March 3, 2017

Sequencing saves lives

The BBC reports today that the Sanger Centre and the maternity unit at a local hospital here in Cambridge have been using sequencing technology to locate and isolate the source of an MRSA outbreak. This marks a significant step towards DNA sequencing becoming part of everyday life in healthcare environments and it is surprising what it has been able to achieve.

The maternity unit was suffering from an MRSA outbreak affecting 12 babies, but they were unable to tell from existing tests whether it was a single outbreak or a series of infections derived from multiple sources. A sample of the bacteria from each case was sampled and compared using bioinformatics techniques to see if they were related - and indeed they were, all having been derived from a single source. In the meantime the outbreak had been treated and cleared up, but a few weeks later it returned, and further sequencing proved it was the same strain once again.

Now simple logic would indicate that in a maternity unit, where the population changes regularly and after even a few days it is likely that every bed will be occupied by a new individual, the recurrence of the exact same strain of a bacteria is unlikely to have been caused by an external factor but will be something to do with the hospital environment itself - either carried by a staff member, or found within the building itself. 

Using sequencing technology once more, and taking full advantage of the cost reduction in this process over the last few years, all the staff that came into contact with the maternity unit had swabs taken and the bacteria on those swabs were sequenced. One individual was found to be carrying that exact strain of the MRSA bug and was subsequently treated to cure it. The outbreak has not returned.

Only because of the low cost of sequencing and the fast turnaround in the lab and the bioinformatics that analyse the resulting data was this possible. Only a year or two ago it would not have been reasonable to run this type of experiment, yet today not only is it possible but the cost is reducing so fast that it is conceivable that this technique will become the norm for all future outbreaks of any disease within a confined environment, enabling rapid detection not only of the exact disease in question but also of its source. This could be a major breakthrough for public health.

Topics: Bioinformatics