The transfer of penicillinases between cells can occur by conjugation. The diagram below was used to illustrate a number of points about sulfonamide resistance. Sulfonamides block the folate synthase by a process of non-competitive inhibition. The organism can overcome this blockade by increasing production of para-aminobenzoic acid. Humans are intrinsically resistant to sulfonamides.
Transformation requires the pre-existence of a resistance gene.
Transformation is a laboratory curiosity easily shown with Pseudomonas, but is not thought to be a clinically relevant process by which resistance occurs. The replica plate experiment is rationalized based on transformation. The year is now 2050. The majority of Staph strains are still susceptible to Pen G. Staph are intrinsically resistant to Pen G. Staph are acquiring resistance to Pen G through mutation. Staph are acquiring resistance to Pen G through transduction.