@anon144463 - I agree. This definitely helps to explain why it is dangerous to use broad-spectrum antibiotics without medical supervision.
Some people use antibiotics that were previously prescribed for another infection. Some people get broad-spectrum antibiotics from Canada or Mexico without a prescription and self medicate without adequate information.
The final result is that new strains of antibiotic resistant bacteria develop and thrive from the misuse and overuse of these meds. Then, when you really need the medicine to kill the bacteria, it won't work.
The bacteria has made itself stronger than the antibiotic because it had the opportunity to become familiar with the potency of the medicine (so to speak).