Egg on your plate
There’s something about a Saturday morning breakfast with the lads. Not a flake of low cal muesli in sight. The ‘continental’ option was Vegemite on toast. But some of the boys caught the scent of bacon on the breeze, threw caution to the wind, along with tomatoes, bacon and eggs. Fried, of course. Eggs, sunny side up can be a bit messy, squashed between layers of butter, bacon, tomato and plain white bread. But they’re hard to beat in the early morning sun, when there’s still a bit of chill in the air.
Bacon and eggs have been a bit of a theme this week. Particularly the egg bit, since this was the week I met my first Eggerthella. This is not quite what it sounds like – some newly discovered egg-laying dinosaur, or a egg-shaped mushroom species. No, Eggerthella is an interesting bacterium that very occasionally causes human infection. That is, of course, how we met.
Eggerthella lenta is still new enough to appear in case reports, as an unusual cause of infection. It is an anaerobic commensal of the human intestine, and is a Gram positive bacillus that does not form spores and is not motile. Bloodstream infection is potentially fatal, hence the importance of being able to accurately identify E. lenta from clinical specimens, especially blood and other normally sterile sites. The genus in which this species belongs is a part of a recently proposed group of bacteria within the Actinobacteria. This significance of this new perspective on intestinal bacteria is hard to grasp for us egg and bacon sandwich munchers whose most recent claim to taxonomic fame (that must be an oxymoron) is the discovery of a new bacterial genus – only our second. But Eggerthella lenta has another twist to its human significance. It is able to metabolise the cardiac drug digoxin, altering its serum concentration and urinary elimination. This new species has opened a new window on the interaction between oral medication and the intestinal microbiome. The genus takes its name from Arnold Eggerth who discovered it in the 1930s. Until 1999 it was known as Eubacterium lentum.
You wouldn’t pick it
The other new species to challenge the gnome this week was an oxidase positive, Gram negative environmental bacterium called Ralstonia mannitolilytica. This species has been encountered before in healthcare associated outbreaks of infection attributed to medical devices, and has recently been named and shamed as an emerging pathogen. The species was previously known as a subgroup of Ralstonia pickettii, until it was given a species name of its own. Consequently, some clinical laboratory identification systems may incorrectly label clinical isolates after near-neighbour species such as R. pickettii or even Burkholderia species. More up to date methods of bacterial identification, such as MALDI-TOF mass spec or sequencing of 16S and RecA genes are needed to be sure one way or the other.
We’ll be dredging up more new bacteria from clinical specimens in the near future, as sure as eggs are eggs.