Question 1

A patient presents with a raised, red, tender, localized lesion that is hot to the touch and contains pus, as shown in the first image. Which organism is most likely responsible for this infection, and what is a key virulence factor used for its identification?

Accepted Answer

Staphylococcus aureus (MRSA); coagulase

Question 2

A culture from a skin lesion is grown on blood agar, as shown in the second image. The organism is Gram-positive, catalase-positive, and beta-hemolytic. Which test would you perform next to distinguish between Staphylococcus aureus and other staphylococci, and what result would you expect for S. aureus?

Accepted Answer

Perform a coagulase test; S. aureus is coagulase-positive

Question 3

Which of the following best explains why MRSA is a significant concern in both hospital and community settings?

Accepted Answer

It is resistant to multiple antibiotics and can survive on surfaces for extended periods.

Question 4

A child presents with a red, maculopapular rash that began on the head and spread to the trunk and extremities, as shown in the fifth image. Koplik’s spots are observed in the mouth. Which disease is most likely, and what is a serious neurological complication associated with it?

Accepted Answer

Measles; subacute sclerosing panencephalitis

Question 5

The fourth image shows a dramatic increase in measles cases in 2019. Which of the following best explains this resurgence in the United States?

Accepted Answer

Decreased vaccination rates and increased vaccine hesitancy

Question 6

A child presents with a 'slapped cheek' rash, as shown in the sixth image. Which virus is responsible for this condition, and what is the most appropriate treatment?

Accepted Answer

Parvovirus B19; supportive care only

Question 7

A newborn develops widespread skin desquamation and bullous lesions, as shown in the seventh image. Which bacterial toxin is responsible for this condition, and what is the recommended immediate intervention?

Accepted Answer

Exfoliative toxin; systemic antibiotics

Question 8

A patient presents with a honey-colored, crusty lesion around the mouth, as shown in the tenth image. Which two organisms are most commonly responsible for this infection, and what is a distinguishing laboratory feature of Streptococcus pyogenes?

Accepted Answer

Staphylococcus aureus and Streptococcus pyogenes; beta-hemolysis

Question 9

A patient develops a painless, black eschar on the skin after handling animal hides, as shown in the sixteenth image. Which organism is responsible, and what is the primary virulence factor that allows it to survive harsh conditions?

Accepted Answer

Bacillus anthracis; endospore formation

Question 10

A patient presents with a ring-shaped, scaly lesion on the skin, as shown in the nineteenth image. Which group of organisms is responsible, and what is their primary virulence factor?

Accepted Answer

Dermatophytes; ability to digest keratin

Question 11

A newborn presents with a purulent eye discharge, as shown in the twenty-sixth image. Which two organisms are the most common causes of neonatal conjunctivitis, and how are they transmitted?

Accepted Answer

Neisseria gonorrhoeae and Chlamydia trachomatis; vertical transmission during birth

Question 12

A patient with a history of chickenpox develops a painful, vesicular rash along a single dermatome, as shown in the thirteenth image. Which virus is responsible, and what is the recommended vaccine for prevention in adults over 50?

Accepted Answer

Human herpesvirus 3 (HHV-3); Shingrix

Question 13

A patient presents with a rapidly spreading area of redness, warmth, and swelling on the lower leg, accompanied by fever and lymphangitis. Which two organisms are most commonly responsible for cellulitis in healthy individuals?

Accepted Answer

Streptococcus pyogenes and Staphylococcus aureus

Question 14

A patient presents with a maculopapular rash and joint pain after returning from a region with a known rubella outbreak. Which laboratory test would best confirm a diagnosis of rubella?

Accepted Answer

Detection of IgM antibody to rubella antigen by ELISA

Question 15

A patient presents with a painless, black eschar after exposure to contaminated mail. What is the recommended prevention strategy for high-risk individuals?

Accepted Answer

Vaccination only for high-risk persons and the military

Question 16

A patient presents with a superficial, scaly, hypopigmented patch on the skin, as shown in the twenty-fourth image. Which organism is most likely responsible, and what is the most appropriate treatment?

Accepted Answer

Malassezia species; topical antifungal ointment

Question 17

A patient presents with a red, watery eye discharge and reports recent use of contact lenses. Which of the following is the most likely cause, and what is the best initial treatment?

Accepted Answer

Adenovirus; supportive care

Question 18

A patient with a history of oral herpes develops a painful, red eye with corneal clouding, as shown in the twenty-seventh image. Which organism is responsible, and what is the recommended treatment?

Accepted Answer

Herpes simplex virus type 1; trifluridine or acyclovir

Infectious Diseases Affecting the Skin and Eyes: Microbiology Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards