Why is it important to get a bacterial lawn rather than colonies for a bacitracin susceptibility test?
Bacitracin is rarely tested for standardized susceptibility because it is too toxic for routine in vivo use. It is commonly tested as a screening method to quickly recognize certain streptococci and with this method a lawn is seldom used because it would take too long to prepare and would not be cost effective. It is true however that without a standardized lawn, the results are not as reliable and if this drug was to be used in vivo, it would require a more accurate test method such as Kirby-Bauer’s.
