than the skin of the person in the tropics.
C) The constant secretion of high amounts of sweat would produce a highly salty environment on the skin of a person in the tropics. This would provide a local environment that would be too hostile for microbes to survive, so the number of microbes on the skin of the person in the tropics would be lower than that of the person in the desert.
D) The constant secretion of large amounts of sweat would wash bacteria off of the skin of the person in the tropics. As such, the person in the desert should have much more bacteria on their skin than the person in the tropics would.
E) The very high humidity of the desert would lead to slow evaporation of sweat and sebum from a person's skin. Bacteria thrive on these secretions, using them for a nutrient source. Thus bacteria would be found in much higher numbers on the skin of a person in the desert than the skin of the person in the tropics.

Question 42

Why is the immunization for rubella important for both boys and girls?

A) As this is a sexually-transmitted disease, vaccinating girls AND boys early in their lives prevents the spread of the disease in adulthood.
B) We want to achieve herd immunity, and there's no reason why only girls would be infected by this virus. By vaccinating the entire population, we achieve a higher degree of herd immunity than is possible by vaccinating only girls.
C) Only boys get this disease, and one of the common complications of it is sterility, so they should be vaccinated against this virus.
D) While this disease is quite very symptomatic in girls, it is completely asymptomatic in boys. Boys can be carriers and transmit it easily to girls without realizing it. This can lead to large-scale and dangerous outbreaks in the female population.
E) Although boys get this disease, it doesn't cause any health problems for them, so they do not need vaccination. If girls get the disease, it almost always leads to encephalitis, so they should be protected by vaccination.

Question 43

What is the epidemiological significance of shingles?

A) It shows that, as a latent viral infection, there is always a possible reservoir available to reinfect new susceptible individuals.
B) It shows that we must always be vigilant against this deadly and highly infectious secondary infection in elderly and immunocompromised individuals.
C) It shows that, as a chronic viral infection, individuals infected are always infectious to others around them, even when they do not show outward symptoms.
D) It shows that our fight for long-term eradication of varicella zoster virus will be a long one, depending on immunizing all newly born individuals until all the people who had ever had contracted the illness have died.
E) It shows that, as a latent viral infection, there is always a possible reservoir available to reinfect new susceptible individuals AND it shows that our fight for long-term eradication of varicella zoster virus will be a long one, depending on immunizing all newly born individuals until all the people who had ever contracted the illness have died.

Question 44

The existence of extensive scalded skin syndrome does not indicate that Staphylococcus is growing in all the affected areas. Why not?

A) This condition is caused by an exotoxin produced by certain strains of this microbe, and NOT directly by the microbe itself.
B) This condition is caused by an endotoxin produced by certain strains of this microbe, and NOT directly by the microbe itself.
C) This condition isn't caused by Staphylococcus at all.
D) This microbe grows in the blood; endotoxins it releases are transported to the skin, where it causes the observed effect.
E) Scalded skin occurs when a person eats exfoliatin-contaminated food, not by an infection.

Question 45

The MMR vaccine is used to protect against

A) mononucleosis, mange, rubeola.
B) measles, mumps, rubella.
C) measles, mange, rubeola.
D) mononucleosis, mumps, rubella.
E) mumps, rubella, varicella.

Question 46

Varicella is a member of the herpes family of viruses and produces a latent infection.

Question 47

Which genus does not include skin-invading molds?

A) Epidermophyton.
B) Microsporum.
C) Trichophyton.
D) Ixodes.
E) These are all skin molds.

Question 48

An important diagnostic sign of measles is

A) Koplik's spots.
B) giant cells.
C) fever.
D) swollen lymph nodes.
E) red, weepy eyes.

Question 49

The most serious consequence of rubella is

A) encephalitis.
B) birth defects.
C) meningitis.
D) deafness.
E) subacute sclerosing panencephalitis.

Question 50

A public health official was asked to speak about immunizations during a civic group lunch. One parent asked if rubella was still a problem. In answering the question, the official cautioned women planning to have another child to have their present children immunized against rubella. Why did the official make this statement to the group?

A) Rubella is spread very easily by respiratory secretions and is largely asymptomatic. However, it can cause birth defects/stillbirth in pregnant women. Women with other children would want to prevent these children from acquiring the virus before attempting to conceive a new child in order to protect the fetus.
B) Rubella is passed very easily between children, so the official was trying to protect the child that would soon be born from this infection that might be brought in by its siblings after it was born.
C) The official is getting kickbacks and bribes from the companies making the vaccines, and he's trying to pad his pockets by getting as many people immunized as possible, regardless of whether they need it or not.
D) Rubella infections often lead to very serious and potentially fatal complications. While a woman is pregnant, she may not be able to take care of a sick child as easily. The vaccine will prevent the child already in the family from falling ill and potentially dying due to these possible complications.
E) All of the answer choices are correct.

