Ch. 17 - Skin and Eye Infections

Norman-McKay- Microbiology: Basic and Clinical Principles 2nd Edition

Norman-McKay2nd EditionMicrobiology: Basic and Clinical PrinciplesISBN: 9780137661619Not the one you use?Change textbook

Norman-McKay 2nd Edition

Ch. 17 - Skin and Eye Infections

Problem 16

Chapter 17, Problem 16

A frantic mother comes into your clinic because her two-year-old child has had a very high fever for two days now, with mild diarrhea and coldlike symptoms. As you consider the differential list, which is the most likely causative agent if the fever breaks and is replaced with a rash by tomorrow?
a. Human parvovirus B19
b. Hand, foot, and mouth disease
c. Roseola
d. Rubella
e. Measles

Verified step by step guidance

Step 1: Identify the key clinical features described: a high fever lasting for about two days, followed by the fever breaking and the appearance of a rash the next day, along with mild diarrhea and coldlike symptoms.

Step 2: Recall the typical clinical progression of common childhood exanthems (rash-causing illnesses), focusing on the timing of fever and rash appearance for each option:

- Human parvovirus B19 (causes fifth disease) usually presents with a 'slapped cheek' rash but does not typically have a high fever that breaks before rash onset.

- Hand, foot, and mouth disease presents with fever and rash but the rash is usually vesicular and localized to hands, feet, and mouth, not generalized after fever breaks.

- Roseola (caused by HHV-6) is characterized by a sudden high fever for several days that abruptly ends, followed by the appearance of a rash.

- Rubella and Measles both cause fever and rash, but the rash usually appears while the fever is still present or gradually resolving, not after the fever breaks abruptly.

Step 3: Match the clinical pattern described (high fever for 2 days, fever breaks, then rash appears) to the disease known for this pattern, which is roseola.

Step 4: Conclude that the most likely causative agent is the one associated with roseola, which is human herpesvirus 6 (HHV-6).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Clinical Presentation of Roseola

Roseola, caused by human herpesvirus 6 or 7, typically affects young children and presents with a sudden high fever lasting 3-5 days. After the fever subsides, a characteristic pink maculopapular rash appears, starting on the trunk and spreading. Mild respiratory or gastrointestinal symptoms may precede the fever.

Differential Diagnosis of Febrile Rash in Children

Several viral infections cause fever followed by rash in children, including measles, rubella, parvovirus B19, and hand, foot, and mouth disease. Each has distinct rash patterns, prodromal symptoms, and timing relative to fever, which help differentiate them clinically.

Pathophysiology and Timing of Rash Appearance

In viral exanthems, the rash often appears as the immune system responds to the infection, typically after the fever breaks. Understanding the timing of rash onset relative to fever is crucial for diagnosis; for example, roseola’s rash appears after fever resolution, unlike measles or rubella where rash coincides with or precedes fever decline.

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Related Practice

Textbook Question

Your patient is reminiscing about her childhood diseases while reviewing her medical history. She claims she had a really bad case of rubella (German measles) when she was a child and that she was very sick. You think she is confusing it with rubeola (measles) because:

a. measles can cause congenital rubella syndrome.

b. German measles causes a mild rash and is not likely to make a patient very sick.

c. the largest concern is for secondary infections like pneumonia.

d. she didn’t mention Koplik’s spots in the mouth or raised lesions.

e. the raised red rash usually begins on the trunk and spreads from there.

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Textbook Question

A child comes into your clinic with impetigo. The lab cultures a sample for further analysis. If the sample is S. aureus, which lab results would you expect?

a. Gram-positive cocci in clusters, catalase and coagulase positive

b. Gram-negative diplococci, catalase positive, and coagulase negative

c. Gram-positive cocci in clusters, catalase negative, and coagulase positive

d. Gram-positive cocci in chains, catalase positive, and coagulase negative

e. Gram-positive cocci in chains, catalase negative, and coagulase positive

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Textbook Question

Select the false statement about trachoma:

a. The causative agent is bacterial.

b. It is the leading cause of infectious blindness in the United States.

c. It is transmitted by unhygienic items, such as flies, fingers, and fomites.

d. Uncomplicated cases can be resolved with antibiotics.

e. Severe cases require surgery.

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Textbook Question

Acanthamoeba protozoa species are associated with:

a. keratitis.

b. conjunctivitis.

c. river blindness.

d. trachoma.

e. all of the above.

Textbook Question

Your diabetic patient has a foot wound that has developed into serious necrosis and the recommended treatment has been sessions in the hyperbaric oxygen chamber. You are explaining to him what has contributed to this condition, including the causative agent, which is:

a. Bacillus anthracis.

b. Clostridium perfringens.

c. Corynebacteria diphtheriae.

d. Streptococcus pyogenes.

e. Pseudomonas aeroginosa.

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Textbook Question

A 65-year-old patient calls the nursing hotline to ask about some painful blisters arranged in a band on one side of his waist. After hearing about the lesions, you ask him if he had chickenpox as a child. This is because you feel you are hearing about a case of:

a. candidiasis.

b. measles.

c. herpes.

d. shingles.

e. rubella.

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