Gram-positive cocci in clusters, catalase positive, tube coagulase negative, novobiocin resistant. Which organism is most likely?

Prepare for the CAMLPR Microbiology Test. Utilize flashcards and engaging multiple-choice questions, each equipped with descriptions and explanations. Ready yourself for an excellent performance!

Multiple Choice

Gram-positive cocci in clusters, catalase positive, tube coagulase negative, novobiocin resistant. Which organism is most likely?

Gran-positive cocci in clusters that are catalase positive point to Staphylococcus species. A tube coagulate test that is negative means it is not Staphylococcus aureus, which is coagulase positive. Among coagulase-negative staphylococci, the key differentiator is antibiotic susceptibility: Staphylococcus saprophyticus is typically resistant to novobiocin, while other coagulase-negative staph (like Staphylococcus epidermidis) are usually susceptible. So this pattern—Staph in clusters, catalase positive, coagulase negative, and novobiocin resistant—best fits Staphylococcus saprophyticus. (Note: Bacillus would be Gram-positive rods, not cocci.)

Gran-positive cocci in clusters that are catalase positive point to Staphylococcus species. A tube coagulate test that is negative means it is not Staphylococcus aureus, which is coagulase positive. Among coagulase-negative staphylococci, the key differentiator is antibiotic susceptibility: Staphylococcus saprophyticus is typically resistant to novobiocin, while other coagulase-negative staph (like Staphylococcus epidermidis) are usually susceptible. So this pattern—Staph in clusters, catalase positive, coagulase negative, and novobiocin resistant—best fits Staphylococcus saprophyticus. (Note: Bacillus would be Gram-positive rods, not cocci.)

More practice questions