Blood Culture Results from Healthy Captive and Free‐Ranging Elasmobranchs

Abstract

Blood culture is a diagnostic tool used in confirming bacterial disease in teleostean and elasmobranch fishes. Unlike teleosts, elasmobranchs have a normal microflora in multiple organs, but their blood has generally been considered to be sterile. In regular exams of elasmobranchs conducted at a public aquarium, occasional blood samples have tested positive on culture. This finding prompted a blood culture survey of healthy captive and wild elasmobranchs (sharks and stingrays), which showed that 26.7% of all animals were positive. Stingrays alone showed a 50% occurrence of positive blood cultures, although the total number of animals was low and freshwater species were included in this number. When elasmobranchs other than stingrays were evaluated according to metabolic category, pelagic animals had a higher percentage of positive cultures than nonpelagic animals (38.7% versus 13.9%). These results indicate that a single positive blood culture without other corroborating diagnostics is not sufficient to confirm septicemia in elasmobranchs.

The environmental and host‐associated bacterial microbiota of Arctic seawater‐farmed Atlantic salmon with ulcerative disorders

“…; Mylniczenko et al . ; Arias, Koenders & Larsen ; Tao, Bullard & Arias ; Tarnecki, Patterson & Arias ). This challenge the conception that presence of bacteria in blood is indicative of systemic disease in fish.…”

“…In terms of ulcerative salmon, already immunocompromised individuals could increase susceptibility to infection and developing sepsis of secondary pathogens. However, an increasing number of studies from a variety of (healthy) fish species report the presence of bacteria in blood or internal organs using culture-dependent and independent techniques (Toranzo et al 1993;Mylniczenko et al 2007;Arias, Koenders & Larsen 2013;Tao, Bullard & Arias 2014;Tarnecki, Patterson & Arias 2016). This challenge the conception that presence of bacteria in blood is indicative of systemic disease in fish.…”

Emergence of the acute-phase protein hemopexin in jawed vertebrates

“…Additionally, recent work in mice has shown that Hx can suppress the production of TNF and IL6 by macrophages in response to LPS (Liang et al , 2009). As bacteria can be routinely cultured from the organs and blood of healthy sharks (Mylniczenko et al , 2007) perhaps high levels of Hx act to ‘dampen’ the immune response to their commensal microflora? Although this important question remains unresolved, with the cloning of shark Hx we have finally identified the 5S ‘pink protein’ which was first described during chromatography of shark serum over 45 years ago (Marchalonis and Edelman, 1965).…”

Disseminated Phaeohyphomycosis in Weedy Seadragons (Phyllopteryx Taeniolatus) and Leafy Seadragons (Phycodurus Eques) Caused by Species of Exophiala, Including a Novel Species

“…are commonly found in sea water and likely represent opportunistic invaders or potential members of normal skin flora. 7,43 Although a variety of Gram-negative bacteria were isolated from skin lesions, no species of bacteria was consistently isolated. Cutaneous lesions in the seadragons were often advanced when examined histologically so that a determination as to whether the inciting lesion was bacterial, fungal, or traumatic was not possible.…”