London is teeming with bacteria—some of which have developed resistance to antibiotics. These microbes are mostly harmless, but if they do cause an infection, it can be hard to treat. And there is a chance that they could transfer their resistance to more dangerous strains, experts warn.

In a new study, researchers in England and their colleagues found that frequently touched surfaces—such as elevator buttons, ATMs and bathroom-door handles—can be reservoirs of drug-resistant staphylococcus, or staph, bacteria.

The researchers collected 600 samples from locations throughout East and West London such as hospitals, public washrooms and ticket machines, finding 11 species of staphylococci. Nearly half of the samples—including 57 percent in East London and about 41 percent in less crowded West London—contained bacteria resistant to two or more frontline antibiotics. Just under half of the staph found in hospital public areas was drug resistant, compared with 41 percent in community settings, the team reported in August in Scientific Reports.

“Resistance genes and elements present in these bacteria can spread to human pathogens and result in the emergence of new [antimicrobial-resistant] clones,” says Hermine Mkrtchyan, a senior lecturer at the University of East London, who headed the team that conducted the research. “Although these bacteria are nonpathogenic, the increased levels of antibiotic resistance that we found in general public settings in the community and in hospitals pose a potential risk to public health.”

Should people be worried?

“So long as you wash your hands after going out into public areas, it should be fine,” says Richard Stabler, co-director of the Antimicrobial Resistance Center at the London School of Hygiene & Tropical Medicine, who was not involved in the work. “I certainly recommend washing your hands after being out in London.”

Despite the high ick factor of the idea of touching potentially dangerous bacteria in familiar settings, Stabler concedes that these species are commonly found on skin, so it is no surprise that they would be found in public places where people are constantly shedding skin and microbes.

These bacteria do not pose a real danger right now, Stabler says, because although some of them were resistant to two common antibiotics, they cannot evade the entire medical arsenal. “This is potentially a problem out there, but at the moment, it’s still quite containable,” he says.

Antimicrobial resistance is a major public health threat across the globe, Mkrtchyan notes. Every year, more than 700,000 people die because of it, and the toll is predicted to rise to 10 million by 2050. Resistance means patients will stay sick for longer, which increases the cost of health care, Mkrtchyan says. “Our research highlights that general public areas (part of our everyday life) can be reservoirs for multidrug-resistant bacteria and alerts us that concrete global efforts are required to tackle the problem.”

Mkrtchyan and her colleagues previously found similar drug-resistant bacteria in a study of London hotel rooms. They are now comparing the genes of the 11 species found in both studies to better understand how they evade drugs and the physical environments that support their development and transmission.

Knowing about the presence of antibiotic-resistant bugs is useful, Stabler adds, because public officials can utilize the information to prepare and guide treatment. “It’s okay that they’re out there,” he says. “We have to live with them rather than trying to exterminate them—because that doesn’t work.”

The study is a somber reminder that the overuse of antibiotics has consequences, says W. Ian Lipkin, a professor of epidemiology at Columbia University’s Mailman School of Public Health, who was also not involved in the research. Lipkin has found similar results in studies of rats and mice in New York City subways and apartment buildings. A 2015 study by another group found that nearly half of the bacteria, viruses and additional microbes collected from the city’s subway system did not match any known organism.

Lipkin and others blame global antibiotic resistance on the overprescription of antibiotics for viral infections and other situations where they will not help, the problem of patients not taking their medications as prescribed and the vast overuse of antibiotics in farm animals. “The good news is that if we restrict the use of antibiotics to situations where they are truly needed, bacteria will regain their sensitivity to antibiotics,” Lipkin says.

Lipkin notes that some antibiotic resistance exists naturally. Researchers have found resistant microbes in isolated caves, he says, suggesting that some bacteria have evolved to tolerate natural antibiotics. But humans have dramatically increased the prevalence of these microbes by using antibiotics inappropriately.

The findings are concerning but not a reason to panic, Lipkin says. Similar drug resistance has been found in other places for years. “It’s just another call to be more sensible about how we use antibiotics,” he explains. Still, “the fact that they’re there at all means that they’re capable of moving into people.”