Co-existence of mphA, oqxAB and blaCTX-M-65 on the IncHI2 Plasmid in highly drug-resistant Salmonella enterica serovar Indiana ST17 isolated from retail foods and humans in China. (December 2020)

• Record Type: Journal Article
• Authors: Zhang, Zengfeng; Yang, Jingxian; Xu, Xuebin; Zhou, Xiujuan; Shi, Chunlei; Zhao, Xiaodong; Liu, Yanhong; Shi, Xianming
• Is Part Of: Food control. Volume 118(2020)
• Publication Date: 2020-12
• Subjects: Salmonella Indiana -- Azithromycin -- mphA -- oqxAB -- blaCTX-M-65 -- IncHI2; Food -- Quality -- Periodicals; Food -- Analysis -- Periodicals; Food handling -- Periodicals; Food industry and trade -- Quality control -- Periodicals; Aliments -- Industrie et commerce -- Qualité -- Contrôle -- Périodiques; Aliments -- Qualité -- Périodiques; Aliments -- Analyse -- Périodiques; Hygiène alimentaire -- Périodiques; Food -- Analysis; Food handling; Food -- Quality; Periodicals; Electronic journals; 664.07
• DOI: 10.1016/j.foodcont.2020.107269
• Languages: English
• ISSNs: 0956-7135

Abstract

Abstract: Salmonellosis is an important global foodborne disease, and Salmonella isolates that are resistant to a wide variety of antibiotics have become a major public health concern. The aim of this study was to investigate the distribution and transmission of mph A gene in azithromycin-resistant Salmonella isolates and characterize the plasmid bearing mph A. In this study, the azithromycin resistance was shown in 15 Salmonella enterica serovar Indiana ( S . Indiana) isolates from chicken, duck and humans with concurrent resistance to ciprofloxacin and ceftriaxone, two of which were resistant to all antibiotics tested except colistin and imipenem. MLST and PFGE results suggested that these 15 isolates were closely related in phylogeny. The azithromycin resistance gene ( mph A), extended-spectrum beta-lactamase (ESBL)-encoding genes ( bla CTX-M-65, bla CTX-M-14 and bla CTX-M-15 ) and plasmid-mediated quinolone resistance (PMQR) genes [ oqx AB, qep A, qnr A and aac(6′)-Ib-cr ] with mutations in the quinolone resistance determining region (QRDR) ( gyr A and par C) were identified in these S. Indiana isolates. Plasmid conjugation and transformation were performed in these 15 isolates. The co-existence of the mph A gene with oqx AB- bla CTX-M-65 was observed on the IncHI2 plasmid with a size of~240 kbp in 7 transformants, and these 7 transformants exhibited the resistance to azithromycin (MIC from 32 μg/mL to 64 μg/mL) and ceftriaxone (MIC≥ 256 μg/mL). The complete sequence of an IncHI2 type plasmid, p13520, was determined. An approximately 80-kbp of multidrug resistance region (MRR) comprising 29 antimicrobial resistance genes (ARGs) including mph A, oqx AB, bla CTX-M-65, fos A3 and rmt B interspersed with different insertion sequences (ISs) (IS 26, IS Aba1, IS 91, IS 1006 and IS 903B ) was located on the plasmid. The typical IS26- mph A- mrx - mph R-IS 6100 transposable structure was identified in the IncHI2 plasmid of nine transformants via genome sequencing and PCR mapping, which suggested that azithromycin resistance in S . Indiana was probably due to the dissemination of the IncHI2 plasmid carrying the mph A- mrx - mph R cluster. This study highlighted the emergence of S. Indiana isolates with concurrent resistance to azithromycin, ciprofloxacin and ceftriaxone in humans and retail foods in China. This is likely due to the co-existence of mph A, oqx AB and bla CTX-M-65 carried by the IncHI2 plasmid. These findings emphasized the importance of ongoing surveillance for the prevalence and transmission of the p13520-like plasmid in S. Indiana, so as to better understand the potential threat to public health. Highlights: Azithromycin, ciprofloxacin and ceftriaxone co-resistant isolates were found. mph A, PMQR genes with mutations in QRDR and ESBLs genes were detected. mph A co-existence with oqx AB- bla CTX-M-65 was found on ～240 kbp IncHI2 plasmid. IS26- mph A- mrx - mph R-IS 6100 transponson was identified in the IncHI2 plasmid.