Infections caused by an antibiotic-resistant strain of E. coli have undergone a "dramatic increase since 2008," especially in the elderly and people living in nursing homes, according to a new study released Tuesday.
The "superbug," E. coli ST131, was first discovered in 2008 and is immune to most standard antibiotics. Though infections were rare in the first few years after the strain was discovered, it accounted for more than a quarter of the 299 infections that researchers at the University of Minnesota studied from Olmsted County in Minnesota between February and March of 2011. In nursing homes, ST131 accounted for more than three quarters of all E. coli cases studied and was much more common in elderly patients.
James Johnson, one of the researchers involved in the study, says that because the strain can be transmitted from person to person, it has increasingly popped up in healthcare settings.
"Folks in long-term care facilities receive a lot of antibiotics, which allows a bug like this to persist and flourish," he says. "In those facilities, the patients have close contact with one another. There's just a lot more opportunity for bugs like this to spread around."
Previous strains of E. coli have exhibited similar antibiotic resistance, but those strains were easily beaten by the body's immune system. ST131 is considered to be more dangerous, Johnson says.
"It seems to be a little more virulent and better at adapting than some of the other strains," he says. "Other strains, yes, they were resistant, but this one also has a reasonable amount of oomph. That, combined with its resistance, makes it a concern."
Though the bacteria is resistant to standard antibiotics, it is not yet untreatable, which makes it less of a concern than other superbugs seen in healthcare settings, such as CRE, a bacteria that kills half of the patients it infects. Several backup antibiotics still work, but, like other superbugs, the bacteria could eventually develop further resistances.
For now, the strain causes the most amount of trouble in settings where doctors might not realize that a patient is infected with a resistant strain.
"Doctors are still following old-fashioned practices that worked well 20 years ago but don't work now," he says. "In spite of the fact that their patients aren't getting better, some doctors will prescribe another round of the same old antibiotic."
Johnson says several deaths have been attributed to ST131 infection.
"Our backs are not yet against the wall, but doctors don't recognize that patients need different drugs—they treat it like something that's not a big deal, so patients stay sicker longer," he says. "There have definitely been some deaths, and this is just the tip of the iceberg."