Epidemiological Study on Prevalence, Serovar Diversity, Multidrug Resistance, and CTX-M-Type Extended-Spectrum β-Lactamases of Salmonella spp. from Patients with Diarrhea, Food of Animal Origin, and Pets in Several Provinces of China.

EPIDEMIOLOGY AND SURVEILLANCE crossm Epidemiological Study on Prevalence, Serovar Diversity, Multidrug Resistance, and CTX-M-Type Extended-Spectrum ␤-Lactamases of Salmonella spp. from Patients with Diarrhea, Food of Animal Origin, and Pets in Several Provinces of China Wei Wang,a Li Zhao,b Yujie Hu,a Tania Dottorini,c Séamus Fanning,a,d,e Jin Xu,a Fengqin Lia a NHC Key Laboratory of Food Safety Risk Assessment, China National Center for Food Safety Risk Assessment, Beijing, China b School of Public Health, Shandong University, Jinan, China c School of Veterinary Medicine and Science, University of Nottingham, Nottingham, United Kingdom d UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland e Institute for Global Food Security, School of Biological Sciences, Queen’s University Belfast, Belfast, Northern Ireland A total of 2,283 Salmonella isolates were recovered from 18,334 samples, including samples from patients with diarrhea, food of animal origin, and pets, across 5 provinces of China. The highest prevalence of Salmonella spp. was detected in chicken meats (39.3%, 486/1,237). Fifteen serogroups and 66 serovars were identified, with Salmonella enterica serovars Typhimurium and Enteritidis being the most dominant. Most (85.5%, 1,952/2,283) isolates exhibited resistance to ⱖ1 antimicrobial, and 56.4% were multidrug resistant (MDR). A total of 222 isolates harbored extended-spectrum ␤-lactamases (ESBLs), and 200 of these were of the CTX-M type and were mostly detected in isolates from chicken meat and turtle fecal samples. Overall, eight blaCTX-M genes were identified, with blaCTX-M-65, blaCTX-M-123, blaCTX-M-14, blaCTX-M-79, and blaCTX-M-130 being the most prevalent. In total, 166 of the 222 ESBLproducing isolates had amino acid substitutions in GyrA (S83Y, S83F, D87G, D87N, and D87Y) and ParC (S80I), while the plasmid-mediated quinolone resistance (PMQR)-encoding genes oqxA, oqxB, qepA, qnrB, and qnrS were detected in almost all isolates. Of the 15 sequence types (STs) identified in the 222 ESBLs, ST17, ST11, ST34, and ST26 ranked among the top 5 in number of isolates. Our study revealed considerable serovar diversity and a high prevalence of the co-occurrence of MDR determinants, including CTX-M-type ESBLs, quinolone resistance-determining region (QRDR) mutations, and PMQR genes. This is the first report of CTX-M-130 Salmonella spp. from patients with diarrhea and QRDR mutations from turtle fecal samples. Our study emphasizes the importance of actions, both in health care settings and in the veterinary medicine sector, to control the dissemination of MDR, especially the CTXM-type ESBL-harboring Salmonella isolates. ABSTRACT KEYWORDS CTX-M, MLST, PMQR, QRDRs, Salmonella spp., antimicrobial resistance S almonella infections have been proven to be a major cause of global morbidity and mortality in both humans and animals (1, 2). Worldwide, 93.8 million salmonellosis cases occur annually, with 155,000 resulting in death (3). In China, more than 20% of all foodborne illnesses are estimated to be caused by Salmonella spp. (4). In 2013, unpublished data from the China CDC surveillance system showed that the rate of human carriage of Salmonella spp. was 549 per 100,000 people. This is more than 30 times higher than the number of human Salmonella infections in Europe in 2017 (19.7 per 100,000) and the United States in 2018 (18.3 per 100,000) (5, 6). Moreover, the indiscriminate use of wide-spectrum antibiotics creates an additional threat, repreJuly 2020 Volume 64 Issue 7 e00092-20 Antimicrobial Agents and Chemotherapy Citation Wang W, Zhao L, Hu Y, Dottorini T, Fanning S, Xu J, Li F. 2020. Epidemiological study on prevalence, serovar diversity, multidrug resistance, and CTX-M-type extended-spectrum β-lactamases of Salmonella spp. from patients with diarrhea, food of animal origin, and pets in several provinces of China. Antimicrob Agents Chemother 64:e00092-20. https://doi.org/10 .1128/AAC.00092-20. Copyright © 2020 American Society for Microbiology. All Rights Reserved. Address correspondence to Jin Xu, , or Fengqin Li, . Received 14 January 2020 Returned for modification 15 March 2020 Accepted 14 April 2020 Accepted manuscript posted online 20 April 2020 Published 23 June 2020 aac.asm.org 1 Wang et al. Antimicrobial Agents and Chemotherapy sented by the appearance and dissemination of multiantibiotic resistance profiles in the pathogen population. Multidrug-resistant (MDR) Salmonella spp. potentially arising due to selective pressure from sustained antimicrobial exposure are more likely to be the causative agents of invasive disease (7). Of concern is the increased incidence of infections caused by extended-spectrum ␤-lactamase (ESBL)-producing organisms, including Salmonella spp., because they are resistant not only to most of the ␤-lactam antimicrobials but also to other antimicrobial classes, leaving few treatment options and the potential for clinical outcomes worse than those of infections caused by non-ESBL-producing strains (8, 9). During the last decade, the most frequently encountered (particularly in areas of Europe and Asia) ESBL genes were those encoding the CTX-M enzyme family, primarily carried by transferable plasmids and transposons (10). The emergence of CTX-M-type ESBL-producing Salmonella spp. has been reported in clinical cases, animals, and food samples worldwide, including China (11–13). Worryingly, the plasmids and transposons carrying the gene for CTX-M can also contain genes for resistance to other antimicrobials, like fluoroquinolones (14). This brings big challenges to clinical treatment, as extended-spectrum cephalosporins (ESCs) and fluoroquinolones are the drugs of choice for the treatment of invasive Salmonella infections (15). The mechanism of quinolone resistance has been elucidated to be plasmid-mediated quinolone resistance (PMQR) and chromosomal mutations in the quinolone resistance-determining regions (QRDRs) (16, 17). PMQR can be classified into three different resistance mechanisms, AAC(6=)-Ib-cr acetylating ciprofloxacin and norfloxacin, Qnr proteins mediating target protection, and OqxAB and QepA mediating drug efflux (17), while mutations in QRDR genes, encoding DNA gyrase or topoisomerase IV, are also frequently found in quinolone-resistant Salmonella isolates (16). The co-occurrence of ESBLs (especially the CTX-M gene on plasmids and transposons) and PMQR in Salmonella spp. is a cause for concern because plasmids can spread with relative ease between different reservoirs, and such spread may be extremely difficult to control. In this study, we therefore investigated ESBL-producing Salmonella isolates collected from patients with diarrhea, food of animal origin, and pets across 5 provinces of China. We dissected the serovar diversity, the prevalence of antimicrobial resistance (AMR), the multilocus sequence types (MLSTs), and the co-occurrenc (...truncated)