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At the request of the public health authorities, 31 public amenity premises in England and Wales containing animals of various species were investigated for the presence of verocytotoxigenic Escherichia coli (VTEC) O157 between 1997 and 2007, because of putative associations with human cases. VTEC O157 was confirmed in one or more species on 19 (61.3 per cent) of the premises. There were significant associations between the presence of VTEC O157 and the number of species sampled, the size of the enterprise, the presence of young cattle and the presence of adult pigs. E coli O157 was isolated from 305 (17.8 per cent) of 1715 samples taken from all the premises, and verocytotoxin genes were detected by PCR in 184 (98.4 per cent) of 187 representative isolates. On positive premises, the highest mean proportion of positive samples (29.0 per cent) was in cattle, followed by sheep (24.4 per cent), donkeys (14.6 per cent), pigs (14.3 per cent), horses (12.3 per cent) and goats (9.9 per cent). A high proportion of positive samples was obtained from camelid species sampled on three of the premises. The main phage types (PT) were 2 and 21/28, which were those most commonly isolated from human cases during the same period. A single PT was detected on 14 of the 19 positive premises, with up to six different species having the same PT.

Verocytotoxin-producing Escherichia coli (VTEC) causes a wide spectrum of disease in humans, from mild diarrhoea to haemolytic uraemic syndrome (HUS). The verocytotoxin (vtx) and intimin (eae) genes of VTEC strains, other than those of serogroup O157, were subtyped to identify common properties that may be associated with increased pathogenicity. Strains were isolated from patients with HUS, those with diarrhoea or from asymptomatic individuals. Strains of VTEC that carried vtx(2) gene subtypes vtx(2) and vtx(2c) were most commonly associated with HUS, whereas strains from patients with less severe disease and from the healthy control group were more likely to have vtx(1c) or vtx(2d) genes. The eae gene was detected more frequently in strains isolated from HUS patients than in those associated with cases of diarrhoea; beta-intimin was the most common intimin subtype in strains isolated from both groups of patients. None of the strains from the healthy control group carried the eae gene.

During the decade to 1999, the incidence of human infections with the zoonotic pathogen verocytotoxin-producing Escherichia coli O157 (VTEC O157) increased in England and Wales. This paper describes the results of a survey of 75 farms to determine the prevalence of faecal excretion of VTEC O157 by cattle, its primary reservoir host, in England and Wales. Faecal samples were collected from 4663 cattle between June and December 1999. The prevalence of excretion by individual cattle was 4.2 per cent (95 per cent confidence interval [CI] 2.0 to 6.4) and 10.3 per cent (95 per cent CI 5.8 to 14.8) among animals in infected herds. The within-herd prevalence on positive farms ranged from 1.1 to 51.4 per cent. At least one positive animal was identified on 29 (38.7 per cent; 95 per cent CI 28.1 to 50.4) of the farms, including dairy, suckler and fattening herds. The prevalence of excretion was least in the calves under two months of age, peaked in the calves aged between two and six months and declined thereafter. The phage types identified most widely were 4, 34 and 2, which were each found on six of the 29 positive farms.

Aims: Strains of Verocytotoxin-producing Escherichia coli (VTEC) from Scottish beef cattle on the same farm were isolated during four visits over a period of eight months. Characteristics of these strains were examined to allow comparisons with strains of VTEC associated with human infection. Methods and Results: Strains were characterized to investigate the relationship between these bovine isolates with respect to serotype, Verocytotoxin (VT) type, intimin-type, and presence or absence of the enterohaemolysin genes. VT genes were detected in 176 of 710 (25%) faecal samples tested using PCR, although only 94 (13%) VTEC strains were isolated using DNA probes on cultures. Forty-five different serotypes were detected. Commonly isolated serotypes included O128ab:H8, O26:H11 and O113:H21. VTEC O26:H11 and O113:H21 have been associated with human disease. Strains harbouring the VT2 genes were most frequently isolated during the first three visits to the farm and those with both VT1 and VT2 genes were the major type during the final visit. Of the 94 strains of non-O157 VTEC isolated, 16 (17%) had the intimin gene; nine had the gene encoding β-intimin and seven strains had an η/ζ-intimin gene. Forty-one (44%) of 94 strains carried enterohaemolysin genes. Conclusions: Different serotypes and certain transmissible characteristics, such as VT-type and the enterohaemolysin phenotype, appeared to be common throughout the VTEC population at different times. Significance and Impact of the Study: Detailed typing and subtyping strains of VTEC as described in this study may improve our understanding of the relationship between bovine VTEC and those found in the human population.

EHEC O157 were isolated from faeces of Belgian and Polish beef slaughter cattle. In Belgium, 1281 faecal samples were analysed by immunomagnetic separation [IMS] after enrichment in buffered peptone water from June 1998 till July 1999. Eighty-one samples (6.3%) were positive for E. coli O157. Phage type 8 was most frequently found. Bulls between 1 and 2 years old, slaughtered in September and October were most frequently found positive. Atypical biochemical features were observed in some isolates: 22 (27%) isolates were urease positive and 1 (1.2%) isolate was unable to ferment lactose. In Poland, 551 faecal samples, taken from January 1999 till December 1999, were examined using exactly the same techniques. Four faecal samples (0.7%) were positive for O157 EHEC, yielding seven phage type 8 isolates. All positive samples were from cattle younger than 2 years. Positive samples occurred in August, September and October.

