This HiDip slide is recommended for total bacteria count and isolation and differentiation of lactose fermenting and lactose non fermenting enteric bacteria with inactivation of disinfectant. 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. Mac Medium w/ Neutralizers: A selective medium for detection of Enterobacteriaceae and is based on lactose fermentation with neutral red as indicator. Bile salt mixture and crystal violet are the selective agent. Lecithin , sodium thiosulphate, tween 80 and histidine are the neutralizers.