Draft genome sequence of a multidrug-resistant Salmonella enterica serotype Kentucky ST198 with chromosomal integration of blaCTX-M-14b isolated from a poultry slaughterhouse in China

Abstract

Objectives: The aim of this study was to characterise the draft genome sequence of a multidrug-resistant (MDR) Salmonella enterica serotype Kentucky strain (XJ9S) isolated from a poultry slaughterhouse in China.

Methods: The genome was sequenced using an Illumina HiSeq platform and was assembled using SPAdes_3.12.0. The CGE Bacterial Analysis Pipeline was used to identify the sequence type (ST) as well as the presence of antimicrobial resistance genes (ARGs) and plasmids in strain XJ9S. Gaps among contigs that carried MDR Salmonella genomic island 1 (SGI1) fragments were filled in by PCR linkage and sequencing.

Results: The draft genome of strain XJ9S was assembled into 54 contigs with a total assembly size of 4 785 059 bp. XJ9S belonged to ST198 and harboured five acquired ARGs [bla_CTX-M-14b, sul1, tetA(A), aacCA5 and aadA7]. The bla_CTX-M-14b gene was located on a 2849-bp ISEcp1-mediated translocatable unit inserted in the chromosome. The other four acquired ARGs were carried by a new variant of SGI1 (SGI1-XJ9S; 38 593 bp) belonging to the SGI1-K group. Moreover, point mutations in the quinolone resistance-determining region (QRDR) were found at positions 83 (Ser83Phe) and 87 (Asp87Gly) of GyrA and at position 80 (Ser80Ile) of ParC.

Conclusion: In this study, a new SGI1 variant (SGI1-XJ9S) was characterised for the first time. The draft genome sequence of S. Kentucky ST198 strain XJ9S isolated from a poultry slaughterhouse provides valuable information for tracing the potential spread of this MDR clone from poultry product processing to consumption, and even to humans.

Keywords: Multidrug resistance; ST198; Salmonella Kentucky; Salmonella enterica; Salmonella genomic island 1.