H. pylori infection - Symptoms, Causes, Treatment & Prevention

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Overview

Helicobacter pylori (H. pylori) is a spiral‑shaped, gram‑negative bacterium that colonises the stomach lining. It is one of the most common chronic bacterial infections worldwide. The organism can survive the harsh acidic environment of the stomach by producing urease, which neutralises acid and creates a protective niche.

Who it affects: The infection can affect anyone, but it is most prevalent in children and adolescents living in low‑ to middle‑income countries where crowded living conditions and limited sanitation are common. In high‑income nations, infection rates are lower but still affect about 30–40 % of the adult population.

Prevalence: According to the World Health Organization (WHO) and the International Agency for Research on Cancer, roughly half of the world’s population harbours H. pylori at some point in life. Prevalence varies widely:

• Developing regions (e.g., Africa, South‑America, parts of Asia): 70–90 %
• Developed regions (e.g., United States, Western Europe): 25–40 %

Most infected individuals remain asymptomatic, yet the bacterium is a recognised cause of peptic ulcer disease, gastric adenocarcinoma, and MALT (mucosa‑associated lymphoid tissue) lymphoma.<sup>1</sup>

Symptoms

Only about 10–20 % of people with H. pylori develop noticeable symptoms. When they do appear, they often mimic other gastrointestinal disorders.

• Upper abdominal pain or discomfort – a burning or gnawing sensation that may improve or worsen with eating.
• Bloating and early satiety – feeling full after a small amount of food.
• Frequent belching – excess gas release can be a sign of gastritis.
• Nausea or vomiting – occasional episodes, sometimes with undigested food.
• Loss of appetite – can lead to unintentional weight loss.
• Heartburn or acid reflux – though not specific, many patients report these symptoms.
• Dark or tarry stools (melena) – indicates digested blood from the stomach lining.
• Vomiting of blood (hematemesis) – a red‑flag sign of ulcer bleeding.
• Unexplained iron‑deficiency anemia – chronic low‑grade bleeding can lower iron stores.

Causes and Risk Factors

H. pylori infection is acquired primarily through oral‑to‑oral or fecal‑to‑oral routes.

Primary causes

• Person‑to‑person contact – especially within families; parents often transmit the bacterium to children.
• Contaminated water or food – untreated municipal water, raw vegetables washed with unsafe water, or unpasteurised milk.
• Living conditions – crowded housing, poor sanitation, and limited access to clean water increase risk.

Risk factors

• Age < 10 years (higher colonisation rates in early childhood).
• Socio‑economic status – low income, limited education.
• Geographic location – higher prevalence in Asia, Africa, and Latin America.
• Smoking – impairs gastric mucosal defence and promotes bacterial persistence.
• Long‑term use of non‑steroidal anti‑inflammatory drugs (NSAIDs) – synergises with H. pylori to cause ulcers.
• Genetic predisposition – certain HLA types may affect immune response to the bacterium.

Diagnosis

Because many infections are asymptomatic, testing is usually pursued when a patient has unexplained dyspepsia, ulcer disease, or a family history of gastric cancer.

Non‑invasive tests

• Urea breath test (UBT) – considered the gold standard for active infection. The patient ingests a carbon‑13 or carbon‑14 labelled urea; H. pylori’s urease splits it, releasing labelled CO₂ detectable in the breath.
• Stool antigen test – detects H. pylori proteins in feces. It is useful for both diagnosis and confirming eradication after therapy.
• Serology (blood antibodies) – identifies past exposure but cannot distinguish active from resolved infection; therefore, not ideal for confirming cure.

Invasive tests (endoscopy‑based)

• Upper gastrointestinal (GI) endoscopy with biopsy – allows direct visualisation of gastritis, ulcers, or cancer. Biopsy samples can be examined by:
  • Rapid urease test (CLO test)
  • Histology (special stains)
  • Culture (for antibiotic susceptibility)
• Gastric mucosal brushings – less common, used mainly in research settings.

Choosing a test depends on clinical context, local availability, and whether the result will affect management (e.g., before starting long‑term NSAIDs).

Treatment Options

Current guidelines (American College of Gastroenterology, Maastricht V/Florence Consensus) recommend combination therapy to overcome bacterial resistance.

