Simple sites containing spacers derived from 59-be. The sequences at the ends of the aadA1 and aadA2 cassettes with the complete 59-be and derivatives with simple sites are aligned. Colons indicate identity. Core sites are in boldface type and are labeled as described in the legend to Fig. 1, and spacers are boxed. The sequence from the adjacent 3′-CS or gene cassette is indicated with lowercase letters. The stop codons of the aadA1 and aadA2 genes are marked by asterisks. The sources of the sequences are as follows: aadA1, GenBank accession no. X12870; aadA2, GenBank accession no. X68227; aadA1 and 3′ CS, GenBank accession no. AJ278514; aadA2 and 3′ CS with RH spacer, GenBank accession no. AF156486; aadA2 and 3′ CS with LH spacer, GenBank accession no. AF227505; blaVIM-2 and 3′ CS, GenBank accession no. AF302086; and blaVIM-2, GenBank accession no. AF191564.