title: Cytotoxic and pathogenic properties of Klebsiella oxytoca isolated from laboratory animals.
abstract: Klebsiella oxytoca is an opportunistic pathogen implicated in various clinical diseases in animals and humans. Studies suggest that in humans K. oxytoca exerts its pathogenicity in part through a cytotoxin. However, cytotoxin production in animal isolates of K. oxytoca and its pathogenic properties have not been characterized. Furthermore, neither the identity of the toxin nor a complete repertoire of genes involved in K. oxytoca pathogenesis have been fully elucidated. Here, we showed that several animal isolates of K. oxytoca, including the clinical isolates, produced secreted products in bacterial culture supernatant that display cytotoxicity on HEp-2 and HeLa cells, indicating the ability to produce cytotoxin. Cytotoxin production appears to be regulated by the environment, and soy based product was found to have a strong toxin induction property. The toxin was identified, by liquid chromatography-mass spectrometry and NMR spectroscopy, as low molecular weight heat labile benzodiazepine, tilivalline, previously shown to cause cytotoxicity in several cell lines, including mouse L1210 leukemic cells. Genome sequencing and analyses of a cytotoxin positive K. oxytoca strain isolated from an abscess of a mouse, identified genes previously shown to promote pathogenesis in other enteric bacterial pathogens including ecotin, several genes encoding for type IV and type VI secretion systems, and proteins that show sequence similarity to known bacterial toxins including cholera toxin. To our knowledge, these results demonstrate for the first time, that animal isolates of K. oxytoca, produces a cytotoxin, and that cytotoxin production is under strict environmental regulation. We also confirmed tilivalline as the cytotoxin present in animal K. oxytoca strains. These findings, along with the discovery of a repertoire of genes with virulence potential, provide important insights into the pathogenesis of K. oxytoca. As a novel diagnostic tool, tilivalline may serve as a biomarker for K oxytoca-induced cytotoxicity in humans and animals through detection in various samples from food to diseased samples using LC-MS/MS. Induction of K. oxytoca cytotoxin by consumption of soy may be in part involved in the pathogenesis of gastrointestinal disease.
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Alison
authors: A
authors: Darby
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Kvin
authors: K
authors: Lertpiriyapong
authors: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge. Massachusetts, United States of America.
authors: Ujjal
authors: U
authors: Sarkar
authors: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge. Massachusetts, United States of America.
authors: Uthpala
authors: U
authors: Seneviratne
authors: Pharmaceutical Sciences and Pharmacogenomics Graduate Program, University of California, San Francisco, California, United States of America.
authors: Danny S
authors: DS
authors: Park
authors: Section of Genetic Medicine, Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America.
authors: Eric R
authors: ER
authors: Gamazon
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Chara
authors: C
authors: Batchelder
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Cheryl
authors: C
authors: Cheung
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Ellen M
authors: EM
authors: Buckley
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Nancy S
authors: NS
authors: Taylor
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Zeli
authors: Z
authors: Shen
authors: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge. Massachusetts, United States of America; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Steven R
authors: SR
authors: Tannenbaum
authors: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge. Massachusetts, United States of America.
authors: John S
authors: JS
authors: Wishnok
authors: Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge. Massachusetts, United States of America.
authors: James G
authors: JG
authors: Fox
mesh_terms: D000818:Animals; D058947:Bacterial Secretion Systems / Q000235:genetics; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D001570:Benzodiazepinones / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D000882:Haplorhini; D006367:HeLa Cells; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology / Q000662:veterinary*; D041121:Klebsiella oxytoca / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism / Q000472:pathogenicity*; D051379:Mice; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D051381:Rats; D013025:Glycine max / Q000737:chemistry; D013552:Swine
chemical_list: D058947:Bacterial Secretion Systems; D001427:Bacterial Toxins; D001570:Benzodiazepinones; D010936:Plant Extracts; C093067:tilivalline