Ch. 21 - Microbial Diseases of the Skin and Eyes

Tortora - Microbiology: An Introduction 14th Edition

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Tortora 14th Edition

Ch. 21 - Microbial Diseases of the Skin and Eyes

Problem 4

Chapter 21, Problem 4

A 12-year old boy had a fever, rash, headache, sore throat, and cough. He also had a macular rash on his trunk, face, and arms. A throat culture was negative for Streptococcus pyogenes.
All of the following are complications of this disease except
a. Middle ear infections.
b. Pneumonia.
c. Birth defects.
d. Encephalitis.
e. All are complications of this disease.

Verified step by step guidance

Step 1: Identify the disease based on the symptoms provided: fever, rash (macular on trunk, face, and arms), headache, sore throat, cough, and a negative throat culture for Streptococcus pyogenes. These symptoms are characteristic of measles (rubeola).

Step 2: Review common complications associated with measles. These typically include middle ear infections, pneumonia, and encephalitis, which are known to occur due to the viral infection and secondary bacterial infections.

Step 3: Understand that birth defects are generally not a complication of measles infection in a child; however, congenital infections like rubella can cause birth defects. Measles itself is not linked to causing birth defects.

Step 4: Compare each option to the known complications of measles: middle ear infections (yes), pneumonia (yes), birth defects (no), encephalitis (yes).

Step 5: Conclude that the exception (the complication not associated with this disease) is birth defects, as measles does not cause congenital abnormalities.

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Key Concepts

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

Clinical Presentation of Viral Exanthems

Viral exanthems are diseases characterized by fever and widespread rash, often accompanied by symptoms like headache, sore throat, and cough. Recognizing the pattern of rash distribution and associated symptoms helps differentiate viral infections from bacterial causes, such as Streptococcus pyogenes, which was ruled out by a negative throat culture.

Complications of Viral Exanthems

Certain viral exanthems can lead to complications including middle ear infections, pneumonia, and encephalitis due to secondary bacterial infections or direct viral effects. However, some complications like birth defects are specific to infections during pregnancy and are not typical outcomes in pediatric cases.

Differential Diagnosis and Exclusion of Streptococcal Infection

A negative throat culture for Streptococcus pyogenes excludes streptococcal pharyngitis, guiding diagnosis toward viral causes. This distinction is crucial because treatment and potential complications differ significantly between bacterial and viral infections.

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Differential Staining

Related Practice

Textbook Question

A patient has conjunctivitis. If you isolated Pseudomonas from the patient’s mascara, you would most likely conclude all of the following except that

a. The mascara was the source of the infection.

b. Pseudomonas is causing the infection.

c. Pseudomonas has been growing in the mascara.

d. The mascara was contaminated by the manufacturer.

e. All of the above are valid conclusions.

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Textbook Question

A 12-year old boy had a fever, rash, headache, sore throat, and cough. He also had a macular rash on his trunk, face, and arms. A throat culture was negative for Streptococcus pyogenes.

The boy most likely had

a. Streptococcal sore throat.

b. Measles.

c. Rubella.

d. Smallpox.

e. Hand-foot-mouth disease.

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Textbook Question

You microscopically examine scrapings from a case of Acanthamoeba keratitis. You expect to see

a. Nothing.

b. Viruses.

c. Gram-positive cocci.