Ampicillin-resistant non-?-lactamase-producing Haemophilus influenzae in Spain: Recent emergence of clonal isolates with increased resistance to cefotaxime and cefixime - García-Cobos, S.; Campos, J.; Lázaro, E.; Román, F.; Cercenado, E.; García-Rey, C.; Pérez-Vázquez, M.; Oteo, J.; De Abajo, F. (Antimicrobial Agents and Chemotherapy, 2007)