A 12-month abattoir survey was conducted between January 1999 and January 2000, to determine the prevalence of faecal carriage of verocytotoxin-producing Escherichia coli O157 (VTEC O157) in cattle and sheep slaughtered for human consumption in Great Britain. Samples of rectum containing faeces were collected from 3939 cattle and 4171 sheep at 118 abattoirs, in numbers proportional to the throughput of the premises. The annual prevalence of faecal carriage of VTEC O157 was 4.7 per cent (95 per cent confidence interval 4.1 to 5.4) for cattle and 1.7 per cent (1.3 to 2.1) for sheep, values which were statistically significantly different from each other (P < 0.001). The organisms were recovered from both cattle and sheep slaughtered throughout the year and at abattoirs in all regions of the country, but the highest prevalence was in the summer. The most frequency recovered VTEC O157 isolates were phage types 2, 8 and 21/28 in cattle and 4 and 32 in sheep, the five most frequently isolated phage types associated with illness in people in Great Britain during the same period.

Strains of Escherichia coli, hybridising with a DNA probe for enteroaggregative E. coli (EAggEC), were isolated from patients with infectious intestinal disease (IID) or gastro-enteritis, and healthy controls during the study of IID in England. Of 3506 cases presenting with an IID, 160 (4.6%) had faecal EAggEC as compared with 46 (1.7%) of 2772 healthy controls, 53% of EAggEC isolated from each of the 'case' and the 'control' groups adhered in a 'stacked-brick' formation. Strains from cases and controls belonged to over 39 and 14 different serogroups respectively, and approximately half of the strains isolated did not react with antisera in the current somatic antigen serotyping scheme. Forty-nine cases with EAggEC (31%) had a known history of foreign travel. Over 50% of strains isolated from cases and controls were resistant to one or more of eight antimicrobials, and antimicrobial resistance was not statistically significantly more common among cases with a known history of foreign travel (p = 0.57). These data form part of the largest investigation carried out on these organisms in the UK to date and provide the most comprehensive analysis of strains of EAggEC isolated from the general population of England.

Verocytotoxin-producing Escherichia coli (vTEC) 0157 phage type 2 (PT2) was isolated from three calves and two goats on a farm open to the public. Phenotypic and DNA-based typing showed that the strains were identical or very closely related to those obtained from an outbreak of VTEC 0157 infection in two separate family groups who visited the farm. No VTEC 0157 PT2 was isolated again from the farm during a 12-month longitudinal bacteriological study undertaken after the infected animals had been removed. However, phenotypically and genotypically indistinguishable VTEC 0157 PT21/28 strains were detected in two of 474 faecal samples collected at monthly visits from 15 species of animals of various ages. The two isolates were obtained from calves from different sources sampled 146 days apart, suggesting that the infection had persisted on the farm although it was not detected in the other species. The same strain was subsequently isolated from another calf housed in the same pen as one of the infected calves. The longest period during which the organism was excreted was seven days. No VTEC 0157 was isolated either from 204 replacement animals (including 138 orphan lambs and 10 calves) brought in from various sources, and sampled while they were kept in isolation for two weeks before being introduced to the farm, or from environmental samples. During the study a visitor became ill with VTEC 0157 PT2. However, the isolate was distinct from those recovered from the farm and there was no evidence to suggest that the visit was the source of the infection.

In this case-control study multi-resistant Escherichia coli isolates were characterized on a molecular level and risk factors for their development were identified. Thirty-two multi-resistant E. coli strains were isolated from the urine of 13 patients attending a renal clinic for chronic urinary tract infection (UTI) and from different sites of 11 terminally ill patients with nosocomial infections hospitalized on five different wards. All 32 isolates were resistant to ciprofloxacin, cotrimoxazole and produced beta-lactamase. All strains contained plasmids of 2-110 MDa of which a 50 MDa and a 100 MDa plasmid were present in 81% of the strains. Pulse-field gel electrophoresis (PFGE) analysis demonstrated 17 genotypes among 32 strains which indicates a polyclonal outbreak with some geographic clustering. Monitoring of patients over the study period showed that either the resident genotype remained the same and that these retained strains underwent changes in their plasmid contents, or that they were replaced by a different genotype after several months of therapy for chronic UTI. Univariate analysis indicated that multi-resistant E. coli develop in the presence of long-term selective ciprofloxacin pressure at a dosing regimen of 250 mg bid for more than 20 days and that treatment with a broad spectrum antimicrobial for more than three days favours the selection of multi-resistant E. coli in the flora of terminally ill patients with multiple disorders.

