Suppurative necrotizing bronchopneumonia caused by <i>Nocardia cyriacigeorgica</i> infection in a stranded striped dolphin (<i>Stenella coeruleoalba</i>) in Japan

Abstract

On a coastline in Miyazaki Prefecture, Japan, a wild subadult female striped dolphin was found dead. Necropsy revealed poor nutritional status and bilateral pneumonia, which was histologically diagnosed as severe suppurative necrotizing bronchopneumonia. Special staining detected numerous intralesional filamentous, branching bacteria, which was identified as Nocardia cyriacigeorgica by sequencing of 16S ribosomal RNA and gyrB genes. Other main histological findings included lymphoid depletion in the spleen and superficial cervical and pulmonary lymph nodes. Suppurative nocardiosis without a granulomatous reaction is uncommon, and it is assumed its pathogenesis was related to the host’s immune status. This paper discusses the variable inflammatory response to nocardiosis and describes the first case of N. cyriacigeorgica infection in a wild striped dolphin in Japan.

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

“…Based on lesion severity and distribution, the disseminated pattern was the most common presentation yet a primary pulmonary form with pulmonary lymph node involvement was detected in all dolphins [ 12 ]. This distribution pattern lends support to a major airborne route of entry for Nocardia in these cases [ 12 , 14 , 15 ]. This contrasts with the apparent lack or exceedingly rare evidence of inter-individual transmission of Nocardia in infected humans and animals [ 27 ].…”

“…Published accounts of nocardiosis in cetaceans reveal a high prevalence in captive animals, particularly in adults and juveniles, without any evidence of sex predisposition [ 12 , 15 ]. In this study, N. farcinica was confirmed in two subadult striped dolphins (cases 1 and 2) and N. otitiscaviarum was confirmed in one subadult striped dolphin and a calf bottlenose dolphin (cases 4 and 5).…”

“…In cetaceans, confirmed Nocardia species and host species are N. asteroides (in a captive Atlantic bottlenose dolphin, captive killer whale, wild striped dolphin, captive harbor porpoise, and captive pilot whale), N. farcinica (in captive killer whale and captive beluga whale), N. brasilensis (in a captive Pacific bottlenose dolphin and captive beluga whale), N. cyriacigeorgica (in a captive beluga whale), N. levis (in a captive Atlantic bottlenose dolphin), N. otitisdiscaviarum (in a captive Pacific bottlenose dolphin), and N. cyriacigeorgica (in a free-ranging striped dolphin) [ 12 , 15 , 16 ]. The most common pattern of nocardial infection in cetaceans is the disseminated form with frequent involvement of lungs and lymph nodes [ 12 ].…”

“…In cetaceans, nocardiosis occurs more often as a systemic form, involving two or more organs [ 12 , 13 , 14 ]. Frequently concomitant with the systemic pattern, pulmonary nocardiosis is also common and infection has been described in striped dolphins ( Stenella coeruleoalba ), short-finned pilot whales ( Globicephala macrorhynchus ), Pacific bottlenose dolphins ( Tursiops gilli ), Atlantic bottlenose dolphins ( Tursiops truncatus ), killer whales ( Orcinus orca ), and beluga whale ( Delphinapterus leucas ) [ 12 , 15 , 16 ]. Secondary nocardial mastitis was reported in an adult beluga whale [ 17 ].…”

“…Secondary nocardial mastitis was reported in an adult beluga whale [ 17 ]. To date, nocardial species known to affect cetaceans include Nocardia asteroides , N. farcinica , N. brasilensis , N. cyriacigeorgica and N. levis [ 12 , 15 ]. Here we report the pathologic features of nocardiosis in five free-ranging delphinids from Spain, specifically from the Canary Islands and Andalusia.…”