Thursday, December 19, 2013

Henry Dawson as the Margaret Atwood of medicine : heterogeneous survival

Margaret Atwood made famous the old quip that  Americans want to leave the wilderness a success, while Canadians are merely grateful to leave it a survivor.

Henry Dawson, a Canadian doctor, encountered this for real when he went to New York to work among American medical scientists who expected him to focus on virulence in bacteria.

These are incredibly tiny , often immobile, beings who yet are successful in attacking their human hosts and frequently even kill them , despite the army of human medical opponents ranged against them.

In the alpha male world of medicine circa 1940 , virulence = success.

But Dawson was more interested in how these tiny beings persisted in surviving with, on and in us  , despite our bodies' best efforts to detect and kill them.

Because virulence is very much a two edged sword for bacteria : it may kill the host and then where do the successful bacteria live ? 

Or it might provoke a counterattack on the virulent bacteria that kills all of them but ignores their non-virulent kin.

Dawson seems to have been agnostic on the whole division between virulent and avirulent : merely seeing endless varieties of sub-strains among his chosen area of focus : oral commensal strep bacteria.

His team (as well as others) gave the different appearing sub strain bacteria colonies letter descriptions : R , S , L , M.

His team members later went on to study others that have been given names instead, such as vegetative/biofilm, dormants and persisters.

R were rough in colony appearance and didn't seem virulent in many species - unlike the smooth looking  S colonies, while the mucoid M were very virulent in some species.

R had normal bacterial walls, but S and M also had extra jelly-like capsules that made them harder to eat by our white blood cells, if they got in our blood system.

To over-simplify , R forms, because they lack a thick jelly cover , do much better at clinging to our throats and surviving long term by being low key and avoiding entering our blood streams.

L forms ,named after the Lister Foundation in London where they were first discovered, are wall-less. 

The strong but flexible wall of a bacteria (a wall beyond the sack like skin that all cells must have to be a cell ) is usually considered the secret to the bacteria world's successful survival as Life's oldest and most widespread form.

So a bacteria without a wall is a real curiosity - it seems to survive in places of calm where the water around it doesn't suddenly get very salty or very un-salty (to describe vital things osmotic as simple as possible ).

Its lack of bacterial wall even fools the human immune system into considering it not a harmful microbe but rather a part of us.

That film of bacteria we can easily feel on our unbrushed teeth is a biofilm .

When it lands on our previously slightly damaged heart valves, it becomes bigger and harder (literally heart valve calculus) often called a vegetative form and in both cases, provides a safe home for various types of bacteria and their sub strains.

We could call them B or V type bacteria.

Dawson started studying them when he started his pioneering use of penicillin to cure vegetative type endocarditis.

Some sub strains, his team members were the very first to discover in 1942, are naturally slow growing and survive antibiotics because they normally only hit bacteria that are actively growing.

These P types are called now called persisters and they make both teeth bacteria type endocarditis and TB truly awful diseases to fully conquer.

Others deep inside the biofilms don't grow at all normally and are called dormant (D type).

They will happily grow when the normal bacteria population closer to the surface of the biofilm have all been killed by antibiotics , leaving more food for the dormants to eat.

Wow : R,S,M.L,V,P,D forms --- where will it all end ?

Who knows?

The point Dawson was trying to make was that bacteria weren't really invaders, seeking only to enter Man to kill him, but extremely tiny creatures to whom a human adult body was literally the same size to them that the Earth is to us.

They saw us merely as home - just as we regard the Earth .

Yes a sometimes comfortable and sometimes hostile home - just as Earth often is to us - and seemingly they survived life's ups and downs by being 'careless' in their eugenic practises, as least as seen by eugenically-minded humans in the 1930s.

There were, in fact, no perfect pure bacteria clones ---- nothing an Aryan superman would recognize as perfection --- instead they shockingly seemed to tolerate all kinds of cripples and defectives in their population.

Because as the environment varied, what was a defect one day (slow growing or no growing, no capsule, no wall) was a means of survival the next day as the formerly virulent fell like ten pins all around them.

Dawson didn't dismiss the 4Fs of the bacteria world as "useless mouths and life unworthy of life" anymore than he later didn't dismiss the 4Fs of the human world either.

Dawson's close examination of how messily but effectively Reality really works proved much more accurate than all the armchair theories of the purist scientists, like Hitler or Einstein....

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