Deck 22: Anaerobes of Clinical Importance

Question 1

Which of the following is considered a better specimen for anaerobic culture than a swab?

A) Aspirate
B) Washing
C) Scraping
D) Lavage

Answer 1

A

Question 2

All of the following organisms are found on the skin under normal conditions, except

A) Propionibacterium.
B) Peptostreptococcus.
C) Streptococcus.
D) Clostridium.

Answer 2

D

Question 3

What organism mostly commonly causes gas gangrene?

A) Clostridium difficile
B) C. tetani
C) C. perfringens
D) C. botulinum

Answer 3

C

Question 4

All the following are categories of bacterial growth requirements for oxygen and carbon dioxide, except

A) ambient air (95% O₂ and 5% CO₂).
B) microaerophilic (5% O₂).
C) anaerobic (0% O₂).
D) capnophilic (about 15% O₂ and 5% to 10% CO₂).

Question 5

What are two important factors that must be taken into consideration when transporting specimens for anaerobic culture?

A) Making sure there is enough specimen in a tightly closed container
B) Minimum exposure to oxygen and preventing drying out
C) Minimum exposure to oxygen and making sure the specimen is transported in a tightly closed screw-cap container
D) Drying out and proper nutrition

Question 6

What is an obligate anaerobe?

A) An organism that requires some oxygen but moderate concentrations of CO₂ to live
B) An organism that requires small amounts of oxygen and carbon dioxide to live
C) An organism that grows only in the absence of molecular oxygen
D) An organism that can live with very little oxygen

Question 7

Which of the following is characteristic of members of the genus Clostridium?

A) Catalase positive
B) Spore-forming anaerobic bacilli
C) Spore-forming anaerobic cocci
D) Facultative anaerobes

Question 8

Which of the following bacteria is most likely the cause of tooth abscesses?

A) Bacteroides fragilis
B) Porphyromonas asaccharolytica
C) P. gingivalis
D) Mobiluncus

Question 9

What disease does Clostridium botulinum cause?

A) Botulism
B) Tetanus
C) Lyme disease
D) Myonecrosis

Question 10

Anaerobes outnumber aerobes in all of the following locations, except

A) skin.
B) oral cavity.
C) gastrointestinal (GI) tract.
D) genitourinary tract.

Question 11

All the following organisms are found in the GI tract, except

A) Bacteroides.
B) Clostridium.
C) Propionibacterium.
D) Bifidobacterium.

Question 12

What is an anaerobe?

A) An organism that can live with very little oxygen
B) An organism that does not require oxygen to live
C) An organism that requires some oxygen but moderate concentrations of CO₂ to live
D) An organism that requires small amounts of oxygen and carbon dioxide to live

Question 13

Bacterial vaginosis is a synergistic infectious process involving all the following bacteria, except

A) Eubacterium.
B) Bacteroides.
C) Gardnerella.
D) Peptostreptococcus.

Question 14

All of the following are non-spore-forming, anaerobic, gram-positive bacilli, except

A) Actinomyces.
B) Bifidobacterium.
C) Eubacterium.
D) Clostridium.

Question 15

What disease does Clostridium perfringens cause?

A) Botulism
B) Tetanus
C) Food poisoning
D) Toxic shock syndrome

Question 16

The four major groups of anaerobic gram-negative bacilli include all the following, except

A) Bacteroides fragilis.
B) Porphyromonas.
C) Prevotella.
D) Mobiluncus.

Question 17

What disease does Clostridium tetani cause?

A) Botulism
B) Tetanus
C) Food poisoning
D) Myonecrosis

Question 18

What substances do organisms that use oxygen have to protect themselves from superoxide anions?

A) Hyaluronidase and proteases
B) Exotoxins and superoxide dismutase
C) Enterotoxins and lipase
D) Superoxide dismutase and catalase

Question 19

An immunosuppressed patient notices sinus tracts that are draining pus. He also notices that there appear to be small, hard "nuggets" in the pus. What disease is he most likely suffering from?

A) Gas gangrene
B) Pseudomembranous colitis
C) Actinomycosis
D) Myonecrosis

Question 20

An Older adult patient in a nursing home is recovering from bacterial pneumonia. The patient has been on a lengthy regiment of antimicrobial agents. Subsequently, the patient is diagnosed with pseudomembranous colitis. What organism is the most likely cause?

