A victim of the food poisoning is treated at Gia Định Hospital. — VNA/VNS Photo

HCM CITY — The number of people with food poisoning after having bánh mì (Vietnamese sandwiches) from two stores in HCM City has risen to 316, according to the municipal Health Department.

Authorities have identified the poisoning agent as Salmonella enteritidis and Salmonella spp. bacteria, detected through blood and stool cultures from the patients.

Last week, more than 200 people were hospitalised with symptoms including abdominal pain, diarrhoea, vomiting and fever after eating sandwiches sold under the brand name 'Bánh mì cóc cô Bích' in two HCM City stores - one on Nguyễn Thái Sơn Street, Hạnh Thông Ward, and the other on Lê Quang Định Street, Bình Lợi Trung Ward.

Most of the patients have already been discharged from hospital, although around 60 are continuing treatment.

One severe case involves a patient with underlying conditions of pneumonia, hypertension and atrial fibrillation, who is being treated in intensive care at Gia Định People's Hospital. The patient has been taken off the ventilator and showed stable vital signs as of Wednesday.

The Health Department has directed hospitals and the HCM City Centre for Disease Control to coordinate with the Oxford University Clinical Research Unit to conduct microbiological culture tests and gene sequencing of isolated bacterial strains to clarify the cause, as well as other factors related to the food poisoning cases.

According to the authority, the bánh mì store on Nguyễn Thái Sơn street is about 20sq.m and directly processes ingredients including chicken, butter and pickles. It also purchases food from various sources, some of which are without invoices or proof of origin.

The other branch, located on Lê Quang Định Street, has not yet registered its business licence.

Both stores have suspended operations.

The HCM City Food Safety Management Authority has collected food samples from both locations for testing to determine the source of the incident.

“This is a case with a large number of infections, several of which are severe. Tracking and compiling data on the patients is challenging, since the cases occurred in the community,” said the agency.

The agency recommended that the HCM City People’s Committee instruct relevant departments to coordinate in supporting the investigation, while the Department of Health continues updating the list of patients for epidemiological analysis as required.

Associate Professor Dr Đỗ Văn Dũng, a senior lecturer at the Faculty of Public Health at the University of Medicine and Pharmacy in HCM City, explained that Salmonella is a bacterium found in the intestinal tracts of some livestock and poultry, noting that meat and eggs can easily become contaminated.

People who consume food made from meat or eggs that are not properly sterilised — particularly children with weak immune systems — can develop Salmonella food poisoning.

Dr Võ Đăng Toàn, a gastroenterology specialist, said that Salmonella infection is typically accompanied by symptoms such as diarrhoea, abdominal cramps, fever, nausea, vomiting, chills and sometimes blood in the stool.

The illness usually lasts several days to a week, with diarrhoea possibly lingering before the intestines return to normal.

In healthy individuals, proper treatment with suitable antibiotics, hydration and electrolyte replacement usually leads to recovery within a few days, along with symptomatic relief for pain and diarrhoea.

However, severe complications can still occur in elderly people, young children or those with underlying health conditions. Complications can include septic shock, sepsis, acute kidney injury due to dehydration and electrolyte imbalance, and even death.

While the cause of the food poisoning linked to Bánh mì cóc cô Bích is still under investigation, a separate incident occurred on November 10, when 50 workers from Eternal Prowess Việt Nam JSC in HCM City's Đông Hưng Thuận Ward were hospitalised.

The workers showed symptoms including nausea, abdominal pain, red rashes and facial itching after having lunch at the company.

Most of them have since been discharged from hospital in stable condition.

Initial investigations found that Eternal Prowess had provided 410 lunch portions for employees on November 10.

The meals were supplied by another company under a catering contract. That supplier is licensed for food safety compliance.

The HCM City Food Safety Management Authority is currently verifying the incident and collecting samples for laboratory testing to identify the cause. — VNS