1. Health Protection Agency South West Regional Laboratory, Bristol Royal Infirmary, Bristol BS2 8HW
2. Vaccine Evaluation Unit, Health Protection Agency South West, Gloucestershire Royal Hospital, Great Western Road, Gloucester GL1 3NN
3. Respiratory and Systemic Infection Laboratory, Centre for Infection, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT
4. Department of Microbiology, Taunton and Somerset Hospital, Taunton TA1 5DB, United Kingdom