Helicobacter pylori is the number one cause of peptic and duodenal ulcers. Most patients are asymptomatically colonized with H. pylori, and it’s possible that they never have any symptoms. It’s unclear why in some patients the organism is more virulent, but possibly has to do with the amount of organism at a given time..
This organism is unique in where it lives, it actually lives INSIDE the stomach. To survive this ridiculous environment, the organism secretes urease which neutralizes a small section of stomach acid around the organism so it can survive. The bacteria will eventually attach to the stomach epithelium and burrow into the lining to avoid being flushed out with the stomach contents. This can cause bouts of gastritis, or remain asymptomatic forever.
In making the pH more basic, the organism creates ammonia as a by product, this will damage the epithelial cells and begins to damage the gastric mucosa to the point where it creates a peptic or duodenal ulceration. Peptic ulcerations are typically worsened with food, and duodenal ulcers are relieved with food. This can cause the patient to have nausea, vomiting, fever, and persistent abdominal pain that can last months.
If this infection is not treated properly, the constant inflammation and constant epithelial proliferation to heal the wounds can lead to gastric adenocarcinoma. It has also been associated with Mucosal-Associated Lymphatic Tissue (MALT) lymphomas, which is a non-Hodgkin’s lymphoma.
To diagnose this infection, the best method is by detecting anti-Helicobacter IgG antibodies in the serum, but you can only use this prior to therapy since the patient will still be positive for antibodies even after the infection. You can also detect antigens in the stool, which is often used to check to make sure you’ve cleared the organism from the patient. The most famous method is the “urea breath test,” although most scientists agree that this is not very sensitive. Typically, the patient will swallow radiolabeled urea, and you’ll detect whether or not it’s broken by the urease created by H. pylori.
Treatment is called bismuth quadruple therapy which includes bismuth subcitrate, metronidazole, tetracycline, and a proton-pump inhibitor.
Vibrio species are Gram-negative curved rods that can grow in salt water, they don’t require it, but can grow in it. They have a single flagellum which helps them navigate the salty and brackish waters where they normally live. There are three Vibrio spp. that are important to human health.
Vibrio vulnificus is a waterborne organism that causes myonecrosis with 70% mortality and sepsis with 50% mortality. This typically infects patients who collect, harvest, or eat bivalves like oysters. Oysters are filter feeders and can collect and harbor these organisms. Treatment for this will be immediate surgical debridement, and antibiotics to prevent spread.
Vibrio parahemolyticus is the number one cause of seafood-related gastroenteritis. It is typically transmitted through eating oysters. It will cause explosive, watery diarrhea that resolves within 72 hours. Treatment for this is going to be just fluid replacement.
The most famous though, is Vibrio cholerae, which causes…cholera. This is typically waterborne and is either endemic in the region or occurs as epidemics in contaminated water sources, especially after natural disasters like tsunamis or earthquakes. This will cause profuse, watery diarrhea this is typically described as “rice-water” stool, and this is because the patient has pooped out all the fecal matter and is now just excreting water, electrolytes, and epithelial cells from the lining of the gut.
You have to be very careful about dehydration that can occur in these patients. This can be very deadly without treatment. There is a live, attenuated vaccine, and a few killed vaccines that can be given to travelers if they are going to an endemic area.
The most famous virulence factor of all time (not a debatable fact) is the Cholera Toxin. This is the classic A-B toxin. The B subunit binds to the receptor on the enterocytes, the A subunit does the action. The A subunit activates the Gs subunit of adenyl cyclase increasing cAMP, which activates a few different ion channels. This causes the secretion of electrolytes and water will osmotically follow creating the watery diarrhea.
This diarrhea is caused by the Cholera Toxin, and not an invasion into the gastric mucosa, which is why this diarrhea is never bloody.
There’s a differential media called Thiosulfate-Citrate-Bile Salts -Sucrose (TCBS) agar. It contains bile salts to inhibit Gram-positives, sucrose for fermentation, a high salt concentration, an alkaline pH, and allows for sulfur reduction, all to selectively grow Vibrio spp.
