Brucella sp. vertebral osteomyelitis with intercurrent fatal Staphylococcus aureus toxigenic enteritis in a...

A previously beach-stranded, juvenile, male, bottlenose dolphin (Tursiops truncatus) was diagnosed with vertebral osteomyelitis of unknown etiology. Antemortem serological testing suggested past or current Brucella sp. infection; however, this could not be confirmed prior to death despite multiple isolation attempts from aspirates, blood, and biopsies. Systemic antibiotics were administered for over a year to control the suspected infection; however, the animal succumbed peracutely to infection by a highly pathogenic, enterotoxin-secreting Staphylococcus sp. Gross necropsy findings included a fistulous tract leading to locally extensive osteomyelitis of a coccygeal vertebra with sequestra and osteophytes from which a Brucella species was isolated. Histopathological examination of intestine revealed pseudomembranous enteritis with a uniform population of intraluminal Gram-positive cocci. Staphylococcus aureus was isolated in pure culture from the intestine and tested positive for the staphylococcal enterotoxin A gene by polymerase chain reaction analysis. Serum taken shortly before death had endotoxin and elevated antibody titers to staphylococcal enterotoxin A when compared to samples collected during a period of apparent good health 18 months earlier. The isolation of a pyrogenic toxin superantigen-producing staphylococcal isolate, clinical signs, and diagnostic findings in this animal resembled some of those noted in human toxic shock syndrome. The present case highlights the clinical challenges of treating chronic illnesses, complications of long-term antibiotic use, and promotion of pathogenic strains in cases of prolonged rehabilitation of marine mammals.