Helicobacter cetorum

• Helicobacter cetorum is a Gram-negative, microaerophilic, spiral-shaped bacterium within the Helicobacter genus. 
• It was first identified in the gastrointestinal tracts of marine mammals, including dolphins and whales. 
• This discovery expanded the understanding of Helicobacter species and their association with non-human hosts, particularly in aquatic environments. 
• H. cetorum has been studied for its potential role in gastric diseases in marine mammals, drawing parallels to Helicobacter pylori in humans.

Morphology and Characteristics 

• H. cetorum exhibits several defining features typical of the Helicobacter genus. 
• The bacterium is spiral-shaped, which facilitates its movement through the mucus layers of the gastrointestinal tract. 
• It is Gram-negative, characterized by a thin peptidoglycan layer and an outer membrane. 
• As a microaerophilic organism, H. cetorum thrives in environments with reduced oxygen levels, such as the gastrointestinal tracts of marine mammals. 
• The bacterium is urease-positive, enabling it to hydrolyze urea into ammonia and carbon dioxide, which helps neutralize stomach acid and supports its survival in the acidic gastric environment.

Isolation and Host Association 

• The initial isolation of H. cetorum occurred during studies of marine mammals, including Atlantic white-sided dolphins (Lagenorhynchus acutus), Pacific white-sided dolphins (Lagenorhynchus obliquidens), and beluga whales (Delphinapterus leucas). 
• It has been detected in both the stomach and fecal samples of these animals. 
• The consistent presence of H. cetorum in marine mammals suggests a specific ecological relationship and highlights its potential role in the health of these hosts.

Taxonomy and Nomenclature 

• The species name “cetorum” reflects its association with cetaceans, a group of marine mammals that includes whales, dolphins, and porpoises. 
• Genetic and phenotypic analyses confirmed its classification as a distinct species within the Helicobacter genus. Its genome has been sequenced, providing insights into its evolutionary relationships with other Helicobacter species, particularly Helicobacter pylori.

Pathogenic Potential and Clinical Relevance 

• H. cetorum has been associated with gastric diseases in marine mammals, including gastritis, ulcers, and mucosal hemorrhages. 
• Symptoms observed in infected animals include intermittent inappetence, lethargy, chronic regurgitation, and weight loss. 
• Endoscopic examinations have revealed esophageal and gastric ulcers in some cases. 
• While its exact pathogenic mechanisms remain unclear, H. cetorum is thought to play a role in the development of these conditions, similar to the role of H. pylori in human gastric diseases.

Public Health and Research Implications 

• The discovery of H. cetorum underscores the importance of studying Helicobacter species in non-human hosts. 
• While there is no evidence to suggest zoonotic transmission, monitoring Helicobacter species in marine mammals is essential for understanding their ecological roles and potential impacts on animal health. 
• Research into H. cetorum may also provide insights into the evolution of gastric Helicobacter species and their adaptations to different hosts.