When Should I Take Antibiotics?
An infectious disease expert explains bacterial infections, when antibiotics should be prescribed, and the implications of antibiotic resistance.
While most bacteria found in the environment and our bodies — such as on the skin and in the gut — are harmless (and can even be helpful), a small fraction can cause infections.
“Bacteria are single-celled organisms that can reproduce quickly and become infectious,” says Dr. David M. Goldberg, an internal medicine physician at NewYork-Presbyterian Medical Group Westchester. “There are many different types of bacterial infections, including pneumonia, which causes the air sacs in your lungs to fill up with fluid or pus; urinary tract infections; and infections of the nervous system, such as meningitis (inflammation of the lining around the brain and spinal cord).”
Bacteria, the source of bacterial infections, have the capacity to live on their own, while viruses, the source of viral infections like the common cold, are pieces of RNA or DNA wrapped in a coat and cannot live independently. Bacterial infections can be treated with antibiotics, which don’t work on viruses.
According to the Centers for Disease Control and Prevention (CDC), about 5 out of 6 people are prescribed an antibiotic each year and at least 30% of antibiotic use is unnecessary. “As we give more antibiotics, the bacteria become more resistant,” says Dr. Goldberg. “The bacteria learn to avoid effects of the antibiotics.” Recently, the CDC released a report that found that infection rates from a drug-resistant bacteria called NDM-CRE — nicknamed “nightmare bacteria” — rose by more than 460% between 2019 and 2023.
Health Matters spoke with Dr. Goldberg to learn more about bacterial infections, how best to treat them, and what to know about antibiotic resistance.
Dr. David Goldberg
When should someone take an antibiotic?
Dr. Goldberg: Antibiotics are an effective treatment that saves lives, but they’re not always the answer. The first questions a doctor asks are: what kind of bacterial infection is it and how serious is the infection? Some cases can resolve without treatment, but others may need to be treated with antibiotics.
For example, urinary tract infections can get better on their own, especially in healthy young people, by simply drinking lots of fluids. But other bacterial infections need to be treated to prevent complications. For example, if left untreated, strep throat can lead to rheumatic fever, a condition that causes inflammation in the heart, blood vessels, and joints.
Another scenario is pelvic inflammatory disease, an infection of the female reproductive organs, usually caused by sexually transmitted organisms such as chlamydia and gonorrhea. Pelvic inflammatory disease should be treated with antibiotics, even if mild, since the infection may lead to infertility.
For certain vulnerable populations, like people who have weak immune systems or have other comorbidities, such as cancer, even if they are given the right antibiotics, they may not recover. And in general, some bacteria have become resistant to antibiotics, so doctors have to be careful in prescribing them correctly and patients need to take them exactly as prescribed.
How do antibiotics work?
Think of the healing process from a bacterial infection as a tug of war between the bacteria and our immune system. The antibiotics add one extra player to our side, and that can help pull someone over the line. But it is not the antibiotics doing it by themselves. It is a battle between the bacteria and the immune system. Antibiotics give us a hand by killing the bacteria or slowing their growth.
There are two kinds of antibiotics: bactericidal and bacteriostatic. Bactericidal antibiotics kill the bacteria, while ones that are bacteriostatic make the bacteria static (slows their growth). Static antibiotics can work perfectly well — simply suppressing the bacteria from growing is enough because we have an immune system.
It’s important to note that antibiotics do not work on viral infections, like cold, flu, and COVID.
Are antibiotics administered differently, depending on the case?
It is usually oral, but every now and then there is an infection that needs to be treated with intravenous antibiotics. In most cases, the blood levels of antibiotics are much higher if given intravenously than if given orally, since the antibiotic may not be fully absorbed when given by mouth. If someone is seriously ill, and we want to make sure they have high levels of antibiotics, or if someone is unable to take oral antibiotics because of vomiting or some other reason, we give it to them intravenously.
Sometimes you can give an antibiotic topically, meaning by a cream, especially for certain skin infections. Occasionally, antibiotics are given as a nebulizer, as inherent to the lungs or the nose; that is much less common.
What is Antibiotic Resistance?
According to the CDC, antibiotic resistance occurs when bacteria or fungi no longer respond to the drugs that were made to remove them, meaning that they continue to grow. In the U.S., about 2.8 million people have bacterial infections that are resistant, resulting in more than 35,000 deaths.
The CDC’s recent report on the rise of nightmare bacteria found that the infections — which include pneumonia, bloodstream infections, urinary tract infections, and wound infections — were extremely hard to treat and resistant to some of the strongest antibiotics available. According to the CDC, the increase in nightmare bacteria, “means we face a growing threat that limits our ability to treat some of the most serious bacterial infections.”
Dr. Goldberg says that before he prescribes antibiotics he discusses the severity of the infection with the patient, goes over their health history, and addresses the side effects of the antibiotics. “These are reasons that can help a doctor decipher whether or not to prescribe and reasons that can help a patient know if they should take antibiotics,” he says.
What are the side effects of antibiotics?
There can be many side effects. The most important is probably an allergic reaction. People can swell up and have trouble breathing. There are also milder side effects, such as diarrhea, nausea, and a rash.
There’s quite a large number of antibiotics. And that is good news. Back in the 1940s, all we had was penicillin. And now we have many types (or classes of antibiotics). Even if you are allergic to one class of antibiotics or even two or three, there is almost always another antibiotic that you can get
What are sepsis and septic shock? Can bacterial infections lead to these conditions?
Sepsis is a serious reaction to infection that is life-threatening and requires immediate care in a hospital. About 1.7 million adults in the U.S. develop sepsis, and at least 350,000 die during their hospitalization, according to the CDC.
Most of the time, it is caused by bacterial infections, such as a skin infection from a cut or a lung infection like pneumonia, but can also be caused by viral infections. Sepsis causes inflammation across large areas of the body and can damage tissue and multiple organs, such as the heart, brain, lungs, and kidneys. The risk of a bacterial infection leading to sepsis is much higher for infants, older adults, and people who are immunocompromised.
When someone develops sepsis, they may experience breathing problems. When the oxygen levels fall, they often become confused. People with sepsis may also experience symptoms like a fast heartbeat, chills, and low blood pressure, as they have less blood going to the brain.
Septic shock is the most severe stage of sepsis, where the blood pressure drops to dangerously low levels. Even if you give the person fluids, the blood pressure stays low. If in septic shock, a person is taken right to the intensive care unit.
What should people keep in mind if they think they may have a bacterial infection?
Most bacterial infections do not lead to sepsis or septic shock. But it is important to assess the severity of a bacterial infection with your doctor — not just how bad it may be now, but the risk of complications. A doctor can help determine the best course of action depending on the source of infection and health of the patient.
David M. Goldberg, M.D., is an internist and infectious disease specialist at NewYork-Presbyterian Medical Group Westchester and assistant professor of medicine at Columbia University Vagelos College of Physicians and Surgeons. He is board-certified in Internal Medicine and Infectious Diseases and has a special interest in travel medicine, Lyme disease, HIV, and community-acquired infections.