Microbiome Shifts Associated With the Introduction of Wild Atlantic Horseshoe Crabs (Limulus polyphemus) Into a Touch-Tank Exhibit.

The Atlantic horseshoe crab (Limulus polyphemus) is a common marine aquarium species and model organism for research. There is potential monetary and conservation value in developing a stable captive population of horseshoe crabs, however, one major impediment to achieving captivity is a lack of knowledge regarding captive diseases. We utilized 16S rRNA gene amplicon sequencing to track changes in the microbiomes of four body locations in three wild-caught (tracked over 14 months in captivity) and three tank-acclimated (>2 years in captivity) adult L. polyphemus in a touch tank at Shark Reef Aquarium at Mandalay Bay in Las Vegas, NV. The wild population hosted diverse and distinct microbiomes on the carapace (260 ± 96 amplicon sequence variants or ASVs), cloaca (345 ± 77 ASVs), gills (309 ± 36 ASVs), and oral cavity (359 ± 37 ASVs), which were dominated by classes Gammaproteobacteria, Bacteroidia, and Alphaproteobacteria. A rapid decline in richness across all body locations was observed within 1 month of captivity, with tank-acclimated (>2 years) animals having <5% of the initial microbiome richness and a nearly completely restructured microbial community. Tank-acclimated horseshoe crabs possessed distinct microbiomes that were highly uneven and low in species richness on the carapace (31 ± 7 ASVs), cloaca (53 ± 19 ASVs), gills (17 ± 2 ASVs), and oral cavity (31 ± 13 ASVs). The carapace, oral cavity, and gills of the tank-acclimated animals hosted abundant populations of Aeromonas (>60%) and Pseudomonas (>20%), both of which are known opportunistic pathogens of aquatic animals and can express chitinases, providing a plausible mechanism for the development of the carapace lesion pathology observed in this and other studies. The cloaca of the tank-acclimated animals was slightly more diverse than the other body locations with Aeromonas, Enterococcus, Shewanella, and Vagococcus dominating the community. These results provide an important baseline on the microbiomes of both wild and tank-acclimated horseshoe crabs and underscore the need to continue to investigate how native microbial populations may protect animals from pathogens.

Initial ED oxygen saturation ≤90% increases the risk of a complicated hospital course in pediatric asthmatics requiring admission.

Emergency physicians are responsible for admitting children with asthma who do not respond to initial therapy. We examined the hypothesis that an initial room air pulse oximetry ≤90% elevates the risk of a complicated hospital course in children who require admission with acute asthma. METHODS: Charts of all patients ages 2 years-17 years admitted for asthma from January 2017 to December 2017 were reviewed. An explicit chart review was performed by trained data extractors using a standardized form. RESULTS: A total of 244 children meeting inclusion criteria were admitted for asthma from the ED during the study period. All patients had an initial room air pulse oximetry documented. Sixty-five were admitted to PICU status (27%), and 179 (73%) were admitted to floor status. The relative risk of a complicated course in those patients presenting with a saturation of ≤90% was 11.3 (95% CI 3.9-32.6). The mean initial pulse oximetry on patients with a complicated course was 85% versus 93% for those without a complicated course (p < 0.005). CONCLUSION: Our data suggest that in pediatric asthmatics that require admission from the ED, those with pulse oximetry readings less than or equal to 90% on presentation are at higher risk of a complicated hospital course.