Treatment of Helicobacter pylori infection: Past, present and future

Table 1 Factors reported to negatively affect the outcome of therapies for Helicobacter pylori infection

Pathogen-related	Host-related
Development of resistance to antibiotics	Non-compliance to treatment
High bacterial load in the stomach	Non-ulcer dyspepsia
Protective effect of the gastric mucus layer	Smoking
Intracellular location of many bacteria	CYP2C19 status (rapid metabolizer)
CagA negative
Presence of dormant coccoid forms (not susceptible to antibiotics)
Heteroresistant status (co-existence of strains susceptible and resistant to the same antibiotic)