First‑line regimens (7–14 days)

• Triple therapy – a proton‑pump inhibitor (PPI) + clarithromycin 500 mg twice daily + amoxicillin 1 g twice daily (or metronidazole if penicillin‑allergic). Efficacy declines where clarithromycin resistance >15 %.
• Bismuth quadruple therapy – PPI + bismuth subsalicylate + tetracycline + metronidazole. Preferred in areas with high clarithromycin resistance.
• Concomitant (non‑bismuth) quadruple therapy – PPI + clarithromycin + amoxicillin + metronidazole. Often given for 10–14 days.

Second‑line (salvage) regimens

• Levofloxacin‑based triple therapy – PPI + levofloxacin + amoxicillin.
• High‑dose dual therapy – high‑dose PPI (twice daily) + amoxicillin 1 g three times daily for 14 days.

Supportive measures

• Probiotics (e.g., Saccharomyces boulardii or lactobacilli) may reduce antibiotic‑associated side effects and modestly improve eradication rates.<sup>2</sup>
• Avoid NSAIDs, alcohol, and tobacco during treatment to enhance mucosal healing.

Follow‑up testing

To confirm eradication, repeat a non‑invasive test (UBT or stool antigen) at least 4 weeks after completing therapy and after stopping PPIs for 1–2 weeks. Persistent infection warrants susceptibility‑guided therapy.

Living with H. pylori Infection

Even after successful eradication, many patients worry about recurrence or lingering symptoms. Below are practical tips for daily management.

• Maintain a balanced diet – emphasise fruits, vegetables, whole grains, and lean protein. Limit spicy, fatty, or highly processed foods that can irritate the stomach.
• Stay hydrated – drink clean, filtered water; avoid unpasteurised milk and untreated water sources.
• Use PPIs or H2‑blockers judiciously – occasional use for heartburn is fine, but long‑term, unsupervised use may mask symptoms of recurrent infection.
• Quit smoking – nicotine impairs gastric blood flow and increases ulcer risk.
• Limit alcohol – excessive intake can damage the gastric mucosa and interfere with medication absorption.
• Practice good hygiene – wash hands with soap after bathroom use and before meals; ensure food is properly cooked.
• Monitor for warning signs – keep a symptom diary; report new or worsening pain, vomiting, or black stools promptly.
• Regular medical review – if you have a history of ulcers or gastric cancer in the family, schedule periodic endoscopic surveillance as advised by your gastroenterologist.

Prevention

Because transmission is largely environmental, prevention focuses on sanitation and personal habits.

• Drink water from safe, treated sources; boil or filter if unsure.
• Eat foods that are thoroughly cooked; wash fruits and vegetables with clean water.
• Practice strict hand‑washing, especially after using the toilet and before handling food.
• Avoid sharing eating utensils or drinking vessels with someone known to be infected, if possible.
• In high‑risk settings (e.g., daycare, institutions), implement infection‑control measures such as routine cleaning of surfaces.
• Vaccines are still under investigation; currently, no licensed H. pylori vaccine exists.

Complications

If left untreated, chronic H. pylori infection can lead to serious gastrointestinal disease.

• Peptic ulcer disease – up to 70 % of duodenal ulcers and 30 % of gastric ulcers are H. pylori‑related.
• Gastric adenocarcinoma – infection is classified as a Group 1 carcinogen by the International Agency for Research on Cancer; lifetime risk increases 2‑ to 6‑fold.
• MALT lymphoma – a low‑grade B‑cell lymphoma of the stomach that often regresses after eradication therapy.
• Gastric atrophy and intestinal metaplasia – precancerous changes to the stomach lining.
• Iron‑deficiency anemia & Vitamin B12 deficiency – chronic low‑grade bleeding or impaired absorption.

When to Seek Emergency Care

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References:
1. World Health Organization. Helicobacter pylori. 2023.
2. Zhang Y, et al. Probiotics adjunctive therapy for H. pylori eradication: a meta‑analysis. J Clin Gastroenterol. 2022;56(4):291‑300.
3. American College of Gastroenterology. ACG Clinical Guideline: Management of Helicobacter pylori Infection. 2022.
4. Mayo Clinic. Helicobacter pylori infection. Updated 2024.
5. CDC. Antibiotic Resistance Threats in the United States, 2023.

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