Investigation and management of an outbreak of multispecies mycobacteriosis in Australian lungfish (Neoceratodus fosteri) including the use of triple antibiotic treatment

Abstract

Disease due to non-tuberculous mycobacteria (NTM) is common in fish. Current recommendations focus on outbreak management by depopulating entire fish stocks and disinfecting tanks. Treatment is not advocated. Treatment may be appropriate, however, where individual, valuable fish are concerned. ZSL London Zoo managed an outbreak of mycobacteriosis in a valuable group of imported F1 captive-bred Australian lungfish (Neoceratodus fosteri) by depopulation, isolation, extensive testing and daily oral antibiotic treatment. Four species of Mycobacterium (M. marinum, M. fortuitum, M. chelonae and M. peregrinum) were involved in this outbreak, each with unique antibiotic sensitivities. Triple therapy with rifampicin, doxycycline and enrofloxacin for 8 months was the most effective antibiotic combination, resulting in full disease resolution. No side effects were noted and, more than 18 months post-treatment, no recurrence had occurred. This is the first report of mycobacterial disease in lungfish and the first report of a polymycobacterial outbreak in fish involving these four species of Mycobacterium. This report demonstrates the value of extensive isolation and identification. Also, as therapies currently advised in standard texts did not reflect the antibiotic sensitivity of the NTM found in the fish reported here, we recommend that antibiotic treatment should always be based on sensitivity testing.

Antibiotic treatment of zebrafish mycobacteriosis: tolerance and efficacy of treatments with tigecycline and clarithromycin

“…; Strike et al . ). The dosages we used were in the ranges used for the treatment of human mycobacterial infections (Muralidharan et al .…”

“…This challenge is also true in the case of mycobacteriosis infections in other fish species such as valuable zoo collections (Strike et al . ). There is a need to explore alternative methods for disease management, such as antibiotic treatment.…”

“…For example, if an outbreak occurs in during an ongoing experiment or in a valuable mutant line, depopulation and rederivation may not be an option (Whipps et al 2012). This challenge is also true in the case of mycobacteriosis infections in other fish species such as valuable zoo collections (Strike et al 2016). There is a need to explore alternative methods for disease management, such as antibiotic treatment.…”

Systemic Edwardsiella tarda infection in a Western African lungfish (Protopterus annectens) with cytologic observation of heterophil projections

“…Unionized ammonia (NH 3 ) was not calculated as water temperature was unknown. Meanwhile, nitrite (NO 2 ) (0.33 mg/L) was above the recommended concentration (<0.04 mg/L) and above the acceptable range for both Protopterus aethiopicus and Neoceratodus forsteri (Strike, Feltrer, Flach, Macgregor, & Guillaume, ; Walakira, Molnar, Phelps, & Terhune, ). Water hardness was 205 mg/L (150–300 mg/L), and alkalinity (102 mg/L) was lower than recommended alkalinity for Protopterus aethiopicus (164 mg/L, Walakira et al., ).…”

“…Strike et al. () documented an outbreak of atypical mycobacteria in a collection of Australian lungfish ( N. forsteri ). In the present case, acid fast performed on coelomic fluid and spleen was negative, although sensitivity of this test is considered low.…”