Bacteria become resistant to antibiotics by becoming familiar to how the drug acts and then changing their structure in order to resist being destroyed by the antibiotic. The more antibiotics a person takes, the easier it is for the germs to accumulate enough stamina to resist the drug effects. The precise way they do this is not exactly understood, else scientists would have been able to keep ahead of the uncanny bacteria that fight back.
Ideally, antibiotics are taken only when absolutely necessary and not randomly for every light illness that causes a fever. Certain drugs are better at certain diseases and while there are broad spectrum group that treat numerous bacterial infections, the only way to know for sure whether a certain drug is right for a particular disease is to test it. An example: Sputum is collected and is mixed with the drug and after a length of time, about three days, a microscopic test will show how the battle went. Are the bacteria still active or have they been killed?
How do germs replenish their arsenal for survival? It takes time. When antibiotics were new in the late forties and early fifties, they were truly a miracle drug. There were no problems. But over time and with over use, and with the relative ease of using drugs to combat even mild bacterial illnesses, the germs managed to change their chemical structure in ways that allowed them to gradually withstand the attack from the converted molds - how penicillin was developed - that almost wiped them out.
In time, not only humans with infections were treated with these new miracle drugs, but so where farm animals that would later end up on tables. In this way, over a period of ten, fifteen, twenty years, an average person had built up a considerable amount of antibodies in their system, and this was readable by the hardiest of the germs. These persons with so much of their system loaded with drugs and the resisters changing their own chemistry to resist, when certain powerful infections occurred, the drugs became inert and useless. The only thing they did was add fuel to their opponents, the bacteria.
Scientist have been kept busy with drugs that are effective but at times it seems to be a losing battle. What they need is an educated public that knows how to build up their own immune systems by healthful diets, by allowing time, rest, and common sense to cure many of the colds, flu like symptoms. Most people know, if the truth be known, that their illness would run its course if they stayed home from work, drank lots of fluids, and rested, and stayed away for others they could infect in the meantime.
Then, when a terrible life threatening disease strikes, and an antibiotic is necessary to save their lives, it will be given and it will be effective. Yet, the public seldom listens. Unfortunately, the newer generations have grown up believing that for every ailment there is a pill, capsule, or an injection that can do away with it. Why should they worry or change their lifestyle? Society is now seeing the results of this lack of knowledge of the human body and its needs, purpose, and is suffering the consequence of its own neglect. Technology and science can race ahead, but what good does it do when the enemy, the enlightened bacteria, is also keeping tract of its potential victims.