AIMS: To use serology to investigate an outbreak of verocytotoxin (VT) producing Escherichia coli O157 in a hospital nursery, following the detection of faecal E coli O157 (phage type 49) producing VT type 2. METHODS: ELISA and immunoblotting techniques, based on lipopolysaccharide (LPS) purified from E coli O157; diagnostic bacteriology; serotyping and phage typing; DNA probes for VT. RESULTS: 29 of 126 sera contained antibodies to the LPS of E coli O157: 10 were from children, three were from staff, and 11 were from hospital kitchen staff. Five parents of children attending the nursery were antibody positive. Sixty four sera from other hospital staff and controls did not contain antibodies to the LPS of E coli O157. CONCLUSIONS: Serology detected evidence of infection with E coli O157 in 23% of sera examined. By bacteriology alone, only a single case of infection with E coli O157 would have been detected. Serology is valuable in providing evidence of infection with E coli O157.

Summary Background Recent outbreaks of vero cytotoxin (shiga toxin) producing Escherichia coli 0157 (VTEC 0157) infection have stimulated debate on food safety. However, 90% of cases in England and Wales are sporadic. We report a case-control study of sporadic VTEC 0157 infection. Methods We compared 85 sporadic cases of VTEC 0157 infection, identified through population surveillance, with 142 controls, randomly selected from general practitioners' lists. We matched cases and controls for age, sex, and family doctor's practice. Exposures to foods, water, animals, farms, and environmental factors were recorded. We visited the premises concerned when cases had eaten beefburgers or cooked sliced meats from caterers or had had contact with a farm. Findings Consumption of a beefburger from a catering premises other than from a fast-food chain A (a national chain) and consumption of cold cooked sliced meat (eg, in a salad or sandwich) from caterers, but not butchers, was associated with VTEC 0157 infection (odds ratios 4·63 [95% Cl 1·33–30·14] and 3·36 [1·04–12·74], respectively). Policies for ensuring thorough cooking of burgers by one national fast-food chain differed from the other catering premises we visited. There was evidence of person-to-person spread and transmission of VTEC 0157 infection from animals. Interpretation Local inspection of catering establishments that serve cooked meats together with public education to prevent spread on farms and in houses would reduce the burden of VTEC 0157 infection by about 10% for each risk factor.

A study of the incidence of resistance to antimicrobial drugs in Escherichia coli from blood and CSF made in England and Wales in the 6-year period 1991 1996 has demonstrated a significant increase in the incidence of strains resistant to ampicillin and ciprofloxacin, two antibiotics used for first-line therapy of invasive disease. In particular, there has been a dramatic change in the occurrence of isolates with low level or high level resistance to ciprofloxacin; over 90% of isolates in the high level group were also resistant to at least four other antimicrobials. Physicians in England and Wales should be aware that there is now an increasing possibility of treatment failures when ciprofloxacin is used for the treatment of invasive E. coli infections.

In a survey of wild birds (mainly gulls), 0.9% of the bacterial isolates from faecal samples at an urban landfill site and 2.9% of bacterial isolates from faecal samples on intertidal sediments in Morecambe Bay were Vero cytotoxin-producing Escherichia coli O157. Isolation procedures employing commonly used cultural methods were hindered by the selection of a large number of false positives. The only procedure which resulted in the isolation of E. coli O157 from bird faecal samples was: enrichment (18 h) in a selective tryptone soya broth followed by filtration using hydrophobic grid membranes and growth on Chromagar O157. The majority of isolates selected as potential E. coli O157 by characteristic growth on Chromagar O157 could be eliminated by subsequent growth on CT-SMAC or CR-SMAC. This second identification (characterization) stage reduced the number of potential E. coli O157 requiring further confirmation by typing methods (serotype and Vero cytotoxin) by more than 70%.

Aims Evaluation of multilocus variable number tandem repeat analysis (MLVA) to subtype all isolates of Vero cytotoxin-producing Escherichia coli O157 phage type 8 in England and Wales. Methods and Results Over a 13 month period from December 2010, 483 isolates of VTEC O157 PT8 were tested by MLVA; 39% were received in the first 4 months of 2011, when infections are generally low. One profile, or single locus variants of it, was present in 249 (52%) isolates but was not common previously. These cases represented a national increase in PT8, associated epidemiologically with soil-contaminated vegetables. Most of the 177 other MLVA profiles were unique to a single isolate. Profiles shared by >1 isolate included cases from two small community, food-borne outbreaks and 11 households. Several shared profiles were found among 23 isolates without known links. Apart from one group, isolates linked to travel abroad had very diverse profiles. Conclusions Multilocus variable number tandem repeat analysis discriminated apparent sporadic isolates of the same PT and assisted in detection of cases in an emerging national outbreak. Significance and Impact of the Study Multilocus variable number tandem repeat analysis is an epidemiologically valid complement to surveillance and applicable as a rapid, practical test for large numbers of isolates.

