No specific link in two related EIEC outbreaks - study

Two Enteroinvasive E. coli (EIEC) outbreaks were reported in Nottingham, UK, within two days in 2014; outbreak A was linked to a takeaway restaurant and outbreak B to a wedding party.

The epidemic curves were indicative of two common-source outbreaks linked to a restaurant and a wedding party in another restaurant within 0.1 miles of one another.

Outbreak A stopped after the restaurant was closed, and in outbreak B, no cases were identified outside of the wedding party.

Lettuce was the suspected vehicle of infection in outbreak A but the source remained unknown.

Almost 160 people ill​

For both outbreaks there were 157 probable case-patients; 27 were laboratory-confirmed as EIEC O96:H19–positive.

Researchers did a case–control study for outbreak A and a cohort study for outbreak B and tested microbiological and environmental samples, including by using whole genome sequencing.

All food and environmental samples were sent to the PHE Food, Water and Environment laboratory in York to test for enteric pathogens. E. coli–positive isolates were then sent to the GBRU for PCR testing for ipaH​, culture and serotyping.

For outbreak A, PHE was notified of 142 persons with gastrointestinal illness; 108 (76%) were interviewed, resulting in 19 confirmed cases, 88 probable and one excluded due to foreign travel.

Food items with the highest percentage of case-patients exposed were lettuce (80.4%), cucumber (74.8%), tomatoes (71%), and onions (68.2%).

Inspections of the restaurant identified opportunities for cross-contamination between raw meats and ready-to-eat foods during storage, washing, and cooking; chilled food items being stored above the temperature required by law; and inadequate handwashing facilities and practices.

Of the 12 food handlers associated with this outbreak, nine tested positive for EIEC, but most reported they were asymptomatic, so it is unclear how or when they acquired their infection.

Information for those linked to outbreak B was obtained for 41 people (68% of attendees).

Of those, 15 persons met the outbreak case definition (three confirmed and 12 probable cases), 24 had no signs or symptoms, and two were excluded because they did not have food at the wedding.

Multivariable analysis showed the risk for illness was five times higher among those who ate salad, six times higher for those who drank tap water  and four times higher among those who ate chicken curry compared with those who did not consume these items.

Cooking trends and Campylobacter link ​

In a separate study, researchers found cooking trends are linked to increasing Campylobacter infections.

They estimated that 19%–52% of livers served commercially in the UK fail to reach 70°C and predicted Campylobacter survival rates are 48%–98%.

The team used photographs to assess chefs’ ability to identify chicken livers meeting safe cooking guidelines.

They hypothesized that the trend toward including rarer, pinker meat in the recipes of chefs and by mass media representation of meat cooking may be contributing to changes in the way chicken livers are consumed.

More than 1,030 members of the public were surveyed, of which 43% ate chicken livers and were asked to select the chicken liver dishes they preferred and which they thought met FSA guidelines.

Chefs’ preferences, rather than their ignorance of FSA microbiological guidelines, seem to be leading them to serve undercooked livers, according to the study.

Chefs outperformed the public at identifying whether chicken livers had been cooked to FSA guidelines.

“We found that chef preferences for serving chicken livers were inconsistent with their perceptions of safe cooking—they preferred to serve livers more rare than is microbiologically safe and believed that their customers also prefer them more rare than is safe. ​

“Chefs systematically over predicted their customers’ preferences for pinkness of livers served.​

“The trend toward serving meat more pink has now extended from meats such as beefsteaks to meats such as chicken livers, for which the microbiological risks associated with rareness are far greater.”​

Source: Emerg Infect Dis. 2016 Jul (EIEC outbreak)

DOI: 10.3201/eid2207.152080​

"Two linked enteroinvasive Escherichia coli outbreaks, Nottingham, UK, June 2014"​

Authors: Newitt S, MacGregor V, Robbins V, Bayliss L, Chattaway MA, Dallman T, et al

Source: Emerg Infect Dis. 2016 Jul (Campylobacter study)

DOI: 10.3201/eid2207.151775​

“Restaurant cooking trends and increased risk for ​Campylobacter​ infection”​

Authors: Jones AK, Rigby D, Burton M, Millman C, Williams NJ, Jones TR, et al