Granulomatous lesions in a wild mullet population from the eastern Ligurian Sea (Italy): mycobacteriosis vs. pseudotuberculosis

Abstract

Mycobacterium spp. and Photobacterium damselae subsp. piscicida are recognized as the most frequent causative agents of granulomatous lesions in fish. Although frequent episodes of mycobacterial infections have been reported in wild fish worldwide, only sporadic cases have been documented to date in Italy. To investigate for the presence of lesions referable to mycobacteriosis and to identify the mycobacterial species involved, a total of 159 wild mullets were fished from the eastern coast of the Ligurian Sea, killed and necropsied. Liver and spleen samples were collected from all fish for histopathological and microbiological analyses. Molecular investigations for identification of Photobacterium damselae subsp. piscicida were performed. Gross examination revealed granulomatous lesions in one animal; microscopically, 42.14% of fish displayed granulomas with various histological features, 19.50% resulted positive at Ziehl-Neelsen staining, and were confirmed as mycobacterial lesions by culture. The identified colonies were characterized as M. fortuitum, M. abscessus, M. flavescens, M. chelonae, M. septicum and M. nonchromogenicum. In all, 35% of animals resulted positive for Photobacterium damselae subsp. piscicida. These data suggest widespread mycobacterial infection also by Photobacterium damselae subsp. piscicida infections in wild fish. Moreover, the pathogenicity of some mycobacterial species, previously considered as saprophytic, was demonstrated.

Mycobacteriosis caused by Mycobacterium marinum in reared mullets: first evidence from Sardinia (Italy)

“…Other authors that investigated mycobacteriosis in mullets (Varello et al . ) reported a higher prevalence of ZN‐positive granulomas (19.5%) than what we observed (8.5%). This discrepancy could be related to the different environmental characteristics of the two sampling areas (eastern coast of the Ligurian Sea vs. north‐eastern Sardinia).…”

“…At present, acid‐fast bacterial infections in wild Mugilidae are scarcely reported worldwide: Othman () observed several cases in Liza aurata from Libya; Rodrigues & Fernandes de Araujo () in a single Mugil curema from Brazil; Couch () in an adult of Mugil cephalus from the Gulf of Mexico; and, more recently, Varello et al . () in a number of species from Italy. Furthermore, fish mycobacteriosis was also detected in cultured mullets (Perez, Conroy & Quiñones ; Salati et al .…”

Molecular and Immunohistochemical Diagnosis of Photobacterium damselae Subspecies piscicida During Naturally Occurring Disease in Egypt

“…Phdp and Mycobacterium species are considered as the most frequent causative agents of granulomatous lesions in marine fish (Varello et al ). In our study, some granulomas contained large bacterial colonies in central necrotic area that gave a positive reaction with IHC.…”

“…The sections were stained with hematoxylin and eosin and examined under a microscope. The samples with granulomatous lesions were stained with hematoxylin and eosin and histochemical Ziehl–Neelsen stain (ZN) to detect acid‐fast bacilli (Varell et al ).…”

Mycobacterium abscessus, an Emerging and Worrisome Pathogen among Cystic Fibrosis Patients

“…Mab and other NTM subspecies are also commonly found in urban water plumbing and water systems, sometimes in symbiosis with Amoebae [18,19,20,21,22,23,24,25,26,27]. Moreover, Mab has been isolated from fish [28,29,30,31,32,33] and animals [34,35,36,37,38,39,40], who could also represent reservoirs for human infections. This makes exposure common and disinfection difficult, which is very problematic in healthcare settings [7,15,16,19,23].…”