Novel complex class 1 integron carrying qnrB10 and blaCTX-M-2 in a twin variable region 2 found in a clinical Citrobacter freundii from Argentina. Navegación de entradas A fusion plasmid harboring blaCTXM-15 and qnrB2 isolated from a clinical Escherichia coli: the multiresistant outcome of multiple complex genomic rearrangements between two conjugative plasmids Population genetic structure, serotype distribution and antibiotic resistance of Streptococcus pneumoniae causing invasive disease in children in Argentina