A lower animal that spreads a zoonotic disease but doesn't participate in its actual transmission. A human who is clinically ill and shedding the infectious agent. A non-living agent which carries an infectious agent. A human who is asymptotic but is capable of shedding an infectious agent. A lower animal that is a participant in the spread of a zoonotic disease.
Humans are intrinsically resistant to penicillins.
The replica plate experiment describes the behavior of an intrinsically resistant microbial culture. The graph shows the development of Penicillin G-resistant strains over time. The trend seen with Staphylococcus is based upon genetic transfer of resistance information by conjugation with selection eliminating susceptible strains. Even back in the 1940's there were Staphylococcal strains resistant to Pen G. 7. Mathematical analysis demonstrated that this could not have occurred by mutation.