Culture Media MCQs

Q. Each of the following statements concerning the Gram stain is correct except: Mycobacterium tuberculosis stains blue because it has a thick lipid layer Escherichia coli stains pink because it has a thin peptidoglycan layer Streptococcus pyogens stains blue because it has a thick peptidoglycan layer Mycoplasma pneumoniae is not visible in the Gram’s stain […]

Q. The identification of bacteria by serologic tests is based on the presence of specific antigens. Which of the following bacterial components is least likely to contain useful antigens? Ribosomes Cell wall Capsule Flagella Answer: Ribosomes

Q. The cogulase test is used to differentiate Staphylococcus aureus from Staphylococcus epidermidis Streptococcus pyogens from Enterococcus faecalis Staphylococcus epidermidis from Neisseria meningitidis Streptococcus pyogens from Staphylococcus aureus Answer: Staphylococcus aureus from Staphylococcus epidermidis

Q. Which of the following bacteria has the lowest 50% infective dose (ID50)? Shigella sonnei Campylobacter jejuni Salmonella typhi Vibrio cholerae Answer: Shigella sonnei