Deck 38: Central Nervous System

Question 1

If you were an organism and wanted to cause meningitis, you would enter through the blood brain barrier located in the:

A) dura mater.
B) subarachnoid space.
C) arachnoid membrane.
D) pia mater.

Answer 1

subarachnoid space.

Question 2

Many infectious agents enter the ear via the

A) auditory canal.
B) tympanic membrane.
C) labyrinth.
D) eustachian tube.

Answer 2

eustachian tube.

Question 3

On the first day of examination of the primary plates of an eye culture from a 10-year-old female, the following results were noted:
BAP: moderate growth of small, alpha-hemolytic colonies showing some depressions in the center of each colony
CHOC: moderate growth of small, colonies showing depressions in the center of each and surrounded by a green zone of discoloration
MAC: no growth
Results of testing of the alpha hemolytic colony:
Gram stain: gram-positive cocci in pairs and short chains
Catalase: no bubbles
Optochin susceptibility: 16 mm
Susceptibility testing on Mueller-Hinton with sheep blood agar against 1 ?g oxacillin: 17 mm
Given the testing results above, this organism is possibly a

A) penicillin-sensitive Streptococcus viridans.
B) penicillin-sensitive Streptococcus pneumoniae.
C) penicillin-resistant Streptococcus viridans.
D) penicillin-resistant Streptococcus pneumoniae.

Answer 3

penicillin-resistant Streptococcus pneumoniae.

Question 4

Which of the following individuals is most prone to meningitis due to Staphylococcus not S. aureus?

A) 5-year-old male who has not received his vaccinations
B) 14-year-old with head trauma from a skateboard accident four weeks ago
C) 14-month-old female with hydrocephalus
D) 20-year-old female college student

Question 5

A 18-year-old female contact lens wearer presents to her eye doctor with severe pain due to keratitis. He treats her empirically with acyclovir for herpes simplex, virus but the infection does not resolve. He should now suspect

A) Chlamydia trachomatis.
B) Neisseria gonorrhoeae.
C) adenovirus.
D) Acanthamoeba spp.

Question 6

Testing on cerebrospinal fluid provides the following results: Cell count: 200 lymphocytes/mm³
Glucose level: 50 mg/dl
Protein level: 100 mg/dl
You would expect these results in an individual with meningitis due to

A) Mycobacterium tuberculosis.
B) West Nile virus..
C) Listeria monocytogenes..
D) either a and b.

Question 7

One causative agent of aseptic meningitis is

A) Cryptococcus neoformans.
B) Acanthamoeba spp.
C) Mycobacterium tuberculosis.
D) herpes simplex virus.

Question 8

After a bad cold, a 47 year old female sees her physician because of hearing loss and severe dizziness with accompanying nausea and vomiting. Which of the following specimens will her physician submit to the microbiology laboratory to confirm the causative agent and diagnosis?

A) Culture is not necessary
B) Blood
C) Nasopharyngeal swab
D) Ocular scrapings

Question 9

Direct antigen testing on cerebrospinal fluid can be of value when

A) used to detect any pathogen other than Streptococcus pneumoniae.
B) there is a history of antibiotic use prior to collection of the CSF.
C) the patient demonstrates normal protein and glucose CSF levels.
D) the individual has received the Hib vaccine.

Question 10

A physician suspects his patient has meningitis due to enterovirus. The viral culture of the cerebrospinal fluid is negative. What additional specimen type might you receive for confirmation of the original diagnosis?

A) Urine
B) Throat swab
C) Blood
D) Brain biopsy

Question 11

A specimen collected via tympanocentesis is received in a capped syringe on evening shift at 4:00 pm. The specimen was placed in the refrigerator until processed at 10:00 pm. The direct Gram stain is provided.
Source: CDC/Dr. Mike Miller
At 24 and 48 hours, the sheep blood, chocolate, and MacConkey agars are all negative for growth. Which of the following best explains the discrepant results?

A) The organism is fastidious.
B) The patient is taking antibiotics.
C) The organism autolyzed.
D) The organism is an anaerobe.

Question 12

You only receive enough intraocular fluid to inoculate one agar plate and a liquid broth. Which of the following would you select to inoculate?

