yersinia pestis, insidious you are

Where to start, bacteria? Or plague?

In this post, I hope to focus mostly on the insidious bio-agent, Yersinia Pestis aka, Y. pestis, bringer of plagues. I stray but I come back (you’ll know by my tone).

Pathogen infection blocks flea’s esophagus. Unable to feed, it jumps from animal to animal in attempt to get nourishment. During this process it regurgitates infection into each bite wound until it dies of starvation.

Plague derives from the Greek, plēgē, meaning a blow or stroke. Latin plungere, meaning to beat or strike and also to bewail or lament.

I want to indicate idea of pandemic in some way. I mention to Dr. Sandra Reuter, I am considering collaging a world map into my study of Y. pestis.

She responds: I like the idea of the world map and spreading of disease. That is very much what I am interested in now, and it does also apply to the plague, as it has travelled the world several times, too! Especially in the middle ages, it spread along the trade routes. Even today, it survives in some places like Madagascar, China, Russia, and even in remote parts of the US.

Some bugs are like that, they like to travel and make use of how people move. Compared to the middle ages, the spread nowadays is much quicker, though, because of air travel! That’s why this corona virus pandemic has hit the whole world within a couple of months, whereas the plague travelled much slower, and the big pandemic of the Black Death took several years to spread around Europe.

At start of composition, I know I want to indicate the plague and it’s history so I collage onto my surface, a global map. I want to add a phylogenetic tree but I fill the space with symbolic fingerprints instead. This detail eventually goes.

Plague, infectious disease, zoonotic in nature meaning it’s transmitted between animals and humans. The main vector, a small flea, passes causative agent, Y. pestis to another living creature, in this case, a rat, aka, the reservoir host.

Can I refer to this as one cycle? Because we also have another cycle that involves the human.

Flea is vector, rat is reservoir host (first victim), and the bacteria being passed is non-motile, rod shaped, bipolar staining (looks like a closed safety pin). I especially enjoy drawing the rat. Felt a little bad for flea. Safety pins were nearby…fun photo op.

Humans are contaminated in various ways:  flea bite (blood meal / flea throw-up),  direct contact with infected animal or tissue, or by inhalation of droplets coughed by infected human or animal.

While the disease is important, I get so caught up in it (fyi, it’s fascinating and there’s a lot on it, look it up).  And in the case of this study of Y. pestis, I wander into genome sequencing too (and also get lost).

Trying to understand a complicated set up, I eventually have to return to the focus for my visual…the pathogenic bug. 

As I look at and draw in the  bacteria, I recall Sandra telling me most look fairly similar and are small. She’s right, they do and they are.

Y. pestis, Gram-negative, nonmotile, rod shaped bacterium, I’ve decided I have an aversion to you. I can’t think straight to write about you.

You are facultative anaerobic which basically means you grow (survive) with or without oxygen (with or without oxygen!). You are held by some sort of slime layer that prevents you from being destroyed by king of the phagocytes (→macrophage).

Enter neutrophil, lymph node and macrophage.(replacing fingerprints)

You manage to colonize macrophages, reaching lymph nodes, and because the immune system doesn’t take you down you can enter the blood stream and organs leading to bubonic plague, septicemic plague or pneumonic plague. And if you’re inclined, you take people down quick!

The history of the plague and the details of the various transmissions are out there to read about. And genome sequencing helps to tie up the story as it passes through time.

Though unlike my last study where I manage to pull it all together (at least in my head and on my painting surface) – this pathogen and its disease has me going from one complexity to another. I keep wishing I was painting on a large sheet of paper that I can erase and rework instead of circular, 11.5″ form. Oh well.

Questions I have as I learn about Y. pestis and its disease:

Who is the victim in the end? Every life form that comes into contact with Y. pestis, is my guess.
And who survives? (I sort of asked this question in the last post) My best guess is, it all depends on who, what and when. There are lots of fleas and rats, after all, and maybe many humans too (in other words overpopulation).
Will the bacteria be destroyed completely? Does it serve a purpose?
Does the bacteria’s nonmotile quality benefit it in some way? It seems to me it would want to move.

Any comments or questions? Please share them!

Thank you Sandra, for introducing me to your work, past and present. And helping me along as I organize my thoughts. I will say this study and how I moved through it, in some weird way, activated my imagination and maybe at times even each of my senses.
#LotsOfActivity

I especially enjoyed our conversation about DNA (and RNA) and the common thread (strands) that connects us all. I’ll hope to come back to this one day.

More → Dr Sandra Reuter and her work.

Postscript: It was hard for me to keep this information organized so I could understand. Maybe because I quit drinking coffee this last month…who knows. Anyway, it’s interesting to be looking at this topic in the context of this last year. It moves me into looking forward. All life seeks to survive.

