Deck 66: Bloodstream Infections

Question 1

A 76-year-old man with intermittent fevers has blood cultures drawn three times.The second set is positive and grew out of a Corynebacterium spp.This organism is considered:

A)pathogenic.
B)virulent.
C)a contaminant.
D)normal flora.

Answer 1

C
Growth of Bacillus spp. ,Corynebacterium spp. ,Propionibacterium acnes,or coagulase-negative staphylococci in one of several cultures should be considered a probable contaminant.

Question 2

In the case of infants and small children,how much blood is usually drawn for bacterial culture?

A)0.5 mL
B)1 mL
C)1 to 5 mL
D)No more than 10 mL

Answer 2

C
For infants and small children,only 1 to 5 mL of blood should be drawn for bacterial culture.

Question 3

Brucella infections usually result in which type of bacteremia?

A)Transient
B)Intermittent
C)Continuous
D)Spontaneous

Answer 3

C
In septic shock,bacterial endocarditis,and other endovascular infections,organisms are released into the bloodstream at a fairly constant rate (continuous bacteremia).In addition,during the early stages of specific infections,including typhoid fever,brucellosis,and leptospirosis,bacteria are continuously present in the bloodstream.

Question 4

The possibility of an abscess should be considered if this bacterial group is isolated in the blood:

A)Clostridium septicum.
B)Bacteroides fragilis.
C)Streptococcus anginosus.
D)Aeromonas hydrophila.

Question 5

A patient who has an existing heart condition has dental surgery but neglects to inform her dentist of this disorder.She later develops endocarditis as a consequence of the procedure.Which of the following organisms most likely caused endocarditis?

A)Escherichia coli
B)Staphylococcus aureus
C)Streptococcus mutans
D)Pseudomonas aeruginosa

Question 6

If tachyzoites are found circulating in blood,then the infection would be classified as a:

A)parasitemia.
B)bacteremia.
C)viremia.
D)fungemia.

Question 7

A 26-year-old woman who has a Gardnerella vaginalis infection becomes immunocompromised,which causes the organism to enter the bloodstream.She has several fever spikes;therefore blood cultures are drawn and placed in blood culture media containing sodium polyanethol sulfonate (SPS).After 5 days of incubation,the blood cultures are negative.Which of the following statements explains this discrepancy?

A)G.vaginalis stays localized in the female genital tract and does not enter the bloodstream.
B)The blood culture media is most likely expired.
C)The automated blood culture system is most likely not correctly functioning.
D)G.vaginalis is usually inhibited by this anticoagulant,making recovery difficult.

Question 8

Which virus found in the blood involves infecting certain T lymphocytes and possibly macrophages?

A)Cytomegalovirus (CMV)
B)Epstein-Barr virus (EBV)
C)Rubella virus
D)Human immunodeficiency virus (HIV)

Question 9

A 36-year-old emergency medical technician (EMT)is exposed to a patient with brucellosis.Blood cultures are drawn from the EMT and reported as negative after 1 week.Which of the following statements explains this discrepancy?

A)The blood culture system is most likely not correctly functioning.
B)Brucella does not grow in the blood.
C)The blood culture bottles are most likely expired.
D)The blood should have been incubated for a minimum of 3 weeks.

Question 10

Granulicatella spp.and Abiotrophia spp.are dependent on which nutritional additive for optimal growth?

A)Vitamin K
B)Vitamin B₆
C)Vitamin B₁₂
D)Vitamin D

Question 11

The BACTEC automated blood culture system detects organisms by monitoring a rise in carbon dioxide (CO₂)levels using which type of sensor?

A)Fluorescence
B)Colorimetric
C)Isotopic
D)Saponin

Question 12

A consequence of sepsis is disseminated intravascular coagulation (DIC),which is characterized by numerous small blood vessels becoming clogged with clotted blood and bleeding as a result of the depletion of coagulation factors.Although any circulating pathogen can cause DIC,it is most often a consequence of ________ sepsis.

A)fungal
B)viral
C)gram-positive
D)gram-negative

Question 13

Saponin,polypropylene glycol,SPS,and ethylenediaminetetraacetic acid (EDTA)are all components in which blood culture system?

A)BACTEC system
B)BacT/ALERT system
C)ESP system
D)Lysis centrifugation system

Question 14

Patients receiving lipid-supplemented parenteral nutrition are at risk for developing fungemia caused by which organism?

A)Histoplasma capsulatum
B)Malassezia furfur
C)Coccidioides immitis
D)Candida albicans

Question 15

The most common portal of entry for bacteremia is:

A)the genitourinary tract.
B)the respiratory tract.
C)an abscess.
D)the biliary tract.