Ch. 16 - Respiratory System 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. 16 - Respiratory System Infections

Problem 10

Chapter 16, Problem 10

Give two reasons why the bacillus Calmette–Guérin (BCG) vaccine is not routinely recommended in the United States to prevent tuberculosis.

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Understand that the Bacillus Calmette–Guérin (BCG) vaccine is primarily used to prevent tuberculosis (TB), especially severe forms in children.

Recognize that one reason BCG is not routinely recommended in the United States is because the incidence of TB is relatively low, so the risk-benefit ratio does not favor widespread vaccination.

Identify that another reason is that the BCG vaccine can interfere with the interpretation of the tuberculin skin test (TST), which is commonly used in the U.S. for TB screening, leading to false-positive results.

Consider that the BCG vaccine has variable efficacy against pulmonary TB in adults, which is the most common and contagious form of TB in the U.S., reducing its overall utility in this population.

Summarize that due to low TB prevalence, interference with diagnostic tests, and variable vaccine efficacy, the U.S. public health policy does not recommend routine BCG vaccination.

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Key Concepts

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

BCG Vaccine and Its Purpose

The Bacillus Calmette–Guérin (BCG) vaccine is derived from a weakened strain of Mycobacterium bovis and is primarily used to protect against tuberculosis (TB). It is most effective in preventing severe forms of TB in children, such as TB meningitis and miliary TB, but its efficacy against pulmonary TB in adults varies widely.

Tuberculosis Epidemiology in the United States

In the United States, the incidence of tuberculosis is relatively low compared to many other countries. Due to effective public health measures, including screening and treatment of latent TB infections, routine BCG vaccination is not considered necessary for the general population.

Interference with Tuberculin Skin Test (TST)

BCG vaccination can cause false-positive results in the tuberculin skin test, which is commonly used in the U.S. to detect latent TB infection. This interference complicates TB diagnosis and surveillance, making the vaccine less practical for routine use in low-incidence settings.

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Related Practice

Textbook Question

The __________ vaccine is a childhood vaccine to protect against tetanus, diphtheria, and pertussis; in contrast, the __________ vaccine is a booster shot recommended for adolescents and adults to protect against tetanus, diphtheria, and pertussis.

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Textbook Question

List the three stages of pertussis, and provide some general characteristics of each stage.

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Textbook Question

Rapid diagnosis and treatment of streptococcal pharyngitis (strep throat) are important mainly because

a. Streptococcal pharyngitis is painful.

b. Streptococcal pharyngitis is highly contagious.

c. Failure to treat streptococcal pharyngitis can compromise the efficiency of the DTaP vaccine.

d. Streptococcal pharyngitis can cause certain autoimmune complications.

e. Not treating streptococcal pharyngitis leads to antibiotic resistance.

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Textbook Question

Indicate the true statements, and then correct the false statements so that they are true.

a. The most common viruses that cause human respiratory system infections are cold viruses.

b. Viruses can be treated with antibiotics.

c. People who have been exposed to cold and/or wet conditions are statistically more likely to develop a cold.

d. Many respiratory illnesses that are not caused by influenza viruses have flu-like symptoms.

e. The flu vaccine is not recommended for children under 2 years of age.

f. Pneumonia is a rare healthcare-acquired infection.

Match the following:

Choose the general agent of the disease (select ONE choice of agent from the options after each illness):

a. Pneumococcal pneumonia is caused by a (virus, bacterium, fungus).

b. Pneumocystis pneumonia is caused by a (virus, bacterium, fungus).

c. Tuberculosis is caused by a (virus, bacterium, fungus).

d. Histoplasmosis is caused by a (virus, bacterium, fungus).

e. Influenza is caused by a (virus, bacterium, fungus).

f. Colds are caused by (viruses, bacteria, fungi).

g. Coccidioidomycosis is caused by a (virus, bacterium, fungus).

h. Diphtheria is caused by a (virus, bacterium, fungus).

i. Pertussis is caused by a (virus, bacterium, fungus).

j. Scarlet fever is caused by a (virus, bacterium, fungus).

k. Legionellosis is caused by a (virus, bacterium, fungus).

l. Q fever is caused by a (virus, bacterium, fungus).

m. Hanta pulmonary syndrome is caused by a (virus, bacterium, fungus).

n. Streptococcal pharyngitis is caused by a (virus, bacterium, fungus).

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