What the H?

As far as I can remember, I was never a medically minded person up until Christmas 2019. I knew what food poisoning was, blastomycosis, blood clots,  and cracked ribs were, but that was it. I'm sure I knew of others, but I never gave them a second thought as I was spared much in the way of illness. It's funny how such things shaped my life, and I never gave them any hold in my mind until much later. Not that these diagnoses were as profound as say, a cancer diagnosis, but they impacted me in many ways. All this to say, that was my breadth of awareness of the medical field, the corpsmen (God love them, seriously) were no help to teach me. I do remember vividly for some reason I can't explain, the time I found out about H. pylori, the "H" in the title. I had a buddy at the time with some gnarly, debilitating stomach pain. Boy did I not known what the hell to do about that. Ibuprofen? Acetaminophen? Nah, I know better now. And that. bug, and subsequent complications, are now part of my dual interests of infections and cancer. 

Short aside, check out This Podcast Will Kill You: Ep 120 on acetaminophen. Much more fantastic than my blog post and actually educational. That is all. 

Actually, another aside is I think they also have another episode on H. pylori. I digress. 

Mr. HP, Helicobacter pylori not Harry Potter or Halloween pumpkin, is a gram negative bacteria that normally resides in the stomach of humans. HP can also be found in dogs, cats, pigs, cows, and horses among other animals. It is microaerophillic, which means that it likes lower levels of oxygen than in the atmosphere, and capnophillic, which means it loves to wear different baseball caps every day of the week. Or is that one who loves to collect bottle caps? No? Oh right, they need extra CO2. 

So how does one get HP? It is a common infection estimated at effecting 50% of the world's population (more in developing nations) and can be transmitted fecal-oral, oral-oral, or sexually. Once inside, they burrow into the lining of the stomach to escape the acid which resides there. They have six little horror tentacles (flagella) that they use to move around and away from the more acidic regions of the body. If that was not enough, they produce enzymes that break down components of stomach acid including urease (breaks urea), catalase (break down hydrogen peroxide into H20 and O2), and oxidase (something about taking a hydrogen and giving it to an oxygen). All these -ases break down urea into CO2 and ammonia, neutralizing stomach acid. If you know anything about ammonia, you know thats not a good thing, think hepatic encephalitis. 

The damage (at least some of it) comes from the released ammonia along with other chemicals produced which damage the cells of the stomach leading to the death of said cells and inflammation of the stomach lining. This causes the stomach to produce more of the cells (G cells) that release gastrin which increases the output of stomach acid. Add the increased acid, to the inflammation, dead cells, and all the other chemicals the HP produces and it is not a good thing. Some infections are, of course worse than others, HP pathogenicity ranges across the world which is why that 50% number does not mean that 50% of people have terrible stomach pain all the time. Asymptomatic infections are more prevalent by far. To confirm the diagnoses, a urea breath test, biopsy or fecal sample are needed. 

All this damage sounds bad right? Yup, aside from the pain, which is what I recall, there are other complications. The increase in acid can lead to ulcers due to atrophy of the stomach lining and damage to the pyloric (get it?) sphincter and pylorus can allow more acid into the duodenum causing duodenal ulcers. Depending on the severity of the ulcers, there is a risk for anemia, malnutrition and anorexia depending how they affect ones appetite, chronic ITP,  and cancers. The chronic inflammation is what makes HP a carcinogen and a drive of cancer rates. What I found out is that aside from stomach cancer, HP has been linked (with varying degrees of surety) to diffuse large B-cell lymphoma of the stomach and extra nodal marginal zone B-cell lymphoma. I gotta look more into that, but either way, there is a risk of some cancers. 

It is also suspected that HP can reduce the incidents of esophageal cancer and premalignant conditions through the neutralization of stomach acid. This may minimize the damage done by conditions such as GERD. 

To treat this bug, triple therapy is the standard including a proton pump inhibitor (PPI) and two antibiotics, generally clarithromycin and amoxicillin. Bismuth is sometimes used first line but is definitely included in antibiotic resistant infections. Other options for antibiotics include metronidazole, levofloxacin, tetracycline, tinidazole, rifabutin, ciprofloxacin, among others. Fun fact, PPIs have some antibacterial properties against HP. These 3-4 drug combos are given for between 10-14 days, or 21 days for salvage therapy. 

That is that, and that is HP who is indeed a wiley bugger. I hope you enjoyed at least a few words of the diatribe above. Share this and the podcast of the same name to anyone you think may be interested and comment on either if you want my 2 cents on anything else or have cool ideas. Love y'all. 

References 
From Antibiotic Resistance to Antibiotic Renaissance: A New Era in Helicobacter pylori Treatment in Cureus by Godavarthy and Puli in 2023 

H. pylori from the Best Practice Advocacy Centre New Zealand

H. pylori infection: ACG updates treatment recommendations by Randel in Am Fam Physician 2018

H. pylori from StatPearls at the NIH and from the NCI: National Cancer Institute 

Helicobacter pylori and Gastric Cancer: Factors That Modulate Disease Risk by Wroblewski, Peek, and Wilson in Clinical Microbiology Reviews 2010

Helicobacter pylori in animals affecting the human habitat through the food chain from Anitcancer research 1999 by Dimola & Caruso

Image of H. pylori from BioCare Medical 

Management of Helicobacter pylori Infection from Gastroenterology 2018 by Myron & Zarbock