Shewanella putrefaciens – a new opportunistic pathogen of freshwater fish

Abstract

In recent years, Shewanella putrefaciens, commonly known as a halophilic bacteria, has been associated with serious health disorders in freshwater fish. Therefore, it has been described as a new aetiological agent of the disease, named shewanellosis. S. putrefaciens is a heterogeneous group of microorganisms, belonging to the Alteromonadaceae family. Based on different criteria, three biovars and biogroups as well as four genomic groups have been distinguished. The first infections of S. putrefaciens in fish were reported in rabbitfish (Siganus rivulatus) and European sea bass (Dicentrarchus labrax L.). Outbreaks in farmed fish were reported in Poland for the first time in 2004. The disease causes skin disorders and haemorrhages in internal organs. It should be noted that S. putrefaciens could also be associated with different infections in humans, such as skin and tissue infections, bacteraemia, otitis. Investigations on pathogenic mechanisms of S. putrefaciens infections are very limited. Enzymatic activity, cytotoxin secretion, adhesion ability, lipopolysaccharide (LPS), and the presence of siderophores are potential virulence factors of S. putrefaciens. Antimicrobial resistance of S. putrefaciens is different and depends on the isolates. In general, these bacteria are sensitive to antimicrobial drugs commonly used in aquaculture.

Winter kill in intensively stocked channel catfish (Ictalurus punctatus): Coinfection with Aeromonas veronii, Streptococcus parauberis and Shewanella putrefaciens

“…However, S. parauberis and S. putrefaciens showed resistance or intermediate susceptibility to oxytetracycline and romet, respectively. Multidrug resistance was reported for A. veronii , S. parauberis and S. putrefaciens previously (Haines et al., ; Meng, Kanai, & Yoshikoshi, ; Nawaz et al., ; Paździor, ; Pękala et al., ). According to our anecdotal observation, fish mortality ceased completely 10 days postadministration of Aquaflor ® to catfish in the raceways at a dose of 10 mg florfenicol/kg fish/d for 10 consecutive days.…”

“…Of late, it was isolated from cultured tilapia ( Oreochromis niloticus ) from an Egyptian fish farm (El‐Barbary, ). Therefore, it has been described as a new aetiological agent of the disease, named shewanellosis, with three distinguished biovars as well as four genomovars (Paździor, ).…”

Shewanella khirikhana sp. nov. – a shrimp pathogen isolated from a cultivation pond exhibiting early mortality syndrome

“…In addition, the TH2012 T genome contains a putative prophage (Fig. ) (Wechprasit et al , ) and some virulence genes found in some Shewanella isolates (Paździor, ; Yousfi et al , ) such as putative haemolysins, chitinases and proteases (Wechprasit et al , ).…”

Systemic polymicrobic infection involving Shewanella putrefaciens group in koi

“…As part of the physiological microbiota of gills and intestine, S. putrefaciens group is now considered an opportunistic aetiological agent (shewanellosis) also in fishes (Pakingking, Palma, & Usero, 2015;Paździor, 2016). The first report was on a marine fish species (rabbitfish) (Saeed, Alamoudi, & Al-Harbi, 1987).…”

“…The first isolation related to health disorders in freshwater fishes dates back to 2004 in Poland; since then, episodes of infection have been reported in different fresh and saltwater species, including koi (Cyprinus carpio L.). Skin necrotizing and ulcerative lesions and gill necrosis are the main gross pathologic findings, and polymicrobic infections have been recorded (Altun et al, 2014;El-Barbary, 2017;Esteve, Merchán, & Alcaide, 2017;Korun, Akgun-Dar, & Yazici, 2009;Kozińska & Pękala, 2004;Paździor, 2016;Pękala et al, 2015;Qin, Zhu, & Xu, 2014;Rusev, Rusenova, Simeonov, & Stratev, 2016).…”