Helicobacter salomonis

• Helicobacter salomonis is a gram-negative, spiral-shaped bacterium that primarily colonizes the stomachs of dogs and cats but has also been detected in humans with gastritis and gastric disorders. 
• As a member of the non-Helicobacter pylori Helicobacter (NHPH) species, H. salomonis is part of a diverse group of gastric bacteria that can infect both animals and humans, raising concerns about its zoonotic transmission and potential role in human gastric disease.
• First isolated from dogs with chronic gastritis, H. salomonis is closely related to other canine-associated Helicobacter species, such as H. bizzozeronii and H. felis. 
• While its exact contribution to gastric disease in humans is not fully understood, increasing evidence suggests that it may be an underrecognized cause of chronic gastritis and ulceration in individuals exposed to infected animals.

Morphology and Unique Characteristics

• H. salomonis is a highly motile, helical bacterium, measuring approximately 2–5 µm in length. It possesses multiple flagella, which enable it to move efficiently through the mucus layer of the stomach and establish persistent colonization in the gastric mucosa.
• Like other gastric Helicobacter species, H. salomonis has evolved mechanisms to survive in the acidic stomach environment, including:
  • Urease production – Neutralizes stomach acid by breaking down urea into ammonia.
  • Adherence to gastric epithelial cells – Facilitates persistent colonization and inflammation.
  • Biofilm formation – May contribute to long-term survival and antibiotic resistance.
• These features allow H. salomonis to thrive in the stomachs of both animals and humans, potentially leading to chronic infection and gastric pathology.

Host Range and Zoonotic Transmission

• H. salomonis was initially identified in the stomachs of dogs, where it is often associated with mild to moderate gastritis. It has since been detected in:
  • Cats – Although less common, it has been found in feline gastric samples.
  • Humans – Several cases of H. salomonis infection have been reported in patients with chronic gastritis and dyspeptic symptoms.
• The primary risk factor for human infection appears to be close contact with dogs and cats, suggesting zoonotic transmission through:
  • Oral-oral transmission – Direct contact with infected animal saliva.
  • Fecal-oral transmission – Exposure to contaminated food, water, or surfaces.
  • Handling of infected animals – Particularly among pet owners, veterinarians, and animal shelter workers.
• While H. pylori is almost exclusively human-associated, H. salomonis is a true zoonotic pathogen, capable of crossing the species barrier and establishing infections in humans.

Pathogenesis and Disease Associations

• The role of H. salomonis in gastric disease is still being investigated, but current research suggests it may contribute to:
  • Chronic Gastritis and Dyspepsia: Infected dogs and humans often exhibit chronic gastritis, characterized by:
    • Persistent inflammation of the stomach lining.
    • Mild to moderate mucosal damage.
    • Symptoms such as nausea, bloating, and abdominal discomfort.
    • Although many infections are asymptomatic, some individuals experience prolonged gastric distress, particularly those with pre-existing stomach conditions.
  • Gastric Ulcers and Potential Malignancy: H. salomonis has been detected in human patients with peptic ulcers and mucosa-associated lymphoid tissue (MALT) lymphoma, a rare stomach cancer. While H. pylori remains the primary bacterial cause of gastric cancer, H. salomonis and other NHPH species may contribute to:
    • Gastric ulcer formation – Through chronic inflammation and mucosal damage.
    • Lymphoid hyperplasia – Potentially leading to MALT lymphoma in rare cases.
    • Further research is needed to determine the full extent of H. salomonis’s role in gastric malignancies.
  • Possible Extra-Gastric Effects: Emerging evidence suggests that Helicobacter species, including H. salomonis, may be associated with extra-gastric diseases, such as:
    • Liver disorders – Helicobacter DNA has been found in hepatic tissues of patients with liver disease.
    • Immune system modulation – Chronic infection may contribute to autoimmune and inflammatory conditions.
• Although these associations remain speculative, they highlight the need for further investigation into H. salomonis’s systemic effects.

Diagnosis and Detection

• Detecting H. salomonis infection in both humans and animals requires specialized diagnostic techniques, as it does not grow well under standard laboratory conditions. Common methods include:
  • PCR (Polymerase Chain Reaction) – Detects H. salomonis DNA in gastric biopsies or fecal samples.
  • Histopathology – Examines stomach tissue for bacterial colonization and inflammation.
  • Serology – Measures antibody responses against H. salomonis, though specificity issues exist.
• Because most clinical tests are optimized for detecting H. pylori, many non-H. pylori Helicobacter infections—including H. salomonis—may be underdiagnosed in humans.

Treatment and Control Strategies

• Since H. salomonis shares similarities with H. pylori, it is often treated using similar antibiotic regimens, including:
  • Proton pump inhibitors (PPIs) – Reduce stomach acid to enhance antibiotic effectiveness.
  • Triple therapy – Combination of clarithromycin, amoxicillin, and metronidazole.
  • Alternative regimens – Tetracycline-based treatments in cases of antibiotic resistance.
• However, H. salomonis may exhibit resistance to some antibiotics, making eradication challenging. For pet owners and veterinary professionals, preventive measures include:
  • Practicing good hygiene when handling pets.
  • Avoiding direct contact with animal saliva.
  • Proper sanitation of pet food and water bowls.
• Although human infections are rare, awareness is essential for individuals at higher risk of exposure, such as those with frequent animal contact.

Future Research and Clinical Implications

• As an emerging zoonotic pathogen, H. salomonis raises important questions about gastric disease transmission between animals and humans. Key areas of research include:
  • Understanding its role in human gastric disease – Is it a primary pathogen or an opportunistic colonizer?
  • Clarifying its link to gastric malignancies – Can it contribute to MALT lymphoma, as seen with other Helicobacter species?
  • Improving diagnostic techniques – Developing better tools for detecting non-H. pylori Helicobacter infections.
• With advances in microbiology and gastroenterology, it is likely that H. salomonis and related species will become more widely recognized as potential human pathogens.