FIG 3.

Mass screening for H. pylori infection. Noninvasive tests, including the urea breath test (UBT), the stool antigen test (SAT), serology, or antibody detection from urine samples, are preferred methods for mass screening for Helicobacter pylori infection among communities. The positive serology results should be further confirmed by other specific methods (such as RT-PCR) on gastric biopsy or stool specimens. Patients who test positive are subjected to clarithromycin susceptibility-guided eradication therapy (when clarithromycin resistance is over 15% in that population) or clarithromycin-based empirical therapy (when clarithromycin resistance is below 15% in that population). After the completion of eradication therapy, patients are subjected to the assessment of successful eradication with either the UBT or SAT. In case of the failure of eradication therapy, a biopsy specimen-based bacterial culture is suggested to evaluate the antibiotic resistance by phenotypic (antimicrobial susceptibility testing [AST]) or genotypic (evaluation of the mutations conferring the resistance) methods, which allow selection of AST-guided therapy.