Staphylococcus epidermidis bacteria

The bacterium Staphylococcus epidermidis has developed resistance to multiple antibiotics, complicating the treatment of people infected with the common microbe. Credit: Eye of Science/SPL

Antibiotics

Skin bacterium learns to shrug off antibiotic of last resort

Microbes that are part of the normal human flora have given rise to drug-resistant strains that are now found in healthcare facilities worldwide.

Antibiotic-resistant strains of a bacterium that can cause hospital-acquired infections have spread around the globe.

The bacterium Staphylococcus epidermidis lives on human skin and is normally harmless to its host. But when the skin is breached, the bacterium can cause infections, particularly among people with medical implants, such as long-term catheters, or prosthetics, such as artificial heart valves.

Benjamin Howden at the Peter Doherty Institute for Infection and Immunity in Melbourne, Australia, and his colleagues looked at hundreds of samples of S. epidermidis collected from 96 hospitals and research centres across 24 countries. They found that three bacterial lineages that are resistant to almost all antibiotics have spread around the world during the past few decades.

The researchers also found that some of the genetic mutations identified in these lineages confer resistance not only to an antibiotic called rifampicin but also to last-resort antibiotics such as vancomycin. Clinical guidelines often recommend co-administering both rifampicin and vancomycin for the treatment of Staphylococcus infections to prevent the development of drug resistance. But the authors’ findings suggest that the combination may instead fuel resistance in S. epidermidis.