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The risk for diarrhea-associated HUS was higher for children infected with Escherichia coli O157 phage type (PT) 2 and PT21/28 than for those infected with other PTs.

A total of 88 uropathogenic Escherichia coli isolates, including 68 isolates from urine and 20 isolates from blood, were characterized by multilocus sequence typing (MLST). MLST has identified an important genetic lineage of E. coli, designated sequence type 131 (ST-131), represented by 52 of these isolates, 51 of which were resistant to extended-spectrum cephalosporins. ST-131 appears to be a drug-resistant uropathogenic strain of E. coli responsible for causing urinary tract infections and bacteremia and is widely disseminated among both community and hospital patients from different geographical areas in the northwest of England. Application of MLST has helped to define the population biology which may underpin the epidemiology of pathogenic E. coli strains. The portability of MLST allows the accurate monitoring of this antibiotic-resistant uropathogenic strain of E. coli and will enhance surveillance for this important group of organisms.Urinary tract infection (UTI) is the most common laboratory-confirmed bacterial infection encountered in medical practice in Europe and North America (9). Escherichia coli is a major cause of UTI, and it accounts for approximately 70 to 95% of community-acquired cases and 50% of all hospitalacquired infections (9). These organisms are responsible for significant social and economic costs for both communities and public health resources. It has been estimated that 150 million cases of UTI occur on a global basis per year and cost about 6 billion dollars for national health resources (6).UTI due to E. coli can progress to bacteremia, which is associated with significant mortality. E. coli is recognized as the one of the two most common causes of bacteremia in England and Wales, and the Health Protection Agency reported 32.5 bacteremia cases per 100,000 subjects in 2005 (7). There is no comprehensive surveillance for community-acquired UTIs in England, and currently, there is only voluntary national surveillance for bacteremia; therefore, it is very difficult to estimate the true incidence of UTI infections and monitor the spread of these organisms (12).In recent years, there has been an increase in the occurrence cephalosporin-resistant strains of E. coli causing UTI and invasive infections (10). These organisms, which are often also resistant to other widely used antibiotics such as fluoroquinolones and trimethoprim, have particular clinical significance due to the limited therapeutic options that are available. Furthermore, the prevention and control of the spread of uropathogenic E. coli infections are hampered by a poor understanding of the population biology of these pathogens. The potential of particular lineages of antibiotic-resistant or uropathogenic E. coli to disseminate and cause disease is unknown. Improved strain characterization and phylogenetic analysis would improve our understanding of the epidemiology of this pathogen and will allow the development of a rapid assay for monitoring of uropathogenic E. coli.Multilocus sequence typing (MLST) is a DNA sequencebas...

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A total of 3429 isolations of verocytotoxin-producing Escherichia coli O157 (VTEC O157) was con®rmed from human sources in England and Wales during the period 1995±1998. The largest annual total was 1087 in 1997. Most infections occurred in the third quarter of each year. The overall rate of infection ranged from 1.28 to 2.10=100 000 population and showed regional variation. The highest incidence was in children aged 1±4 years. Annually, between 5% and 11% of strains were from patients who had travelled abroad. There were 67 general outbreaks of infection represented by 407 (11.9%) VTEC O157 isolates. Outbreaks involved transmission by contaminated food or water, person-toperson spread and direct or indirect animal contact, and ®ve were associated with foreign travel. The majority (76%) of strains carried verocytotoxin (VT) 2 genes and 23.3% were VT1 VT2. Most strains had the¯agellar antigen H7, but c. 14% were non-motile. Approximately 20% of isolates were resistant to antimicrobial agents, predominantly streptomycin, sulphonamides and tetracycline. In addition to VTEC O157, strains of serogroup O157 that did not possess VT genes were identi®ed. These were either derivatives of VTEC O157 that had lost VT genes or were strains with H antigens other than H7 that have never been associated with VT production. Strains of VTEC other than O157 were characterised. Most were associated with diarrhoea, bloody diarrhoea or haemolytic uraemic syndrome and had virulence markers in addition to VT.