SummaryAn outbreak of infections due to multiple antibiotic-resistant bacteria took place over a period of approximately 18 months in a renal unit. Strains ofEscherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Citrobacterspp. andPseudomonasspp. were involved, and a variety of antibiotic resistances was encountered. Closely related plasmids encoding resistance to aztreonam, ceftazidime and piperacillin, possibly derived from an archetypal plasmid of 105 kb were found in the majority of isolates examined. After limiting the use of aztreonam the incidence of new patient isolates of multiple-resistant organisms was greatly reduced. This study demonstrated how molecular studies can contribute to the control of an outbreak situation in a hospital unit by providing an impetus to reduce the use of specific antibiotics.

Diagnoses of Shigella flexneri in the United Kingdom (UK) are usually travel-related. However, since 2009, there has been an overall increase in UK-acquired cases. The Health Protection Agency has been investigating a national outbreak of S. flexneri detected in 2011 and which is still ongoing. Cases occurred mostly in men who have sex with men and were of serotype 3a. The investigation aimed at obtaining epidemiological data to inform targeted outbreak management and control.

Fifty-four of 310 (17%) samples of raw beef products contained Vero cytotoxin (VT)-producing Escherichia coli (VTEC) detected by DNA probes for the VT genes. VTEC strains examined in detail from a selection of the positive samples belonged to several O serogroups, some of which have been associated with human diarrhoea or haemolytic uraemic syndrome. Some of the strains possessed properties that may contribute to virulence in man. None of the food samples contained VT-producing E. coli O157 when tested by a combination of VT probe tests and colony immunoblotting with commercially available anti-O157 serum. Quantification of the immunoblotting technique indicated that O157 VTEC could be recovered from artificially-inoculated meat samples at a level of less than one organism per gram. Five of the food samples carried E. coli O157 strains that did not produce VT and differed in other properties from O157 VTEC.

Lipopolysaccharide antigen-antibody cross-reactions between Escherichia coli O157 and other members of the Enterobacteriaceae were examined. Using serotyping schemes established in the Laboratory of Enteric Pathogens (LEP), cross-reactions were demonstrated between E. coli O157, Vibrio cholerae O1-Inaba and group N (O = 30) salmonella. SDS-PAGE and immunoblotting showed that the lipopolysaccharide (LPS) of E. coli O157 contained epitopes shared with LPS expressed by group N salmonella. These cross-reactions were also detected using sera from patients with haemolytic uraemic syndrome (HUS) caused by E. coli O157:H7. Rabbit antibodies, prepared to the LPS of V. cholerae O1-Inaba reacted with the LPSs of both E. coli O157 and V. cholerae O1-Inaba, whilst rabbit antisera prepared to E. coli O157 did not react with the LPS of V. cholerae O1-Inaba. Antibodies in sera from patients with HUS, which reacted with the LPS of E. coli O157, did not react with the LPS from V. cholerae O1-Inaba. We concluded from our study that cross-reactions between E. coli O157 and other bacterial species are rare; and that patients infected with bacteria known to share epitopes with E. coli O157 are unlikely to give false positive results when their sera were tested for E. coli O157 serology.

Shiga toxin bildende Escherichia coli (STEC), wichtige durch Lebensmittel ubertragbare Erreger, konnen milde bis schwere blutige Durchfalle (BD), manchmal gefolgt von lebensbedrohlichen Komplikationen wie dem Hamolytisch-uramische Syndrom (HUS), verursachen. Insgesamt wurden 44 STEC O157 Stamme, die von verschiedenen Patienten in den Jahren 2000 bis 2009 in der Schweiz isoliert wurden, weiter charakterisiert und die dazugehorigen anamnestischen Daten aufgearbeitet. 15.9% der Patienten hatten nicht blutigen Durchfall, 61.4% der Patienten zeigten BD und 29.5% entwickelten ein HUS. Alle Stamme gehorten zum MLST Typ 11, waren stx2, eae und ehxA positiv und nur zwei Stamme zeigten Antibiotikaresistenzen. Unter den 44 Stammen wurden 9 Phagen-Typen (PT) nachgewiesen, die haufigsten waren; PT 32 (43.2%) und PT 8 (18.2%). Die Genotypisierung (Pulsfeld Gelelektrophorese) ergab 39 verschiedene Muster. Die hohe genetische Vielfalt innerhalb der Stamme fuhrt zu der Schlussfolgerung, dass STEC O157 Infektionen in der Schweiz haufig als Einzelfalle und nicht als grossere Ausbruche aufgetreten sind. Summary: Shiga toxin-producing Escherichia coli (STEC), an important foodborne pathogen, can cause mild up to severe bloody diarrhoea (BD), sometimes followed by life-threatening complications such as haemolytic uraemic syndrome (HUS). A total of 44 STEC O157 strains isolated from different patients from 2000 through 2009 in Switzerland were further characterized and linked to anamnestic data. Non-bloody diarrhoea was experienced by 15.9%, BD by 61.4% of the patients, and 29.5% developed HUS. All strains belonged to MLST type 11, were positive for stx2, eae and ehxA and only two strains showed antibiotic resistances. Among the 44 strains, 9 phage types (PTs) were detected, the most frequent ones being PT 32 (43.2%) and PT 8 (18.2%). By pulsed-field gel electrophoresis (PFGE), 39 different patterns were found. This high genetic diversity within the strains leads to the conclusion that STEC O157 infections in Switzerland most often occur as single and sporadic cases.

