Drug Allergies: Penicillin as case study MicroBiotics Admin. December 19, 2013 Food/Industrial/Pharmaceutical Microbiology/Biotechnology, Medical Microbiology/Infections & Diseases/Immunology While the advent of drugs has greatly alleviate the sufferings of man in the hands of various diseases, our immune system may not always agree with all of them chiefly because of the differences in our body make-up.