Clinical Information

Helicobacter pylori is a spiral-shaped gram-negative bacterium that may cause chronic gastritis, peptic ulcer disease, or gastric neoplasia. In adults of industrialized countries, an estimated 0.5% of the susceptible population becomes infected each year, although the incidence has been decreasing over time. The organism may asymptomatically colonize humans.

In suspected H pylori-associated disease, the H pylori with clarithromycin resistance prediction polymerase chain reaction (PCR) test or urea breath test is recommended for patients younger than 60 years old without alarming signs and symptoms (see Helicobacter pylori Diagnostic Algorithm). If clarithromycin resistance is predicted by the PCR test, endoscopy with biopsy should be considered for H pylori culture with antimicrobial susceptibility testing. For those 60 years old or older who have alarming signs and symptoms, endoscopy with biopsy is recommended, with consideration for H pylori culture with antimicrobial susceptibility testing on the gastric biopsy. If patients fail to respond to treatment, endoscopy with biopsy should be considered for H pylori culture with antimicrobial susceptibility testing.

The Clinical and Laboratory Standards Institute (CLSI) recommends agar dilution for H pylori antimicrobial susceptibility testing. Amoxicillin, clarithromycin, levofloxacin, metronidazole, rifampin, and tetracycline are routinely tested. CLSI has defined interpretive categories for clarithromycin. The antimicrobials for which the European Committee on Antimicrobial Susceptibility Testing defines interpretive categories include amoxicillin, clarithromycin, levofloxacin, metronidazole, rifampin, and tetracycline.