SUMMARYEnterotoxigenicEscherichia coli(ETEC) from Burma, central Africa (Rwanda and Zaire) and Peru, were screened by enzyme-linked immunoassays for the colonization factor antigens (CFAs) and putative colonization factors (PCFs): CFA/I, CFA/II, which consists of three coli surface-associated (CS) antigens, CS1, CS2 and CS3, CFA/III, CFA/IV (CS4, CS5, CS6), CS7, PCFO9, PCFO159.H4, PCFO166, and CS17. The highest proportion of ETEC with identifiable colonization factors (71%) were found in the strains from Burma, which were mainly positive for CFA/I (38%), but strains producing CFA/II (4%), CFA/IV (11%), CS7 (10%), CS17 (4%), PCFO159.H4 (2%) and PCFO166 (2%) were also found. Sixty-nine percent of the ETEC from central Africa were positive for known colonization factors. While CFA/I positive strains were important (12%), a higher number of ETEC producing CFA/IV (33%) and CS17 (24%) were found. Fifty-two percent of the Peruvian strains produced identifiable colonization factors. The largest group of strains produced antigens of the CFA/IV complex (17%), while ETEC producing CFA/II (6%), CFA/III and CS6 (2%), CS7 (6%), PCFO9 (6%), PCFO166 (8%) and CS17 (7%) were also found. These surveys show that there is a considerable variation in the proportions and types of colonization factor found in different geographical areas. From 29 to 48% of the ETEC did not possess an identifiable colonization factor. These were particularly of the LT only producing type. These results have important implications for vaccine formulation.

Shigella sonnei is a significant cause of gastroenteritis in both developing and industrialized countries. Definition of the diversity and antimicrobial susceptibility of S. sonnei isolates may be helpful in the management of individual cases and outbreaks. Antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE) were performed with 67 isolates of S. sonnei predominantly ( n = 59) from three counties in the west of Ireland. Phage typing ( n = 17), plasmid profiling ( n = 28), and integron analysis ( n = 24) were performed with subsets of strains. PFGE typing permitted recognition of two major clusters: PFGE type A ( n = 53) and PFGE type B ( n = 14). PFGE type A was associated with resistance to ampicillin, streptomycin, and sulfonamides (51 of 53 isolates), and those that were phage typed ( n = 6) were phage type 3. PFGE type B was associated with resistance to streptomycin, sulfonamides, tetracycline, and trimethoprim (11 of 14 isolates) and phage type 6 (9 of 11 isolates). Fifteen different plasmid profiles were identified among the 28 isolates analyzed. A class 2 integron was present in all 14 PFGE type B isolates. One of these isolates also contained a class 1 integron and showed a unique variant of the PFGE type B pattern. Sequence analysis of the gene cassette structures contained within these integrons identified distinct open reading frames that encoded determinants of resistance to trimethoprim, streptomycin, and streptothricin. Our data demonstrate two predominant PFGE types among S. sonnei isolates circulating in this region. The limited diversity of the S. sonnei isolates in this region means that detection of isolates indistinguishable by PFGE and according to their antibiograms in two or more patients is not persuasive evidence of a common-source food- or waterborne outbreak. Indistinguishable plasmid profiles in addition to indistinguishable PFGE and antibiogram types may be more suggestive of an epidemiologically relevant link between cases.

Strains of Escherichia coli, hybridising with a DNA probe for enteroaggregative E. coli (EAggEC), were isolated from patients with infectious intestinal disease (IID) or gastro-enteritis, and healthy controls during the study of IID in England. Of 3506 cases presenting with an IID, 160 (4.6%) had faecal EAggEC as compared with 46 (1.7%) of 2772 healthy controls, 53% of EAggEC isolated from each of the 'case' and the 'control' groups adhered in a 'stacked-brick' formation. Strains from cases and controls belonged to over 39 and 14 different serogroups respectively, and approximately half of the strains isolated did not react with antisera in the current somatic antigen serotyping scheme. Forty-nine cases with EAggEC (31%) had a known history of foreign travel. Over 50% of strains isolated from cases and controls were resistant to one or more of eight antimicrobials, and antimicrobial resistance was not statistically significantly more common among cases with a known history of foreign travel (p = 0.57). These data form part of the largest investigation carried out on these organisms in the UK to date and provide the most comprehensive analysis of strains of EAggEC isolated from the general population of England.

A 12-month abattoir survey was conducted between January 1999 and January 2000, to determine the prevalence of faecal carriage of verocytotoxin-producing Escherichia coli O157 (VTEC O157) in cattle and sheep slaughtered for human consumption in Great Britain. Samples of rectum containing faeces were collected from 3939 cattle and 4171 sheep at 118 abattoirs, in numbers proportional to the throughput of the premises. The annual prevalence of faecal carriage of VTEC O157 was 4.7 per cent (95 per cent confidence interval 4.1 to 5.4) for cattle and 1.7 per cent (1.3 to 2.1) for sheep, values which were statistically significantly different from each other (P0.001). The organisms were recovered from both cattle and sheep slaughtered throughout the year and at abattoirs in all regions of the country, but the highest prevalence was in the summer. The most frequency recovered VTEC O157 isolates were phage types 2, 8 and 21/28 in cattle and 4 and 32 in sheep, the five most frequently isolated phage types associated with illness in people in Great Britain during the same period.

