Isolation of Helicobacter pylori using leftover tissue in the rapid urease test kit

Abstract

Isolation of Helicobacter pylori is considered difficult because of the requirement of the additional biopsy tissue and the effort involved in the isolation of the bacterium. We investigated whether Hpylori can be cultured from tissue samples used for the rapid urease test (RUT). Totally, 174 specimens from 87 patients referred for endoscopy were prospectively included. During endoscopy, two biopsy specimens were obtained, one each from the gastric antrum and the corpus, and were placed into a commercially available RUT kit. After detection of urease activity, Hpylori was cultured using tissue leftover in the RUT, regardless of the result. Hpylori was successfully isolated using leftover tissue in 72.4% (63/87) of the patients. In 32 patients, Hpylori was isolated from both specimens, while in 31 patients, it was isolated from either antrum or corpus. Eighty-one Hpylori strains were isolated from 141 specimens with positive RUT results (57.4%), whereas 14 strains were isolated from 33 specimens with negative RUT results (42.4%). The median interval between tissue acquisition and inoculation onto the isolation media was 3.6hours (range: 0.5-27.5hours) in cases with successful cultures, compared to 23.5hours (range: 0.5-76.0hours) in cases with failed cultures. Among the positive RUT tissues, 80.4% (45/56) were cultured successfully when the tissue was inoculated within 4hours of the biopsy. RUT kits can be used as transport media for Hpylori, and this media is most efficient when used within 4hours of the test.