lecture 10

Question 1

1. Your patient is a 75-year-old man who has smoked cigarettes
   (two packs a day for more than 50 years) and consumed alcoholic
   drinks (a six pack of beer each day) for most of his adult life. He
   now has the signs and symptoms of pneumonia. Gram stain of
   the sputum reveals neutrophils but no bacteria. Colonies appear
   on buffered charcoal yeast (BYCE) agar but not on blood agar.
   Which one of the following bacteria is most likely to be the cause
   of his pneumonia?
   (A) Bordetella pertussis
   (B) Haemophilus influenzae
   (C) Klebsiella pneumoniae
   (D) Legionella pneumophila
   (E) Pseudomonas aeruginosa
2. Regarding the patient in Question 1, which one of the following is
   the best antibiotic to treat the infection?
   (A) Azithromycin
   (B) Ceftriaxone
   (C) Gentamicin
   (D) Metronidazole
   (E) Piperacillin/tazobactam

Answer 1

(D) Legionella pneumophila

(A) Azithromycin

Question 2

3. Your patient is a 6-year-old boy who is complaining that his ear
   hurts. His mother says this began yesterday and that he has a fever
   of 103°F. On physical exam, you see a perforated eardrum that is
   exuding a small amount of pus. Using a swab, you obtain a sample of the pus and do a Gram stain and culture. The Gram stain
   reveals small coccobacillary rods. There is no growth on a blood
   agar plate, but a chocolate agar plate supplemented with X and
   V factors grows small gray colonies. Which one of the following
   bacteria is the most likely cause of his otitis media?
   (A) Bordetella pertussis
   (B) Haemophilus influenzae
   (C) Klebsiella pneumoniae
   (D) Legionella pneumophila
   (E) Pseudomonas aeruginosa

Answer 2

(B) Haemophilus influenzae

Question 3

4. It’s time to play “What’s my name?” I am a small gram-negative
   rod that causes an important respiratory tract disease. I produce
   an exotoxin that ADP-ribosylates a G protein. One remarkable
   feature of my disease is a great increase in lymphocytes. I don’t
   cause disease commonly in the United States now because of the
   widespread use of the vaccine that induces antibodies against five
   of my proteins, one of which is the exotoxin. The identity of the
   mystery organism is mostly likely which one of the following?
   (A) Bordetella pertussis
   (B) Haemophilus influenzae
   (C) Klebsiella pneumoniae
   (D) Legionella pneumophila
   (E) Pseudomonas aeruginosa

Answer 3

(A) Bordetella pertussis

Question 4

5. Your patient is a 75-year-old woman with a 110-pack-year history
   of cigarette smoking who now has a fever of 39°C and a cough
   productive of yellowish sputum. Gram stain of the sputum shows
   small gram-negative rods. There is no growth on blood agar, but
   colonies do grow on chocolate agar supplemented with hemin
   and NAD. Which one of the following bacteria is the most likely
   cause of her pneumonia?
   (A) Bordetella pertussis
   (B) Haemophilus influenzae
   (C) Klebsiella pneumoniae
   (D) Legionella pneumophila
   (E) Pseudomonas aeruginosa

Answer 4

(B) Haemophilus influenzae

Question 5

6. Your patient is a 5-year-old boy with a high fever and signs of
   respiratory tract obstruction. Visualization of the epiglottis shows
   inflammation characterized by marked swelling and “cherry-red”
   appearance. Which one of the following is the best antibiotic to
   treat the infection?
   (A) Ampicillin
   (B) Ceftriaxone
   (C) Doxycycline
   (D) Gentamicin
   (E) Metronidazole

Answer 5

(B) Ceftriaxone