Is the disk-diffusion technique measuring bacteriostatic or bactericidal activity?
I will take a guess here and say that it measures the bacteriostatic activity. Why? Well, because the disks used have varying concentrations of the substance whose antimicrobial activity is being investigated… This means that one is interested in checking the concentration of the substance to which the organism is susceptible. After doing this you measure the zone of inhibition of growth present around each disk to determine the level of susceptibility of the organism to the substance in question. For bactericidal activity one would be inclined to use something that gives a range to work with..e.g the tube dilution assays.This tests are more exhaustive. They not only show the minimal inhibitory concentration of a substance but also show whether the substance is merely bacteriostatic or bactericidal. This is done by subculturing broth from those tubes that do not show growth into fresh medium without the test substance(whatever substance whose antimicrobial activity you are looking fo
