Sweetly Swimming Salmon(ella)

Salmon is much less appetizing with the -ella at the end of it. But Salmonella is also the couple name of my brother and his girlfriend so thats neat-o. Salmonella is neat-o also but for different reasons. Named after D. E. Salmon, Salmonella  is a gram-negative, rod shaped, non-spore-forming, intracellular, facultative anaerobic bacteria. There are two species, only one of which I will waffle on about here, S. enterica. I will not call it SE because command+I is not my friend today. 

When people hear of SE generally it is in the context of food borne diarrhea and vomiting, typhoid is also caused by SE, just a different serotype. On another note, serotype are variations in a species based on surface antigen. For Salmonella as a whole, there are 2,500 serotypes. Yowza. This is useful for looking at outbreaks and determining which cases are from the same outbreak and which are background noise. If everyone who ate at the unnamed chicken joint has type 1 but this guy who didn't eat there has type 469 then he can probably be excluded from the investigation. 

Speaking of chicken, FYI SE should be heated to 140F or 60C for 12 minutes to kill the buggers. Unless the SE in in peanut butter, then its super powerful and heat resistant. Don't know why, didn't get that far but I guess I have to start cooking my peanut butter more. For the foodies out there, non-typhoidal SE is the greater threat, it comes from all sorts of animal reservoirs and typically causes a gastroenteritis and if left unchecked may cause sepsis. The typical "food poisoning" takes anywhere from 6 hours to 2 days to kick in and can last 2-7 days. These folks may have a handful of nonspecific symptoms such as fever and chills, nausea, cramps, and headache along with the runs. 

For this, SE enters the small intestine and takes root in the cells lining your gut, which is bad enough, but they also release an endotoxin to boot. Side note, as with many diarrheas, certain antibiotics allow SE to flourish while nuking the rest of your gut flora. In those of us with a normal immune system this is ok if inconvenient, unless you have a good toilet read you've been meaning to get to, but for those without the functioning immune system, the malnourished, the young, it can be fatal. The first issues is diarrhea, getting rid of all that fluid and electrolytes can lead to some sequelae not normally linked to diarrhea. Vomiting can lead to metabolic alkalosis and abdominal cramps can lead to less PO intake exacerbating the vomiting or diarrhea side effects. 

For those infants, elderly, and immunocompromised folks, the diarrhea and vomiting may be enough to kill them, but the SE is already doing damage to the gut lining and it would not take much for some gut bacteria to get into the blood. Enter sepsis, either from SE or other gut bugs (looking at you E. coli), and the range of things SE can mess up are even wider than before. I won't list them all but in the blood SE can get anywhere, and thats not good my friends. 

Typhoid fever AKA typhoid is also caused by SE, just a different serotype. Usually a gradual onset, weakness, constipation, vomiting, rashes, headaches, Faget's sign, high fever start to occur. This form of SE prefers the lymph nodes and is caused by the fecal-oral route and has no known animal host. This too may progress to sepsis (much more likely than the food poisoning types). One of the ways SE does this is that when eated (phagocytosed) it will live in the immune cells and stay in the body for longer. 

As with any bacteria, we use antibiotics to kill it, for now. Generally cipro is given for a week but amoxicillin, TMP/SMX, and chloramphenicol are used as well around the world for treatment up to 3 weeks. As the Borg say, resistance is inevitable and this proves right yet again. Multi-drug and extremely drug-resistant strains have been found. Resistance rates for ~11,500 isolated from the United States showed resistance to 4 or more antibiotics in 63% of the samples and 4% resistant to 8 or more. Yet we continue to treat every cough with antibiotics and feed them to all our animals. Some people think aliens are here to save us from nuclear weapons, maybe they want to save us from this stupidity. 

From 2006-present, every year has brought at least 1 and up to 16 food borne SE outbreaks. Those are just the ones we know about. Also watch out for turtles, they are out to get you via SE infections, and apparently hedgehogs have been implicated. Not today Sonic. Here in the U.S.A it's estimated by the CDC that we get 1.2 million cases a year with less than 500 deaths. Across the world, typhoid fever alone is estimated to have killed 215,000 people and infected over 21 million. World wide numbers for the gastroenteritis are not available probably because the number of causes for diarrhea are so great, but we do know that those without access to clean water and sanitation are at a high risk of contracting SE. 

There is more to talk about with SE but those are the basics. Oh, and Typhoid Mary was a carrier of SE but without symptoms so you know that now. Don't you feel smarter? I don't. Remember, cook your chicken, boil your peanut butter, and don't lick your turtles or hedgehogs. Love y'all, bye. 

References 

Antibiotic Resistance in Salmonella typhimurium Isolates Recovered From the Food Chain Through National Antimicrobial Resistance Monitoring System Between 1996 and 2016 by Wang et al., in Frontiers in Microbiology May 2019

Antibiotic-Resistant Salmonella in the Food Supply and the Potential Role of Antibiotic Alternatives for Control by Nair et al., in Foods October 2018

CDC, NIH, and WHO sites on Salmonella, typhoid fever, resistance, and enteritis

Image of Salmonella enteric serovar Typhi from Wikipedia

Medical Microbiology, 4th edition, chapter 21 Salmonella by Giannella from the NIH Library of Medicine

Multidrug-resistant typhoid fever: a review by Zaki & Karande in the Journal of Infection in Developing Countries May 2011

Thermal Inactivation of Salmonella in Peanut Butter by Ma et al., in the Journal of Food Protection August 2009