Deck 18: Aerobic Gram-Negative Cocci

Question 1

The genus Neisseria spp. are gram-negative diplococci that are

A) oxidase and catalase negative.
B) oxidase positive and catalase negative.
C) oxidase negative and catalase positive.
D) oxidase and catalase positive.

Answer 1

oxidase and catalase positive.

Question 2

After 24 hours incubation at 35°C in CO₂, the cystine trypticase agar tubes of an oxidase-positive, gram-negative diplococcus provides the following reactions:
Control tube-yellow
Glucose-yellow
Maltose-yellow
Lactose-yellow
Maltose-yellow
These results

A) indicate a potential pathogen.
B) indicate a nonpathogen.
C) are invalid.
D) should be read again after an additional 24 hours incubation.

Answer 2

are invalid.

Question 3

The end product, indoxyl, appears blue on a paper disk. What enzyme must the organism possess to create this end product?

A) Butyrate esterase
B) Superoxol catalase
C) DNase
D) Beta-galactosidase

Answer 3

Butyrate esterase

Question 4

Thayer-Martin is a selective medium designed to isolate

A) Neisseria gonorrhoeae from normal vaginal flora.
B) Neisseria meningitidis from normal upper respiratory flora.
C) both a and b.
D) neither a nor b.

Question 5

A gram-negative diplococcus, isolated from a purulent inner ear exudate, that produces butyrate esterase will also produce all of the following except

A) beta lactamase.
B) beta-galactosidase.
C) oxidase.
D) DNase.

Question 6

To determine if an individual is a carrier of an oxidase-positive, gram-negative diplococci that is glucose and maltose positive, one should culture the

A) ear.
B) urethra.
C) rectum.
D) nasopharynx.

Question 7

The ability of an oxidase-positive, gram-negative diplococcus to grow on media at room temperature is often associated with

A) Neisseria gonorrhoeae.
B) Neisseria meningitditis.
C) Neisseria cinerea.
D) Moraxella catarrhalis.

Question 8

Which of the following organisms has a strict requirement for CO₂ in order to grow?

A) Neisseria meningitidis
B) N. gonorrhoeae
C) Commensal Neisseria spp.
D) Moraxella catarrhalis

Question 9

A microbiologist arrives at the processing bench to begin her day. Someone had placed the swabs received the previous night in the refrigerator. One was a urethral swab from a 15-year-old male complaining of a penile discharge. The emergency room physician is calling for any preliminary results. Which of the following statements is not appropriate to tell the physician?

A) Neisseria gonorrhoeae cannot be cultured from this swab due to its susceptibility to cold and lack of CO₂.
B) A Gram stain can be performed and, if positive for GNDC, is considered conclusive for gonorrhea.
C) The culture will be processed and results will be available tomorrow.
D) The specimen should be recollected.

Question 10

An oxidase-positive, gram-negative diplococcus produces the following reactions in a set of CTA carbohydrate tubes:
Control-red
Glucose-red
Maltose-red
Lactose-red
Sucrose-red
One would expect to isolate this organism in infections associated with all of the
Following body sites/specimen types except

A) sputum.
B) inner ear.
C) sinus.
D) cerebrospinal fluid.

Question 11

Which of the following oxidase-positive, gram-negative diplococcus relies on its capsule to escape the host's immune system?

A) Butyrate esterase positive
B) Glucose positive
C) Glucose and maltose positive
D) Glucose, maltose, and lactose positive

Question 12

Which of the following patients is most likely to present with meningitis due to Neisseria meningitidis?

A) 19-year-old female college student
B) 3-day-old premature infant male
C) 89-year-old male with pneumonia
D) 33-year-old female with PID

Question 13

Neisseria gonorrhoeae and N. meningitidis share all of the following characteristics except

A) the presence of pili.
B) ability to disseminate.
C) strict pathogen.
D) colisitin resistant.

Question 14

Commensal Neisseria spp. are often recognized by their

A) ability to grow on Thayer-Martin agar.
B) pigment production.
C) sensitivity to colistin.
D) a and b.
E) b and c

Question 15

Which test(s) differentiate Neisseria gonorrhoeae and N. cinerea?

A) Rapid glucose positive
B) Polysaccharide from sucrose
C) Nitrate reduction
D) a and b

Question 16

To differentiate Acinetobacter spp. and Neisseria spp., one could perform a(n)

A) oxidase test.
B) Gram stain.
C) catalase test.
D) review of the colony morphology.

Question 17

A 30-year-old male sees his physician complaining of urinary frequency and burning. A urine and swab of penile discharge were submitted for culture and Gram stain. Review the Gram stain image of the penile discharge. What can be deduced from the penile Gram stain?
Source: CDC and Joe Miller

A) The patient has gonorrhea.
B) The patient probably has a urinary tract infection.
C) There is no need to culture the penile discharge based on the Gram stain.
D) A chocolate agar should be added to the urine culture.

Question 18

A rectal swab from a 58-year-old male is submitted for culture for Neisseria gonorrhoeae. A gray, opaque oxidase positive colony grew on the chocolate and Thayer-Martin agar. The gram-negative diplococcus was weak glucose positive with the CTA carbohydrate tubes. This organism should be

A) identified as N. gonorrhoeae.
B) tested for colistin susceptibility.
C) ignored and reported as normal flora.
D) identified as N. cinerea.

Question 19

An autopsy is performed on a 19-year-old female military recruit. She was healthy 24 hours earlier. Her history was unremarkable, and her vaccinations were up to

A) Moraxella catarrhalis
B) Group A N. meningitidis
C) Group B N. meningitidis
D) Group C N. meningitidis

Question 20

A rectal swab on a 6-year-old male reveals an oxidase-positive, gram-negative diplococcus that grows on chocolate and Thayer-Martin agars. The organism proved to be beta-galactosidase negative, gamma-glutamylaminopeptidase negative, and proline-laminopeptidase positive. Based on these results you would

A) review the colony for pigment production.
B) repeat the identification using a second methodology.
C) report the organism as Neisseria gonorrhoeae.
D) report the organism as normal flora.