Simmons Citrate Agar (Dehydrated) is a solidified medium, modified from Koser citrate medium, used to differentiate Enterobacteriaceae based on their ability to utilize citrate.

It incorporates agar and bromothymol blue, changing from green to bright blue with positive citrate utilization (alkaline reaction), while remaining green if negative.

This medium helps distinguish citrate-positive species like Serratia, Enterobacter, Citrobacter, Klebsiella, Proteus, and Providencia from citrate-negative Escherichia coli, Shigella, Yersinia, Edwardsiella, and specific Salmonella serotypes (e.g., S. typhi, S. paratyphi A). It complies with APHA recommendations.