A killer infection spread around a man’s body faster than desperate surgeons could operate, an inquest was told.

Michael Steadman, a business development administrator, was admitted to the Royal Sussex County Hospital, in Brighton, for a routine heart operation and died just days later.

The 62-year-old woke up with a small blotch on his leg but by 5.45pm he was dead.

An inquest at Brighton County Court was told that Mr Steadman, a divorced father, of West Parade, Worthing, developed necrotising fasciitis (fasciitis), after he was admitted to the hospital in January for a heart operation.

The procedure involved doctors removing part of a vein from his leg.

The aggressive and rapidly spreading infection later developed at the site of the wound.

The inquest was told he was rushed back into the operating theatre where doctors decided to amputate his leg. But the surgery did not go ahead because surgeons realised the infection was spreading so quickly it had already begun to reach his upper body.

Dr Marc Cubbon, consultant microbiologist at the hospital, said the infection was so rare he only saw it in patients about twice a year and had never seen it in a patient following heart surgery.

He said the necrotising fasciitis had probably developed from bacteria normally found in Mr Steadman's body rather than been acquired in the hospital.

The inquest was told that Mr Steadman only started showing signs of feeling unwell the day before he died and no tests could have been carried out earlier to alert doctors to the infection.

Jonathan Hyde, the heart surgeon who carried out the operation, said Mr Steadman had been making a routine recovery from the surgery and he was due to be discharged from hospital in a few days.

He said on 14 January at 9am Mr Steadman had shown no signs of the infection, at 10am a small blotch appeared on his leg and by 5.45pm he was dead.

He said: "We were dealing with something very bad and very rare."

The cause of death was given as necrotising fasciitis.

Deputy Brighton and Hove Coroner John Hooper recorded a verdict of death by medical misadventure.

He said: "The likelihood is the disease did develop from the patient's own flora. It appears Mr Steadman was extremely unfortunate."