Pretreatment antimicrobial susceptibilities of paired gastric Helicobacterpylori isolates: Antrum versus corpus

Background. Antimicrobial susceptibility testing of Helicobacter pylori iso lates is the most useful tool for guiding specific therapy, especially when primary resistance is suspected. However, the most informative gastric bio psy site far detection of resistant H. pylori isolates is uncertain. We sou ght to determine whether susceptibilities to commonly used antimicrobials ( amoxicillin, clarithromycin, minocycline, and metronidazole) were related t o biopsy site. Methods. H. pylori isolates were obtained from patients who had duodenal ul cer and had not received anp therapy directed against H. pylori. Agar-dilut ion mini mum inhibitory concentrations of each antimicrobial were compared between paired H. pylori isolates from the antrum and the proximal corpus. Results. Differences in minimum inhibitory concentrations exceeding twofold were observed within the pairs of H. pylori isolates in 5 of the 40 patien ts tested. In three patients with clarithromycin-resistant isolates and two with metronidazole-resistant isolates, both antral and corporeal specimens revealed resistance. However, no patient had pairs of isolates categorized as resistant at one site and sensitive at the other. Conclusions. While we found that an individual may have a mixed H. pylori i nfection with respect to differing antimicrobial susceptibility in differen t parts of the stomach, a single biopsy specimen from either the antrum or the corpus should provide reliable detection of H. pylori isolates with pri mary resistance.