AUTHOR=Batac Francesca I. , Miller Melissa A. , Moriarty Megan E. , Shen Zeli , Fox James G. , Ottemann Karen M. 

TITLE=Helicobacter spp. in Necropsied Southern Sea Otters (Enhydra lutris nereis) Is Associated With Gastric Ulcers and Sensitive to Multiple Antibiotics

JOURNAL=Frontiers in Marine Science

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.00413

DOI=10.3389/fmars.2020.00413

ISSN=2296-7745

ABSTRACT=<p>Southern sea otters (<italic>Enhydra lutris nereis</italic>) are threatened marine mustelids that commonly have gastric ulcers with secondary hemorrhage (melena) as a contributing cause of death. Although <italic>Helicobacter</italic> spp. infections are known to cause gastric ulcers and gastritis in humans and ferrets, it is unknown if the sea otter bacterium, <italic>H. enhydrae</italic> sp. nov., causes similar gastric pathology. Determining whether <italic>Helicobacter</italic> detection is associated with sea otter gastric pathology is the first step toward using this information to expedite diagnosis and treatment. We investigated the proportion of <italic>Helicobacter</italic> infections in 46 necropsied southern sea otters via quantitative real-time polymerase chain reaction (qPCR) of the 16S rRNA gene. <italic>Helicobacter</italic> DNA was detected in fresh-frozen and formalin-fixed gastric body and pyloric tissues using <italic>Helicobacter</italic> genus-specific 16S rRNA primers. Data from gross necropsy and histopathology were analyzed for associations between <italic>Helicobacter</italic> detection via qPCR and presence/absence of gastric pathology. ETEST<sup>®</sup> gradient strips were utilized to investigate antimicrobial minimum inhibitory concentrations for <italic>H. enhydrae</italic> isolates. <italic>Helicobacter</italic> spp. were detected in the gastric tissue of 85% of sea otters in this study. Fresh-frozen samples were more commonly <italic>Helicobacter</italic> qPCR-positive than formalin-fixed tissue, indicating variable sensitivity of detection in relation to post-necropsy tissue processing methods. Diagnosis of gastric ulcers at necropsy was significantly associated with <italic>Helicobacter</italic> qPCR detection in gastric mucosa (<italic>P</italic> = 0.005), while age, sex, presence of melena, shark trauma, and protozoal infection were not associated (<italic>P</italic> &gt; 0.1). <italic>Helicobacter enhydrae</italic> isolates were sensitive to clarithromycin and tetracycline <italic>in vitro</italic> at physiologically relevant concentrations. Overall, this work suggests that <italic>Helicobacter</italic> spp. might be commonly found in southern sea otters, particularly those with ulcers, and that <italic>H. enhydrae</italic> can be treated with several commonly used anti-<italic>Helicobacter</italic> therapies.</p>