The 50-year-old homeless man was declared dead by a senior doctor in the Indian city and sent immediately to the mortuary – against hospital rules.
Patients pronounced dead are supposed to be kept on the ward for two hours in case the doctor has made an error.
Doctors said the man, named as Prakash, had a metabolic disorder and was delirious when police brought him in.
Local media reported that he was found unconscious at a bus stop.
Speaking at a news conference on Monday, Dr Suleman Merchant, the dean of Lokmanya Tilak Municipal General Hospital, said Prakash was an alcoholic who had “neglected himself” and had maggots on his face and ears.
“Maggots eat human tissues. Usually dead bodies have maggots. He must have been lying around for at least six or seven days,” said Dr Merchant.
He told reporters that the doctor who examined Prakash had checked the patient’s pulse, respiration, and heart.
Dr Merchant said the hospital had launched an inquiry into the breach of protocol that led Prakash to be taken immediately to the mortuary.
Prakash is in a stable condition in the hospital’s intensive care unit where he is being treated for an ear infection and malnourishment, Dr Merchant said.