Which selective agar is used for isolating Yersinia enterocolitica?

CIN agar, or Cefsulodin-Irgasan-Novobiocin agar, is specifically designed for the isolation of Yersinia enterocolitica, which is a pathogen responsible for gastrointestinal infections. The formulation of CIN agar includes selective agents that inhibit the growth of competing flora present in samples that also contain Yersinia enterocolitica. This selectivity allows the organism to grow without interference from other bacteria.

While MacConkey agar is a selective medium primarily used for the isolation of gram-negative bacteria, it does not specifically favor Yersinia enterocolitica over other enteric organisms. Similarly, blood agar is a rich medium that supports the growth of a wide variety of organisms but lacks the selective properties needed to effectively isolate Yersinia enterocolitica. Chocolate agar, like blood agar, is enriched but not selective, thus allowing a broad range of organisms to grow rather than specifically isolating Yersinia enterocolitica.

In summary, CIN agar's selective characteristics make it the medium of choice for isolating Yersinia enterocolitica, as it effectively suppresses non-target organisms while permitting the growth of the target bacteria.