A) Chocolate agar and anaerobic thioglycolate broth
B) Chocolate agar and aerobic thioglycolate broth
C) Sheep blood agar and anaerobic thioglycolate broth
D) Sheep blood agar and aerobic thioglycolate broth

Question 13

A brain biopsy is sent to the microbiology laboratory for aerobic and anaerobic culture. The specimen is in a sterile cup with sterile saline. The patient's diagnosis is listed as a brain abscess. The microbiologist notices the patient name on the handwritten label on the specimen cup does not match the computer labels for the test orders. What action should be taken?

A) Reject the specimen because the names do not match
B) Review and follow the policies and procedures for receipt of a non-recollectable, mislabeled specimen
C) Process the specimen as soon as possible since it is not in an anaerobic transport system
D) Both b and c

Question 14

You receive four tubes of cerebrospinal fluid from a 17-year-old female. Which of the tubes will you select for specimen processing for Gram stain and culture?

A) Tube 1
B) Tube 2
C) Tube 3
D) Tube 4

Question 15

You are given the task of finding ways to save money in the microbiology department. You begin by looking at the reduction of media used for routine cultures. Which of the following situations would be a viable decision for the reduction of media use?

A) Using chocolate agar only for the culture of cerebrospinal fluid
B) Using sheep blood agar only for the culture of cerebrospinal fluid collected via a shunt
C) Using MacConkey agar only for culture of a specimen collected via tympanocentesis
D) Using an aerobic thioglycolate broth only for the culture of intraocular fluid

Question 16

A 4-year-old male is seen by the pediatrician because his ear hurts. The physician notes a bulging and red eardrum. She will

A) collect a specimen via tympanocentesis.
B) treat based on the most likely bacterial pathogens.
C) collect a swab of the ear canal.
D) collect a throat swab.

Question 17

Which of the following situations would warrant contacting the physician with the results immediately?

A) Gram-negative rods observed in vitreous fluid
B) Gram-positive diplococci in tympanocentesis fluid
C) Gram-positive cocci in clusters in cerebrospinal fluid
D) a and c
E) b and c
F) a and b

Question 18

On a hot day in July, an unresponsive 15-year-old male presents with a stiff neck and fever. A cerebrospinal fluid is sent to the microbiology department for routine culture and Gram stain. The results of the direct Gram stain are provided.
Source: CDC and Dr. Norman Jacobs
Which of the following organisms can account for these Gram stain results?

A) Neisseria meningitidis
B) Mycobacterium tuberculosis
C) Naegleria fowleri
D) Herpes simplex virus

Question 19

A clear watery discharge associated with a pink sclera is usually due to

A) Haemophilus aegyptius.
B) Chlamydia trachomatis.
C) allergies.
D) adenovirus.

Question 20

A 2-week-old baby boy is hospitalized with fever, poor feeding, and lethargy. Laboratory results to date include:
Blood cultures: negative to date Cerebrospinal fluid:
4200 WBC/ $\mu$ l with 95% neutrophils Glucose: 2 mg/dl
Protein: 355 mg/dl
Direct Gram stain: few small gram-positive coccobacilli and moderate WBCs
Direct bacterial latex agglutination:
H) influenzae type b, N. meningitidis serogroups A, C, Y, and W135,
S) pneumoniae, Group B Streptococcus, and E. coli K1 - All negative
CSF culture at 24 hours: moderate growth of a gray, white colony with a narrow
Zone of beta-hemolysis
You would expect this organism to be

A) esculin negative.
B) catalase positive.
C) sodium hippurate negative.
D) CAMP negative.

Question 21

A 70-year-old male presents to the emergency room with headache, nausea, fever, lethargy, and confusion over the past three days. A cerebrospinal fluid is sent to the laboratory. Laboratory testing includes:
Direct CSF Gram stain: no organisms seen with rare white blood cells
CSF culture: no growth at 48 hours
Blood culture: no growth at 48 hours
CSF glucose: 60 mg/dl
CSF protein: 62 mg/dl
CSF White blood cell count: 233 lymphocytes
Given these results, what patient history information may be most helpful in
Narrowing down the possible causative agent?

A) Has the patient been exposed to mosquitoes and ticks recently?
B) Has the patient been swimming in fresh water recently?
C) Has the patient recently had the mumps?
D) Does the patient work at a daycare facility?

Question 22

Cerebrospinal fluids should be cultured as soon as they are received. If a spinal fluid is received and there is an unexpected delay in inoculation, which of the following handling methods is acceptable?

A) Hold specimen at 30°C in ambient air
B) Hold specimen in the refrigerator
C) Hold specimen at 37°C in CO₂
D) Hold specimen at - 10°C