Urease-positive bacteria other than Helicobacter pylori in human gastric juice and mucosa.
OBJECTIVE
Many bacteria carry the urease enzyme in different human ecosystems, but Helicobacter pylori is the only known bacterium showing urease activity in gastric ecosystems. For this reason, the rapid urease test (RUT) on gastric biopsies and urea breath test (C-UBT) are used to detect H. pylori infection. The aim of this study was to evaluate the presence of urease-positive bacteria other than H. pylori in gastric juice and mucosa in hypochlorhydric subjects.


METHODS
Twenty-five hypochlorhydric and 10 normochlorhydric patients were analyzed for the presence of H. pylori and bacterial overgrowth both in gastric juice and on the mucosa. During upper gastrointestinal endoscopy at 8.00 a.m. gastric juice samples and biopsy specimens were taken from the antrum and corpus. All samples were analyzed using standard microbiological procedures like aerobic/anaerobic growth, gram-staining, gas chromatography, API test, 96-clone method, and selective medium to search for specific bacteria. In addition, all strains isolated were screened for urease activity using the CP-test. Urease positive strains were tested for the capacity to survive in an acid environment with or without urea (10 mM/L), at pH 7, 4, 3, and 2, respectively, at different times (0, 20, 30, and 60 min).


RESULTS
Six hypochlorhydric patients had 10 strains of urease-positive non-H. pylori bacteria among which Staphylococcus capitis urealiticum showed the strongest urease activity.


CONCLUSIONS
Hypochlorhydric patients present many urease-positive bacteria other than H. pylori. The strong urease activity may be responsible for false positive results at RUT or UBT test in patients with suspected H. pylori infection.
Brandi
Giovanni
G
Institute of Haematology and Medical Oncology (L. e A. Seragnoli), University of Bologna, Bologna, Italy.
Biavati
Bruno
B
Calabrese
Carlo
C
Granata
Marta
M
Nannetti
Anna
A
Mattarelli
Paola
P
Di Febo
Giulio
G
Saccoccio
Gioconda
G
Biasco
Guido
G
D000328:Adult; D000368:Aged; D001419:Bacteria / Q000201:enzymology* / Q000302:isolation & purification; D001706:Biopsy; D005260:Female; D005750:Gastric Juice / Q000201:enzymology / Q000382:microbiology*; D005753:Gastric Mucosa / Q000201:enzymology / Q000382:microbiology*; D005773:Gastroscopy; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D014510:Urease / Q000032:analysis*
D014510:Urease