lecture 12

Question 1

1. Regarding the differences between N. meningitidis (meningococci) and N. gonorrhoeae (gonococci), which one of the following is the most accurate statement?
   (A) Meningococci are oxidase-positive, whereas gonococci are not.
   (B) Meningococci have a thick polysaccharide capsule, whereas
   gonococci do not.
   (C) Meningococci have lipid A, whereas gonococci do not.
   (D) Meningococci produce penicillinase, whereas gonococci do not.
   (E) Meningococci synthesize IgA protease, whereas gonococci do
   not.

Answer 1

(B) Meningococci have a thick polysaccharide capsule, whereas
gonococci do not.

Question 2

2. Your patient is a 14-year-old girl who was sent home from school
   because she had a fever of 102°C and a severe headache and was
   falling asleep in class. When her fever rose to 104°C, her mother
   took her to the emergency room, where a blood pressure of
   60/20 mm Hg and several petechial hemorrhages were found.
   Gram-negative diplococci were seen in a Gram stain of the spinal
   fluid. Which one of the following is most likely to cause the fever,
   hypotension, and petechial hemorrhages?
   (A) Endotoxin
   (B) IgA protease
   (C) Oxidase
   (D) Pilus protein
   (E) Superantigen
3. Regarding the patient in Question 2, which one of the following is
   the best antibiotic to treat the infection?
   (A) Azithromycin
   (B) Doxycycline
   (C) Penicillin G
   (D) Rifampin
   (E) Trimethoprim-sulfamethoxazole

Answer 2

(A) Endotoxin

(C) Penicillin G

Question 3

4. Regarding the differences between N. meningitidis (meningococci) and N. gonorrhoeae (gonococci), which one of the following is the most accurate statement?
   (A) Humans are the reservoir for both organisms.
   (B) Many clinical isolates of meningococci produce β-lactamase,
   but clinical isolates of gonococci do not.
   (C) Meningococci have multiple antigenic types, but gonococci
   have only one antigenic type.
   (D) The conjugate vaccine against gonorrhea contains seven types
   of the pilus protein as the immunogen.
   (E) The main mode of transmission for both organisms is respiratory droplets.

Answer 3

(A) Humans are the reservoir for both organisms.

Question 4

5. Your patient is a 20-year-old man with a urethral exudate. You do
   a Gram stain of the pus and see gram-negative diplococci with
   neutrophils. Which one of the following is the best antibiotic to
   treat the infection?
   (A) Ceftriaxone
   (B) Gentamicin
   (C) Penicillin G
   (D) Trimethoprim-sulfamethoxazole
   (E) Vancomycin

Answer 4

(A) Ceftriaxone

Question 5

1. Your patient is a 20-year-old man with a urethral discharge. Gram
   stain of the pus reveals many neutrophils but no bacteria. You
   suspect this infection may be caused by C. trachomatis. Which
   one of the following is the laboratory result that best supports
   your clinical diagnosis?
   (A) Gram stain of the pus reveals small gram-positive rods.
   (B) The organism produces β-hemolytic colonies on blood agar
   plates when incubated aerobically
   (C) The organism produces α-hemolytic colonies on blood agar
   plates when incubated anaerobically.
   (D) Fluorescent antibody staining demonstrates cytoplasmic
   inclusions in epithelial cells in the exudate.
   (E) There is a fourfold or greater rise in antibody titer against
   C. trachomatis.

Answer 5

(D) Fluorescent antibody staining demonstrates cytoplasmic

Question 6

2. Regarding chlamydiae, which one of the following is the most
   accurate?
   (A) Lifelong immunity usually follows an episode of disease
   caused by these organisms.
   (B) The reservoir host for the three species of chlamydiae that
   cause human infection is humans.
   (C) Their life cycle consists of elementary bodies outside of cells
   and reticulate bodies within cells.
   (D) They can only replicate within cells because they lack the ribosomes to synthesize their proteins.
   (E) The vaccine against C. pneumoniae contains the capsular polysaccharide as the immunogen conjugated to a carrier protein

Answer 6

(C) Their life cycle consists of elementary bodies outside of cells
and reticulate bodies within cells.

Question 7

Which one of the following is the drug of choice for sexually transmitted disease (urethritis, cervicitis) caused by C. trachomatis?
(A) Ampicillin
(B) Azithromycin
(C) Ciprofloxacin
(D) Metronidazole
(E) Rifampin

Answer 7

(B) Azithromycin