ABSTRACT
Some bacteria and associated diseases have been detected in marine mammals for several decades, while reports of others appear to be increasing, either due to a genuine increase in incidence or due to increased interest by investigators. The latter may be applicable to Brucella spp., the wide distribution of which suggests it has been present for a long time, yet was not identified in marine mammals until 1994. Thus, increased diagnostic efforts, including improved and new diagnostic techniques (e.g., targeted cultivation techniques, PCR and sequencing, phylogeny, etc.), as well as a search for association between presence of infectious agents and lesions, may reveal infections and disease conditions that hitherto were unrecognized. Bacterial characterizations using genomic sequencing and phylogenetic studies have improved speciation, and consequently, changes in affiliation and naming of organisms have occurred. For example, the bacterium Trueperella pyogenes was previously named Arcanobacterium pyogenes, Corynebacterium pyogenes, and Actinomyces pyogenes, yet its ability to create abscesses and their characteristic smell remain the same. The challenge in studying marine mammal bacterial infections is determining the associations between organism and disease. A recent review of marine mammal disease reports in North America from 1972 to 2012 concluded that about 20% of cases were associated with bacteria (Simeone et al. 2015). Of these cases, 63% (n = 4,198) were associated with clinical disease, whereas the remaining isolates were obtained without indication of clinical disease, and the cultures were dominated by mixed flora or were established to investigate antibiotic-resistant organisms. The goal of this chapter is to summarize information on the most clinically relevant bacterial infections and diseases in marine mammals, while providing the reader with references to more in-depth sources where available.
