Deck 22: Anaerobes of Clinical Importance

Question 1

Bacterial growth requirements for oxygen and carbon dioxide can be divided into all the following categories 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).

Answer 1

A
Ambient air is usually 21% O₂ and 1% CO₂.

Question 2

An obligate anaerobe is an organisms that:

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

Answer 2

C
Obligate anaerobes, which grow only in the absence of molecular oxygen, vary in their sensitivity to oxygen.They can be classified as moderate anaerobes and strict anaerobes.Oxygen actually kills obligate anaerobes.

Question 3

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

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

Answer 3

A
Specimens collected by needle and syringe are better for anaerobic bacteriology than those collected by swab.They are less likely to be contaminated by indigenous microflora, including endogenous anaerobes.

Question 4

An anaerobe is an organism that:

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

Question 5

An elderly patient in a nursing home is recovering from bacterial pneumonia.The patient has been on a lengthy regiment of antibiotics to kill the organism causing the disease.A few days later, 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 6

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

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

Question 7

All the following organisms are found in the gastrointestinal (GI) tract except:

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

Question 8

What disease does Clostridium botulinum cause?

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

Question 9

Anaerobes outnumber aerobes in all of the following locations except:

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

Question 10

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 will his doctor most likely diagnose?

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

Question 11

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

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

Question 12

A patient goes to the dentist with an abscess.The physician cultures the tooth.Which of the following bacteria is most likely causing this infection?

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

Question 13

What type of bacteria are in the genus Clostridium?

A)Anaerobic cocci
B)Spore-forming anaerobic bacilli
C)Spore-forming anaerobic cocci
D)Anaerobic bacilli

Question 14

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)Minimizing exposure to oxygen and preventing drying out
C)Minimizing exposure to oxygen and making sure the specimen is transported in a tightly closed screw-cap container
D)Drying out and proper nutrition

Question 15

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

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

Question 16

What organism mostly commonly causes gas gangrene?

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

Question 17

What disease does Clostridium tetani cause?

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

Question 18

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

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

Question 19

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 20

What disease does Clostridium perfringens cause?

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

Question 21

A microbiology technologist is reading an anaerobic plate from an intestinal abscess.There is growth on the Bacteroides bile esculin (BBE) plate: gray colonies with a brown color in the area around the colonies.There is also a dark precipitate in the medium in the areas of heavy growth.The microbiologist Gram stains the colonies and observes gram-negative coccobacilli.What is the presumptive identification of this organism?

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

Question 22

All of the following reasons are cited for performing antimicrobial susceptibility testing on anaerobes by the Clinical and Laboratory Standards Institute (CLSI) except to:

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

Question 23

Aerotolerant anaerobes include all the following except:

A)Clostridium.
B)Bacteroides.
C)Actinomyces.
D)Lactobacillus.

Question 24

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

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

Question 25

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 26

What is the ideal anaerobic incubation system?

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

Question 27

A microbiology technologist is reading an anaerobic culture and observes a double zone of hemolysis on an anaerobically incubated sheep blood agar plate.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.clostridioforme

Question 28

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 29

What disk is used to presumptively identify Peptostreptococcus anaerobius?

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

Question 30

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 may 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 31

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 32

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 33

All of the following techniques are used for making definitive identification of anaerobes except:

A)PRAS and non-PRAS tubed biochemical test media.
B)gas-liquid chromatography of metabolic end products.
C)preexisting enzyme-based minisystems.
D)mass spectroscopy.

Question 34

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.