Field of Science

Studying Streptococcus - SGM series

ResearchBlogging.orgThe fourth post now in the SGM series, and this one focuses on Streptococci. Streptococci are a genus of spherical Gram-positive bacteria containing both pathogenic and harmless strains, including the flesh-eating bacteria (which cause the delightfully named necrotizing fasciitis) as well as bacteria responsible for making swiss cheese. Commensally they are found on many parts of the human body, including the mouth, skin, intestine, and upper respiratory tract .

Streptococcus - growth and division leads to long chains of bacteria (image from lenntech)

It's quite a broad topic which allowed plenty of speakers to address their favourite issues with these bugs, but as well as discussions of the virulence factors, biofilm properties and various different intracellular survival properties of the Streptococcus there were also some talks covering new research mechanisms. Rather than focusing on the properties of the bacteria, these talks were about new methods used to study them.

The one that jumped out at me the most was about using Bioluminescent imaging to track a Strep infection. This appealed to me because the iGEM team next door are working on Bioluminescence so it's a word I've heard a lot over the last eight weeks. By adding bioluminescent bacteria to a mouse model, the course of the infection can be tracked over several weeks (using small animal imagine machines it can be tracked in the same mouse). This provides a far better understanding of the pathogenesis of the bacteria; how it spreads through the body and at what point it is most infectious.

The process of using bioluminescence to track diseases (image from the reference).

Using luminescence to study disease progressions isn't a new idea, but the use of whole animal scanning mechanisms now means that fewer animals have to be sacrificed in order for the study to done. The luminescent tissue does not have to be extracted, and the more natural disease progression can be followed.

Other methods explored included the by-now predictable whole genome study analysis to organise the different types and virulence levels of a Streptococcus suis which leads to meningitis in piglets. Comparative genome hybridization studies allow many genomes to be compared at once, giving a better idea of the differences and similarities between them. This helps to separate the strains into serotypes (different groups), and to compare the differences that lead to virulence. Genome comparison work was also being done for Streptococcus equi species which cause infections in horses.

In other news (pretend that was a smooth transition!) the latest Carnival of Molecular Biology is out over at Thoughtomics. There are some brilliant articles covering the intra-cellular happenings of organisms from bacteria to frogs to Tibetans. If you've ever wondered about noisy bacteria, zombie enzymes or what micro-RNA is, go take a look and visit the submissions.

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Timothy C. Doyle, Stacy M. Burns, Christopher H. Contag (2004). In vivo bioluminescence imaging for integrated studies of infection Cellular Microbiology, 303-317 DOI: 10.1111/j.1462-5822.2004.00378.x

7 comments:

Lucas Brouwers said...
This comment has been removed by the author.
Lucas Brouwers said...

Are there any (time lapse) pictures available of the bioluminescent strep infections? I've got a feeling that they should look pretty awesome!

And if you squint a bit, it's a very smooth transition indeed ;)

Rogue Medic said...

Nice.

This does raise one question. When I get the bulk Swiss cheese that does not have the holes in it, am I violating some sort of existential law?

Is it very young cheese, with holes not yet developed?

It is cheese made with different bacteria?

Is it even really Swiss cheese?

Can I only properly enjoy it while drinking Champagne from California?

OK. I can't count to one very well.

Lab Rat said...

@Rogue Medic: The gas is caused by carbon dioxide released by the bacteria used in the manufacturing process and is known as 'eyes'. Cheeses without the holes are called 'blind cheese' although still classified as Swiss Cheese. Blind cheese I would guess is simply not left to develop for as long. I don't know if the bacteria used are different.

With enough Californian champagne, everything can be enjoyed.

@lucas: There probably are time lapse photos, or at the very least slide-show type development stages. Wouldn't know where to find any though, beyond a google search!

diseaseoftheweek said...

One of my colleagues did her honours (kind of like a one year practice PhD, I don't know if it's done anywhere outside of Australia) looking at Nippostrongylus brasiliensis infection in mice. Apparently you can find them in the lung but nobody could work out how the worm got from the site of infection to the lung. Anywho, they used whole animal bioluminescent imaging to track the worms throughout infection. They were trying to do it in both real-time for the acute infection and by compiled photos to map the migration over longer time frames. I don't think it worked very well but its fascinating technology.

Faz said...

Hi, I gave the talk on bioluminescence, and I just ran around my lab screaming "someone blogged about my research !!!".
Your article is now pinned firmly on my desk, and has really made my day.

p.s. It's Streptococcus suis. Streptomyces is a very different bug. It gets confusing, because scientists colloquially refer to both as "strep".

Lab Rat said...

@Faz: Wow, thanks for commenting! It's always amazing to hear from the authors and speakers you blog about, and I'm very glad you liked the post :)

I spent the whole thing trying my hardest to write streptococcus, rather than streptomyces, but I've just seen the time I missed. Ooops! beauty of blog posts is that you can correct them so hopefully next time you come by the blog they will all be streptococcus.