In the era before antibiotics were available one third of all deaths were from infectious disease. The introduction of antibiotics starting with penicillin represented a tremendous advance in the treatment of infectious diseases. We soon learned, however that overuse of antibiotics led quickly to the development of bacteria that became resistant to that antibiotic. Penicillin, for example can only be used for a small number of infectious diseases now including strep infections and syphilis. In this post I will write about both individual and societal harms of overuse of antibiotics and will also discuss conditions for which they should be and should not be used.

Harms of Antibiotics

Bacterial Resistance

Overuse of antibiotics can lead quickly to resistance. Unfortunately, resistance has eventually developed to nearly all currently available antibiotics. Some bacteria, called gram negative bacteria have developed resistance to almost all antibiotics. Antibiotic resistance in the United States kills approximately 23,000 patients a year and incurs over $20 billion in additional medical expenses.

Overuse of antibiotics

The information below comes from an excellent paper from the journal Pharmacy and Therapeutics: The Antibiotic Resistance Crisis.

 in 2010, the last year that we have complete data, 22 doses of antibiotics were prescribed per person in the U.S. In many other countries, antibiotics are unregulated and available over the counter without a prescription. This lack of regulation results in antibiotics that are easily accessible, plentiful, and cheap, which promotes overuse.

Inappropriate Prescribing

Many studies have shown that antibiotic therapy is not necessary in 30% to 50% of cases! Even in intensive care units 30% to 60% of the antibiotics prescribed have been found to be unnecessary, inappropriate, or at inadequate doses.

Extensive Agricultural Use

In both the developed and developing world, antibiotics are widely used as growth supplements in livestock.  About 80% of antibiotics sold in the U.S. are used in animals, to promote growth and to prevent infection. Molecular detection methods have shown that resistant bacteria in farm animals reach consumers through meat products. This happens through the following sequence of events:

1) Antibiotic use in food-producing animals kills or suppresses susceptible bacteria, allowing antibiotic-resistant bacteria to thrive

2) Resistant bacteria are transmitted to humans through the food supply

3) These bacteria can cause infections in humans that are resistant to most antibiotics

Consequences of Antibiotic Resistant Infections

A 2011 national survey of infectious-disease specialists found that more than 60% of the infectious disease doctors had seen a pan-resistant, untreatable bacterial infection within the previous year. Many public health organizations have described the rapid emergence of resistant bacteria as a “crisis” or “nightmare scenario” that could have “catastrophic consequences.”

Antibiotic Effects on Human Microbiome

It is well established that the gut microbiome plays an important role in health.  It prevents disease causing bacterial colonization, regulates gut immunity, provides essential nutrients and metabolites, and is involved in control of energy. A healthy gut microbiome has lots of diversity. Broad‐spectrum antibiotics reduce gut bacterial diversity. While killing the disease causing bacteria of concern antibiotics can also kill beneficial bacteria.

Studies report changes in gut bacterial composition that last for up to 12 weeks after antibiotic treatment has ended with the incomplete restoration of bacterial composition and emergence of antibiotic‐resistant strains.  In one study one short term course of clindamycin (7 days) resulted in significant disturbances in the gut bacterial community that remained for up to 2 years post‐treatment!

When Antibiotics Are Not Necessary

Viral Infections

The vast majority of infections are caused by viruses. Antibiotics do nothing to shorten viral infections or to relieve symptoms. Here are some examples.

Upper respiratory infections

Symptoms are typical cold symptoms, including runny nose, nasal congestion, sore throat and cough. There may or may not be fever. Fever, sometimes high fever is more common in children. Green or brown discharge from the nose is common with viral upper respiratory infections and does not indicate bacterial infection. Viral upper respiratory infections usually last about 10 days, but can persist for several weeks.

Bronchitis

In otherwise healthy people, bronchitis is another example of a viral infection. The only exception to this is people with chronic obstructive lung disease, in which bronchitis may be caused by bacteria. The main symptom of bronchitis is cough, which may be dry or may be productive of sputum. Yellow or green sputum can occur and does not mean that the bronchitis is bacterial. There is usually no fever. Viral bronchitis can last for weeks. RSV virus can cause a severe bronchitis in children and older adults. There is a vaccine for children and adults that prevents RSV virus infections.

Sinusitis

Most sinus infections are viral and antibiotics are not helpful for these. Symptoms can include thick nasal discharge and some discomfort over the maxillary sinuses (underneath the eyes). Occasionally sinusitis can be bacterial and require antibiotics. I will discuss this later under conditions for which antibiotics are appropriate.

GI Viruses

There are other viruses that affect the gastrointestinal system. Symptoms are usually nausea and vomiting and/or diarrhea. Norovirus is the most common one. Staying hydrated is the only treatment for these viruses. Rotavirus affects children, but there is a an oral vaccine for infants that prevents this disease.

Ear Infections (Otitis Media)

Infections behind the ear drum are called otitis media. These occur almost exclusively in children and can be viral or bacterial. We used to treat all inner ear infections in children with antibiotics. We have now learned that most ear infections in children, even the bacterial kind get better without antibiotics. We now use antibiotics only for children with severe ear infections who more commonly have fever and/or severe pain.

When Antibiotics Should Be Used

Most bacterial infections require antibiotics to get better. It is not always possible for you to know whether you have a viral or bacterial infection. If you are concerned that you might have a bacterial infection you need to see your doctor who will decide whether you need antibiotics or not.

Strep Throat

Although many sore throats are viral, sore throat can also be caused by strep (streptococcus). Strep throat does not cause other symptoms like cough and runny nose. It is diagnosed by a rapid strep throat swab which your doctor can do in his/her office.

Bacterial Sinusitis

This usually happens after a viral upper respiratory infection. The most common sequence is that you start to feel better after a week or so and then get worse. Typically pain from bacterial sinusitis is one side, not both sides. The affected sinus becomes very tender to touch. Fever may or may not be present.

Infection in the ear canal (otitis externa)

This kind of infection is different from infections behind the ear. It can be painful and usually there is some pussy discharge from the ear. It usually responds to topical antibiotic ear drops, but when severe can require oral antibiotics

Pneumonia

Pneumonia can be viral, but it is not easy to tell that kind from the more serious bacterial pneumonia. All pneumonias should be treated with antibiotics. Symptoms of pneumonia are fever, sometimes high fever, cough (usually productive) and shortness of breath. A chest x-ray will show fluid in the air sacs in the lungs.

Urinary tract infection

Bladder infections are common, especially in women. The symptoms are frequent urination and pain or burning with urination. Your doctor will send a urine culture to make sure you are on the right antibiotic.

Kidney infections (also called pyelonephritis) are a more serious type of urinary tract infection. Symptoms can include fever, flank pain and feeling very ill. Sometimes kidney infections require getting IV antibiotics in the hospital.

Soft tissue infections (cellulitis)

A scrape or cut on the skin can sometimes get infected. Usually the area around the injury becomes red and painful. This kind of infection usually requires antibiotics. Again, this is a decision your doctor needs to make.

Sepsis

Sometimes a localized infection will spread through the blood stream and affect other organs. This is a medical emergency and requires hospitalization, IV antibiotics and fluids to maintain blood pressure.

Bottom Line

Overuse and inappropriate use of antibiotics has led to bacterial infections that are increasingly resistant to many and sometimes all antibiotics. Antibiotics, even when used appropriately lead to long standing adverse effects on the gut microbiome. The vast majority of infections are viral and do not improve with antibiotics. Bacterial infections do often require antibiotics. Decision about whether antibiotics are appropriate should be made by your doctor. Requesting antibiotics from your doctor can sometimes lead to inappropriate prescribing.