Non-tuberculous mycobacterial disease associated with Mycobacterium montefiorense in salamanders.

Introduction: Mycobacterium montefiorense is one of the causes of non-tuberculous mycobacterial infections in moray eels and salamanders. Although M. montefiorense infection could be a threat to salamanders, little information is available regarding this pathogen and associated infection. This study aimed to provide fundamental information regarding M. montefiorense and its infection in salamanders. Methods: Nine M. montefiorense strains isolated from three species of salamanders, namely, Japanese black salamander (Hynobius nigrescens), Hakuba salamander (H. hidamontanus), and Tohoku hynobiid salamander (H. lichenatus), between 2010 and 2018, were characterized based on phenotypic and genetic examination. We also pathologically observed salamanders infected with the M. montefiorense strains, including Hakuba salamanders and Tohoku hynobiid salamanders. Results: The microbiological and chemical characteristics of the M. montefiorense salamander and an eel strain (reference strain) matched. Susceptibility testing for antimicrobials suggested that clarithromycin may be effective. Regarding disinfectants, phtharal, peracetic acid, glutaral, sodium hypochlorite, and benzalkonium chloride may be effective. Phylogenetic analyses revealed that the strains isolated from salamanders in 2014 and 2018 were genetically closely related, which could indicate an outbreak. The main gross findings in infected salamanders include skin ulcerative lesions or nodules in the enlarged liver. Microscopically, multifocal to coalescent granulomatous lesions composed of massive macrophages containing numerous acid-fast bacilli were prominently observed in the liver. Conclusion: This study contributes to our understanding of the genetic diversity and phenotypic characteristics of M. montefiorense, as well as the pathology of the infection.

A case of mycobacteriosis associated with Mycobacterium pseudoshottsii in aquarium-reared fish in Japan.

In 2019, several aquarium-reared fish died at a sea life park in Japan. Necropsy revealed micronodules on the spleen in the dotted gizzard shad (Konosirus punctatus). Seven of 16 fish exhibited microscopic multifocal granulomas associated with acid-fast bacilli in the spleen, kidney, liver, alimentary tract, mesentery, gills, and/or heart. Bacterial cultures yielded isolates from the dotted gizzard shad and a Japanese sardine (Sardinops melanostictus). Microbiological and molecular biological examinations revealed the isolates as Mycobacterium pseudoshottsii. To our knowledge, this is the first isolation of M. pseudoshottsii from aquarium-reared fish.

Draft Genome Sequences of Eight Mycobacterium montefiorense Strains Isolated from Salamanders in Captivity.

Mycobacterium montefiorense is a nontuberculous mycobacterium that causes infections in fish and salamanders. Here, we report annotated draft genome sequences of eight strains that were isolated in 2014 and 2018 from salamanders reared in an aquarium in Japan.