Comparison of diagnostic techniques for Helicobacter cetorum infection in wild Atlantic bottlenose dolphins (Tursiops truncatus).

Helicobacter cetorum sp. nov. has been cultured from the stomach of Atlantic white-sided dolphins (Lagenorhynchus acutus) and the feces of Pacific white-sided (L. obliquidens) and Atlantic bottlenose (Tursiops truncatus) dolphins and a beluga whale (Delphinapterus leucas). H. cetorum has high homology to Helicobacter pylori as shown by 16S rRNA sequencing, and H. cetorum infection has been associated with gastritis and clinical signs in cetaceans. Because the prevalence of H. cetorum in wild populations is unknown, minimally invasive techniques for detecting H. cetorum were compared for 20 wild bottlenose dolphins sampled as part of a long-term health study. Fecal samples were tested for helicobacter by culture, Southern blotting, and PCR using genus-specific and H. cetorum-specific primers. An enzyme-linked immunosorbent assay (ELISA) was developed to measure H. cetorum immunoglobulin G (IgG). H. cetorum was cultured from 4 of 20 fecal samples, 7 samples were positive using Helicobacter sp. PCR, and 8 samples were positive for H. cetorum using species-specific primers. Two additional fecal samples were positive by Helicobacter sp. Southern blotting, suggesting infection with another helicobacter. All 20 sera contained high levels of IgG antibodies to H. cetorum that were significantly lowered by preabsorption of the sera with whole-cell suspensions of H. cetorum (P < 0.02). Until the specificity of the serum ELISA can be determined by testing sera from dolphins confirmed to be uninfected, PCR and Southern blot screenings of feces are the most sensitive techniques for detection of H. cetorum, and results indicate there is at least a 50% prevalence of H. cetorum infection in these dolphins.