Living with Lead Creates Antibiotic-Resistant ‘Superbugs’

Antibiotic-resistantbacteria are a growing cause of death. According to the most recent worldwide analysis, they killed 1.27 million people in 2019. The overuse of antimicrobial drugs has led to the emergence of better defenses against them.

Heavy metals such as lead, mercury and silver are known to be resistant to antibiotics. Human industries such as mining and transportation are where the metals are found. According to studies in the environment, animals and people, the same genes that help the bacteria protect themselves from the toxic effects of metals have also helped them fight off antibiotics.

Heavy metals can killbacteria because they disrupt their normal cell functions. Somebacteria that live around high metal concentrations have evolved survival skills, such as expelling toxic metal ion. The pumps can help to remove antibiotics.

People with high levels of lead in their urine were more likely to have antibiotic-resistantbacteria in their bodies even after accounting for other factors. Their results are among the first to show a link between the human body and the environment. The study adds antibiotic-resistantbacteria to the list of harms visited upon people without much money or social resources, who are most likely to live in lead-contaminated areas.

The health data of 695 adults who participated in the Survey of the Health of Wisconsin was examined by the researchers. Thirty-four percent of all participants had antibiotic-resistantbacteria, such as resistant Gram-negative bacilli or vancomycin-resistant enterococci, according to saliva and stool samples. Some had methicillin-resistant Staphylococcus aureus. More than 50 percent of participants with the highest levels of lead in their urine tested positive. People who live in a city are three times more likely to test positive for lead in their urine than people who don't live in a city.

White urban residents were less likely to test positive than nonwhite residents. Malecki says that people of color face financial and social barriers that keep them out of older buildings with more lead paint, pipes and other sources of exposure.

The link between heavy metals and antibiotic-resistantbacteria is still a relatively new area of research, and untangling their relationship within the human body will require more studies that follow participants over time. The results help scientists understand where resistance genes are coming from and allow them to develop targeted solutions to prevent these genes from developing and spreading.

Other metals have been linked to the appearance of drug-resistant microbes. A recent study by scientists at Florida A&M University looked at a former nuclear material test site in South Carolina with persistent levels of uranium and mercury in its soil. A strain ofbacteria resistant to 70 percent of antibiotics was found on the site.

The threat of antibiotic resistance around the world is caused by all of these heavy metals. Drug-resistant genes are often found on the strings of bacterial DNA, which can be spread easily among different types ofbacteria. In this way, a resistance gene in a bacterium that doesn't harm humans can quickly spread to one that does, says Michiel Vos, a microbiologist at the University of Exeter in England.

Patrick McNamara, an environmental engineer at Marquette University, says that it's not known how much heavy metals contribute to the global pool of resistance genes. The general thought is that less is better.

McNamara and his colleagues are studying antibiotic resistance in drinking water. The lead-tainted-water crisis inFlint, Mich., was caused by a lack of chemicals in the pipes. According to the Centers for Disease Control and Prevention, pipes are the most common source of lead exposure. He and his team aim to minimize both lead exposure and the proliferation of resistantbacteria by better understanding the impact of different corrosion inhibitors on antibiotic resistance.

The link between heavy metals and antibiotic resistance is an example of why we need to understand global health.