Study investigates the spread of the Klebsiella superbug between humans and the environment

An international team of scientists investigating the transmission of a deadly drug-resistant bacterium that rivals MRSA, has found that while the insects are found in livestock, pets and the wider environment, they are rarely transmitted to humans by this route.

The researchers, led by Professor Ed Feil from the Milner Center for Evolution at the University of Bath, studied the prevalence of Klebsiella, a family of bacterial species that live harmlessly in the intestines, but can be dangerous if spread to other parts of the body.

Klebsiella pneumoniae is the best known species of this family, which can cause pneumonia, meningitis, urinary tract infections and bloodstream infections.

These bacteria are now highly resistant to antibiotics, with some strains even resistant to carbapenems, a class of so-called “last resort” antibiotics that is only used when no other antibiotic treatment works.

Klebsiella has overtaken MRSA as a health problem in the UK, with rates rising steadily. The WHO has recognized the bacterium as a priority healthcare-associated pathogen.

As well as being found in hospitals, the microbe has also been detected in the environment, including livestock and sewage, but until now it was unclear whether the bacterium was transmitted between environments. clinical and non-clinical.

In the largest-ever study, the team collected 6,548 samples over a 15-month period from different locations in and around the Italian city of Pavia, where this pathogen is a major problem in hospitals, and analyzed them using whole genome sequencing techniques to detect and identify any Klebsiella bacteria present.

The team swabbed patients in hospitals and healthy “carriers” in the community, took samples from farms, puddles, pets and even house flies and other insects to detect where the bacteria was present.

From there, they found 3,482 isolates comprising 15 different species of Klebsiellahalf of the positive samples containing K. pneumoniae.

When the team genetically sequenced the bacteria to find which strains were present, they found that there was very little overlap between the insects found in hospitals and those found in the environment.

Professor Ed Feil, who led the study, said: “Klebsiella infections are becoming more and more resistant to antibiotics, so while you used to be able to treat most urinary tract infections easily, it is now more common for patients to get infections that keep coming back and causing problems.

Klebsiella can also cause pneumonia, which kills about half of patients. These bacteria are a bigger problem in the UK than MRSA.

“Our researchers wanted to know if resistant bacteria are now spreading in pets, farms, livestock, plants and water, and so we wanted to determine where Klebsiella is detected and monitors its spread, to inform how best to prevent and control outbreaks.

“We found that it was everywhere, but we were surprised that the strains found in the hospital were different from those found in the environment, indicating that there is very little transfer between the two habitats. : humans almost always catch this from other humans.

“This confirms that the best way to control infection with these bacteria is still strict hospital hygiene, and that there is less chance of outbreaks being caused by contact with animals or the environment than is believed. previously feared, at least in a high-resource country like Italy.”

The fear was that farmers could pick up these bacteria from their livestock or soil, that we could get infected from contaminated salad or get sick if we swim in infected lakes.

Our research has yielded no evidence for this, however, we have found resistant klebsiella in companion animals, such as cats and dogs. Veterinarians and owners should be aware of this, as these animals could pose a risk of spreading the bacteria. »

Doctor Harry Thorpe, first author of the article, University of Oslo (Norway)

The project consortium, called SpARK, was led by Bath but included researchers from the UK (Wellcome Sanger Institute, Universities of Bristol and Glasgow), Norway, France, Finland and Italy. The work was funded by the Joint Programming Initiative on Antimicrobial Resistance (JPI-AMR) and the MRC, and published in Natural microbiology.

Professor Feil said: “This is the largest and most systematic study that has been conducted at one time in a single geographic location.

“We looked at the transmission of strains, but antibiotic resistance can be conferred very easily on other strains when they swap and pick up circular pieces of DNA called plasmids.

“We then want to track how the plasmids are transferred between strains, using a technique called long-read sequencing.”

The team recently received a network grant from JPIAMR to do this, which relies on a GW4 research community and was supported by the GW4 AMR Alliance.


Journal reference:

Thorpe, HA, et al. (2022) A large-scale genomic snapshot of Klebsiella spp. isolates in northern Italy show limited transmission between clinical and non-clinical settings. Natural microbiology.

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