Microbiology Flashcards
6 cards from real Medical Technologist Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Microbiology flashcards as text
Which culture medium is selective for gram-negative enteric bacteria?
Answer: MacConkey agar
MacConkey agar contains bile salts and crystal violet that inhibit gram-positive organisms while supporting gram-negative growth.
A positive catalase test followed by a positive coagulase test identifies which organism?
Answer: Staphylococcus aureus
Catalase-positive and coagulase-positive results are the key biochemical tests identifying S. aureus among staphylococci.
Which stain is used to visualize acid-fast bacilli such as Mycobacterium tuberculosis?
Answer: Ziehl-Neelsen (carbol fuchsin) stain
The Ziehl-Neelsen stain uses carbol fuchsin retained by mycolic acid in the cell wall of acid-fast organisms despite acid-alcohol decolorization.
Colonies with a green metallic sheen on EMB agar are characteristic of which organism?
Answer: Escherichia coli
E. coli produces a green metallic sheen on eosin methylene blue (EMB) agar due to strong lactose and acid production.
Which organism is the MOST common cause of community-acquired pneumonia in the US?
Answer: Streptococcus pneumoniae
Streptococcus pneumoniae (pneumococcus) remains the leading bacterial cause of community-acquired pneumonia in all age groups.
A negative urease test, positive indole test, and positive oxidase test best describes which organism?
Answer: Vibrio cholerae
Vibrio cholerae is oxidase-positive, indole-positive, and urease-negative, distinguishing it from other enteric pathogens.