A marked increase in sporadic cases of enteritis due to enterohemorrhagic Escherichia coli serogroup O157 occurred in Osaka City, Japan, during 1996. To elucidate why the number of cases had increased, the isolates were classified using phage typing, random amplified polymorphic DNA analysis, and pulsed-field gel electrophoresis (PFGE). Fifty-seven percent of the isolates (105/184) belonged to the same phage type (PT-32) and gave the same PFGE pattern; the clone had been isolated during a 3-week period, with a peak on July 15. It was concluded that the majority of the cases identified in July 1996 formed an outbreak, although epidemiological links to a possible common source were not established. The possibility that this outbreak was part of a huge regional outbreak including children at primary schools in Sakai City was discussed.

Verocytotoxin-producing Escherichia coli (VTEC) O157 phage type 2 (PT2) was isolated from three calves and two goats on a farm open to the public. Phenotypic and DNA-based typing showed that the strains were identical or very closely related to those obtained from an outbreak of VTEC O157 infection in two separate family groups who visited the farm. No VTEC O157 PT2 was isolated again from the farm during a 12-month longitudinal bacteriological study undertaken after the infected animals had been removed. However, phenotypically and genotypically indistinguishable VTEC O157 PT2/28 strains were detected in two of 474 faecal samples collected at monthly visits from 15 species of animals of various ages. The two isolates were obtained from calves from different sources sampled 146 days apart, suggesting that the infection had persisted on the farm although it was not detected in the other species. The same strain was subsequently isolated from another calf housed in the same pen as one of the infected calves. The longest period during which the organism was excreted was seven days. No VTEC O157 was isolated either from 204 replacement animals (including 138 orphan lambs and 10 calves) brought in from various sources, and sampled while they were kept in isolation for two weeks before being introduced to the farm, or from environmental samples. During the study a visitor became ill with VTEC O157 PT2. However, the isolate was distinct from those recovered from the farm and there was no evidence to suggest that the visit was the source of the infection.

Three members of a Scottish family, with no history of foreign travel but who had recently visited Bristol, were infected by a strain of Shigella sonnei of phage type 6 (PT 6) that did not ferment rhamnose and was negative for o-nitrophenyl-beta-D-galactopyranoside (ONPG). The incident exposed limitations associated with commercial systems for the identification of strains of S. sonnei with atypical biochemical properties.

A study of Vero cytotoxin producing Escherichia coli (VTEC) O157 infections in Cornwall and West Devon was conducted to identify associations between human infection and contact with farm animals. In three years from November 1994 to October 1997, 63,000 stool specimens were submitted to four participating microbiology laboratories and screened for E. coli O157. Sixty-nine confirmed cases were interviewed to assess the extent of any direct or indirect contact with farm animals. Nine out of 22 investigations conducted on farms--in which animal rectal swabs, faecal specimens, fore-stream milk samples (first draw-off from teats), and various environmental samples were tested--yielded VTEC O157. In seven incidents one or more isolates from animals were indistinguishable from the isolate(s) from the human case(s) using phenotypic and genotypic subtyping. Cases associated with animal contact included farm visitors, holidaymakers, and members of farming families and farm workers.

Three children, one who lived on an open farm and two who visited the farm in school parties, developed Vero cytotoxin producing Escherichia coli (VTEC) O157 infection in 1997. All had been in direct contact with animals. All were admitted to hospital with diarrhoea and two developed the haemolytic uraemic syndrome, one of whom developed severe neurological impairment. E.coli O157 phage type 21 that produced Vero cytotoxin 2 were isolated from the three children and from a goat paddock and two cows at the farm. The isolates were indistinguishable by molecular typing. The farm closed voluntarily for six weeks while recommendations to reduce the exposure of visitors to faecal contamination and to improve hygiene procedures (especially handwashing) were implemented. More research is needed into all aspects of VTEC O157 on farms, including the natural history of carriage in animals, the organism prevalence and factors that affect infectivity to humans. Further consideration is needed about the role of open farms in zoonoses, and how open farms can be assisted in reducing risks for visitors. The public need to be educated about the risks and about their responsibilities, which include the need to wash hands thoroughly and to avoid hand to mouth contact when visiting farms.

