More than 60 people fell ill in Kazakhstan after eating a cake made with raw eggs that was not stored correctly.
A total of 182 people attended a wedding in 2022. Of 138 study participants, 66 became ill. The main symptoms were diarrhea, abdominal pain and fever. Symptom onset occurred between six hours and four days after the event. Fifty people were hospitalized but no deaths were reported.
Honey cake was the only risk factor associated with illness. Honey cakes, which use raw eggs in cream layers, had been stored at room temperature for three days before the event. Salmonella Enteriditis was isolated from all 49 patient stool samples and two honey cake samples. Staphylococcus aureus was detected in 35 of 38 patient gastric lavage samples.
Leftover event food was discarded, disinfection took place, and the restaurant was closed until all health certificates could be obtained and it was re-inspected by officials.
Salmonella Enteritidis is the most frequent cause of non-typhoidal salmonellosis in Kazakhstan. In 2022, there were 23 outbreaks of salmonellosis recorded in the country.
Poor hygiene practices
According to a study published in BMC Infectious Diseases, in June 2022, there was an increase in acute intestinal infections. Initial epidemiological investigations found cases occurred among participants of a wedding held in a restaurant.
Patients were significantly younger than non-patients and they were more likely to have consumed leftovers. The median duration of illness was two days with a range of one to four days.
Fourteen samples were collected from leftover ingredients and prepared dishes. E. coli was detected in cooked liver pancake; E. coli and Enterobacter spp. in uncooked mushrooms; E. coli, Enterobacter, and Salmonella Enteritidis in two samples of honey cake, and E. coli in uncooked horsemeat which is an ingredient of beshbarmak (a traditional Kazakh noodle, onion and boiled meat dish).
Among 100 samples from restaurant food preparation and serving surfaces, E. coli was found in 24 samples, including on plates, tables, and dish racks. No pathogens were detected in nasal and throat swabs collected from the eight restaurant personnel tested, and none of them had any recent illness before the wedding. The extent of contamination across different surfaces and food types was likely the result of poor food hygiene practices, said scientists.
An environmental assessment and site visit revealed the restaurant did not have a valid sanitary and epidemiological certificate, which is required by law to operate and serve food. Also, no personnel held health certificates permitting them to work in a restaurant kitchen. No defects were noted on the surfaces of equipment in the kitchen.
Lack of suitable cake storage
Fourteen honey cakes served at the event were prepared in the home of someone who had not attended. The preparer’s private kitchen did not have adequate refrigerator space to store all the honey cakes; so some were kept at room temperature. This person did not hold a valid health certificate to prepare food for public consumption.
Honey cakes were delivered to the restaurant on the morning of the event; however, the kitchen also did not have enough refrigerator space to store them, so they were kept at room temperature until being served. All other food served was prepared by restaurant cooks onsite.
Although multiple pathogens were identified and cannot be ruled out, Salmonella Enteritidis was the most probable agent based on clinical manifestations and isolation from patients and honey cake samples. Raw ingredients used to prepare honey cakes had been discarded by the time of the environmental assessment so could not be analyzed.
Whole genome sequencing (WGS) was not performed on isolated bacteria, so it was not possible to directly link Salmonella detected in patients and food samples. WGS is not routinely done in Kazakhstan and only a few laboratories in the country have such capacity.
“We cannot definitively conclude if preparation (contaminated ingredients and/or cross-contamination), inappropriate storage, or a combination of the two was the mechanism that led to honey cake contamination with Salmonella. This also limits the ability to conduct further trace back to the source of the products used for the cake,” said researchers.
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