Abstract
Helicobacter have been shown to infect the gastrointestinal tract and biliary system in a wide variety of domestic and wild species.3-5 These microaerophilic, gram-negative, spiral-shaped bacteria can cause, under still not completely understood conditions, varying degrees of gastritis, enteritis, and hepatitis with subsequent neoplastic transformation in some species.3-5 The genetic diversity of Helicobacter may play an important role concerning the outcome of infection.1 To date, all species reported with Helicobacter infections were members of the classes Mammalia or Aves.3-5 Therefore, the detection of spiral-shaped Helicobacter-like bacteria associated with gastritis in one chelonian, member of the class Reptilia, was an unusual finding and prompted this investigation. The purpose of this study was to further characterize the Helicobacter-like organisms and the associated lesions. Stomachs from chelonians (n=28) representing six different turtle and tortoise species were examined histologically. Of 22 animals with gastritis, five were associated with spiral shaped Helicobacter-like organisms, four imported Asian box turtles (Cuora spp.) and one Californian desert tortoise (Gopherus agassizii). Histologically, gastritis in the cases with spiral shaped bacteria was of variable severity and duration characterized by multifocal glandular distension and necrosis with intraglandular heterophils. In more chronic cases there was glandular atrophy and interstitial fibrosis as well as glandular regeneration with epithelial hyperplasia. There were intralesional gram-negative spiral shaped organisms which also were present outside the lesions. Ultrastructurally, the bacteria in the box turtles were morphologically different from those seen in the one desert tortoise. The spiral-shaped bacteria in the turtles were up to 11 µm long, had up to nine spiral turns, bipolar flagella, and distinct polar membranes. In comparison, the bacteria in the desert tortoise were smaller, loosely coiled and had long polar flagella. Because Helicobacter are difficult to culture and appropriate samples were unavailable, the bacteria were further characterized using molecular methods. Bacterial DNA was extracted and amplified, and the 16s rRNA gene sequenced using Helicobacter genus specific primers. To date, partial sequences and one complete 16s rRNA sequence from two turtles and the tortoise were obtained. The sequences demonstrated phylogenetic homology to the Helicobacter genus. These results indicate that chelonians can be naturally infected with Helicobacter and that gastritis is associated with these infections. The turtles in this study represent just a few confiscated individuals of the large numbers of wild-caught turtles, endangered due to their use as food or traditional Chinese medicine.2 At confiscation many of the turtles were debilitated and gastritis may have played a role. Further characterization may contribute to the understanding of diseases in these chelonian species and may provide insight into the evolution of Helicobacter spp. within the animal kingdom. This, to our knowledge, is the first description of Helicobacter infections in the class Reptilia.
Literature Cited
1. Blaser MJ, Berg DE. Helicobacter pylori genetic diversity and risk of human disease. J Clin Invest. 2001;107(7):767–773.
2. Collins D. The Asian Turtle Crisis - Preserving the Place for Turtles. AZA Communiqué. April 2001:19–23.
3. Fox JG. The expanding genus of Helicobacter: pathogenic and zoonotic potential. Semin Gastrointest Dis. 1997;8(3):124–141.
4. Solnick JV, Schauer DB. Emergence of diverse Helicobacter species in the pathogenesis of gastric and enterohepatic diseases. Clin Microbiol Rev. 2001;14(1):59–97.
5. Versalovic J, Fox JG. Helicobacter. In: Murray PR, Barron EJ, Pfaller MA, Tenover FC, Yolken RH, eds. Manual of Clinical Microbiology, 7th ed. Washington DC: ASM Press; 1999:727–738.