Question 51

The MMR vaccine is used to protect against measles, mange, and rubella.

Question 52

Coagulase-positive S. aureus is often involved in disease.

Question 53

Humans are the only reservoir for varicella-zoster virus.

Question 54

Warts are caused by

A) papillomaviruses.
B) parvovirus.
C) adenoviruses.
D) herpes virus.
E) coronavirus.

Question 55

Diseases caused by fungi are called mycoses.

Question 56

Chickenpox and measles are both acquired by the respiratory route.

Question 57

Complications of measles may include pneumonia and encephalitis.

Question 58

Rubella is a member of which virus family?

A) Paramyxoviridae
B) Herpesviridae
C) Togaviridae
D) Papovaviridae
E) Retroviridae

Question 59

The skin-invading molds are collectively called dermatophytes.

Question 60

Which S. aureus virulence factor is not correctly matched with its function?

A) Capsule-avoiding phagocytosis.
B) Hyaluronidase-facilitates spread in tissues.
C) Protein A-interferes with opsonization.
D) α-Toxin-makes holes in host cell membranes.
E) Leukocidin-kills erythrocytes.

Question 61

The portal(s) of entry for varicella-zoster virus is/are

A) the skin.
B) the respiratory tract.
C) the genitourinary tract.
D) the genitourinary tract AND the gastrointestinal tract.
E) the skin AND the respiratory tract.

Question 62

If an immunodeficient person is exposed to VZV and belongs to a non-immune population, how can that person be protected from developing chickenpox?

A) They can be passively immunized with zoster hyperimmune globulin.
B) They can be actively immunized with the MMRV vaccine.
C) They can be passively immunized with the MMRV vaccine.
D) They can not be protected at all-they will get the disease.
E) They can be given prophylactic antibiotics.

Question 63

If an individual in the infectious stage of chickenpox comes into contact with a person who had chickenpox as a child, that second person

A) will be unaffected by the contact.
B) will develop a second case of chickenpox.
C) will develop shingles.
D) will develop a second case of chickenpox OR will develop shingles.
E) will remain healthy if they receive zoster immune globulin.

Question 64

How does coagulase help Staphylococcus aureus evade phagocytes?

A) It coats the surface of the bacterial cells with collagen, a tissue binding protein.
B) It coats the surface of bacterial cells with fibrin, a protein found in blood.
C) It causes formation of small clots in capillaries, slowing progress of phagocytes to the infected area.
D) It causes formation of small clots in capillaries, slowing progress of phagocytes to the infected area AND it coats the surface of bacterial cells with fibrin, a protein found in blood.
E) It causes formation of small clots in capillaries, slowing progress of phagocytes to the infected area AND it coats the surface of the bacterial cells with collagen, a tissue binding protein.

Question 65

Why does the rash of shingles occur in only a limited region, as opposed to the widespread rash of chickenpox?

A) In chickenpox, the replicating virus originates from multiple infected nerve cells, while in shingles it is limited to the bloodstream.
B) In shingles, the replicating virus originates from a single infected nerve cell, while in chickenpox it is spread throughout the bloodstream.
C) In chickenpox, the virus spreads through the bloodstream to all parts of the body, while in shingles, the virus remains in the chest area after inhalation.
D) The chickenpox virus is a double-stranded DNA virus that is able to infect any nucleated cells, while the shingles virus is a single-stranded RNA virus that only infects epidermal cells.
E) This question is misleading because the rash of both chickenpox and shingles is widespread throughout the body.

Question 66

Why is Legionella pneumophila detected using immunofluorescence?

A) It stains poorly with conventional dyes.
B) It is Gram-non-reactive.
C) It is an acid-fast bacterium.
D) It lacks a peptidoglycan cell wall.
E) It is a virus.

Question 67

Why is staphylococcal scalded skin syndrome sometimes fatal?

A) The first line of defense is compromised, putting the patient at risk secondary bacterial infection.
B) The first line of defense is compromised, putting the patient at risk of both dehydration and secondary bacterial infection.
C) The causative organism is Gram-negative and may cause endotoxic shock.
D) Exfoliatin can bind to cardiac cells, causing disruption of the heart rhythm and heart failure.
E) The first line of defense is compromised, putting the patient at risk of severe dehydration.

Question 68

Why is it important to give the MMRV vaccine to healthy, non-immune contacts of people with immunodeficiencies?

A) The MMRV vaccine is a toxoid vaccine, so immunodeficient people cannot receive it. They are protected by herd immunity.
B) The MMRV vaccine is an attenuated vaccine, so immunodeficient people cannot receive it. They are protected by antibodies from their close contacts.
C) The MMRV vaccine is an attenuated vaccine, so immunodeficient people cannot receive it. They are protected by herd immunity.
D) The MMRV vaccine is an inactivated vaccine, so immunodeficient people cannot receive it. They are protected by antibodies from their close contacts.
E) The MMRV vaccine is an inactivated vaccine, so immunodeficient people cannot receive it. They are protected by herd trending.

