Antibiotic resistance is not a modern incidence. Resistant bacteria are ancient. Antibiotics are discovered more than 70 years ago but resistant bacteria existed before the very beginning of human civilization. At the initial stage of antibiotic era, resistant bacteria was not a matter of concern. Now it is a big headache for the scientists. Antibiotic misuse or over use caused this problem.
Mahlon Kline was the first man who begins the novel practice of sending pharmaceutical samples through the mail to doctors across the US.