What characteristic is key to identifying Staphylococcus saprophyticus among coagulase-negative Staphylococcus species?

What characteristic is key to identifying Staphylococcus saprophyticus among coagulase-negative Staphylococcus species?

• A. Novobiocin resistance
• B. Coagulase production
• C. Beta-hemolysis on blood agar
• D. Fermentation of mannitol

Answer: (A)

Novobiocin resistance is the distinguishing trait used to separate Staphylococcus saprophyticus from other coagulase-negative Staphylococcus species. In the lab, after confirming a coagulase-negative Staphylococcus is present, you perform a novobiocin disk diffusion test. If the organism grows close to or on the disk, it’s resistant, pointing to S. saprophyticus. If it’s inhibited by novobiocin, it’s typically another coagulase-negative species such as S. epidermidis. This distinction matters clinically because S. saprophyticus is a common cause of uncomplicated urinary tract infections, and recognizing its resistance pattern helps correctly identify the organism. Other features like coagulase production, beta-hemolysis, or mannitol fermentation aren’t reliable alone for differentiating S. saprophyticus from other coagulase-negative Staph.

Novobiocin resistance is the distinguishing trait used to separate Staphylococcus saprophyticus from other coagulase-negative Staphylococcus species. In the lab, after confirming a coagulase-negative Staphylococcus is present, you perform a novobiocin disk diffusion test. If the organism grows close to or on the disk, it’s resistant, pointing to S. saprophyticus. If it’s inhibited by novobiocin, it’s typically another coagulase-negative species such as S. epidermidis. This distinction matters clinically because S. saprophyticus is a common cause of uncomplicated urinary tract infections, and recognizing its resistance pattern helps correctly identify the organism. Other features like coagulase production, beta-hemolysis, or mannitol fermentation aren’t reliable alone for differentiating S. saprophyticus from other coagulase-negative Staph.