Mechanisms of Helicobacter pylori antibiotic resistance: An updated appraisal

Table 1 Minimal inhibitory concentrations of the different antibiotics (left side) and main mechanisms of resistance induction for each antibiotic (right side)

Antibiotics	MIC in susceptible strains	MIC in resistant strains	Mechanisms of resistance
Clarithromycin	0.016-0.50 mg/L	≥ 1 mg/L (2-256 mg/L)	Point mutations in rRNA
			Efflux pumps system (RND family)
Metronidazole	0.5-2 mg/L	≥ 8 mg/L (16-128 mg/L)	Mutate NADPH reductase
			Mutate NADH oxidase
			Other efflux pumps
Levoxacin	0.25-0.50 mg/L	≥ 1 mg/L (4-32 mg/L)	Point mutations in QRDR of gyrA gene
			Polymorphism in 87 codon of gyrA
Amoxicillin	0.06-0.25 mg/L	≥ 1.0mg/L (1-8 mg/L)	Point mutations in pbp genes
			Point mutations in hpB and hpC genes
			Point mutations in omp25 and omp32 porin genes
Tetracycline	0.25- 2 mg/L	≥ 4 mg/L (2-256 mg/L)	Point mutations in primary binding Tet-P site
			Point mutations in Tet-4 secondary inding site
			Alterations by oxidoreductase

MIC: Minimal inhibitory concentrations.