New genomic technique tracks superbugs in hospitals for faster infection management

 Researchers have developed a new genomic technique that can track the spread of multiple superbugs in a hospital simultaneously, which could help prevent and manage common hospital infections quicker and more effectively than ever before.

The proof-of-concept study, from the Wellcome Sanger Institute, the University of Oslo, Fondazione IRCCS Policlinico San Matteo in Italy, and collaborators, details a new deep sequencing approach that captures all the common infectious bacteria in a hospital at once. Current methods culture and sequence all pathogens separately which takes longer and requires more work. 

Published today (20 August) in the Lancet Microbe, the study captured the whole population of pathogenic bacteria found in multiple hospital intensive care units (ICUs) and ordinary wards during the first wave of the 2020 COVID-19 pandemic. Researchers could see the type of bacteria patients had, including any well-known antibiotic-resistant pathogens found in hospitals. 

They discovered that each ICU patient tested in the study was colonised by at least one such treatment-resistant bacteria, while the majority were colonized by several of them simultaneously.

Researchers believe their approach could be integrated with existing hospital clinical surveillance systems. As drug resistance is a widespread issue in hospitals and other clinical settings, this system could identify, track and limit the spread of common multiple treatment-resistant bacteria at the same time.

Bacteria are commonly found in or on the body without causing harm, known as colonization. However, if certain strains get into the bloodstream due to a weakened immune system they can cause severe and life-threatening infections, unless they can be effectively treated with antibiotics.

As an added challenge for healthcare providers, some of these bacteria are antibiotic-resistant (AMR). Infections caused by AMR bacteria are a major issue in hospitals, with these treatment-resistant bacteria predicted to cause more deaths than cancer by 20501. While some hospitals test for AMR bacteria on arrival, no system effectively tracks all multi-drug resistant bacteria throughout a hospital. 

Over the last 15 years, genomic surveillance has become a powerful tool for tracking pathogen evolution and transmission, giving critical insights to help manage the spread of disease. 

However, current methods involve culturing a single strain of bacteria in a sample at a time and then conducting whole genome sequencing for all of them separately. This is a labor-intensive process, which can easily take several days and only provides a partial snapshot of all the clinically relevant bacteria found in a sample.

In this new study from the Wellcome Sanger Institute, the University of Oslo, Fondazione IRCCS Policlinico San Matteo in Italy, and collaborators, the team developed a new approach that captured whole genome sequencing data across multiple pathogens at once. This is known as a 'pan-pathogen' deep sequencing approach and can provide genomic data as rapidly as hospitals can process the samples. 

The team took samples from 256 patients in an Italian hospital, capturing bacteria found in the gut, upper airways, and lungs. The 2,418 DNA samples could be associated with 52 species of bacteria. 66 per cent (2,148) of these were made up of different strains of the seven most common bacterial infections seen in hospitals.

They found that patients in ICUs were colonized by at least one bacterium with the potential to cause severe disease at any time, and that clinically important AMR genes were present in at least 40 per cent of these.

The team effectively mapped the spread of hospital bacteria across a 5-week sampling timeframe, allowing them to also predict which bacteria were most likely to appear in infections acquired while in the hospital.