Antibiotic-resistant bacteria can spread in hospitals even after deep cleaning, study reveals

Antibiotic-resistant bacteria can linger in hospitals even after deep cleaning, a study has revealed.

Scientists used genome sequencing to monitor how easily a drug-resistant gastrointestinal bacterium can spread within a hospital.

They studied the prevalence of Enterococcus faecium, a bacterium commonly found in the gastrointestinal tract, where it usually resides without causing problems. However, it can lead to a potentially life-threatening infection in immunocompromised patients.

Scientists at the University of Cambridge and the London School of Hygiene and Tropical Medicine followed 149 haematology patients at Addenbroke’s Hospital over a six-month period, taking stool samples and swabs from the hospital environment.

They found that two-thirds of patients acquired E faecium, with just under half (48 per cent) of swabs taken from the hospital environment also testing positive for the bacterium, including 36 per cent of medical devices, 76 per cent of non-touch areas such as air vents, 41 per cent of bed spaces and 68 per cent of communal bathrooms.

“We’ve known for over two decades that patients in hospital can catch and spread drug-resistant E faecium," said Dr Theodore Gouliouris from the Department of Medicine at the University of Cambridge, and joint first author on the study, said. "Preventing its spread requires us to understand where the bacteria lives — its ‘reservoirs’ — and how it is transmitted.

“Most studies to date have relied on culturing the bacteria from samples. But as we’ve shown, whole genome sequencing, looking at the DNA of the bacteria, combined with detailed patient and environmental sampling can be a powerful tool to help us chart its spread and inform ways to prevent further outbreaks.”

The study, published in Nature Microbiology, also found that deep cleaning could not eradicate the bacteria.

When one ward was deep cleaned over a three-day period and with patients moved elsewhere, the team found 9 per cent of samples still tested positive for the bacteria.

Within three days of the patients returning, around half of the samples tested positive.

“The fact that these cases were all linked to another patient or their environment suggests strongly that they had picked up the multi-drug-resistant bacteria while in the hospital,” said Dr Francesc Coll from the London School of Hygiene and Tropical Medicine.

Dr Gouliouris added: “Our study builds on previous observations that drug-resistant strains of E faecium can persist in the hospital environment despite standard cleaning — we were still surprised to find how short-lasting was the effect of deep cleaning.

“We found high levels of hospital-adapted E faecium despite the use of cleaning products and procedures that have proven effective against the bug.

"It highlights how challenging it can be to tackle outbreaks in hospitals.”

Senior author Professor Sharon Peacock, from the Department of Medicine at the University of Cambridge, said the results were also a “sign of how urgently we need to tackle inappropriate use of antibiotics worldwide, which is widely recognised as posing a catastrophic threat to our health and our ability to control infections”.