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

Chapter 21: Infections Caused by Anaerobic Bacteria

A 55-year-old man visits his physician complaining of a severe cough and production of purulent sputum. His breath has a very unpleasant fetid odor. Chest radiography shows a large amount of fluid in the left pleural space and a 5-cm lung cavity with an air-fluid level. A needle is inserted through the chest wall, and some of the fluid in the pleural space is removed; it is thick, yellow-gray in color, and malodorous. Which of the following organisms or sets of organisms are most likely to be cultured from the pleural fluid?

(A) Bacteroides fragilis, Escherichia coli, and enterococci

(B) Prevotella bivia, peptostreptococci, and Staphylococcus epidermidis

(C) Prevotella melaninogenica, Fusobacterium species, and viridans streptococci

(D) Propionibacterium species, peptostreptococci, and Staphylococcus aureus

(E) Streptococcus pneumoniae

An 18-year-old man develops fever with pain in the right lower quadrant of his abdomen. After initial evaluation, he is taken to the operating room. During surgery, a ruptured appendix with an abscess is found. Bacteroides fragilis is cultured from the abscess fluid. Which of the following factors promote abscess formation by B fragilis?

(A) Lipopolysaccharide

(B) Capsule

(C) Superoxide dismutase

(D) Pili

(E) Leukocidin toxin

Infections caused by Bacteroides species can be treated with all of the following antibiotics except

(A) Ampicillin–sulbactam

(B) Clindamycin

(C) Metronidazole

(D) Penicillin

(E) Cefoxitin

A 17-year-old high school senior develops infectious mononucleosis. About 2 weeks later, he develops a significantly higher fever, a worsening sore throat, an inability to swallow, and severe neck and chest pain. Upon admission, he has signs of sepsis and respiratory distress. What is the most likely organism causing this complication?

(A) Fusobacterium necrophorum

(B) Bacteroides ovatus

(C) Prevotella melaninogenica

(D) Clostridium tetani

(E) Actinomyces israelii

The drug of choice for treatment of infections caused by Actinomyces species is

(A) Tigecycline

(B) Cefoxitin

(C) Metronidazole

(D) Imipenem

(E) Penicillin

All of the following statements regarding anaerobes are true except

(A) They possess the enzyme cytochrome oxidase

(B) Many species are part of the normal human microbiota

(C) They are often found along with aerobes in complicated infections

(D) Special techniques are required to ensure their recovery from clinical specimens

(E) Some species are more tolerant of exposure to oxygen than others

Lemierre’s disease is a serious infection of the head and neck associated with which of the following anaerobes?

(A) Prevotella melaninogenica

(B) Bacteroides thetaiotamicron

(C) Porphyromonas gingivalis

(D) Peptococcus niger

(E) Fusobacterium necrophorum

Definitive identification of an anaerobe is likely best accomplished by

(A) Colony morphology on anaerobic media

(B) The presence of pigment

(C) Susceptibility to a variety of antimicrobial disks

(D) Cell wall fatty acid analysis using gas liquid chromatography

(E) Gram stain morphology

A patient who has not maintained good dentition presents with induration and swelling of the mandibular area. On examination, you note purulent material draining from a small opening. The material appears yellowish, and there are some visible granules. You perform a Gram stain, and pleomorphic gram-positive rods with short branches are noted along with cells suggestive of acute and chronic inflammation. You suspect which of the following organisms?

(A) Bacteroides fragilis

(B) Lactobacillus acidophilus

(C) Clostridium perfringens

(D) Actinomyces israelii

(E) Staphylococcus aureus

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Chapter 21: Infections Caused by Anaerobic Bacteria

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Chapter 21: Infections Caused by Anaerobic Bacteria

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