Evaluation of “ Helicobacter heilmannii ” Subtypes in the Gastric Mucosas of Cats and Dogs

Abstract

ABSTRACT Infection with candidatus “ Helicobacter heilmannii ” is associated with gastritis and mucosa-associated lymphoid tissue lymphoma in people. Infection with “ H. heilmannii ” type 1 predominates (80%) and is thought to be acquired from dogs, cats, or pigs. We further examined the zoonotic potential of dogs and cats by amplifying gastric DNA from cats ( n = 45) and dogs ( n = 10) with primers against “ H. heilmannii ” ureB and 16S rRNA genes and sequencing the products. Fluorescence in situ hybridization (FISH) with eubacterial and “ H. heilmannii ”-specific probes was employed to directly visualize “ H. heilmannii ” types and their intragastric distribution. ureB sequences of “ H. heilmannii ” amplicons clustered with human and feline isolates of “ H. heilmannii ” and were distinct from the “ H. heilmannii ”-like organisms (HHLO) H. felis , H. salomonis , and H. bizzozeronii . 16S ribosomal DNA sequences in 20 “ H. heilmannii ”-infected cats and dogs were distinct from “ H. heilmannii ” type 1 and “ H. suis ” and clustered with “ H. heilmannii ” types 2 and 4. FISH confirmed the presence of “ H. heilmannii ” types 2 and 4 in dogs but failed to definitively characterize the “ H. heilmannii ” types present in cats. In infected dogs, “ H. heilmannii ” inhabited the gastric mucus and glands, and in dogs coinfected with other HHLO it shared the same gastric niche. The results indicate that dogs and cats are predominantly colonized by “ H. heilmannii ” bacteria that are distinct from type 1 and from “ H. suis .” As “ H. heilmannii ” type 1 predominates in people, the zoonotic risk posed by dogs and cats is likely small.