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©2020 ALL RIGHTS RESERVED BY MONICA AISSA MARTINEZ

all things bacteria

But where is the bacteria?

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I meet Dr. Sandra Reuter, microbiologist turned bioinformatician. I find her work [so] fascinating, [sooooo] abstract (read between the lines…this is hard stuff). Sandra lives in Germany working at a university hospital. She explains, I have set up the sequencing here so that we can sequence anything of interest!

Bioinformatician’s combine biology, medicine and health-related studies with information technology. They collect and interpret data covering a range of fields. I gather Sandra’s  focus is genomics, pathogens and microbial evolution.

Sandra jumps right in, Generally I am interested in all things bacteria, and especially those that cause disease. And I am interested in how they develop or evolve to cause disease, how they adapt. And lately, also how they move around a hospital system…I use whole genome sequencing to track these changes and adaptions in the genetic code.

In my PhD thesis, I worked on Yersinia. One of the species in this genus is Y. pestis, the plague bacterium, however I was more interested in a distant relative, Y. enterocolitica, that causes diarrhoea. There are different types of Y. enterocolitica, and I was looking into how they each came to be and what made them unique. I also then compared it back to Y. pestis, because both of them being pathogenic with similar markers could mean they both have a common ancestor that also had that trait. In fact, I found that they are not that related, and that they both came up with the same idea of pathogenesis seemingly independently!

I get so caught up in what she actually does as a scientist instead of what I need to focus on for my work. Before my brain has any sort of visual she shares info about superbugs, she simplifies genome sequencing (if this is possible) for me…talking family, ancestry, fingerprint, isolates, transmission chain of infection, bugs from different cities…etc.

The bug talk…one main chromosome, plasmids (extra bits of DNA), antibiotic resistance genes, quorum sensing. Sandra smells the plates, as the bacteria do smell slightly different depending on what they are and eat and which gases they produce (for some reason the latter brings memories of ceramic class).

I ask, do you have visuals, of any bacteria?

No she doesn’t have images of actual bacteria explaining she looks at bacteria in a different way…I draw phylogenetic trees ↓  to show their evolutionary relationships.

Sandra explains: This is a tree (spread-out view ↑) of different Yersinia species. On one side is what we call species complex (SC) 1 – pestis the plague bacillus, its close relative pseudotuberculosis, and also similis (as in similar to pestis and pseudotb). On the other side towards the bottom is enterocolitica (SC5), with different biotypes. In between: all the other environmental species, that don’t cause disease in humans but maybe insects (nurmii, entomophage) and trout (ruckeri). We compared it with the different biochemical tests used to identify the species (the red, blue, and grey boxes) and can see why some tests may be problematic, as they can’t tell species apart with confidence.

EMRSA-15 context: This ↑ is a tree (circular view)…EMRSA-15 isolate from around the UK. She explains details including computer use to organize information.

Though I am not expecting images of this sort and my mind isn’t really registering the content, I like their form and think they’re cool! I will use the circular (already established) format. Maybe I might (might!) bring in the first tree (spread out view).

She also explains gram stain which includes structure and color, something I can hold on to easily!

Gram staining is a way to colour bacteria. Under a microscope they are very tiny, so to see them better, we can put some colours on. And the behaviour comes back to how the cell wall is made up (structure!). The staining is done in several steps. In the first step, you use a purple dye (color!). Then in the second step you first fix the colour and then use ethanol to rinse them. Because the cell wall in Gram positives is thick, they retain the dye and are therefore purple. To stain the Gram negatives, you then use another dye in the last step, so they are red (another color!) in the end.

My last question to Sandra considers what is going on in the world these days, with the pandemic. Who will win? Microbe or human? She talks about both human and microbe becoming more or less aggressive. Both will win, she decides, each will adapt and continue…to survive. I like her attitude and appreciate the answer.

Going into the studio after our meeting, I look closely at the wonderful phylogenetic trees. I’m not certain I can replicate them by hand. (Oops! I really mean to say reproduce here but I’ll leave the word replicate!)

I let go of the bacteria I was hoping to draw via this sketch (note: it’s gram-negative!) so that I can figure out how to approach this next work.

On this particular day I think Gram-positive/Gram-negative. I see the yin/yang and the unplanned (but welcome) DNA strand that makes itself visible.

Finally getting clear, I will focus on Yersinia pestis, plague bacterium. I have an idea and head out to the map store to buy a map of the globe.

Sandra, it was good to spend a Friday morning speaking with you all the way in Germany! I can tell that you love your work! Thank you so much for sharing it with me.

More about → Dr. Sandra Reuter 

Let’s see what I come up with for Y. pestis and the plague!
#flea #rattas #zoonotic #vector #reservoir #puzzle

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©2020 ALL RIGHTS RESERVED BY MONICA AISSA MARTINEZ