Nocardiosis in Free-Ranging Cetaceans from the Central-Eastern Atlantic Ocean and Contiguous Mediterranean Sea.

Pablo Díaz-Santana,Carolina Fernández-Maldonado,Eva Sierra,Antonio Fernández,Manuel Arbelo,Josue Díaz-Delgado,Raquel Puig-Lozano,Lucas Domínguez,Ana Isabel Vela,Cristian Suárez-Santana

doi:10.3390/ani12040434

Abstract

Simple SummaryCharacterization, description, and geographical location of harmful bacterial agents in cetaceans are important for population surveillance and health monitoring around the world. This research compiles the pathologic features of nocardiosis in five free-ranging delphinids from the Canary Islands and Andalusia. All examined animals showed a disseminated pattern of infection with characteristic suppurative to pyogranulomatous lesions with thromboembolism in two or more organs. The obtained results provide the first record of N. otitidiscaviarum in cetaceans, the first account of N. farcinica in free-ranging dolphins, and confirmation of nocardiosis in central eastern Atlantic Ocean.We report the pathologic features of nocardiosis in five free-ranging delphinids from the Canary Islands and Andalusia, namely four striped dolphins (Stenella coerulealba) and one bottlenose dolphin (Tursiops truncatus). All animals had a multiorgan (disseminated) pattern of infection involving suppurative to pyogranulomatous and thromboembolic lesions in two or more organs. Most affected organs were (by decreasing order) lung, pulmonary lymph nodes, liver, kidney, adrenal glands, and central nervous system. Typical intralesional and intravascular branched and filamentous bacteria were highlighted by Grocott’s methenamine silver and Gram stains. Bacterial analysis including 16S rRNA gene sequencing identified Nocardia farcinica in two striped dolphins and Nocardia otitidiscaviarum in one striped dolphin and the bottlenose dolphin. All dolphins tested (n = 4) for cetacean morbillivirus were negative; one dolphin had concurrent cutaneous herpesvirosis. These results provide the first record of N. otitidiscaviarum in cetaceans, the first account of N. farcinica in free-ranging dolphins, and confirmation of nocardiosis in central eastern Atlantic Ocean. These results expand the known geographic range of nocardiosis in cetaceans.

Highlights

Nocardiosis is a relatively uncommon but widely distributed and well characterized disease of humans and animals
This study focused on four striped dolphins (Stenella coeruleoalba) and one bottlenose dolphin (Tursiops truncatus) stranded along the coast of the Canary Islands and Andalusia wherein pathologic examination results were consistent with nocardiosis
In agreement with previous observations in humans and animals, the pathologic lesions of nocardiosis in these free-ranging dolphins consisted of multiorgan pleocellular inflammatory lesions that ranged from suppurative to pyogranulomatous with necrosis, intralesional and intravascular filamentous bacteria, vasculitis/fibrinoid wall necrosis and thromboses/thromboemboli

Summary

Introduction

Nocardiosis is a relatively uncommon but widely distributed and well characterized disease of humans and animals. It is caused by a ubiquitous, saprophytic, Gram-positive, acid-fast variable, filamentous, aerobic, nonmotile, non-spore forming bacteria belonging to the genus Nocardia (Phylum Actinobacteria; order Mycobacteriales; family Nocardiaceae) [1,2,3,4,5]. Presentation overlap may occur, and dissemination is a common sequela after bacterial circumvention of host’s immunological mechanisms, to the central nervous system (CNS) and skeletal soft tissue [8,9,10]

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