A 52-year-old salesman remains in critical condition at Khoo Teck Puat Hospital, nearly 10 days after he ate a meal of yusheng-style or raw fish porridge.
Mr Sim Tharn Chun, who is in intensive care, has been sedated, said his wife.
Mrs Cathryn Sim, 43, told Chinese evening daily Lianhe Wanbao that a doctor said, a day after her husband was admitted, it was likely to be Group B Streptococcus (GBS) bacteria leading to meningitis.
The hospital has refused to confirm any link to the bacteria and would say only that it was reviewing the case.
Yesterday, Mrs Sim gave The Straits Times an update on her husband's condition, saying: "He opened his eyes slightly but he was still very weak. In the afternoon, he suffered a seizure and the doctor had to put him on anti-seizure drugs and sedation, so now he is still in an unconscious state."
Mr Sim had the porridge, from a Tiong Bahru market stall, on Nov 15 after returning from a work trip to the Philippines.
Three days later, he began suffering body aches, headaches, vomiting and had diarrhoea, she said.
Said Mrs Sim: "The pain from his headache felt so intense... It got to a point where he was in a complete state of confusion and I saw my husband, who is an intelligent man, reduced to a terrible state."
Mr Sim was rushed to the hospital by ambulance last Thursday after his legs swelled up and he almost lost consciousness.
GBS is a common bacterium found in the gut and urinary tract of 15 to 30 per cent of adults, and does not usually cause disease in healthy individuals. It is also not known to be transmitted through food and water.
However, it may occasionally cause infections of the bloodstream, skin and soft tissues, joints, lungs and brain.
Mrs Sim said her husband suffered a viral infection 18 years ago that caused him to fall unconscious and be hospitalised after eating medium-rare beef while on holiday in the United States.
He regained consciousness, after five days, on his birthday, but she is worried it could be different this time.
She said: "The doctors told me that chances of recovery are low."
The couple, married for close to 20 years, have three children aged between 13 and 17.
In August, the Ministry of Health said its investigations found an association between GBS infection and the consumption of raw fish sold at food stalls, though it did not elaborate on what the link could be.
It added that there had been a "significant downtrend" in the number of GBS cases since mid-July, after licensed shops and foodstalls were advised to stop selling raw fish dishes using Song fish and Toman fish.
The ministry could not provide an update on its investigations by press time yesterday.