A) Clostridium difficile
B) C. tetani
C) C. perfringens
D) C. botulinum

Question 21

After 24-hour incubation, an SBA from a vaginal culture reveals heavy growth of $\alpha$ -hemolytic, pinpoint, rough colonies. A catalase test is performed, and it is negative. What organism should you suspect?

A) Lactobacillus
B) Diphtheroids
C) Listeria
D) Arcanobacterium

Question 22

All of the following procedures should be performed on clinical specimens to recover anaerobic bacteria, except

A) specimen plating on appropriate tubed and plated media.
B) anaerobic incubation.
C) Kinyoun stain.
D) Gram stain.

Question 23

What is the ideal anaerobic incubation system?

A) Anaerobic chamber
B) Anaerobic jars
C) Anaerobic bags
D) Candle jars

Question 24

How long are anaerobic cultures routinely held in the laboratory?

A) 1 to 2 days
B) 3 to 4 days
C) 5 to 7 days
D) 7 to 9 days

Question 25

How does Clostridium difficile produce pseudomembranous colitis and antibiotic-associated diarrhea?

A) Endotoxin
B) Hyaluronidase
C) Toxin A and toxin B (exotoxins)
D) Protease

Question 26

All of the following are approaches to treating anaerobic infections, except

A) surgical therapy.
B) hyperbaric oxygen.
C) antitoxins.
D) enzyme inactivators.

Question 27

What disk is used to presumptively identify Peptostreptococcus anaerobius?

A) Bile
B) Nitrate
C) Sodium polyanethol sulfonate (SPS)
D) Indole

Question 28

How is the true Gram stain reaction of an anaerobe determined?

A) Special potency disks
B) Shape and colony morphology
C) Aerotolerance
D) Direct fluorescent antibody (DFA)

Question 29

Material from an intestinal abscess produces gray colonies with a brown color in the area around the colonies on a BBE plate incubated anaerobically. There is also a dark precipitate in the medium in the areas of heavy growth. A Gram stain of the colonies reveals gram-negative coccobacilli. What is the presumptive identification of this organism?

A) Bacteroides vulgatus
B) B. fragilis
C) B. pneumoniae
D) B. denticola

Question 30

What is the most common causative agent of gas gangrene?

A) Staphylococcus aureus
B) Neisseria gonorrhoeae
C) Clostridium perfringens
D) Haemophilus influenzae

Question 31

What evidence indicates the presence of anaerobes in cultures?

A) A foul odor upon opening an anaerobic jar or bag
B) Growth on the anaerobic plates, but not on the sheep blood agar (SBA) plates incubated in the CO₂ incubator
C) Colonies on kanamycin-vancomycin laked-blood agar (KVLBA) that fluoresce brick-red under ultraviolet light
D) All of the above

Question 32

All of the following reasons are cited for performing antimicrobial susceptibility testing on anaerobes by the Clinical and CLSI, except

A) to determine the resistance mechanisms in anaerobes.
B) to assist in the management of patients with serious illnesses.
C) to monitor local and regional resistance patterns.
D) to determine susceptibility of anaerobes to new antimicrobials.

Question 33

On egg-yolk agar, Clostridium perfringens will demonstrate:

A) brown to black colonies with a halo
B) bluish-green sheen on surface of colonies
C) off-white precipitate around colonies
D) All of the above

Question 34

A vaginal swab is received for anaerobic culture. How should this request be handled or processed?

A) Plate material to anaerobic plates and incubate
B) Place swab in culture broth and incubate
C) Place swab in sterile saline, vortex, use saline to inoculate anaerobic plates then incubate
D) Contact the physician, this is an unacceptable specimen

Question 35

Gram stains of specimens for anaerobic cultures should be examined for all the following reasons, except

A) the Gram stain reveals various types and relative number of bacteria present.
B) certain morphotypes can provide a presumptive identification and will guide media selection.
C) the Gram stain often reveals the presence of leukocytes.
D) the Clinical and Laboratory Standards Institute (CLSI) guidelines recommend Gram stains on all anaerobic specimens.

Question 36

How are suspected colonies of anaerobes processed?

A) Gram stain morphology and reaction is observed.
B) An aerotolerance test is set up.
C) A pure culture/subculture plate is inoculated and appropriate disks are added.
D) All of the above.

Question 37

An anaerobic culture reveals colonies with a double zone of hemolysis on SBA plate. There was no growth on plates incubated aerobically. The Gram stain of that organism was a boxcar-shaped, gram-positive bacillus. What organism is this?

A) Clostridium perfringens
B) C. difficile
C) C. ramosum
D) C. clostridioiforme