AUTHOR=Komine Takeshi , Ihara Hyogo , Inohana Mari , Kwok Jennifer Caroline , Shimizu Akane , Terasawa Tsumugi , Miyazaki Ayaka , Srivorakul Saralee , Iwao Hajime , Harada Sachiko , Yoshida Mitsunori , Hoshino Yoshihiko , Kurata Osamu , Fukano Hanako , Wada Shinpei 

TITLE=Non-tuberculous mycobacterial disease associated with Mycobacterium montefiorense in salamanders

JOURNAL=Frontiers in Veterinary Science

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2023.1248288

DOI=10.3389/fvets.2023.1248288

ISSN=2297-1769

ABSTRACT=<sec id="sec1"><title>Introduction</title><p><italic>Mycobacterium montefiorense</italic> is one of the causes of non-tuberculous mycobacterial infections in moray eels and salamanders. Although <italic>M. montefiorense</italic> 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 <italic>M. montefiorense</italic> and its infection in salamanders.</p></sec><sec id="sec2"><title>Methods</title><p>Nine <italic>M. montefiorense</italic> strains isolated from three species of salamanders, namely, Japanese black salamander (<italic>Hynobius nigrescens</italic>), Hakuba salamander (<italic>H. hidamontanus</italic>), and Tohoku hynobiid salamander (<italic>H. lichenatus</italic>), between 2010 and 2018, were characterized based on phenotypic and genetic examination. We also pathologically observed salamanders infected with the <italic>M. montefiorense</italic> strains, including Hakuba salamanders and Tohoku hynobiid salamanders.</p></sec><sec id="sec3"><title>Results</title><p>The microbiological and chemical characteristics of the <italic>M. montefiorense</italic> 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.</p></sec><sec id="sec4"><title>Conclusion</title><p>This study contributes to our understanding of the genetic diversity and phenotypic characteristics of <italic>M. montefiorense</italic>, as well as the pathology of the infection.</p></sec>