Infection experts are battling an MRSA outbreak at a neo-natal unit after six babies tested positive for the bug.

The neo-natal unit of the Royal Blackburn Hospital in Lancashire closed to new admissions last month when the PVL strain of the MRSA outbreak was found.

The East Lancashire Hospitals NHS Trust has said MRSA was found to have "colonised" the babies - but had not entered their bloodstream, which can lead to serious complications and death.

A spokeswoman said none of the babies had fallen ill.

Since the outbreak infection control has been called in and no new cases have been found.

The hospital said it hoped the unit would reopen to new admissions soon.

Rineke Schram, medical director for East Lancashire Hospitals NHS Trust, said: "I can confirm our Neonatal Intensive Care Unit has been closed to admissions since mid-September when the MRSA organism was identified in the unit.

"We have very recently found out that the strain is Panton Valentine Leukocidin (PVL) positive MRSA - a strain which can cause more serious illnesses in immuno-suppressed people - that is the elderly, severely ill or people with blood poisoning and wound infections.

"We are closely monitoring the situation and the babies who have been identified as carrying the organism are being treated in accordance with infection control guidelines.

"The babies are not seriously ill due to the PVL positive MRSA and are receiving treatment but continue to be nursed in separate areas within the unit, which is also in line with the guidance.

"Other babies within the unit are being screened on a regular basis to ensure we keep in control of the situation."

Microbiology laboratories across the UK have been asked to be vigilant and have been requested to send any suspicious samples of PVL for further analysis.

The strain can cause cellulitis (inflammation of layers under the skin) and pus-producing skin infections such as abscesses, boils and carbuncles.

They can, on very rare occasions, lead to more severe invasive infections, such as septic arthritis, blood poisoning and pneumonia.

There have been seven deaths in England and Wales associated with the PVL strain of MRSA over the last two years, including the two recently reported at a hospital in the West Midlands.

Most of these were unrelated to hospital care.

PVL-MRSA is resistant to some, but not all, antibiotics, and is therefore treatable.

Dr Schram added: "The Neonatal Intensive Care Unit will be re-opened once we are sure that all the babies are returning a negative result when they are screened for carrying the MRSA organism on their skin.

"We are confident this will be as soon as possible but we are unable to say exactly when that will be. However, as there have been no new outbreaks and the small number of babies affected is getting even smaller by the day, the NICU unit have done an excellent job in keeping the incident contained.

"We are unable to comment on individual cases due to patient confidentiality.

"However we can provide reassurance regarding the difference between colonisation and infection with regards to MRSA.

"Colonisation is where the MRSA organism is present without causing any untoward effect for the individual. This can be on the skin or other parts of the body outside the blood stream.

"A 'colonised' individual would not show any symptoms of illness but would be able to pass the organism on.

"This is different to being infected with MRSA, which only occurs once the organism is present in the blood stream (or possibly elsewhere) and is causing illness.

"MRSA on a normally healthy individual does not need hospitalisation.

"They can normally be treated by their GP with antibiotics.

"Similarly, if a baby is found to have colonised MRSA on their skin and the organism is not in the blood stream or other tissue, then again there is no need for hospitalisation.

"MRSA can live on the skin in up to one in 100 people within the community and as long as they remain fit and healthy and observe good hygiene practice, it should not pose a problem."