A $0.5 \mathrm{McF}$ Arland Standard Is Used in All Microbiology Labs When Performing

question 21

Multiple Choice

A $0.5 \mathrm{McF}$ arland standard is used in all microbiology labs when performing a Kirby-Bauer assay. This standard allows for a visual turbidity reading to achieve reproducibility in the number of bacteria inoculated on a plate. This is most important because:

• A) multiple antibiotics testing requires that bacteria be spread evenly around the plate
• B) the MIC value can only be achieved by serial dilutions
• C) number of organisms placed on an agar surface is inversely proportional to the size of the zone of inhibition
• D) bacterial counts need to be the same across all labs since incubation times can differ
• E) bacterial counts need to be the same across all labs since plate sizes in this assay can differ

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