Wang et al. Gut Pathogens 2013, 5:15 http://www.gutpathogens.com/content/5/1/15

LETTER TO THE EDITOR Open Access Identification of tetrodotoxin-producing spp. from feces of food poisoning patients and food samples Duochun Wang1†, Yonglu Wang2†, Hongnan Huang3, Jie Lin3, Di Xiao1 and Biao Kan1*

Abstract Shewanella spp. is infrequently recovered from clinical specimens. Following two outbreaks of food poisoning, eight Shewanella spp. strains were obtained from the fecal specimens of patients, food and food processing-related materials. Tetrodotoxin (TTX) was identified in the culture supernatants of these strains, and the toxin’s biological activity was detected using a mouse bioassay. This study suggested that Shewanella strains can colonize and survive in human intestines. The study also raises the issues of the accumulation of TTX produced by Shewanella in food and the possible role of TTX-producing Shewanella in food poisoning. Keywords: Tetrodotoxin, Shewanella, Food poisoning

Background source of TTX still a controversial issue, the exact origin Shewanella spp. is Gram-negative, motile bacilli that be- of TTX in the food chain is unknown. long to the order and the family Alteromonadceae, within the gamma subdivision of the . Human infections with members of the Study design and results genus Shewanella are rare and mainly involve the ears On Sept. 29th and Oct. 2nd, 2007, two food poison- [1] and soft tissue [2-5]. The isolation of Shewanella ing incidents occurred following banquet dinners at ’ spp. from patients with diarrhea, poultry and livestock two different restaurants in Ma anshanCity,China.A has also been reported [6]. In most instances, the isola- total of 50 people attended one dinner, and 152 tion of has occurred in the absence of clinical disease people attended the other dinner. Of these individ- and has been considered to involve only colonization, uals, 16 and 22 people, respectively, showed symp- – rather than an active infection [7]. However, in recent toms of food poisoning in 1 4 h, with abdominal years, it was found that Shewanella spp. can produce pain(n=35),diarrhea(n=35,usuallymorethanfive tetrodotoxin (TTX) [8]. TTX and its analogs (TTXs) times and consisting of yellow, watery stool), have been detected in a wide variety of marine animals vomiting (n=24), nausea (n=16), poor peripheral cir- [9]. It has been suggested that TTX is a secondary me- culation with dizziness (n=20) and/or headache tabolite produced by symbiotic in marine organ- (n=14) lasting for several hours. Specimens were col- isms that gradually accumulates in the bodies of marine lected in these two poisoning investigations and inoc- organisms through the food chain [8,10]. With the ulated in selective media (WS, SS, EMB or TCBS Agar) after bacterial enrichment (see Additional file 1: Materials and methods). No common intestinal path- ogens were isolated, such as Vibrio cholerae, Salmon- * Correspondence: [email protected] † ella, Shigella and enteropathogenic Escherichia coli, Equal contributors 1State Key Laboratory for Infectious Disease Prevention and Control/ but eight strains of Shewanella spp. were isolated Collaborative Innovation Center for Diagnosis and Treatment of Infectious from the specimens, which included hand swabs of a Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, P.O. Box 5, Changping, Beijing, China Full list of author information is available at the end of the article

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