Clinical meaning
Helicobacter pylori infects approximately 50% of the world's population and is the most common cause of peptic ulcer disease (PUD) — present in 90% of duodenal ulcers and 70% of gastric ulcers. H. pylori also causes chronic active gastritis, gastric MALT lymphoma (60-90% cure rate with eradication alone), and is classified as a WHO Group 1 carcinogen for gastric adenocarcinoma. Eradication reduces ulcer recurrence from 80% to <5%. The NP must select appropriate eradication regimens based on local clarithromycin resistance rates (<15% = triple therapy acceptable; ≥15% = bismuth quadruple or concomitant therapy). First-line options: (1) Clarithromycin triple therapy: PPI BID + clarithromycin 500 mg BID + amoxicillin 1 g BID × 14 days (only if local clarithromycin resistance <15%); (2) Bismuth quadruple therapy: PPI BID + bismuth subsalicylate 524 mg QID + metronidazole 250 mg QID + tetracycline 500 mg QID × 14 days (preferred when clarithromycin resistance ≥15% or in penicillin-allergic patients); (3) Concomitant quadruple therapy: PPI BID + clarithromycin 500 mg BID + amoxicillin 1 g BID + metronidazole 500 mg BID × 14 days. Eradication must...