Protecting the Last Resort

As antimicrobial resistance persists, finding drugs that effectively fight antagonistic microorganisms becomes a more important endeavor. Often referred to as a “last-resort”, the antibiotic colistin combats several multi-drug resistant bacteria – but even it isn’t immune to the creeping cull of resistance. The gene mcr-1, found in species of gut bacteria, gives microbes the ability to resist the effect of colistin, and, worryingly, its protective traits are transmissible both vertically (via genetic fission; common resistance) and horizontally (via plasmids; mobile resistance).

Of great concern is the widespread impact that transmission might have if left unchecked. Bacteria that acquire colistin resistance through horizontal, or so-called mobile, transfer of mcr-1 could become untreatable in humans and might also give rise to resistance in other common strains of human-borne bacteria. It goes without saying that detection of the gene is essential in order to contain its escalation – which is where a team of researchers from Germany and Austria step in.

Employing a loop-mediated isothermal amplification (LAMP) system, which uses PCR and WGS, the investigators were able to distinguish plasmid-embedded mcr-1 from vertically-transmitted intrinsic mcr-1 in multi-drug resistant “superbug” Enterobacteriaceae, with 100 percent sensitivity and specificity (1). According to the team, this is the only system to have been shown to accurately differentiate between common and mobile resistance gene transmissions, since they are phenotypically identical. The test takes approximately 20 minutes to carry out with only two minutes of hands-on sample-time needed, and the researchers reiterate that its rapid nature is vital to contain the spread of colistin resistance as effectively as possible.

So far, their findings have been taken from bacterial cultures, but the team plans to keep working on the technique to be able to safely implement it as quickly as possible.