1. Department of Microbiology and Biochemistry; Instituto de Productos Lácteos de Asturias (IPLA-CSIC); Villaviciosa; Asturias; Spain
2. Paediatrics Service; Hospital de Cabueñes; SESPA; Gijón; Asturias; Spain
3. Paediatrics Service; Hospital Universitario Central de Asturias; SESPA; Oviedo; Asturias; Spain