What are the causes and treatments of Helicobacter (H.) pylori infection?

Causes of Helicobacter pylori Infection

H. pylori infection is primarily transmitted person-to-person through the fecal-oral and oral-oral routes, typically acquired in childhood, with transmission strongly linked to poor sanitation, contaminated water, crowded living conditions, and low socioeconomic status. 1

Primary Transmission Routes

Person-to-Person Spread

• The fecal-oral route is the major transmission pathway, occurring predominantly within families and households, particularly from infected adults or siblings to young children 1, 2
• Oral-oral transmission occurs through saliva, including kissing, sharing utensils, and exposure to vomitus from infected individuals 2
• H. pylori has been detected in dental plaque, supporting oral-oral transmission as a significant route 2
• Aerosol spread can occur when infected persons vomit or have diarrhea, contaminating the immediate environment 2

Environmental and Water Sources

• Contaminated drinking water serves as a transmission vehicle, particularly in developing countries where sewage contamination occurs and chlorination is inadequate 2
• H. pylori is present in feces, sewage, and water but is killed by routine chlorination 2
• Consumption of raw vegetables fertilized with human feces has been identified as a risk factor, especially in South America 2

Risk Factors for Acquisition

Socioeconomic and Living Conditions

• Poor sanitation, lack of indoor plumbing, and absence of clean water are the strongest environmental risk factors 1
• Crowded living conditions and lower socioeconomic status directly correlate with higher infection prevalence 1
• In affluent countries, prevalence relates directly to socioeconomic status, with previously disadvantaged subpopulations maintaining relatively high infection rates 1

High-Risk Populations

• Immigrants from high-prevalence regions (Central and South America, the Caribbean, Eastern Europe, Asia, and India) serve as reservoirs and maintain infection rates similar to their countries of origin 1
• Native Americans, blacks, and Hispanics in the United States have increased infection risk 1, 3
• Childhood acquisition is typical, with infection persisting for life if untreated 4

Iatrogenic Transmission

• Person-to-person transmission can occur via contaminated endoscopes during medical procedures 2

Geographic and Temporal Patterns

• H. pylori infects approximately 50% of the world's population, making it the most common infectious disease worldwide 5, 4
• In affluent countries, prevalence has steadily declined due to improved sanitation, with successive birth cohorts showing progressively lower infection rates 1
• This decline process is now being repeated in rapidly developing regions 1

Treatment Implications

Eradication of H. pylori is recommended whenever diagnosed, as the infection carries significant risk for peptic ulcer disease (17% lifetime risk), gastric cancer (responsible for 71-95% of cases), and other complications 1, 3, 6

First-Line Treatment Approach

• Bismuth quadruple therapy for 14 days is the preferred empiric regimen when antibiotic susceptibility is unknown 7
• Rifabutin triple therapy or potassium-competitive acid blocker dual therapy for 14 days are suitable alternatives in patients without penicillin allergy 7
• Clarithromycin-based triple therapy should be avoided due to increasing resistance 6

Prevention Strategy

• Testing and treating household members of infected individuals is recommended to prevent reinfection and break the transmission cycle 1
• Population-wide screening and treatment programs have been implemented in high gastric cancer risk countries (Japan, Korea, Taiwan, China) 1

Common Pitfalls

• Do not assume infection is solely food-borne; person-to-person transmission within families is the dominant route 2
• Properly cooking foods and chlorinating water reduces but does not eliminate transmission risk, as person-to-person spread remains the primary concern 2
• Recurrent infection after successful eradication may indicate ongoing intrafamilial exposure rather than treatment failure, necessitating household member testing 1