Helicobacter mastomyrinus

• Helicobacter mastomyrinus is a Gram-negative, microaerophilic, spiral-shaped bacterium within the Helicobacter genus. 
• It was first isolated from the liver and intestines of African rodents, specifically Mastomys natalensis (commonly known as the multimammate mouse). 
• This discovery expanded the understanding of enterohepatic Helicobacter species (EHHS) and their association with rodent hosts. 
• H. mastomyrinus has been studied for its potential role in gastrointestinal and hepatic diseases, as well as its relevance in laboratory animal research.

Morphology and Characteristics 

• H. mastomyrinus exhibits several defining features typical of the Helicobacter genus. 
• The bacterium is spiral-shaped, which facilitates its movement through mucus layers in the gastrointestinal and hepatobiliary systems. 
• It is Gram-negative, characterized by a thin peptidoglycan layer and an outer membrane. 
• As a microaerophilic organism, H. mastomyrinus thrives in environments with reduced oxygen levels, such as the liver and intestines. 
• It is motile, possessing flagella that aid in colonization and persistence within the host. 
• The bacterium is also urease-positive, which helps it survive in acidic environments by neutralizing stomach acid.

Isolation and Host Association 

• The initial isolation of H. mastomyrinus occurred during studies of Mastomys natalensis, a rodent species native to sub-Saharan Africa. 
• The bacterium was recovered from the liver and cecum of these rodents, suggesting a specific ecological relationship with this host species. 
• Its presence in rodents highlights its potential role in gut and liver microbial dynamics and its relevance in understanding Helicobacter-associated diseases in wildlife and laboratory animals.

Taxonomy and Nomenclature 

• The species name “mastomyrinus” reflects its association with Mastomys natalensis. 
• Genetic and phenotypic analyses confirmed its classification as a distinct species within the Helicobacter genus. 
• The type strain of H. mastomyrinus is designated as ATCC BAA-1046 (DSM 22886; CCUG 52417; MIT 97-5574), providing a reference for future studies. 
• Its identification contributes to the expanding taxonomy of Helicobacter species and emphasizes the genus’s adaptability to diverse hosts.

Genome and Genetic Insights 

• The genome of H. mastomyrinus has been sequenced, revealing insights into its genetic composition and potential pathogenicity. 
• Comparative genomic analyses have shown a close phylogenetic relationship with H. hepaticus, another enterohepatic Helicobacter species. 
• The genome encodes genes associated with motility, metabolism, and virulence, including those responsible for cytolethal distending toxin (CDT) production. 
• These findings suggest that H. mastomyrinus may share evolutionary traits with other enterohepatic Helicobacter species.

Pathogenic Potential and Research Relevance 

• H. mastomyrinus has been associated with liver and intestinal pathologies in experimental models. 
• Studies have shown that it can induce focal necrotic hepatitis and inflammation in laboratory mice, highlighting its potential as a model organism for studying Helicobacter-associated diseases. 
• Its ability to produce cytolethal distending toxin (CDT) further underscores its relevance in research on host-microbe interactions and immune responses.

Public Health and Research Implications 

• The discovery of H. mastomyrinus underscores the importance of studying enterohepatic Helicobacter species in wildlife and laboratory animals. 
• While there is no direct evidence to suggest zoonotic transmission, its presence in rodents raises questions about its ecological roles and potential risks. 
• Monitoring H. mastomyrinus in animal populations is essential for understanding its prevalence and implications for both veterinary and public health.