The use of serodiagnosis in the retrospective investigation of a nursery outbreak associated with Escherichia coli O157:H7

Homologous and Heterologous Antibody Responses to Lipopolysaccharide after EnterohemorrhagicEscherichia coliInfection

To evaluate antibody responses against lipopolysaccharide (LPS: O157, O26, and O111) in enterohemorrhagic Escherichia coli(EHEC) infection, sera of 24 schoolchildren associated with the Morioka outbreak in 1997 and of 74 sporadic patients suspected of having EHEC infection were examined. Using a positive standard serum, quantitative evaluation of LPS antibodies by an enzyme-linked immunosorbent assay (ELISA) was established. High levels of specific IgM and IgA antibodies against homologous E. coli LPS were present in the acute period and are characteristic of EHEC. This could be used for the serological diagnosis of EHEC infection, except for early infants and the elderly. In addition to the specific homologous response, multiple antibody responses against different serotypes other than those isolated were demonstrated in many cases by qualitative analysis using Western blotting.

Surveillance of hemolytic uremic syndrome in children less than 15 years of age, a system to monitor O157 and non-O157 Shiga toxin-producing Escherichia coli infections in France, 1996-2006

BACKGROUND

Since the 1980s, Shiga toxin-producing Escherichia coli (STEC), especially E. coli O157:H7, has been an important cause of food borne disease in industrial countries. In France, as there was no routine screening for STEC in clinical laboratories, enhanced surveillance of hemolytic uremic syndrome (HUS) in children less than 15 years of age was established in 1996 to monitor trends in the incidence of STEC infections.

METHODS

The surveillance system was based on a voluntary national network of pediatricians of 31 pediatric nephrology units in public hospitals.

RESULTS

From 1996 to 2006, the mean annual incidence of HUS was 0.71 cases per 100,000 children less than 15 years of age and 1.87 cases per 100,000 children less than 5 years of age. STEC infections were confirmed in 66% of patients; STEC O157 was the most common serogroup identified in STEC-related HUS (83%). In this 11-year period, 96% of HUS cases were sporadic and only 2 outbreaks caused by STEC O157 and by a dual infection of STEC O26 and O80 were detected.

CONCLUSIONS

An evaluation of the surveillance of pediatric HUS showed that it is a simple and useful system for monitoring trends in STEC infections in France. It provides the information needed to measure the impact of new and changing vehicles of STEC transmission, and evaluate the effectiveness of prevention measures.

An outbreak of Escherichia coli O157 gastroenteritis in a care home for the elderly

In the summer of 2001 an outbreak of Escherichia coli O157 gastroenteritis affected staff and residents of a care home for the elderly in the West Midlands, UK. E. coli O157 phage type 2 was isolated from faeces in eight patients and 12 staff members. Thirty-five staff and 40 residents met the case definition for clinical gastrointestinal infection. Serological testing identified a further 14 possible cases of infection amongst asymptomatic staff and residents. The outbreak was atypical, as the disease seemed to be milder than has been observed in past outbreaks in similar settings. The index case, a member of staff, developed bloody diarrhoea and haemolytic-uraemic syndrome (HUS), but only one resident developed bloody diarrhoea and required hospitalization. No deaths occurred, despite the high-risk nature of the affected population. The source of the outbreak could not be identified. The prolonged nature of the outbreak and observed lapses in infection control practices indicated that person-to-person spread was the likely route of transmission. This outbreak illustrates the importance of observing appropriate infection control measures in the institutions providing residential and nursing care to the elderly.

The emerging nosocomial pathogens Cryptosporidium, Escherichia coli O157:H7, Helicobacter pylori, and hepatitis C: epidemiology, environmental survival, efficacy of disinfection, and control measures

New and emerging infectious diseases pose a threat to public health and may be responsible for nosocomial outbreaks. Cryptosporidium parvum and Escherichia coli are gastrointestinal pathogens that have caused nosocomial infections via person-to-person transmission, environmental contamination, or contaminated water or food. Helicobacter pylori has been transmitted via inadequately disinfected endoscopes. Finally, hepatitis C may be acquired by healthcare personnel by percutaneous or mucous membrane exposure to blood or between patients by use of contaminated blood products or via environmental contamination. Rigorous adherence to Standard Precautions, Contact Precautions for patients with infectious diarrhea, disinfection of environmental surfaces, and appropriate disinfection of endoscopes are adequate to prevent nosocomial acquisition of these pathogens.

Nosocomial Escherichia coli O157 infection

Nosocomial transmission of Shiga toxin-producing Escherichia coli O157 to two patients and three nurses is described. The index case presented with rectal bleeding rather than diarrhoea, and additional infection control measures were therefore only instituted after detection of the organism. Of the nurses, two were asymptomatic and detected on a screening programme of all staff in contact with the affected patients. Two patients died, one from Clostridium perfringens bacteraemia. The use by staff of full protective gowns for handling patients from their first onset of diarrhoea is recommended, rather than plastic aprons. Interest from the media was intense, despite the small number of patients and staff affected, and early preparations for media enquiries should be made in such episodes.

The serodiagnosis of infections caused by Verocytotoxin-producing Escherichia coli

Patients with haemolytic uraemic syndrome (HUS) and haemorrhagic colitis (HC) produce serum antibodies to the lipopolysaccharides (LPS) of Escherichia coli O157 and certain other E. coli serogroups. Patients may also make salivary antibodies to the LPS of E. coli O157. Serological tests based on these antibodies can be used to provide evidence of infection in the absence of culturable VTEC or the toxins they produce. Serum antibodies to LPS persist for several months following onset of disease, enabling both current and retrospective serological testing. The LPS of E. coli O157 shares epitopes with strains of Brucella abortus, Yersinia enterocolitica O9, Vibrio cholerae O1 Inaba, group N Salmonella and certain strains of Citrobacter freundii and E. hermanni. Serological tests for serum antibodies to E. coli O157 should be evaluated in the light of these cross-reactions. Serological tests to supply evidence of infection with E. coli O157 have been shown to provide a valuable adjunct to bacteriological procedures for detecting culturable VTEC and VT. The use of well characterized LPS antigens in association with the techniques of ELISA and immunoblotting provide valuable procedures for detecting evidence of infection with E. coli O157 and possibly other VTEC.