Health Matters: Antibiotics: The Good, the Bad, and the Ugly


In 1928, Alexander Fleming, Professor of Bacteriology at St. Mary's Hospital in London, discovered the first antibiotic: penicillin. Since then, modern medicine has done an impressive job of developing new and more powerful antibiotics to give our immune systems a fighting chance against the most virulent bacterial microbes.

The thing that makes antibiotics so useful is that they can mostly tell the difference between the healthy cells we want to keep and foreign bacteria cells that make us sick. Antibiotics attack bad bacteria, usually with very little collateral damage. The challenge we face is this: many bacteria are quick to reproduce and adapt when under attack, and when we do not take antibiotics as prescribed, we contribute to the creation of super bugs—bacteria that no longer respond to antibiotics and for which there are no other effective remedies.

When patients stop taking antibiotics as soon as they feel better rather than finishing all the medicine prescribed by their medical provider, they allow the most drug-resistant bacterial microbes to reproduce. The bacteria most susceptible to the antibiotics die first. The ones with some resistance take longer to kill. If patients only take some of their antibiotics, their immune system may be able to fight off the infection while allowing the most resistant bacterial microbes to remain and spread to other hosts, which means the next infection will be harder to treat with the same medication.

When we have a bacterial infection, it’s best if we can choose the antibiotics that most specifically target the kind of bacteria causing the problem. The less collateral damage, the better. Once bacteria become resistant, we either have to depend on our immune system and hope it can prevail without the assistance of medication, or we have to use medication that is either less effective or has worse side effects, including medication that eliminates good bacteria along with the bad.

Did you know most of us have about five pounds of good bacteria in our guts? Science is only just discovering all the ways a healthy gut biome helps us, from reducing inflammation to converting nutrients into fuel for our cells. There’s even evidence that our gut biomes can affect mood and our propensity to gain weight. When antibiotics take out the good bacteria with the bad and leave us with an unhealthy gut biome, we can end up with diarrhea and other negative side effects, so it’s best if we can prevent bacteria from becoming resistant to the antibiotics that cause the fewest problems.

Antibiotics really are amazing. Not only do we use them to help the body fight infection, sometimes antibiotics can be used to prevent infection—for example, when a person has been exposed to the highly contagious bacteria that cause meningitis or pertussis (whooping cough). In that case, medical providers prescribe what are called prophylactic doses.

Even without antibiotics, our immune systems do a great job of identifying and eliminating threats to our health. They do it all day long and usually we are none the wiser. However, sometimes the body’s natural defenses let us know something is amiss—like when we get a fever. In that case, the body heats things up because many bacteria (and viruses) cannot multiply as quickly in higher temperatures. Activities that bolster our natural immune system include eating nutritious meals, exercising regularly, getting enough sleep, and reducing chronic stress.

Modern medicine has grown and changed to become incredibly effective in many ways, but so have the bacteria that make us sick. By taking antibiotics as prescribed, we can help slow the creation of super bugs and continue to enjoy the benefits antibiotics provide.


Jerry Douglas, MD, is the chief medical officer at MCHC Health Centers—a local, non-profit, federally qualified health center offering medical, dental and behavioral health care to people residing in Lake and Mendocino Counties.

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