OBJECTIVES To identify risk factors for transmission of verocytotoxin producing Escherichia coli O157 (VTECO157) and means of prevention. STUDY DESIGN Outbreak investigation: retrospective cohort study. SETTING A nursery (child care centre) in North Wales. SUBJECTS Children attending (n = 104). METHODS Faeces were examined using sorbitol MacConkey agar (SMAC), with cefixime, tellurite, and rhamnose; enrichment in modified tryptone soya broth; and immunomagnetic separation. Symptoms and exposure data were obtained from questionnaires to parents/guardians and children’s toiletting and feeding records kept at the nursery. MAIN OUTCOME MEASURE A “case” was defined as a child with verocytotoxin producing E coli O157 isolated from faeces, or a history of haemolytic uraemic syndrome (HUS) and antibodies to E coli O157 lipopolysaccharide, during the period 10 August to 30 September 1995. RESULTS The attack rate was 31 in 104. Two children developed HUS. There were higher attack rates among girls and friends who played together. Cases were more likely to attend the nursery more frequently. The mean number of recorded bowel motions/child/half day was 0.51 in cases and 0.21 in well children. Child to staff ratios were high preceding and during the outbreak. CONCLUSIONS A sick child is the most plausible source of infection with subsequent person to person transmission. The record of children’s toiletting discriminated between cases and well children and might have allowed earlier detection of the outbreak. This simple record could be considered by other child care facilities as a means of giving early warning of problems with infectious intestinal diseases.

Seven persons who attended the Glastonbury Music Festival were infected with Vero cytotoxin-producing Escherichia coli O157 and an eighth person had serological evidence of infection. Cases were reported from different parts of England. Patients were interviewed by telephone about clinical symptoms, festival attendance, camping details, food history, water exposure, and contact with mud and animals. The interviews identified no common food source, differing use of water sources and widely dispersed camping sites. Escherichia coli O157 strains from seven persons and from a cow belonging to a herd that had previously grazed the site all belonged to phage type 2 and possessed genes for Vero cytotoxin 2. Drug resistance and DNA-based tests showed that six patients were infected with strains indistinguishable from each other and from the bovine isolate. The most likely vehicle of infection was mud contaminated with Escherichia coli O157 from infected cattle.

In June 1993 an outbreak of Shigella sonnei infection at a primary school in south east England affected 42% of 327 pupils and staff. Attack rates of diarrhoea and fever were 33% for children aged 4 to 8 years, and 8% for those aged 8 to 12 years (p0.00001). Illness was associated with eating canteen food (relative risk 5.9; 95% confidence interval 3.4, -10.3). All strains examined were S. sonnei phage type 3, with the same antibiogram (ttSTSS), and were indistinguishable using colicin typing and biotyping (colicin type 9, E8) and pulse field gel electrophoresis. Molecular epidemiology suggested but could not confirm that the outbreak strain was introduced into the school population from the community.

Recent outbreaks of vero cytotoxin (shiga toxin) producing Escherichia coli O157 (VTEC O157) infection have stimulated debate on food safety. However, 90% of cases in England and Wales are sporadic. We report a case-control study of sporadic VTEC O157 infection.We compared 85 sporadic cases of VTEC O157 infection, identified through population surveillance, with 142 controls, randomly selected from general practitioners' lists. We matched cases and controls for age, sex, and family doctor's practice. Exposures to foods, water, animals, farms, and environmental factors were recorded. We visited the premises concerned when cases had eaten beefburgers or cooked sliced meats from caterers or had had contact with a farm.Consumption of a beefburger from a catering premises other than from a fast-food chain A (a national chain) and consumption of cold cooked sliced meat (eg, in a salad or sandwich) from caterers, but not butchers, was associated with VTEC O157 infection (odds ratios 4.63 [95% CI 1.33-30.14] and 3.36 [1.04-12.74], respectively). Policies for ensuring thorough cooking of burgers by one national fast-food chain differed from the other catering premises we visited. There was evidence of person-to-person spread and transmission of VTEC O157 infection from animals.Local inspection of catering establishments that serve cooked meats together with public education to prevent spread on farms and in houses would reduce the burden of VTEC O157 infection by about 10% for each risk factor.

An outbreak of food poisoning due to Escherichia coli O157 phage type 2 Vero cytotoxin 2 affected 26 people in southern counties of England in May and June 1995. The organism was isolated from faecal specimens from 23 patients, 16 of whom lived in Dorset and seven in Hampshire. Isolates were indistinguishable by phage typing, Vero cytotoxin gene typing, restriction fragment length polymorphism, and pulsed field gel electrophoresis. Three associated cases, linked epidemiologically to the outbreak, were confirmed serologically by detection of antibodies to E. coli O157 lipopolysaccharide. Twenty-two of the 26 patients were adults: four were admitted to hospital with haemorrhagic colitis. Four cases were children: two were admitted to hospital with haemolytic uraemic syndrome (HUS). There were no deaths. Although E. coli O157 was not isolated from any food samples, illness was associated with having eaten cold meats in sandwiches bought from two sandwich producers, in Weymouth and in Portsmouth. Both shops were supplied by the same wholesaler, who kept no records and obtained cooked meats from several sources in packs that did not carry adequate identification marks. It was, therefore, impossible to trace back to the original producer or to investigate further to determine the origin of contamination with E. coli O157. To protect the public health it is essential that all wholesale packs of ready-to-eat food carry date codes and the producer's identification mark. Detailed record keeping should be part of hazard analysis critical control point (HACCP) systems and should be maintained throughout the chain of distribution from the producer to retail outlets.

