Multiple Choice
Which mechanism of antibiotic resistance is shared by both methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA)?
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1. Introduction to Microbiology
Introduction to Bacteria
Multiple Choice
Which type of agar plate is most commonly used to streak a wound culture for the isolation of bacteria?
A
MacConkey agar
B
Mannitol salt agar
C
Sabouraud dextrose agar
D
Blood agar
Verified step by step guidance1
Understand the purpose of streaking a wound culture: it is to isolate and grow bacteria present in the wound to identify the causative agent of infection.
Review the characteristics of each agar type: MacConkey agar is selective for Gram-negative bacteria and differentiates lactose fermenters; Mannitol salt agar is selective for Staphylococci due to high salt concentration and differentiates mannitol fermenters; Sabouraud dextrose agar is used primarily for fungi.
Recognize that blood agar is a nutrient-rich, non-selective medium that supports the growth of a wide variety of bacteria, including many pathogens commonly found in wounds.
Note that blood agar also allows observation of hemolysis patterns, which can help in identifying bacterial species based on their ability to lyse red blood cells.
Conclude that blood agar is the most commonly used agar plate for streaking wound cultures because it supports broad bacterial growth and provides useful diagnostic information.
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