Detection of Potential Human Pathogenic Bacteria Isolated From Feces of Two Colonial Seabirds Nesting on Isla Rasa, Gulf of California: Heermann’s Gull (Larus heermanni) and Elegant Tern (Thalasseus elegans)

Abstract

Some seabird species have shown to be carriers of human pathogenic bacteria, given their occurrence in contaminated coastal areas. This in turn may pose a health risk to humans and become a possible factor in the spread of infectious diseases. In this scenario, we studied whether potential human pathogenic bacteria of genera Escherichia, Vibrio, and Staphylococcus can be traced in the Heermann’s Gull and the Elegant Tern, two seabirds from Isla Rasa, Gulf of California. To this end, freshly deposited fecal droppings from both seabirds were collected and evaluated through several methods (standard bacterial methods, multiplex PCR, 16S rRNA sequencing, and matrix-assisted laser desorption ionization time-of-flight mass spectrophotometry). We identified Escherichia coli isolates, however, no evidence of pathogenicity was found. The analysis of the 16S rRNA sequences allowed the identification of isolates related to Vibrio alginolyticus and Vibrio parahaemolyticus, both previously reported as human pathogens. Also, analysis of 16S rRNA and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) leads to the identification of isolates related to Staphylococcus saprophyticus, Staphylococcus sciuri, and Staphylococcus aureus, also reported as human pathogens. However, the identified bacteria do not represent any of the species or strains that most importantly affect humans. This study represents the first approach to the identification of pathogenic microorganisms in seabirds nesting in the central region of the Gulf of California; however, it was limited to only two species of seabirds and a few microorganisms. Therefore, monitoring and surveillance work like this should be continued and expanded to other species.