The factory of a sandwich producer in England linked to an illness was contaminated by Listeria for almost three years, a report into the incident has found.

In July 2017, Listeria monocytogenes was isolated from the blood of a 53-year-old in a hospital in Yorkshire and Humberside with an underlying health condition. The man had eaten sandwiches made by the company while in the hospital at least 12 times in the three weeks prior to illness.

The isolate was genetically indistinguishable to those from sandwiches and salads produced by the company based in Bradford who supplied National Health Service (NHS) hospitals, other institutions and retailers nationwide.

Listeria monocytogenes was detected in the firm’s products between December 2016 and August 2017, at the manufacturer’s premises and from two hospitals’ in-house sampling. The business and local authority had been trying to control the bacterium at the production site since December 2016. The implicated Listeria monocytogenes strain was found at the site and in products up to July 2019.

The firm continued to supply NHS hospitals but stopped in September 2019 for commercial reasons, according to the report. Food Safety News understands the business referred to is Tiffin Sandwiches. The company has not responded to requests for comment.

In its strategic report for the year ending May 31, 2019, Tiffin Sandwiches reported that since the end of that financial year it had stopped supplying the NHS.

“The company consulted with Public Health England and the Food Standards Agency and following these consultations, proposed this change. Given all the information available to the company, a decision was made to cease the supply of products to hospitals.”

Contamination below legal requirement
An incident management team was set up in August and closed in November 2017. This group involved Public Health England, the Food Standards Agency and Bradford Council. Over the course of the investigation, recovery of Listeria monocytogenes from the company and hospitals was reduced.

All food samples tested, when placed on the market and during shelf life, had levels of Listeria monocytogenes below the legal limit of 100 colony forming units per gram.

The implicated strain was isolated after the investigation had finished in January, February, May, August, October, November and December 2018 as well as January, May and July 2019.

The company produced 40,000 sandwiches a day of which 12,000 were for the NHS. The factory made 88 different sandwiches, salad and other foods with a two-day shelf life. They supplied 213 NHS outlets across the country and 1,250 other establishments including universities, service stations and railways. The firm was a Support, Training & Services (STS) approved NHS supplier and recent audits showed it operated to a high standard.

Procedures were generally good but layout changes to expand the production area had been implemented and issues were identified such as sanitization systems for washing machines. Wheeled trolleys were not disinfected before moving from low to high risk areas. The outdoor to indoor shoe changing area bench was also a concern. One of the floors was draining from a low to high risk area.

Samples cleared by commercial lab
The company replaced the salad washing machine, improved the floor covering and drainage system with drains cleaned daily and deep cleaned at weekend. It was also told to wash the butter depositor prior to use.

Listeria monocytogenes had not been detected in any samples the company sent to a commercial UKAS accredited laboratory. After the incident, the producer changed to having testing done by the PHE Food Water & Environmental (FW&E) laboratory in York.

“The company was under the false impression that their food safety management systems were controlling the bacterium since all samples tested by the commercial laboratory were satisfactory and were reported as not containing Listeria monocytogenes,” according to the report.

Between October 2016 and June 2017, the PHE York FW&E lab tested samples of sandwiches from two hospitals in Yorkshire and Humber and isolated Listeria monocytogenes from 38 out of 297 samples of salads, sandwiches and other products. Listeria was recovered from 84 of 861 food samples made by the company and collected from hospitals including an egg mayonnaise and tuna mayo sandwich, ready-to-eat sweet corn, and washed lettuce.

Risk from hospital sandwiches
Investigations were undertaken at four hospitals. No communication was sent to other hospitals or recipients of the company’s products. Varying measures were implemented at the hospitals, which highlights the need to follow FSA guidance issued in 2016, according to the report.

A risk assessment indicated that under sub-optimal temperature storage conditions, one case of listeriosis could be expected every three years caused by consumption of these sandwiches, which was reduced to one in 20 years under optimal storage conditions.

The report found control measures to reduce or eliminate Listeria monocytogenes from factory environments and maintenance of the cold chain at hospitals are important to reduce listeriosis.

PHE said it was aware of 10 similar incidents in England and Wales of listeriosis from eating pre-prepared sandwiches served in hospitals. Infections have also occurred in Northern Ireland and Scotland.

In 2019, six people died after eating chicken sandwiches supplied to hospitals by the Good Food Chain. Meat was produced by North Country Cooked Meats and distributed by North Country Quality Foods. All three firms went into liquidation and ceased trading.

The British Sandwich and Food to Go Association updated guidance in January 2020 on controlling Listeria in ready-to-eat (RTE) chilled foods in the supply chain.

A report published in 2016 on behalf of the FSA found most outbreaks in hospitals have been linked to sandwiches, and mainly to ready-made sandwiches.