I need to quantify the Antibiotic Resistant Bacteria(ARB) and Total Heterotropic Bacteria(THB) in my samples. I had spread plated a few samples at a serial dilution of 10-4 and found numerous colonies within 24 hours. For enumeration of ARB I will spread plate a serial dilution of 10-4 in antibiotic supplenented medium and incubate for 72 hours as further serial dilutions may lead to loss of ARB. Can I plate a serial dilution of 10-6 in media without antibiotic to quantify THB as the time for incubation has to be the same (i.e 72 hours) for both ARB and THB for comparative analysis?