Non-MRSA PVL identified at Norfolk hospital

Microbiologists are investigating a cluster of non-MRSA Panton-Valentine Leukocidin (PVL) positive S aureus that contributed to the death of a baby at the Norfolk and Norwich University Hospital.

Laboratory tests on the morning of Tuesday, December 19 confirmed a total of five babies who have been in the hospital's neonatal unit have had PVL + S. aureus. Screening indicates that one other baby is a probable positive. This cluster of cases is the first ever to be seen in the 28-cot neonatal unit at the Norfolk and Norwich University Hospital.

The particular infection is a rare strain of Staphlyococcus aureus (S. aureus) which is not the same MRSA-related strain that has been seen recently in the West Midlands. PVL is rarely seen in hospitals but it can be treated. All five babies currently on the unit are being treated with appropriate antibiotics and are doing well. None of the babies affected are actively infected by the organism and are being treated and decolonised successfully. Sadly, a sixth baby, who was born at 26 weeks and very poorly, died of an infection seven days later on December 11. The laboratory tests have since confirmed that child had a PVL infection.

All the unit staff, the close relatives of the babies affected, and all the babies on the unit have been swabbed to screen for PVL+ S. aureus to see if any further antibiotic treatments are necessary. The unit has undergone additional specialist cleaning and has been closed to new admissions from other hospitals. Visiting on the unit is also being restricted to parents only.

The source of the infection is not yet known. Such infections tend not to be hospital-based and it is more likely to have been brought from the community into the unit at some stage over the period 22 November to 19 December. Of the five confirmed cases, two were transferred to Norwich from other East Anglian hospitals, one was a home birth, and two were born at NNUH. Looking back over microbiology records for the past three months the hospital has seen no indicators of PVL+ S. aureus at all prior to this cluster of cases.

Chief Executive Paul Forden said: “Our neonatal unit cares for the very youngest and most critically ill of all our patients. It is tragic that this infection may have played a part in the death of a tiny baby and our thoughts are with the parents concerned.”  

Consultant microbiologist Dr Judith Richards said: “The babies affected in the unit are all successfully being treated and decolonised, and they are all currently clinically well. We believe the control measures introduced mean that these babies, and others in the unit, are not now at any significant risk from this strain of S. aureus.

“Our routine microbiology monitoring did very quickly pick up a rise in background Staphylococcus aureus and rapid further investigation has confirmed PVL in five babies. We have taken prompt action to treat the babies concerned and we are working with the Health Protection Agency to identify the source of this infection.”

Notes to editors

Panton-Valentine Leukocidin (PVL)-positive S aureus has been seen in the UK before but the small numbers of cases reported have usually been in the community rather than a hospital setting.

PVL-producing strains are more commonly contracted in the community and generally affect previously healthy young children and young adults – this contrasts with the so called “hospital-associated MRSA” strains which do not produce PVL and are more commonly associated with causing wound infections and blood-poisoning in more elderly hospitalised patients.  

The infections are caused by strains of S. aureus which carry a toxin (PVL) that destroys white blood cells. The toxin is carried by less than 2 per cent of S. aureus and can be carried by both those that are methicillin sensitive S. aureus (MSSA) and those that are methicillin resistant S. aureus (MRSA).

To date the majority of PVL-related infections in the UK have been caused by MSSA.   Infections caused by PVL-positive strains of S. aureus normally cause pus-producing skin infections (e.g. abscesses or boils) and occasionally cellulitis or tissue necrosis. However they can cause more severe invasive infections such as septic arthritis, bacteraemia (blood poisoning) or community-acquired necrotising pneumonia.