Cliff McDonald, MD, is a former officer in the Epidemic Intelligence Service and is currently the Senior Advisor for Science and Integrity in the Division of Healthcare Quality Promotion at the CDC. This division seeks to protect patients and healthcare personnel and promotes safety and quality in healthcare delivery systems. Dr. McDonald is an expert in Clostridium difficile, an antibiotic resistant bacterium.


An interview with Dr. Cliff McDonald of the Center for Disease Control (CDC)

Antibiotic Risks

Why are antibiotics important?

Only 80 years ago, antibiotics weren’t available. The discovery of penicillin in 1928 by Alexander Fleming was one of the greatest scientific achievements of the 20th century. Some common illnesses, such as strep throat, are now easily treated with antibiotics, but in the past, they often led to serious complications or death. Antibiotics serve an important role in keeping the public healthy.

How do antibiotics affect the good bacteria in and on our body?

Every time you swallow antibiotics, you kill the beneficial bacteria within your intestines. When you do so, you upset the delicate balance of your intestines.  Our mouth and intestines have a rich diversity of bacteria that are essential for our health.

If you take Amoxil for a week, how long does the effect remain in your body?

Even though the antibiotic is out of your system within 24-48 hours, it can take six months or more to rebuild the balance of thousands of different types of healthy bacteria.  The big concern is that other bacteria that are normally controlled take over.

What about taking antibiotics a number of times over the course of a few months?

If you ingest five days worth of antibiotic, it takes up to six months for your intestines to get back to normal.  When you receive a repeated course of antibiotics, in some cases the normal bacteria balance never reestablishes in your body.

What are the real risks of taking antibiotics?

When something upsets the balance of these organisms in your gut, otherwise harmless bacteria can grow out of control and make you sick. You can (1) Develop resistant strains of bacteria. (2) Develop an antibiotic allergy (3) Develop infections such as Clostridium difficile. Knocking out the good bacteria allows for the very damaging bacteria to take over.

Why is Clostridium difficile such a concern?

Clostridium difficile is very difficult to control and treat.  Spores from the C. difficile are very resistant to disinfection.  Purell does not kill the spores. As the bacteria become overgrown they release toxins that attack the lining of the intestines.This bacteria causes diarrhea and more serious intestinal conditions such as colitis. Symptoms include watery diarrhea and fever. Every year there are 500,000 cases of C. difficile, with 14,000 deaths a year.  5% of patients that contract C. difficile while hospitalized will die. Unfortunately, someone who goes in for knee surgery can catch it from another infected patient.

 Do older people have a greater chance of getting C. difficile?

In one study, the risk of becoming infected with C. difficile was ten times greater for people age 65 and older when compared with younger people.  If an older person tells you that they have a “stomach virus” they may be suffering from C. difficile. Ask them three questions: 1) How often they have diarrhea. 2) How often they’ve taken antibiotics within the past three months. 3) If they are suffering from fever, abdominal pain, or vomiting.

If you go with them for treatment, make sure the doctor knows they have taken antibiotics within the past three months.

Does experiencing diarrhea when taking antibiotics mean I have C. difficile?

No.  A person can get diarrhea often when taking antibiotics. The difference is C. difficile diarrhea occurs AFTER you stop taking the antibiotics.

What can we do to avoid C. difficile infection?

1) Avoid taking antibiotics that we don’t need.  2) Before you take an antibiotic, be aware of the risks it poses to the good bacteria in your system.  3) If you visit someone in a hospital or nursing home, avoid touching the railing of the beds and wash your hands for 15 seconds with soap and water. If you’re healthy and have not taken antibiotics within the past three months, you’re not likely to get infected.  4) For the first 30-40 days after you take antibiotics you have a 7-10 times higher risk of getting C. difficile. For the next two months after that you have a 2-3 times higher risk.  60% of people who are hospitalized are given antibiotics – which make them more vulnerable to infection.