Helicobacter pullorum

• Helicobacter pullorum is a Gram-negative, microaerophilic, spiral-shaped bacterium within the Helicobacter genus. 
• It was first identified in 1994 from the liver, duodenum, and cecum of poultry, as well as from humans suffering from gastroenteritis. 
• This bacterium is classified as an enterohepatic Helicobacter species (EHS), meaning it predominantly colonizes the intestines and hepatobiliary systems of its hosts. 
• Its discovery has highlighted its potential zoonotic implications and its association with gastrointestinal and hepatic diseases.

Morphology and Characteristics 

• H. pullorum exhibits several defining features typical of the Helicobacter genus. 
• The bacterium is slightly curved and rod-shaped, with a single polar flagellum that is non-sheathed, aiding in its motility. 
• It is Gram-negative, characterized by a thin peptidoglycan layer and an outer membrane. 
• As a microaerophilic organism, H. pullorum thrives in environments with reduced oxygen levels, such as the gastrointestinal tract. 
• It is urease-negative, distinguishing it from gastric Helicobacter species like H. pylori. Additionally, it produces catalase, reduces nitrates, and lacks indoxyl acetate esterase and alkaline phosphatase activity.

Isolation and Host Association 

• The initial isolation of H. pullorum occurred during studies of poultry and humans with gastroenteritis. 
• It has been detected in the gastrointestinal tracts of broiler and layer chickens, as well as in humans suffering from colitis and hepatitis. 
• Its presence in both avian and human hosts suggests a zoonotic potential, with transmission likely occurring through contaminated poultry meat. 
• The bacterium’s association with both poultry and humans underscores its ecological adaptability and public health significance.

Taxonomy and Nomenclature 

• The species name “pullorum” reflects its association with poultry, as “pullorum” is derived from the Latin word for chicken. 
• Genetic and phenotypic analyses confirmed its classification as a distinct species within the Helicobacter genus. 
• The type strain of H. pullorum is designated as ATCC 51801, providing a reference for future studies.

Pathogenic Potential and Clinical Relevance 

• H. pullorum has been associated with gastrointestinal and hepatic diseases in humans and poultry. 
• In humans, it has been linked to colitis, hepatitis, and inflammatory bowel disease (IBD). 
• The bacterium produces cytolethal distending toxin (CDT), which induces cytopathogenic effects on intestinal epithelial cells, including actin cytoskeleton remodeling, G2/M cell cycle arrest, and cellular distension. 
• These effects highlight its role as a virulence factor and its potential impact on host health.

Public Health and Research Implications 

• The zoonotic potential of H. pullorum underscores the importance of monitoring its prevalence in poultry and humans. 
• Further research is needed to clarify its transmission dynamics, pathogenic mechanisms, and antibiotic resistance patterns. 
• Understanding its role in gastrointestinal and hepatic diseases will provide valuable insights into its significance as an emerging pathogen.