This HiDip slide is recommended for total bacterial count and screening urine bacteria. Plate Count Agar, PCA : Recommended for determination of plate counts of microorganisms in food, water, waste water & clinical . Also called as Standard Methods Agar. It is recommended by APHA and FDA for determination of counts. MacConkey Agar - A selective medium for detection of Enterobacteriaceae and is based on lactose fermentation with neutral red as indicator. Sodium taurocholate is the selective agent.