title: Enterobacter sakazakii: infectivity and enterotoxin production in vitro and in vivo.
abstract: Enterobacter sakazakii has been implicated as the causal organism in a severe form of neonatal meningitis, with reported mortality rates of 40 to 80%. Dried infant formula has been identified as a potential source of the organism in both outbreaks and sporadic cases. In this study, clinical and foodborne isolates of E. sakazakii were evaluated for enterotoxin production by the suckling mouse assay. In addition, suckling mice were challenged both orally and by intraperitoneal injection. Of 18 E. sakazakii strains evaluated, four were found to test positive for enterotoxin production. All strains of E. sakazakii were lethal to suckling mice at 10(8) CFU per mouse by intraperitoneal injection, while two strains caused death by the peroral route. In in vitro assays, CHO, Vero, and Y-1 cells demonstrated both cell lysis and rounding when exposed to E. sakazakii strain LA filtrates. This is the first report describing any putative virulence factors of E. sakazakii.
authors.affiliation: Bureau of Microbial Hazards, Food Directorate, Health Products and Food Branch, Health Canada, Postal Locator 2204A2, Ottawa, Ontario, Canada K1A 0L2. franco_pagotto@hc-sc.gc.ca
authors.forename: Franco J
authors.initials: FJ
authors.lastname: Pagotto
authors.forename: Maria
authors.initials: M
authors.lastname: Nazarowec-White
authors.forename: Sabah
authors.initials: S
authors.lastname: Bidawid
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Farber
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000833:Animals, Suckling; D002478:Cells, Cultured; D004754:Enterobacter / Q000378:metabolism / Q000472:pathogenicity*; D004768:Enterotoxins / Q000096:biosynthesis*; D005516:Food Microbiology; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000382:microbiology; D007274:Injections, Intraperitoneal; D007928:Lethal Dose 50; D016920:Meningitis, Bacterial / Q000209:etiology; D051379:Mice; D014774:Virulence
chemical_list: D004768:Enterotoxins