Which agar is specifically formulated for the isolation of Yersinia enterocolitica?

B. Cefsulodin-irgasan-novobiocin (CIN) agar is specifically formulated for the isolation of Yersinia enterocolitica, which is an important enteric pathogen. This selective medium contains inhibitors such as cefsulodin and irgasan that suppress the growth of competing flora in fecal samples, allowing for the selective growth of Yersinia species. Additionally, the medium is enriched with novobiocin, which further enhances its effectiveness in isolating Yersinia enterocolitica, particularly from stool specimens and environments where other bacteria might dominate.

The choice of other agars does not target Yersinia enterocolitica effectively; for instance, Thiosulfate-Citrate-Bile Salts-Sucrose (TCBS) Agar is primarily used for isolating Vibrio species and would not be suitable for Yersinia. Buffered charcoal yeast extract is formulated for the growth of fastidious respiratory pathogens like Legionella, not for enteric pathogens. Skirrow's medium is a selective medium for Campylobacter species and would not support the growth of Yersinia enterocolitica. Hence, CIN agar is the correct choice for targeting this specific bacterium.