Potentially Pathogenic Bacteria in Nesting Olive Ridley Turtles in Northwestern Mexico

Abstract

Olive ridleys (Lepidochelys olivacea) are the most common sea turtle found in the Gulf of California. Unfortunately, the bacterial flora of nesting olive ridley turtles is still unknown. We conducted a study to identify, characterize, serotype, and determine the antibiotic resistance of potentially pathogenic bacteria isolated from olive ridley turtles nesting in northwestern Mexico. Bacteria were isolated and identified from the oral cavity and cloaca of 47 postnesting turtles. Escherichia coli and Vibrio parahaemolyticus were characterized, and antibiotic resistance testing was performed. One hundred bacteria belonging to 21 species were isolated, 53 from the oral cavity and 47 from the cloaca, the most prevalent being Pseudomonas aeruginosa, followed by Aeromonas hydrophila, Vibrio alginolyticus, Vibrio parahaemolyticus, Klebsiella pneumoniae, and E. coli, among others. Moreover, two to three different bacterial species were found co-colonizing both anatomical sites in some turtles. E. coli phylogroups B1, A, F, and unknown were identified as diarrheagenic E. coli (enteroaggregative and enteropathogenic E. coli). O1, O4, K8, K12, OUT, and KUT of V. parahaemolyticus serogroups were identified, also comprising pathogenic and nonpathogenic strains. Finally, 100% of the bacterial species tested were antibiotic resistant, and both MDR and XDR strains were found. In conclusion, olive ridley turtles are colonized by a diversity of bacterial species with a high rate of antibiotic resistance, some with pathogenic potential to turtles, representing a health risk factor for the species.

Keywords: Bacteria; Escherichia coli; Nesting; Olive ridley turtles; Vibrio parahaemolyticus.