Actress Leslie Ash is suffering from an infection that attacks the nervous system, her spokesman has said.
Ash was admitted to hospital on Friday
The 43-year-old fell ill with Methicillin-Sensitive Staphylococcus Aureus (MSSA) after a stay in the Chelsea and Westminster Hospital.
The Merseybeat star was admitted to the west London hospital with a broken rib and collapsed lung on 24 April.
She is now in the Charing Cross Hospital, where her spokesman said she continued to respond well to treatment.
Neil Reading said Ash would be moved out of intensive care to a private ward later on Monday.
"The co-ordination and feeling in her legs has continued to improve within
the last 24 hours," he added.
"Her husband, Lee Chapman, and sons remain at her bedside. They are encouraged
by the good news of her progress."
Ash was admitted to Charing Cross Hospital on Friday.
Unlike the so-called "hospital superbug" MRSA, which is resistant to the powerful antibiotic
drug methicillin, MSSA can be treated with antibiotics.
But it can cause a wide range of health problems - from boils and abscesses to pneumonia and toxic shock syndrome.
The infection initially attacked the actress's nervous system and for a period Ash lost the feeling below her waist.
Mr Reading said: "There has been a great improvement in the feeling in the lower part of her body."
Ash spent five days in the Chelsea and Westminster Hospital before being discharged on Wednesday - two days before she entered the Charing Cross Hospital with the infection.
The Chelsea and Westminster NHS Trust said in a statement: "We are
very sorry to hear that Leslie Ash is unwell - as she is no longer under our
care, we cannot comment on her current state of health.
"We have been informed that the test results have confirmed that she did not
have MRSA but staphylococcus aureus. This is a common bacteria found in the
community and, as such, it's very difficult to know if it was acquired at
Chelsea and Westminster or not."
Mr Reading said it was not clear how long Ash's latest stay in hospital would last.