Chemo helps bacteria evolve to tolerate antibiotics

Infections are a serious threat to cancer patients. The chemotherapy used to kill cancer cells temporarily wipes out the immune system. That leaves patients vulnerable to bacteria and other threats.

St. Jude researchers have found another way chemo can increase infection risk. The chemo creates a “perfect storm” that helps bacteria learn to tolerate antibiotics.

Recently, an infant with leukemia developed an infection during chemo. The bacteria—vancomycin-resistant Enterococcus faecium (VRE)—is always tough to treat. The baby received antibiotic treatment, but the infection continued for 28 days. It ended only when infant’s immune system recovered.

Why didn’t the antibiotics work? Scientists decided to find out. They sequenced the DNA of bacteria from the patient. The researchers found a single mutation that helps bacteria survive the stress of antibiotic treatment. The patient’s weakened immune system may also help the mutant bacteria survive.

“The same conditions may be present in other patients whose immune systems have been compromised by chemotherapy or disease,” said Joshua Wolf , MBBS, of St. Jude Infectious Diseases.

The research appeared in the journal mBio.

Read the news release.