Ch. 24 - Microbial Diseases of the Respiratory System

Tortora - Microbiology: An Introduction 14th Edition

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Tortora 14th Edition

Ch. 24 - Microbial Diseases of the Respiratory System

Problem 7

Chapter 24, Problem 7

In San Francisco, ten animal health care technicians developed pneumonia 2 weeks after 130 goats were moved to the animal shelter where they worked. Which of the following is false?
a. Diagnosis is made by a blood agar culture of sputum.
b. The cause is Coxiella burnetii.
c. The bacteria produce endospores.
d. The disease was transmitted by aerosols.
e. Diagnosis is made by complement-fixation tests for antibodies.

Verified step by step guidance

Step 1: Understand the context of the problem. Ten animal health care technicians developed pneumonia two weeks after 130 goats were moved to their shelter. This suggests a zoonotic infection potentially linked to the goats.

Step 2: Identify the causative agent mentioned: Coxiella burnetii. This bacterium is known to cause Q fever, a zoonotic disease often transmitted from goats, sheep, and cattle to humans, primarily via aerosols.

Step 3: Review the characteristics of Coxiella burnetii. It is an obligate intracellular bacterium that forms a spore-like structure but is not a true endospore-forming bacterium like Bacillus or Clostridium species.

Step 4: Analyze the diagnostic methods listed. Blood agar culture of sputum is generally not effective for Coxiella burnetii because it is difficult to culture and requires special cell culture techniques. Instead, serological tests such as complement-fixation tests for antibodies are commonly used for diagnosis.

Step 5: Evaluate the transmission mode. Coxiella burnetii is typically transmitted by inhalation of aerosols contaminated with animal birth products, urine, feces, or milk, which aligns with the aerosol transmission option.

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Key Concepts

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

Coxiella burnetii and Q Fever

Coxiella burnetii is the bacterium that causes Q fever, a zoonotic disease often transmitted from animals like goats to humans. It primarily spreads through inhalation of contaminated aerosols from animal waste or birth products, leading to pneumonia-like symptoms in humans.

Bacterial Endospore Formation

Endospores are highly resistant, dormant structures formed by certain bacteria such as Bacillus and Clostridium species. Coxiella burnetii does not produce true endospores, although it can survive harsh conditions by other means, making the statement about endospore production false.

Diagnostic Methods for Q Fever

Diagnosis of Q fever is typically done using serological tests like complement-fixation or immunofluorescence assays to detect antibodies. Culture of Coxiella burnetii is difficult and hazardous, and blood agar culture of sputum is not a standard diagnostic method for this pathogen.

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Match the following choices to the statement in the question given below:

a. Bordetella pertussis

b. Corynebacterium diphtheriae

c. Legionella pneumophila

d. Mycobacterium tuberculosis

e. None of the above

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List the causative agent, mode of transmission, and endemic area for the diseases histoplasmosis, coccidioidomycosis, blastomycosis, and Pneumocystis pneumonia.

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Which of the following leads to all the rest?

a. Catarrhal stage

b. Cough

c. Loss of cilia

d. Mucus accumulation

e. Tracheal cytotoxin

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Match the following choices to the culture descriptions in questions 3 through 6:

a. Chlamydia

b. Coccidioides

c. Histoplasma

d. Mycobacterium

e. Mycoplasma

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Textbook Question

A patient has been diagnosed as having pneumonia. Is this sufficient information to begin treatment with antimicrobial agents? Briefly discuss why or why not.