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Jawetz, Melnick, & Adelberg’s Medical Microbiology, 27e

Chapter 22: Legionella, Bartonella, and Unusual Bacterial Pathogens

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Humans become infected with Legionella pneumophila by

(A) Kissing a person who is a legionella carrier

(B) Breathing aerosols from environmental water sources

(C) Receiving a mosquito bite

(D) Consuming undercooked pork

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

(A) Pasteurella multocida

(B) Streptobacillus moniliformis

(C) Francisella tularensis

(D) Bartonella bacilliformis

(E) Yersinia pestis

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?

(A) Legionella pneumophila serogroup 1

(B) Legionella micdadei serogroup 4

(C) Legionella bozemanii serogroup 2

(D) Legionella longbeachae serogroup 2

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

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

(A) Streptococcus pneumoniae pneumonia

(B) Legionella pneumophila pneumonia

(C) Haemophilus influenzae pneumonia

(D) Mycoplasma pneumoniae pneumonia

(E) All of the above

Routine sputum cultures for the patient grow normal microbiota. Treatment with ampicillin for 2 days yields no improvement. A diagnosis of Legionnaires’ disease is considered, and bronchoscopy is done to obtain bronchial alveolar lavage fluid and deep airway specimens. Which of the following would suggest a diagnosis of disease caused by Legionella pneumophila serotype 1?

(A) Legionella urinary antigen assay

(B) Direct fluorescent antibody on the bronchial alveolar lavage fluid

(C) Culture of the bronchial alveolar lavage on charcoal yeast extract medium with antibiotics

(D) Antibody assay on paired (acute phase and convalescent phase) sera

(E) All of the above

Charcoal is present in buffered charcoal yeast extract agar used to isolate Legionella pneumophila to

(A) Provide the growth factors ordinarily provided by free-living amebas present in environmental water

(B) Serve as a carbon source for the growth of Legionella pneumophila

(C) Prevent hemolysis of the red blood cells in the medium

(D) Provide a dark background

(E) Act as a detoxifying agent

A 23-year-old, otherwise healthy woman presents with a 3-day history of low-grade fever and headache. Examination reveals enlarged and slightly tender lymph nodes near her left elbow and in the left axilla. Approximately 2 weeks earlier, she had visited a friend whose cat had scratched her on the left arm; the site later developed a reddish papule. Which of the following statements about this disease is correct?

(A) Characteristic histopathology in response to infection is acute, neutrophilic inflammation.

(B) The diagnosis is based on a suggestive history and physical examination.

(C) β-Lactam/β-lactamase inhibitor combinations are the agents of choice for treatment.

(D) The diagnosis is based on negative routine bacterial cultures of pus aspirated from involved lymph nodes.

(E) The disease rapidly leads to sepsis even in immunocompetent people.

Which of the following statements about bacillary angiomatosis is most correct?

(A) It is caused by Bartonella bacilliformis.

(B) It is typically confined to the skin.

(C) The major differential diagnosis is Kaposi sarcoma.

(D) The etiologic agent can be grown in 1–2 days in routine culture on sheep blood agar.

(E) Dogs are the reservoir for the etiologic agent.

An important factor in the pathogenesis of Legionnaires’ disease is that

(A) Legionella pneumophila kills polymorphonuclear cells.

(B) Alveolar macrophages phagocytose Legionella pneumophila using coiled pseudopods.

(C) Legionella pneumophila invades pulmonary capillaries, leading to dissemination and systemic illness.

(D) Legionella pneumophila induces alveolar macrophage phagosomes to fuse with lysosomes.

(E) Legionella pneumophila outer surface protein A (OspA) is important for invasion of alveolar macrophages.

True statements regarding Tropheryma whipplei include all of the following except

(A) It is easy to cultivate on chocolate agar after 3 days of incubation.

(B) It is a gram-positive actinomycete.

(C) It causes fever, abdominal pain, diarrhea, weight loss, and migratory polyarthralgia.

(D) It stains with PAS.

All of the statements below regarding infections with Legionella are correct except

(A) Hospitals that care for patients at risk for Legionella infections should know if their potable water systems contain Legionella.

(B) Human-to-human transmission is the major mechanism of transmission of Legionella infection.

(C) Legionella species can be visualized with Gram stain if carbolfuchsin is used for the counter stain.

(D) The chest radiograph of a patient who has Legionella pneumonia is indistinguishable from that of patients with pneumonia caused by other pathogens.

(E) A macrolide or quinolone are the drugs of first choice for treatment of Legionella infections.

Which of the following best represents the role of the Mip protein in Legionella pathogenesis?

(A) It prevents phagosome–lysosome fusion.

(B) It acts as a siderophore to capture iron.

(C) It prevents phagocytosis.

(D) It facilitates adherence to the macrophage and stimulates cellular invasion.

(E) None of the above.

Pontiac fever is a severe form of pneumonia caused by Legionella pneumophila serotypes 1 and 6.

(A) True

(B) False

All of the following statements regarding Streptobacillus moniliformis are correct except

(A) It is susceptible to penicillin.

(B) It causes the disease rat-bite fever.

(C) It causes Haverhill fever from ingestion of contaminated food.

(D) The morphology of the organism is spiral shaped.

The diagnosis of Whipple’s disease is best made by

(A) Paired serum obtained 8 weeks apart

(B) Prolonged culture on mycobacterial media

(C) Nucleic acid amplification testing performed on tissue

(D) Histopathology

(E) None of the above

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Chapter 22: Legionella, Bartonella, and Unusual Bacterial Pathogens

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Chapter 22: Legionella, Bartonella, and Unusual Bacterial Pathogens

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