You’ve probably seen Helicobacter pylori show up as “that spiral bug” tied to ulcers—but on exam day it’s really a pattern-recognition game: ulcer location + acid status + complications + best test/treatment. Here’s a quick-hit, shareable guide that turns H. pylori into an easy set of contrasts.
The 10-second mental image (visual mnemonic)
Picture a spiral “H” drilling into the stomach mucus, wearing a hard hat labeled “Urease”, blowing ammonia bubbles to neutralize acid right around it. The drilling causes chronic inflammation, which can lead to ulcers and—even years later—cancer/lymphoma.
One-liner: H. pylori is a urease-positive, spiral Gram-negative bug that colonizes the gastric antrum, increases gastrin → increases acid, causes duodenal and gastric ulcers, and predisposes to adenocarcinoma and MALT lymphoma.
High-yield ID: what Step questions are really asking
Classic microbiology hooks
- Gram-negative, curved/spiral rod
- Motile (flagella) → swims through mucus
- Urease positive → converts urea → NH₃ + CO₂
- NH₃ buffers local acidity → helps survival but also mucosal injury
- Typically colonizes the antrum
Pathophysiology in one chain
Antral colonization → ↓ somatostatin (D cells) → ↑ gastrin (G cells) → ↑ acid (parietal cells)
→ especially predisposes to duodenal ulcers
Comparison table: H. pylori vs key look-alikes (ulcer/upper GI differentials)
| Feature | H. pylori | NSAID/PUD (no H. pylori) | Zollinger–Ellison (gastrinoma) | Stress ulcers (Curling/Cushing) |
|---|---|---|---|---|
| Primary driver | Infection + inflammation | ↓ Prostaglandins → ↓ mucus/bicarb, ↓ blood flow | Gastrin-secreting tumor | Mucosal ischemia + acid (critically ill) |
| Acid level | ↑ (esp antral infection) | Often normal/↓ | Markedly ↑↑ | Variable; often ↑ relative to mucosal defense |
| Typical ulcer location | Duodenal > gastric | Gastric > duodenal | Multiple, refractory; may be distal duodenum/jejunum | Gastric (diffuse superficial erosions) |
| Symptoms | Epigastric pain; may improve with meals (duodenal) | Similar | Severe/refractory ulcers + diarrhea/steatorrhea | Occult GI bleed in ICU, burns, head trauma |
| Key diagnostic clue | Positive urea breath or stool Ag | H. pylori negative | High gastrin, low pH; secretin test | Clinical context (ICU) |
| Treatment | Eradication regimen + PPI | Stop NSAIDs + PPI | PPI + tumor localization/resection | PPI prophylaxis + treat underlying stressor |
The “ulcer pattern” table (exam favorite)
| Ulcer type | Pain with meals | Weight change | Acid secretion | Most common association |
|---|---|---|---|---|
| Duodenal ulcer | Improves with meals; returns 2–3 hrs later, nocturnal pain | Weight gain | ↑ | H. pylori |
| Gastric ulcer | Worsens with meals | Weight loss | Normal/↓ | NSAIDs or H. pylori |
Step tip: Duodenal ulcers classically improve with food because food buffers acid transiently; gastric ulcers worsen because food stimulates acid secretion and irritates the ulcer bed.
Testing: what to order and when (super practical)
Best noninvasive tests (preferred for initial dx and test-of-cure)
- Urea breath test (high sensitivity/specificity)
- Stool antigen test
Invasive test (often during endoscopy)
- Rapid urease test on biopsy
Common Step pitfall: false negatives
PPIs, bismuth, and antibiotics can suppress H. pylori and cause false-negative breath/stool tests.
- Practical rule: hold PPI ~2 weeks and antibiotics/bismuth ~4 weeks before testing (when clinically feasible).
Treatment: know the regimens (and the logic)
First-line concept
You need:
- Acid suppression (PPI) to promote healing and boost antibiotic efficacy
- Two (or more) antibiotics to reduce resistance
- Sometimes bismuth for additional antimicrobial/mucosal protection
Common high-yield regimens
- Bismuth quadruple therapy (very commonly tested)
- PPI + bismuth + tetracycline + metronidazole
- Clarithromycin triple therapy (use depends on local resistance patterns)
- PPI + clarithromycin + amoxicillin (or metronidazole if penicillin allergy)
Always confirm eradication in most patients (especially if ulcer complications, cancer risk, persistent symptoms) with breath or stool test, not serology.
Complications you must associate with H. pylori
Cancer/lymphoma links
- Gastric adenocarcinoma (intestinal type classically linked via chronic gastritis → atrophy → intestinal metaplasia → dysplasia)
- MALT lymphoma
- Big board-relevant pearl: early MALT lymphoma can regress with H. pylori eradication
Ulcer complications (general)
- Upper GI bleeding
- Perforation
- Gastric outlet obstruction (from edema/scarring)
Quick-hit “if you see this, think H. pylori” prompts
- Duodenal ulcer + high acid + nocturnal pain
- Urease positive organism
- Chronic gastritis, especially antrum-predominant
- MALT lymphoma in a patient with dyspepsia
- Positive urea breath test after stopping PPIs appropriately
Micro one-liners (rapid recall)
- Urease: makes ammonia to buffer acid; injures mucosa.
- Antrum colonization: removes the brakes (↓ somatostatin) → ↑ gastrin → ↑ acid.
- Cancer link: chronic inflammation sets the stage for metaplasia/dysplasia and MALT proliferation.