THE antibiotic apocalypse is accelerating, with US scientists warning treatment-resistant bacteria is spreading faster than expected, and with increasing stealth.
Researchers at Harvard's T.H. Chan School of Public Health examined antibiotic resistant Enterobacteriaceae (CRE) - a large family of bacteria that includes many of the more familiar pathogens such as Salmonella - found to be causing disease in four US hospitals.
Researchers took a 'snapshot' of hospitals in Boston and California, looking at 250 samples from patients suffering antibiotic resistant infections.
They found a wide variety of resistant species as well as a diversity of genetic traits enabling the bacteria to resist antibiotics.
The findings of the study, published in the journal PNAS (Proceedings of the National Academy of Sciences) suggest that resistant bacteria is more widespread than previously thought, and may well be transmitting from person to person undetected because it shows no symptoms.
This has led to a call from the researchers for greater surveillance of the dangerous bacteria.
"While the typical focus has been on treating sick patients with CRE-related infections, our new findings suggest that CRE is spreading beyond the obvious cases of disease," said William Hanage, associate professor of epidemiology at Harvard Chan School and senior author of the study.
"We need to look harder for this unobserved transmission within our communities and healthcare facilities if we want to stamp it out."
CDC Director Tom Frieden has called them 'nightmare bacteria' because they are resistant to some of the last-ditch treatments available to doctors battling resistant infections.
CRE are a class of bacteria resistant to multiple antibiotics, including carbapenems, which are considered last-resort drugs when other antibiotics have failed.
But there is a growing 'riot of diversity' among antibiotic resistant bacteria species and the genes within them displaying resistance to carbapenems.
These genes are 'moving easily' between bacteria species, accelerating the evolving threat from CRE.
Such bacteria tend to initially spread in hospitals and long-term care facilities, causing thousands of infections and even death each year.
"The best way to stop CRE making people sick is to prevent transmission in the first place," Hanage says. "If it is right that we are missing a lot of transmission, then only focusing on cases of disease is like playing Whack-a-Mole; we can be sure the bacteria will pop up again somewhere else."
According to the US Centers for Disease Control and Prevention (CDC), the incidence of infections caused by CRE is on the rise.
The CDC this week said a superbug resistant to every available antibiotic recently killed a woman in Reno, Nevada.
The woman, who had returned from India shortly before falling ill, died in September after 26 different antibiotics failed to cure her infection.