Draft genome sequences of two fluoroquinolone-resistant CTX-M-15-producing Escherichia coli ST90 (ST23 complex) isolated from a calf and a dairy cow in South America.

OBJECTIVES

Farm animals have been recognised as important carriers and reservoirs of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli. The aim of this study was to report the draft genome sequences of two multidrug-resistant (MDR) CTX-M-15-producing E. coli strains (47VL and 13B) isolated from different bovine hosts (a calf and a dairy cow), housed separately in a commercial dairy farm in Brazil.

METHODS

Total genomic DNA of the E. coli isolates was sequenced using an Illumina MiSeq paired-end 300-bp sequencing platform. Sequence reads were de novo assembled using the A5-miseq pipeline and polishing assembly in Geneious v.R9. The NCBI Prokaryotic Genome Annotation Pipeline v.3.2 was used for genome annotation, whereas whole-genome sequences were analysed using bioinformatic tools from the Center of Genomic Epidemiology and EnteroBase.

RESULTS

E. coli 47VL generated a total of 3238770 and E. coli 13B a total of 1422808 paired-end reads of ca. 190× and ca. 80×, respectively. The resistome revealed that both isolates carried resistance genes to aminoglycosides, β-lactams, macrolides, sulphonamides, trimethoprim and tetracycline. Comparative analyses revealed clonal relatedness. In fact, both isolates belonged to sequence type ST90 (clonal complex CC23) and phylogroup AxB1.

CONCLUSION

To our knowledge, these are the first draft genome sequences of CTX-M-15-producing E. coli ST90 isolated from bovines in South America. These data can be used to elucidate genetic features that contribute to colonisation and adaptation of CTX-M-15-producing E. coli in dairy cattle.