Question 1

Which of the following is a function of normal skin microbiota that helps protect against pathogenic microbes?

Accepted Answer

They metabolize sweat, producing acids that lower skin pH and inhibit pathogens.

Question 2

A patient presents with a rapidly spreading, painful skin infection after a minor cut. The tissue is necrotic, and the infection is diagnosed as necrotizing fasciitis. Which virulence factor is most likely responsible for the rapid tissue destruction?

Accepted Answer

Exotoxin A, a superantigen produced by Streptococcus pyogenes

Question 3

Which of the following statements best explains why Staphylococcus epidermidis is a common cause of infections associated with indwelling medical devices such as catheters?

Accepted Answer

It forms biofilms on surfaces, protecting it from host defenses and antibiotics.

Question 4

A newborn develops conjunctivitis a few days after birth. Laboratory tests reveal the presence of Gram-negative diplococci. Which organism is most likely responsible, and what is the best prevention strategy?

Accepted Answer

Neisseria gonorrhoeae; administer antibiotic eye drops at birth

Question 5

Which of the following best describes the pathogenesis of shingles (herpes zoster)?

Accepted Answer

Reactivation of latent varicella-zoster virus in sensory ganglia leads to a localized, painful rash along a dermatome.

Question 6

A patient with a history of recent antibiotic use develops white patches in the oral cavity. Microscopy reveals budding yeast with pseudohyphae. What is the most likely diagnosis and the underlying reason for this infection?

Accepted Answer

Thrush caused by Candida albicans; overgrowth due to suppression of competing bacteria

Question 7

Which of the following is a distinguishing feature of Staphylococcus aureus compared to Staphylococcus epidermidis?

Accepted Answer

S. aureus is coagulase-positive and produces golden-yellow colonies.

Question 8

A child presents with a 'slapped-cheek' facial rash and mild flu-like symptoms. Which virus is most likely responsible, and what is the name of the disease?

Accepted Answer

Human parvovirus B19; Fifth disease (erythema infectiosum)

Question 9

Which of the following mechanisms allows Streptococcus pyogenes to evade the host immune system?

Accepted Answer

Production of M proteins external to the cell wall

Question 10

A patient develops a self-limiting rash after swimming in a public pool. The causative agent is a Gram-negative, aerobic rod that produces blue-green pus in other infections. What is the most likely organism?

Accepted Answer

Pseudomonas aeruginosa

Question 11

Which of the following best explains why children under 1 year old should not receive the MMR (measles, mumps, rubella) vaccine?

Accepted Answer

Their immune systems are not mature enough to respond effectively to the vaccine.

Question 12

Which of the following is a correct pairing of a fungal disease and its typical site of infection?

Accepted Answer

Tinea capitis – scalp

Question 13

A patient presents with fever, vomiting, shock, and organ failure. Laboratory tests reveal the presence of toxic shock syndrome toxin 1 (TSST-1) in the bloodstream. Which organism is most likely responsible?

Accepted Answer

Staphylococcus aureus

Question 14

Which of the following best describes the role of keratin in the skin's defense against microbial infection?

Accepted Answer

Keratin is a waterproofing protein that forms a barrier to microbial invasion.

Question 15

A patient with a history of unsanitary contact lens use develops conjunctivitis. Which of the following organisms is most likely involved?

Accepted Answer

Pseudomonas aeruginosa

Question 16

Which of the following is a key difference between cutaneous and subcutaneous mycoses?

Accepted Answer

Subcutaneous mycoses penetrate the stratum corneum and are usually more serious.

Question 17

Which of the following best explains why MRSA (methicillin-resistant Staphylococcus aureus) infections are a significant concern in healthcare settings?

Accepted Answer

MRSA strains are resistant to many antibiotics, making infections difficult to treat.

Question 18

A patient presents with a macular rash, cold-like symptoms, and red spots on the oral mucosa opposite the molars. What is the most likely diagnosis and the causative agent?

Accepted Answer

Measles (Rubeola); measles virus

Question 19

Which of the following best describes the transmission and prevention of rubella in pregnant women?

Accepted Answer

Rubella is transmitted via the respiratory route and prevented by the MMR vaccine, which is not recommended for pregnant women.

Question 20

A patient develops vesicles on the skin after participating in contact sports. Laboratory analysis reveals a herpesvirus. Which condition is most likely, and what is the causative agent?

Accepted Answer

Herpes gladiatorum; HSV-1

Microbial Diseases of the Skin and Eyes: Comprehensive Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards