For what appears to be the first time in history, whole genome sequencing has helped identify the cause of, and ultimately bring a halt to, a potentially threatening infectious disease outbreak.
With the help of researchers, a UK hospital was able to successfully sequester the outbreak of a contagious staph bacteria known as MRSA (methicillin-resistant staphylococcus aureus) at their facility. Hospital workers detected the presence of MRSA in infants during a routine screening process and immediately moved to identify the cause of this newfound outbreak before it spread any further. From the outset, their biggest challenge was determining if the outbreak was isolated only to their ward (suggesting a single carrier as the source), or if it was the result of more than one carrier who had recently visited the facility.
In this particular instance, the danger associated with MRSA was twofold. First, not only is the staph bacteria highly contagious, but it is also highly resistant to a wide range of antibiotics. And second, the symptoms associated with MRSA are not always visibly obvious to, or active in, their carriers. Due to these two factors, this leaves clinical testing as one of the only remaining means to clearly identify source carriers and carry out the necessary treatment.
A team of researchers from the University of Cambridge and the Sanger Institute assisted the UK hospital by sequencing the genomes of each infected individual. Then, following an analysis of this sequencing data, researchers employed a novel approach to aid with the identification of the outbreak’s source. According to this method, researchers would use the data to help manufacture a pseudo-”family tree” of the bacteria. This “family tree” would enable them to see if there was any shared relationship across the various MRSA strains. The identification of a shared relationship among all the observed cases would denote the cause of the outbreak as a single carrier. Divergences in the strains, however, would denote multiple carriers. In this case, the data pointed researchers in the direction of a single source carrier. Following a thorough sanitization of the ward, a reoccurrence of the disease was noticed, prompting researchers to screen its staff members. Following this process, they were able to successfully find the original carrier, treat them and eliminate the infection.
In general, the outcome of these events represents a major milestone for sequencing technology. Without this technology at the hospital’s disposal, this outbreak could have grown to much larger proportions. After all, it is important to remember that only a few years ago, whole genome sequencing was a highly expensive process and available to only the most well-funded facilities. Today, the growing trend of democratized sequencing capabilities has changed all of that and helped make success cases like this one possible. With any luck, the industry is moving in the direction that will make whole genome sequencing standard practice for hospitals and testing facilities worldwide.