Truncated Class 1 Integron Gene Cassette Arrays Contribute to Antimicrobial Resistance of Diarrheagenic Escherichia coli

Figure 1

(a) General structure of class 1 integrons (c1-integrons). The red arrows show the positions of primers used for detection of intI1, qacEΔ1, and sul1. The blue arrows show the positions of primers used for sequencing. P indicates the promoter. (b) Intact c1-integron cassette arrays that were confirmed by sequencing of PCR products, along with the corresponding resistance patterns. (c) Truncated c1-integron cassette arrays that were confirmed by next-generation sequencing analysis, along with the corresponding resistance patterns. EAEC: enteroaggregative Escherichia coli; EPEC: enteropathogenic E. coli; STEC: Shiga toxin-producing E. coli; CTX: cefotaxime; SXT: sulfamethoxazole-trimethoprim; (S) streptomycin; (C) chloramphenicol; (K) kanamycin; AM: ampicillin; NA: nalidixic acid; TE: tetracycline; aadA1: aminoglycoside resistance gene; dfrA: dihydrofolate reductase gene (trimethoprim resistance); OUT: O-serogroup-untypeable. All insertion sequences designated “IS1” belong to the IS1 family.

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