Question 69

Which description of vegetative Bacillus anthracis is correct?

A) It is an endospore-forming, Gram-positive, motile, rod-shaped bacterium.
B) It is an endospore-forming, Gram-negative, non-motile, rod-shaped bacterium.
C) It is a Gram-positive, non-motile, spherical, encapsulated bacterium.
D) It is a Gram-positive, non-motile, encapsulated, spore-forming, rod-shaped bacterium.
E) It is an acid-fast, non-motile, spherical, nonspore-forming, encapsulated bacterium.

Question 70

The portal of entry of Bacillus anthracis is the

A) respiratory tract.
B) epidermis.
C) gastrointestinal tract.
D) epidermis OR gastrointestinal tract.
E) respiratory tract, epidermis, OR gastrointestinal tract.

Question 71

Please select the TRUE statement regarding impetigo.

A) Signs and symptoms of impetigo result from inflammation in the keratinized outer epidermal layer.
B) The causative organism of impetigo is Cutibacterium acnes.
C) Patients with impetigo experience fever, pain, and malaise.
D) Impetigo is an example of a pyoderma-a superficial skin disease characterized by pus production.
E) Treatment of impetigo requires administering at least two different antibiotics.

Question 72

Why is Rickettsia rickettsii difficult to grow in culture?

A) It is a double-stranded DNA virus.
B) It is an obligate intracellular parasite.
C) It is resistant to multiple antibiotics.
D) It is an obligate anaerobe.
E) It is Gram-negative.

Question 73

Which statement regarding Staphyloccocus aureus is FALSE?

A) MRSA strains that can be traced to hospitals and clinics are referred to as HA-MRSA (hospital-acquired MRSA).
B) CA-MRSA strains have a group of genes that codes for a leukocyte-destroying leukocidin.
C) Evidence proves that CA-MRSA strains are more virulent than HA-MRSA because they produce leukocidin.
D) MRSA strains are resistant to nearly all β-lactam antibiotics except ceftaroline, a new cephalosporin.
E) Some hospitals screen patients for MRSA when they are discharged so they do not take a MRSA strain home with them.

Question 74

What is eschar (a sign of cutaneous anthrax)?

A) A small, red, fluid-filled vesicle
B) An ulcer surrounded by swelling
C) A large black scar
D) Dead tissue resembling a flat scab
E) Swelling with trapped gas

Question 75

The vector for RMSF is a(n)

A) mosquito.
B) flea.
C) tick.
D) fly.
E) deer.

Question 76

How does protein A help Staphylococcus aureus evade phagocytes?

A) It binds the Fc portion of antibodies, interfering with opsonizaton and phagocytosis.
B) It binds the Fab portion of antibodies, interfering with opsonizaton and phagocytosis.
C) It coats the bacterial cell, destroying LPS and preventing recognition by phagocytes.
D) It makes holes in the cytoplasmic membrane of phagocytes, killing them.
E) It degrades complement protein C5a, preventing phagocyte recruitment and attachment.

Question 77

Rickettsia rickettsii is an obligate intracellular pathogen. This means that

A) it is a virus.
B) it needs oxygen for growth.
C) it cannot grow in the presence of oxygen.
D) it is non-motile.
E) it can only grow within host cells.

Question 78

Which of the following statements regarding S. aureus and S. pyogenes is FALSE?

A) S. aureus appears as clusters of spherical cells while S. pyogenes appears as chains of spherical cells.
B) S. aureus stains purple with the Gram stain while S. pyogenes stains pink with this procedure.
C) S. aureus is catalase positive and coagulase positive while S. pyogenes is catalase negative and coagulase negative.
D) The Fc receptor of S. aureus is protein A while the Fc receptor of S. pyogenes is protein G.
E) S. aureus is a facultative anaerobe while S. pyogenes is an obligate fermenter.

Question 79

Which of the following is not involved in the pathogenesis of RMSF?

A) The pathogen releases an A-B toxin that attaches to receptors on TH cell cytoplasmic membranes, leading to destruction of those cells.
B) Endotoxin released into the bloodstream from the rickettsial cell walls results in systemic inflammation.
C) Disseminated intravascular coagulation that leads to organ damage may occur following release of endotoxin into the bloodstream.
D) Host cells rupture following damage caused by bacterial cells propelling themselves from one cell to another.
E) Vasculitis leads to clotting and small areas of necrosis, causing a hemorrhagic skin rash and damaging tissue in the brain, heart, kidneys, and other organs.

Question 80

Which of the signs and symptoms of Rocky Mountain spotted fever is not typical of other diseases that manifest in a similar way?

A) Fever
B) Muscle pain
C) Headache
D) Joint pain
E) Rash