Hi, welcome back to Sketchy Micro. This is Andrew. We're going to be covering Salmonella, and specifically two subspecies of Salmonella, Salmonella typhi and Salmonella interididis. And although these subspecies are very different, I think there are enough shared features that it warrants us including them in the same sketch. This way we can really clump together the commonalities and then highlight the differences. Alright, so let's get to sketching this out. I think the topic for this sketch should be a salmon dinner. Salmon is a pretty obvious association with salmonella. I imagine you guys have at least subconsciously made that association, so let's not change it. But I think having it be a dinner will allow us to expand more and include more features. Let's start by drawing a table. Then on top of the table we'll have our salmon dish. A little thing that we'll include with the salmon is to have the tail flopping around just to give action to it so that you remember that salmonella is motile. That's a big feature, salmonella is motile. And as a quick tie-in to this, it's also H2S positive. You can remember that all enteric bacteria that are motile are also H2S positive, which means that it grows black colonies on the hecto-inaugur plate. But just to really drill it in, we'll go ahead and paint the plate that the fish is on black. Okay, so that black plate should trigger a memory of, you know, black colonies on the hecto-inaugur plate, which means H2S positive. Another shared feature between both Salmonella subspecies is that they're encapsulated. We can represent this by just drawing a glass dome over the salmon dish. I like this, it kind of looks like what those fancy bakeries use to serve their pastries. Should be a good reminder. The next feature that both share is that they're acid labile. This is important because if they're acid labile, they get easily degraded in the stomach. So that means that you need a really high dose to cause infection. This is opposed to Shigella, which isn't acid labile and only needs a few organisms to cause infection. So then additionally, it would make sense that if you're taking omeprazole or had pernicious anemia or had any other conditions that lowered stomach acidity, you'd be more susceptible to infection. So how do we remember this? Well a lot of people like lemon with their salmon, so we can add a slice of lemon, which you would equate with acid, and you'll just have to remember that it's acid labile. So now it's time to differentiate between the two subspecies of Salmonella. Over on the left, we'll have Salmonella interididis, and on the right, Salmonella typhi. On the left we'll have a chicken. This will remind us that we acquire Salmonella interidotis by eating undercooked chickens, and that chickens are the main reservoir. Okay, on the other side of the page we'll have a seagull. This is to represent gallbladder. I know it's a little more of a stretch, but I think you should be okay with it. And this is to remind us that chronic carriers of Salmonella typhi harbor it in their gallbladder. Let's focus in on Salmonella typhi for a bit, and also strengthen the connection between Salmonella typhi and the seagull by adding this apron on the seagull. This will help remind us of Typhoid Mary, the chef. If you haven't heard about Typhoid Mary, I'd check it out quickly on Wikipedia, it's somewhat interesting and it might help you remember. We'll add red spots to the apron to represent the rose spots, or red macules, that patients with enteric fever get on their abdomen. This only happens about 25% of the time, but that's enough for it to be testable, so you'll want to be able to recognize it. One of the important clinical features we have to remember for Salmonella typhi is that it's the number one cause of osteomyelitis in patients with sickle cell disease. So we'll go ahead and erase the head of the salmon and expose the bones. This should help you remember osteomyelitis. Then we'll add a sickle to the hand of the seagull and have it looming ominously right above the bone. And that should be a strong enough association. Typhoid fever is generally associated with constipation, but it can cause diarrhea, and when it does, it's said to resemble pea soup. So we'll go ahead and draw some bird droppings here, the color of pea soup, to help remind you of that. Another difference between salmonella typhi and enteritidis is that typhi is treated with an antibiotic, most often a fluoroquinolone. So we'll go ahead and draw a flower on the table closest to the seagull to represent fluoroquinolone. Salmonella typhi also has a live attenuated vaccine. We'll draw this syringe and it'll be sticking the leg of the seagull. This should remind you that it's Salmonella typhi and not Salmonella interididis that has the vaccine. Alright, let's bring our attention back to the chicken. The main thing I want you to remember is that Salmonella interididis causes inflammatory diarrhea. So we'll show you by having the chicken light the candle, and this flame will remind you of inflammatory. A very loose factor for salmonella that you'll also see pop up for Shigella and Yersinia pestis is that it contains a type 3 secretion system. This is a protein that not only detects eukaryotic cells, but when it does, it secretes a protein that helps with infectivity. And unfortunately, this is something you'll have to remember. We'll draw this turkey baster near the chicken, and this will be a symbol for the type 3 secretion system. We'll keep reusing it in future drawings, and hopefully by then it'll be really fixed. We're almost done with the sketch, but there is one more point I want to bring up about the pathogenesis of both subtypes. So say we do ingest a dose sufficient enough to cause disease. What happens is it passes through the stomach, through the small intestine, into the colon, and there it invades the lymphatics. It actually gets taken up by macrophages and then carried into the blood. So the important point is that it's facultative intracellular, but specifically within macrophages. So we're going to draw these bird cages behind both birds. And the doors are open, so this kind of signifies that they can go in and out of the cages, okay? That represents facultative intracellular. You can remember that it's macrophages because it rhymes with cages. Or if that doesn't work, we'll just write the M5 symbol on the cages, and if you're a visual learner, you'll remember it that way. And that's all the information we're going to cram into this sketch. Let's go over it all again one more time. First, we have the salmon representing salmonella. Then we have his tail flapping around to remind you that it's motile. We painted the plate black to remind you of H2S positive and that it forms black colonies on the hecto and agar plate. We have this glass dome representing the capsule, and the side of lemons will represent that it's acid labile. On the left, the chicken will represent Salmonella interidotis. It's also the reservoir. On the right, we have the seagull for Salmonella typhi, seagull for gallbladder, which is the reservoir. The apron serves a dual purpose. It reminds us of Typhoid Mary the Chef and the rose spots seen in typhoid fever. The seagulls holding the sickle above the fish bones to remind us of osteomyelitis in sickle cell patients. And we have the pea soup droppings for pea soup diarrhea. We have the syringe representing the live attenuated vaccine and the flower for fluoroquinolones. The turkey baster is the type 3 secretion system. The matches are for inflammatory diarrhea. And the two cages in the back have their doors open to remind us that they're facultative intracellular and macrophages. This is our fast recall symbol for salmonella. It's red because salmonella is gram-negative, and gram-negatives show up red on gram stain. We'll refer back to this symbol in future drawings to group organisms and re-access your memory of this sketch. Finally, I want to challenge you to think about salmonella in one week, and see how much you remember. I'm sure you'll be surprised. That's it for Samanoa. There is a lot of information, but I think it's very manageable. Follow us on Twitter for updates and check us out at www.sketchymicro.com. There you can print up some PDFs to take notes or even add to the sketches. And we'll check out your comments on YouTube so that we know what we're doing right and what we can improve upon. Thanks a lot.