Isolation of Shewanella algae from rectal swabs of patients with bloody diarrhoea.

Shewanella algae is an emerging bacteria rarely implicated as a human pathogen. It was infrequently recovered from clinical specimens probably because of inadequate processing of non-fermenting oxidase-positive gram-negative bacilli. We report here isolation of S. algae in pure culture and mixed with E. coli from two cases of acute gastroenteritis with bloody mucous containing diarrhea occurring at the same time. As this organism is not a normal flora of the gut, the possible source of infection may be fish contaminated with the organism. Whether this bacterium can be considered an enteric pathogen needs to be evaluated. The cases were clinically diagnosed as acute bacillary dysentery. The bacterium was identified by 16S r-RNA gene sequence analysis.

Isolation and characterization of Shewanella spp.from patients of food poisoning / 中华流行病学杂志

Objective To identify the isolates of Shewanella spp.from specimens of food poisoning based on biological and biochemical analysis.Methods Strains were obtained from the investigation on two food poisoning episodes in September and October,2007 in Ma'anshan city,Anhui province.In accordance with the national standard protocol(GB/T 4789),all specimens were enriched and isolated on selective medium,and the suspected strains were ldentified by the VITEK-32 and API20E systems.For Shewanella spp.identified by the biochemical system,more characteristics were analyzed using auxiliary biochemical,growth,hemolytic and drug-resistance tests.DNAs of Shewanella spp.were extracted,16S rDNA was PCR amplified and sequenced with universal 16S rDNA primers.Phylogenetic tree was constructed with MEGA 4.0.Results After enrichment, all specimens were inoculated to selective medium and Shewanella spp.strains were isolated from 8 samples with single colony on both TCBS and BP media.The characteristics of growth in the Triple Sugar Iron (TSI) agar appeared to have had hydrogen sulfide production but no gas production or positive oxidase.No Shewanella spp.strain was detected in WS,SS and EMB media.The 8 strains were identified as Shewanella algae(S.algae) or Shewanella putrefaciens(S.putrefaciens) by VITEK-32,as S.putrefaciens by API20E system.No other enteropathogenic bacteria,including Vibrio cholerae,Salmonella,Vibrio parahaemolyticus,Proteus vulgaris or Staphylococcus aureua,were detected from those 8 samples.From 16S rDNA phylogenetic trees,7 out of 8 ShewaneUa spp.were identified as S.algae.1 as S.putrefaeiens.Conclusion Strains of Shewanella spp.were lsolated from samples of the food poisoning episodes,providing a possible clue to investigate the role of Shewanella spp.on food poisoning