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Chapter 22: Legionella, Bartonella, and Unusual Bacterial Pathogens

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Humans become infected with Legionella pneumophila by

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(A) Kissing a person who is a legionella carrier

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(B) Breathing aerosols from environmental water sources

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(C) Receiving a mosquito bite

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(D) Consuming undercooked pork

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An 11-year-old girl developed an acute onset of fever, chills, headache, vomiting, and severe migratory arthralgias (joint pain) and myalgias (muscle pain). Two days later, she developed a maculopapular rash over her palms, soles, and extremities. At the same time, her left knee became extremely painful and swollen. On examination, fluid was demonstrated in the knee. Further history disclosed that the patient had a pet rat. Culture of the fluid from her knee on 5% sheep blood agar showed 2-mm colonies after 3 days of incubation. Broth culture showed small puffball-like growth. Gram staining showed a gram-negative bacillus 0.5 μm wide and 1–4 μm long. Some extremely long forms (up to 150 μm) with beadlike chains, fusiform swellings, and large round bodies were seen. The microbiologist who observed the Gram-stained smear immediately knew the cause of the girl’s infection to be

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(A) Pasteurella multocida

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(B) Streptobacillus moniliformis

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(C) Francisella tularensis

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(D) Bartonella bacilliformis

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(E) Yersinia pestis

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A 70-year-old man presents with bilateral pneumonia. His Legionella urinary antigen test result is positive. Which of the following is the likely cause of his pneumonia?

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(A) Legionella pneumophila serogroup 1

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(B) Legionella micdadei serogroup 4

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(C) Legionella bozemanii serogroup 2

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(D) Legionella longbeachae serogroup 2

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(E) All of the above because the urinary antigen test is genus specific and not species or serotype specific.

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A 65-year-old man comes to the emergency department feeling feverish and “really tired.” He has a chronic cigarette cough, but this has dramatically increased in the past week and he has been producing whitish sputum. The previous day he had a temperature of 38°C and watery diarrhea. Physical examination reveals inspiratory and expiratory wheezes and rales over the right lower lung field. Chest radiography shows a patchy right lower lobe infiltrate. The differential diagnosis of this patient’s disease is

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(A) Streptococcus pneumoniae pneumonia

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(B) Legionella pneumophila pneumonia

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