If the growth is yellow on TCBS, then it’s Vibrio cholerae
If the growth is blue/green, then it’s Vibrio parahaemolyticus or V. vulnificus
A 24-year-old male presents to the emergency department with a two-day history of abdominal pain, nausea, and vomiting. His temperature was 98F, blood pressure was 117/70 mmHg, pulse was 72 bpm, and respiratory rate was 14 breaths/min. He has experienced chronic, crampy, intermittent epigastric pain for the past three years, and has experienced a 13-pound unintended weight loss over the past two months. Physical examination revealed a non-distended abdomen that was soft with mild tenderness in the epigastrium, and bowel sounds were normal. Laboratory studies reveal leukocytosis and a high level of C-reactive protein. An upper endoscopy revealed a few nonbleeding, gastric atrum erosions and multiple clean-based duodenal ulcers. If this condition remains untreated, what is the most likely complication?
A. Barrett Esophagus
B. Kaposi Sarcoma
C. Burkitt Lymphoma
D. MALT Lymphoma
First, diagnose the patient.
The patient is presenting with several duodenal ulcerations. No medications were listed, therefore the most likely cause of the ulcerations is an infection with Helicobacter pylori.
A. Barrett esophagus is a long-term complication for patients with undiagnosed gastroesophageal reflux disease (GERD)
B. Kaposi sarcoma is when patches of abnormal tissue grow on the skin and oral cavity which is caused by long-term infection with human herpesvirus-8
C. Burkitt lymphoma is a lymphoma that is very aggressive and usually forms fast-growing masses around the jaw and neck, especially affecting young males that is caused by an infection with Epstein-Barr Virus.
D. The most common cancerous complication of untreated Helicobacter pylori infection is actually gastric cancer, but this wasn’t listed in the answer choices. Another cancerous growth associated with H. pylori is the formation of lymphomas within the mucosal-associated lymphoid tissues (MALT) which normally present as masses found during colonoscopy.
Therefore,
A 49-year-old male presents to the emergency room with fever, chills, and severe pain and swelling in both lower extremities for the past four hours. Vital signs reveal a temperature of 103F, a blood pressure of 90/60 mmHg, a pulse was 150 bpm, and a respiratory rate of 25/min. Physical examination reveals that skin over the lower legs and buttocks was erythematous with areas of necrosis, and the absence of creptius. The patient works as a fisherman off the coast of South Carolina. Tissue biopsy cultured an aerobic, Gram-negative, curved bacillus that produced green colonies on TCBS agar. What is the most likely causative agent?
A. Vibrio cholerae
B. Vibrio vulnificus
C. Vibrio parahaemolyticus
D. Helicobacter pylori
First, diagnose the patient.
This patient is presenting with fever, swollen reddened tissues, tachycardia, hypotension, and tachypnea. The areas on the legs show areas of necrosis which highly suggests myonecrosis.
- Necrotic condition especially of the muscle tissues
- Can occur with or without creptius (gangrene)
- Is a surgical emergency
A. V. cholerae is a common cause of profuse, watery diarrhea. This organism would produce yellow colonies on TCBS agar, because it can ferment the sucrose that’s within this agar.
B. V. vulnificus can cause myonecrosis when it is directly inoculated into open wounds, like those that commonly occur during the work conditions of fisherman. Vibrio spp. also love warm, salty waters like those on the coast of South Carolina. V. vulnificus will produce green colonies on TCBS agar, because it doesn’t ferment sucrose.
C. V. parahemolyticus is a great guess, it would definitely fit the description of the organism that was grown in culture including growing green colonies on TCBS agar. However, this is more often a cause of gastroenteritis instead of myonecrosis.
D. Helicobacter pylori can sometimes cause sepsis if it disseminates from the stomach, but it is not often associated with myonecrosis. It is a Gram-negative, curved rod, but this is microaerophilic and would not grown on TCBS agar due to the high salinity.
Therefore,
References:
https://www.cdc.gov/cholera/vaccines.html
https://microbewiki.kenyon.edu/index.php/Vibrio_cholera
https://microbewiki.kenyon.edu/index.php/Helicobacter_pylori
https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(16)30237-3/fulltext
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6103271/
https://pubmed.ncbi.nlm.nih.gov/31105433-helicobacter-pylori-colonisation-in-heterotopic-gastric-mucosa-in-meckel-diverticulum-case-report-and-review-of-the-literature/?from_term=case+report+for+helicobacter+pylori&from_filter=simsearch2.ffrft&from_filter=pubt.review&from_filter=language.english&from_pos=1
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5424574/
https://www.jstage.jst.go.jp/article/internalmedicine1962/29/3/29_3_313/_pdf/-char/en
https://www.asmscience.org/content/book/10.1128/9781555816728.chap52
The Bradley Lab 