The Pathogenicity ofShewanella algaeand Ability to Tolerate a Wide Range of Temperatures and Salinities

Abstract

Shewanella algae is a rod-shaped Gram-negative marine bacterium frequently found in nonhuman sources such as aquatic ecosystems and has been shown to be the pathogenic agent in various clinical cases due to the ingestion of raw seafood. The results of this study showed that S. algae was present in approximately one in four samples, including water and shellfish samples. Positive reactions (API systems) in S. algae strains were seen for gelatinase (gelatin); however, negative reactions were found for indole production (tryptophan). S. algae is adapted to a wide range of temperatures (4°C, 25°C, 37°C, and 42°C) and salinity. Temperature is a key parameter in the pathogenicity of S. algae as it appears to induce hemolysis at 25°C and 37°C. S. algae exhibits pathogenic characteristics at widely varying temperatures, which suggests that it may have the ability to adapt to climate change.

Characterization of putative pathogenic Shewanella algae isolated from ballast water

“…Additional phenotypic characteristics such as the ability to grow at 42°C, tolerance to high salt concentration (6-8%), and hemolysis on sheep blood agar distinguished the S. algae isolates from other species such as S. putrefaciens, S. haliotis and S. xiamenensis as described in the previous study [44]. These characteristics grouped the S. algae isolates into mesophilic and halophilic Shewanella strains as reported by several studies [45][46][47]. The biochemical characteristics of S. algae isolate from this study were similar to S. algae from the first Danish cases of S. algae bacteremia [48], shrimp (P. vannamei) [26], and type strain IAM 14159 [49].…”

“…In general, hemolytic activity has been considered as an important virulence marker for Shewanella spp. to predict potentially virulent strain [61][62][63]. In a mouse pathogenicity study performed by Khashe and Janda [34], S. algae was observed to be the more virulent species compared to S. putrefaciens, and it was speculated that hemolytic activity could play an important virulence factor.…”

Comparative Genomics Reveals Pathogenicity-Related Loci in Shewanella algae

“…Currently, there are at least three other Shewanella species found in clinical specimens and S. algae accounts for the majority of isolates from humans [5,6]. S. algae has also been reported to cause diseases in marine animal, both wild and cultured [7][8][9]. However, there is scarce literature related to the understanding of the genetic background of virulence determinants in S. algae.…”

Non-Necrotizing Bullous Cellulitis and Bacteremia: A Rare Presentation of the Shewanella Algae Infection

“…Shewanella species are a group of bacteria frequently isolated from salt and fresh water as well as food and human sewage. This is a nonlactose fermenting Gram-negative marine bacillus that produces hydrogen sulfide as one of its most prominent features [ 1 - 2 ]. Shewanella spp., although still relatively rare, are becoming an increasingly recognized cause of human infections including cellulitis, bacteremia, and necrotizing fasciitis with a predilection for certain sub-population such as immunocompromised individuals, individuals with chronic skin breakdown.…”