Meet <em>Escherichia albertii</em>, A Pathogen To Watch

11/16/2015 03:27 EST | Updated 11/16/2016 05:12 EST
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Chemist holding a sample of bacterial culture

When it comes to foodborne illness, the most feared enemy has to be Escherichia coli, or as we all know it, E. coli. This bug has been causing troubles for decades leaving people with diarrhea and other complications. Some of the members of this microbial group, with names like ETEC (traveller's diarrhea), and O157:H7 have proven to be particularly dangerous and even at times, lethal.

The actual contribution of E. coli to human gastrointestinal illness is not as bad as we might think. Looking at numbers alone, other pathogens, such as Salmonella, Campylobacter, and norovirus strike far more people including Canadians each year. But nothing strikes fear quite like well-publicized outbreaks and in this regard, E. coli is king. In 2006, the bacterium led to an outbreak that spanned 26 States. In Canada, the most famous outbreak was the 2001 Walkerton tragedy that led to a government inquiry. Though these represent only two of the outbreaks, they have had staying power in keeping this species at the top of the public's health concerns.

But that soon may change thanks to a relative of this headline grabber with the potential to cause significant troubles in the future. Over the last twelve years, a bacterium has been quietly causing infections in several countries although until recently, has never been given any credit. It's known as Escherichia albertii and based on its current trajectory, you may be hearing about it sooner than anyone might like.

The E. albertii story began back in 2003. While examining a collection of fecal samples from children in Bangladesh, a group of researchers came across a rather odd bacterium. At first glance, it looked like E. coli. But taking a closer look revealed it wasn't exactly the same. Instead, it was an entirely new species. After much discussion it was eventually named after one of the microbiologists working in Bangladesh, M. John Albert.

Normally, when a new pathogen is found, immediate surveillance is undertaken in order to at least find out where it may be hiding in the environment and whether it has caused any troubles in the past. When the microbe is entirely unique, this isn't a problem. But, E. albertii is unique in its ability to evade detection making it an even more dangerous enemy.

The trick to evasion isn't due to any specialized function, however. Instead, the bacterium simply masks itself as its better known cousin, E. coli. They both make the same toxin, they both grow in the presence of similar nutrients, and at the genetic level there are more similarities than differences.

This similarity has meant detection methods for E. coli are not entirely trustworthy and E. albertii may be silently spreading around the world -- presumably in birds. The only proof, however, comes from a 2012 study looking solely at E. albertii. Indeed, the bacterium is far more prevalent in several nations and causes far more infections than believed.

There are only two routes to go forward to ensure public safety. The first is to examine how the bug grows in the lab and identify any possible differences from E. coli. There are a few but they could take time to detect and may not be valuable should an outbreak occur. The other is to use genetic methods to identify the bacterium based on its DNA. They are rapid, effective and can give answers in a matter of hours instead of days.

But, there is one problem. To make this work, the bacterium needs to be examined for any unique stretches of DNA. Without this knowledge, the technique simply can't be done. Until last week, there had been no comparative study to distinguish E. albertii from E. coli. But now, thanks to the work of an international collaboration published last week, those differences have been found. Using genetic analysis the team found several differences between the two allowing researchers to finally figure out the difference with confidence.

Of course, being able to tell the two Escherichia species apart is just the beginning. To date, less than a dozen countries have been examined for the bacterium. Once a proper test is developed, widespread surveillance can begin -- including in Canada -- to find out where this pathogen calls home. If Canada does end up being positive to which there is little doubt, then even more caution may be needed upon identification of gastrointestinal illness or outbreak. Instead of relying on the good old fashioned E. coli, we may have to give the credit to this newer species and deal with the consequences as well.

Thankfully, for anyone looking to consume meats, fruits, and vegetables raw or undercooked, there may be one slight silver lining. E. albertii is more sensitive to food preservation and preparation treatments. Staying with the usual guidelines for food safety should help to keep you free from infection from either species.


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