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Escherichia coli strains were isolated as the dominating organism of faecal cultures from 65 children with acute diarrhoea, 13 with persistent diarrhoea and from 35 healthy controls in whom Salmonella sp, Shigella sp or Campylobacter jejuni were not isolated. Nor were parasites detected. Enterotoxigenic E. coli were the most commonly detected enterovirulent organism. Enteroaggregative E. coli were also isolated more frequently from cases than controls (p<0.01). The ability to invade Caco-2 cells at 28-1% was significantly more common among E. coli isolated from cases than from controls (p<0.001). None of the strains carried the enteroinvasive inv plasmid. Seven invasive strains belonged to EPEC serotypes. Of iron-acquiring mechanisms studied, transferrin-binding was expressed by 26 strains from acute diarrhoea, 4 from persistent diarrhoea and from 10 healthy children (cases-controls, p<0.001). Production of haemolysin was more common in strains isolated from cases than from controls (p<0.05) but siderophores were rarely produced (9 strains from cases and three from controls). Transferrin-binding was mediated by at least three surface proteins of M around 40 kD, 42 kD and 80 kD. In some strains the expression of these proteins was inducible, and only detected after growth in iron-depleted medium. Transferrin-binding appeared to be a common iron-acquiring mechanism expressed by enterovirulent E. coli particularly during growth in iron-depleted medium. [ABSTRACT FROM AUTHOR]

It is critical to avoid delays in detecting strain manipulations, such as the addition/deletion of a gene or modification of genes for increased virulence or antibiotic resistance, using genome analysis during an epidemic outbreak or a bioterrorist attack. Our objective was to evaluate the efficiency of genome analysis in such an emergency context by using contigs produced by pyrosequencing without time-consuming finishing processes and comparing them to available genomes for the same species. For this purpose, we analyzed a clinical isolate of Francisella tularensis subspecies holarctica (strain URFT1), a potential biological weapon, and compared the data obtained with available genomic sequences of other strains. The technique provided 1,800,530 bp of assembled sequences, resulting in 480 contigs. We found by comparative analysis with other strains that all the gaps but one in the genome sequence were caused by repeats. No new genes were found, but a deletion was detected that included three putative genes and part of a fourth gene. The set of 35 candidate LVS virulence attenuation genes was identified, as well as a DNA gyrase mutation associated with quinolone resistance. Selection for variable sequences in URFT1 allowed the design of a strain-specific, highly effective typing system that was applied to 74 strains and six clinical specimens. The analysis presented herein may be completed within approximately 6 wk, a duration compatible with that required by an urgent context. In the bioterrorism context, it allows the rapid detection of strain manipulation, including intentionally added virulence genes and genes that support antibiotic resistance. [ABSTRACT FROM AUTHOR]

On November 15, 2004, a cluster of three cases of Salmonella Thompson infection was registered by the Norwegian reference laboratory. In the following days further cases occurred, prompting a case-control study among the first 13 cases and 26 matched controls. By December 31, 21 cases had been reported, with the first onset on October 24. Consumption of rucola lettuce (Eruca sativa, also known as rocket salad or arugula) (OR 8,8 [1,2-infinity]) and mixed salad (OR 5,0 [1,0-infinity]) was associated with illness. On November 26, Swedish authorities notified the finding of Salmonella Thompson in rucola lettuce through the EU Rapid Alert System for Food and Feed. Later, several countries reported finding this and other Salmonella serovars and Campylobacter in rucola produced in Italy. In response to our alert through the international Enter-net surveillance network, Sweden and England also reported an increase of cases. Salmonella Thompson isolates from products and patients from several countries showed high similarity by pulsed-field gel electrophoresis, but some isolates showed significant differences. We think that the outbreak in Norway reflected a larger international outbreak caused by rucola imported from one Italian producer. Findings of other pathogens indicate a massive contamination, possibly caused by irrigation with nonpotable water. Rapid international information exchange is invaluable when investigating outbreaks caused by internationally marketed products.