BACTERIA ISOLATED FROM DUGONGS (DUGONG DUGON) SUB-MITTED FOR POSTMORTEM EXAMINATION IN QUEENSLAND, AUSTRALIA, 2000–2011

Abstract

Microbial infection may contribute to disease in a significant proportion of marine mammal mortalities, but little is known about infectious bacterial species and their prevalence in dugongs (Dugong dugon). This study represents a survey of the species of bacteria and fungi isolated from dugongs submitted to the University of Queensland's School of Veterinary Science for postmortem examination. Thirty-six dugongs were included in the survey, with 23 species of bacteria and four species of fungus cultured from lesions that were suspected of contributing to local infection, systemic infection, or both. The most abundant bacteria included Aeromonas spp., Clostridium spp., Vibrio spp., Enterococcus faecalis, and Pseudomonas spp. In six cases, the microorganism(s) cultured were considered to have been associated with disease. Mixed infections containing Aeromonas spp. and Vibrio spp.; Morganella morganii, Pasteurella multocida, and Serratia marcescens; and Actinomyces spp. and Peptostreptococcus spp. were associated with pneumonia or pleuritis, and Enterococcus faecalis was associated with a multisystemic infection in a neonate. Clostridium spp. was cultured from two animals with peritonitis and likely septicemia. The significance of many of the other isolates is uncertain because the samples were taken after death, and some of the species isolated may represent postmortem overgrowth. It is also difficult to fulfil Koch's postulates through experimental infection in marine mammals. Regardless, this information will assist clinicians working with dugongs to make treatment decisions and the baseline data on the prevalence of bacterial and fungal species is of value for monitoring coastal water habitat health and risks of zoonotic disease transmission.

Aeromonas dhakensis pneumonia and sepsis in a neonate Risso’s dolphin Grampus griseus from the Mediterranean Sea

“…Aero monas spp. were the predominant Gram-negative bacteria found in post-mortem studies in dugongs Dugong dugon, contributing to pyogranulomatous pneumonia in this species, frequently as mixed infections (Nielsen et al 2013). The only report relating A. hydrophila with disease in cetaceans was a case of multifocal necrotizing dermatitis and supportive bronchopneumonia described in a captive bottlenose dolphin in 1973 (Cusick & Bullock 1973).…”

“…However, in contraposition to the extensive literature implicating Aeromonas in fish diseases, few cases of Aeromonas infections have been reported in marine mammals (Cusick & Bullock 1973, Krovacek et al 1998, Thornton et al 1998, Nielsen et al 2013. Moreover, it has been shown that routine phenotypic identification of Aeromonas spp.…”

Hematology of dugongs (Dugong dugon) in southern Queensland

“…Opportunistic necropsies of dugong carcasses washed ashore in Queensland, Australia, have provided some information regarding antemortem health status but for a significant proportion of animals, the cause of death has not been determined . Suggested factors contributing to mortality include specific ( Cryptosporidium parvum , Toxoplasma gondii ) and nonspecific (septicemia, pneumonia) infectious etiologies, and some carcasses indicate exposure to pollutants (eg, heavy metals, organochlorides) . These studies have provided limited information regarding the health of live dugong populations.…”

Novel insights into pasteurellosis in captive pinnipeds

“…While several members of the family Pasteurellaceae have been identified as part of the normal flora of healthy pinnipeds, P. multocida has been isolated from cases of septicaemia, mortality and pneumonia in pinnipeds as well as cetaceans (Dunn et al, 2001;Hansen et al, 2012;Nielsen et al, 2013). Fatal septicaemic pasteurellosis has been reported in cetaceans and pinnipeds, where the most common origin of generalized pasteurellosis in captive and wild pinnipeds is bite wounds inflicted by conspecifics (Hansen et al, 2012).…”