Bacteriological and histopathological findings in cetaceansthat stranded in the Philippines from 2017 to 2018

The relatively high frequency of marine mammal stranding events in the Philippines provide many research opportunities. A select set of stranders (n=21) from 2017 to 2018 were sampled for bacteriology and histopathology. Pertinent tissues and bacteria were collected from eight species (i.e. Feresa attenuata, Kogia breviceps, Globicephala macrorhynchus, Grampus griseus, Lagenodelphis hosei, Peponocephala electra, Stenella attenuata and Stenella longirostris) and were subjected to histopathological examination and antibiotic resistance screening, respectively. Lesions that were observed in tissues of 19 cetaceans include congestion, hemorrhage, edema, hemosiderosis, glomerulopathy, Zenkers necrosis, atrophy, atelectasis, and parasitic cysts. These lesions may be associated with factors possibly contributing to the death, debility, and stress of the animals during their strandings. On the other hand, the resistance profiles of 24 bacteria (belonging to genera Escherichia, Enterobacter, Klebsiella, Proteus, and Shigella) that were isolated from four cetaceans were determined using 18 antibiotics. All 24 isolates were resistant to at least one antibiotic class, and 79.17% were classified as multiple antibiotic resistant (MAR). The MAR index values of isolates ranged from 0.06 to 0.39 with all the isolates resistant to erythromycin (100%; n=24) and susceptible to imipenem, doripenem, ciprofloxacin, chloramphenicol, and gentamicin (100%; n=24). The resistance profiles of these bacteria can be used as basis for selecting antibiotics needed in the medical management of stranded cetaceans that need to be rehabilitated. Overall, the histopathological and bacteriological findings of the study demonstrate the challenges faced by cetacean species in the wild, such as but not limited to, biological pollution through land-sea movement of effluents, fisheries interactions, and anthropogenic activities.