Q1. Will the omission of the 7.5% NaCl in MSA medium affect its specificity or sensitivity? Explain.
Q2. Will the addition of only 1/10th of mannitol in the MSA medium affect its specificity or sensitivity? Explain.
Q3. In clinical settings, Blood Agar plates are used to detect b-hemolysin producers. Suppose that after processing a patientâs sample, you saw growth on Blood Agar plate, but with no single colonies. Of the areas that showed growth, you observe full clearing of the blood cells. What conclusions would you draw about the presence of the b-hemolysin producers and a-hemolysin producers? Explain.
Q4. On EMB plates, colonies that would normally appear pink may turn into a metallic green shade if left sitting on the plate for multiple days. Explain why that is the case. Is this a specificity or sensitivity problem?
Q5. One of the features that separate E. coli from closely-related species are its ability to ferment lactose very efficiently. (A) If the lactose in the EMB plate is replaced with glucose, will it affect the specificity or sensitivity of the media?
(B) If the amount of lactose in EMB is reduced by 75%, will that impact the specificity or sensitivity of the medium?
Q1. Will the omission of the 7.5% NaCl in MSA medium affect its specificity or sensitivity? Explain.
Q2. Will the addition of only 1/10th of mannitol in the MSA medium affect its specificity or sensitivity? Explain.
Q3. In clinical settings, Blood Agar plates are used to detect b-hemolysin producers. Suppose that after processing a patientâs sample, you saw growth on Blood Agar plate, but with no single colonies. Of the areas that showed growth, you observe full clearing of the blood cells. What conclusions would you draw about the presence of the b-hemolysin producers and a-hemolysin producers? Explain.
Q4. On EMB plates, colonies that would normally appear pink may turn into a metallic green shade if left sitting on the plate for multiple days. Explain why that is the case. Is this a specificity or sensitivity problem?
Q5. One of the features that separate E. coli from closely-related species are its ability to ferment lactose very efficiently. (A) If the lactose in the EMB plate is replaced with glucose, will it affect the specificity or sensitivity of the media?
(B) If the amount of lactose in EMB is reduced by 75%, will that impact the specificity or sensitivity of the medium?
