Abstract

In Mexico there are two different types of marine parks, opened and closed facilities. The first ones use water from the natural environment, while the others assure water quality by filtration. Information available, regarding microbiological aspects of bottlenose dolphins, describes pathogenic bacteria associated with stranded dolphins and there are only a few reports describing normal flora in these cetaceans. This information would enhance the knowledge of the bacterial participation in respiratory and reproductive disorders, and their possible role in zoonotic diseases. The aim of this study was to determine bacteria and yeast associated with the respiratory tract and genital area of clinically healthy bottlenose dolphins, housed in closed and opened facilities, during the different seasons.

Twenty nine clinically healthy bottlenose dolphins (16 females and 13 males) from eight different marine parks in Mexico were sampled. The dolphins were between 2-17 years old. The dolphins' health status was corroborated by physical inspection, clinical records, cytology, and hemograms. The handling of the dolphins was through operant conditioning with positive reinforcement. The samples were obtained during the period of August of 2006 to May of 2007.

A total of 212 samples were collected for microbiological studies. One hundred and seventy bacteria and 19 yeasts were isolated from the respiratory tract; 189 bacteria and one species of yeast were obtained from the genital area. These isolates were identified by API 20 system (Biomerieux, France). The results showed a greater diversity of bacterial species in opened facilities when compared with closed facilities. Additionally, a higher number of bacterial and yeast isolates were obtained from the opened facilities.

Results also showed the presence of several microorganisms that can be considered as part of the normal flora of healthy animals, since most of them were isolated in absence of any apparent clinical disease. These microorganisms can become opportunistic pathogens when dolphins are immunosuppressed. This knowledge may contribute in the understanding of the role of the bacteria in stranded dolphins, as well as some of their reproductive and respiratory disorders.

Acknowledgements

To CONACYT-Mexico and UNAM for the sponsorship received. The authors wish to thank to marine parks Convimar, S.A. de C.V., Via Delphi, S.A. de C.V. Delfiniti, S.A. de C.V. and Six Flags México, S.A. de C.V., as well as Drs. José Luis Solórzano Velasco, María Concepción López Romahn, Raúl Torres Salcedo, Juan José Bolaños Guerra, Alejandro Hernández Alarcón, Aurora Ramos Garduño and Marcela Bárbara.