Infection with Vero cytotoxin producing Escherichia coli O157 (VTEC O157) is a growing public health problem and the commonest cause of acute renal failure in children in the United Kingdom. Foodborne outbreaks of VTEC O157 infection have been reported in the United Kingdom, other European countries, and North America. Most cases of infection are sporadic, however, and the contribution of food vehicles, animal contact, and person to person spread in the acquisition of infection needs to be clarified. The PHLS is starting a case control study in England to identify and estimate the relative importance of risk factors for the acquisition of VTEC O157 infection. The study will run for 12 months. This article describes its objectives and asks microbiologists, public health physicians, clinicians, and others who may be asked for details about cases or to find suitable controls for their help in achieving a successful outcome.

We have reviewed all general outbreaks of infection due to Vero cytotoxin producing Escherichia coli (VTEC) O157 reported in England and Wales from 1992 to 1994. One hundred and seventy-three people were affected in 18 outbreaks, compared with 76 people in seven outbreaks in the preceding three years (1989 to 1991). Outbreaks occurred throughout England and Wales. Thirty-eight per cent of cases were admitted to hospital, 21% developed haemolytic uraemic syndrome, and 3% died. VTEC O157 infection causes particular concern because of its serious complications--haemorrhagic colitis and haemolytic uraemic syndrome, its capacity to spread from person to person as well as by food and water, and its reservoir in dairy and beef cattle.

During the summer of 1994, four cases of bloody diarrhoea and/or haemolytic uraemic syndrome were reported to the consultants in communicable disease control in Nottingham and Leicester. One case was an adult, and there were three children aged 2 to 4 years. The initial investigation failed to reveal any common foodstuff as the cause of the outbreak, but all four cases had attended a farm visitor centre in Leicestershire in the three weeks before they became ill. A further three cases were found who had visited the same farm. A joint investigation took place with environmental health officers and the local veterinary investigation centre of the Ministry of Agriculture, Fisheries and Food. A questionnaire designed to ascertain possible sources of infection was sent to all cases. Several of the animals on the farm were sampled for Escherichia coli O157 and the farm's facilities for food preparation and hygiene were assessed. The pattern of infection did not suggest a point source for the outbreak. Analysis of responses to the questionnaires failed to reveal any common factor other than the visit to the farm, and all but one case remembered stroking and feeding the animals. Food preparation in the farm restaurant appeared to be satisfactory and there was no evidence of contamination of food with pathogenic bacteria. E. coli O157: H7, PT2, VT2 was isolated from four of the seven human cases and also from four cattle and six goats. Further analysis using restriction fragment length polymorphism (RFLP) showed that the four human strains were indistinguishable from nine of the 10 animal strains. It was concluded that the most likely cause of this outbreak was direct contact with the animals. This was further supported by poor handwashing facilities and lack of information for the visitors on the importance of personal hygiene.

SUMMARYPlasmids belonging to the FImeincompatibility group were found in seven different serogroups of multiply antimicrobial-resistantEscherichia coliisolated from patients with urinary tract infection (UTI) and living in south-east London. Although widespread inSalmonellaspp., FImeplasmids have only previously been described inE. coliin a strain of serogroup O15 K52 H1 responsible for an extensive and protracted outbreak of invasive community-acquired infection in south-east London in 1986. Our findings suggest either a wider background occurrence of FImeplasmids inE. coliassociated with UTI than previously reported or alternatively, the dissemination and subsequent molecular diversification of the FImeplasmid associated with the epidemic strain of serogroup O15 K52 H1.

Citrobacter freundii strain E69366 was detected in a colony immunoassay with a rabbit antiserum prepared to a strain of Escherichia coli belonging to serogroup O157. Lipopolysaccharide (LPS) was shown to contain the epitope(s) involved in antibody binding. LPS prepared from strain E69366, with hot phenol contained core-LPS that migrated to the water-phase and long-chain LPS that separated into the phenol-phase. A total of 36 strains of Cit. freundii were analysed for their LPS profiles by SDS-PAGE. Sixteen could be allocated into five groups (A(3), B(7), C(2), D(2) and E(2)) based on similarities in LPS profile. The remaining strains either expressed unique SDS-PAGE profiles (18) or did not express long-chain LPS (2). All strains with a profile 'A' reacted with the antiserum prepared to E. coli O157, whereas those with other profiles did not. The two strains of Cit. freundii expressing LPS profiles designated 'E' reacted with an antiserum prepared in rabbits to E. coli O45.

SUMMARYA small cluster of dysenteric illness, due to Shigella flexneri, was identified among technical assistants of a primate research unit. All of the affected individuals had been in regular contact with a colony of cynomolgus macaque monkeys, one of which was known to have suffered from acute haemorrhagic colitis in the preceding few weeks. Four monkeys were found to be excreting S. flexneri bacilli of identical antigen type (lb) to that isolated from the human cases. Investigation of working practices revealed the potential for inadvertent faecooral spread and the need to improve existing control methods. We conclude that this small outbreak of shigellosis represents a primate-associated occupational zoonosis. The risk may not be fully appreciated by handlers or their doctors.