Which of the following is commonly used to isolate Streptococcus species?

Blood agar is commonly used to isolate Streptococcus species because it provides a nutrient-rich medium that supports the growth of various bacteria while also allowing for the detection of hemolytic activity. Streptococcus species can exhibit different hemolytic patterns, such as alpha (partial hemolysis), beta (complete hemolysis), or gamma (non-hemolytic), which can be observed on blood agar. This characteristic enables microbiologists to identify and differentiate between various species of Streptococcus based on their hemolytic properties, making blood agar an essential tool in clinical microbiology for diagnosing infections caused by these bacteria.

Chocolate agar, while also supportive of bacterial growth, does not provide the necessary hemolytic properties that are useful for identifying Streptococcus species specifically. MAC agar is selective for gram-negative bacteria, primarily enteric Gram-negative rods, and therefore would not be suitable for isolating Streptococcus species, which are gram-positive. Sabouraud agar is typically used for fungi rather than bacteria and would not be effective for isolating Streptococcus.