Part XVIa. Infectious Disease

Question 1

The presence of ____ per low-power field in a sputum specimen is highly suggestive of a specimen contaminated with oral secretions.

Answer 1

more than 10 epithelial cells

Question 2

What is a rapid and accurate technique that is based on generating a protein fingerprint of an organism and comparing that fingerprint to a library of known organisms to produce an identification?

Answer 2

Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS)

Question 3

This solution dissolves cellular and organic debris and facilitates detection of fungal elements in clinical specimens.

Answer 3

Potassium hydroxide (KOH)

Question 4

This stains stool specimens for identification of protozoa.

Answer 4

Trichrome stain

Question 5

This is added to wet preparations of fecal specimens for ova and parasites to enhance contrast of the internal structures (nuclei, glycogen vacuoles)

Answer 5

Lugol iodine stain

Question 6

Differential time to positivity of ____ or more between paired blood cultures drawn simultaneously from a catheter and peripheral vein has been cited as an indicator of catheter-related bloodstream infection.

Answer 6

2 hrs

Question 7

The optimal amount of blood to collect from a pediatric patient varies depending on the weight of the child. The Clinical and Laboratory Standards Institute (CLSI) and Cumitech provide guidance on the amount of blood that is safe to collect from children of different sizes. Give the suggested amount of blood to be collected in each of the ff weight groups.
a. 3 to < 12kg
b. 12 to < 36kg
c. 36 to < 50kg
d. > 50kg

Answer 7

a. 3-5 ml
b. 5-10 ml
c. 10-15 ml
d. 20 ml

Question 8

CSF is routinely cultured on what?

Answer 8

Blood agar and chocolate agar

Question 9

What are the organisms most frequently isolated from shunt infections?

Answer 9

Propionibacterium and coagulase- negative staphylococci

Question 10

colony count used to define growth as significant in a urine culture by suprapubic aspirate?

Answer 10

any growth

Question 11

colony count used to define growth as significant in a urine culture by catheterization?

Answer 11

≥10^3 to 10^4 organisms/mL

Question 12

colony count used to define growth as significant in a urine culture by clean-voided urine?

Answer 12

≥10^4 to 10^5 organisms/mL

Question 13

Cultures for Bordetella pertussis can be obtained by aspiration or swabbing of the nasopharynx using a ____ swab.

Answer 13

Dacron or calcium alginate swab.

Question 14

The diagnosis of pulmonary tuberculosis in young children is best made by?

Answer 14

culture of early-morning gastric aspirates, obtained on 3 consecutive days.