Dataset Information

Clonal spread of mcr-1 in PMQR-carrying ST34 Salmonella isolates from animals in China.

ABSTRACT: Since initial identification in China, the widespread geographical occurrence of plasmid-mediated colistin resistance gene mcr-1 in Enterobacteriaceae has been of great concern. In this study, a total of 22 Salmonella enterica were resistant to colistin, while only five isolates which belonged to ST34 Salmonella enterica serovar Typhimurium (S. Typhimurium) were mcr-1 positive. Four of them shared nearly identical PFGE type, although they were from different host species and diverse geographical locations. All the mcr-1-positive S. Typhimurium exhibited multi-resistant phenotypes including ampicillin, streptomycin, gentamicin, florfenicol, nalidixic acid, tetracycline, trimethoprim-sulfamethox, in addition to colistin. The oqxAB and aac(6')-Ib-cr genes were present alone or in combination in four (80.0%) and five (100%) isolates, respectively. The mcr-1 gene was located on a transferable IncI2 plasmid in the four genetically related strains. In the other one strain, mcr-1 was located on an approximately 190 kb IncHI2 plasmid. In conclusion, we report five mcr-1-positive S. Typhimurium/ST34 isolates. Both clonal expansion and horizontal transmission of IncI2-type plasmids were involved in the spread of the mcr-1 gene in Salmonella enterica from food-producing animals in China. There is a great need to monitor the potential dissemination of the mcr-1 gene.

SUBMITTER: Li XP

PROVIDER: S-EPMC5137007 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Clonal spread of mcr-1 in PMQR-carrying ST34 Salmonella isolates from animals in China.

Li Xing-Ping XP Fang Liang-Xing LX Song Jia-Qi JQ Xia Jing J Huo Wei W Fang Jin-Tao JT Liao Xiao-Ping XP Liu Ya-Hong YH Feng Youjun Y Sun Jian J

Scientific reports 20161205

Since initial identification in China, the widespread geographical occurrence of plasmid-mediated colistin resistance gene mcr-1 in Enterobacteriaceae has been of great concern. In this study, a total of 22 Salmonella enterica were resistant to colistin, while only five isolates which belonged to ST34 Salmonella enterica serovar Typhimurium (S. Typhimurium) were mcr-1 positive. Four of them shared nearly identical PFGE type, although they were from different host species and diverse geographical ...[more]

PMID: 27917926

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Project description:This study aimed to investigate the prevalence and genomic characteristics of the colistin resistance gene mcr in Salmonella enterica in China. In total, 445 S. enterica isolates from animals and food products were screened through PCR and sequencing for the presence of mcr. The mcr genes were detected in nine Salmonella strains (2.02%), with complete mcr-1 in S. enterica serovar Indiana (n = 1) and an S. Typhimurium monophasic variant (S. 4,[5],12:i:-; n = 1), mcr-4.3 in S. enterica serovar London (n = 1), and an incomplete mcr-1 in S. Indiana (n = 6). They exhibited MIC values of 0.25 to 8 mg/L to colistin and showed resistance to multiple antimicrobial agents. Whole-genome sequencing was performed on mcr-positive Salmonella strains using Illumina HiSeq or PacBio single-molecule real-time sequencing. The complete mcr-1 gene was located on conjugative IncN1-IncHI2 plasmid and IncX4 plasmid, respectively, with high similarity to other mcr-1-bearing plasmids belonging to the same incompatibility type. Together with an additional 13 antimicrobial resistance genes, the incomplete mcr-1 was embedded in an 81,442-bp multiresistance region on the chromosome in S. Indiana YZ20MCS6. The Δmcr-1-pap2 segment and a set of tellurite resistance determinants (terYXWZABCDEF) in six S. Indiana strains were similar to other IncHI2 plasmid backbones. The mcr-4.3 gene was located on an untyped plasmid pYULZMPS10. Although low prevalence of mcr was observed in Salmonella, continuous surveillance of this gene in Salmonella is required. Plasmids play an important role in mcr transmission, and mcr-1, although incomplete, can be captured by chromosomes with the help of mobile elements. IMPORTANCE Colistin is a last-resort antibiotic for severe infections caused by multidrug-resistant (MDR) Gram-negative pathogens. Colistin resistance genes mcr, particularly mcr-1, have been found in Enterobacteriaceae around the world, mainly in Escherichia coli and Salmonella. Salmonella enterica is a major foodborne pathogen, with MDR Salmonella being considered a "Serious Threat Level pathogen" by the Centers for Disease Control and Prevention. Therefore, the prevalence of mcr in Salmonella strains must be monitored. In this study, a low mcr prevalence (2.02%) was observed in Salmonella strains from animals and food products, with plasmid-borne mcr-1 in S. enterica serovar Indiana and an S. Typhimurium monophasic variant (S. 4,[5],12:i:-) and chromosomally located mcr-1 in S. Indiana. The mcr-4.3 gene was first identified in S. enterica serovar London associated with an untyped plasmid. Although this study reports a low mcr prevalence in Salmonella, the transmission ability of mcr-positive Salmonella strains to humans via the food chain is a public health concern.

Project description:Mobile colistin resistance (mcr) genes are present mainly in plasmids and can disseminate clonally or horizontally via either plasmids or insertion sequences in different genomic locations among the Enterobacteriaceae. A nationwide large-scale study on mcr prevalence and transmission in nontyphoidal Salmonella isolates is still lacking. Here, we identified 140 mcr-positive Salmonella isolates out of 7,106 isolates from 29 provinces in China from 2011 to 2020. We aligned short reads to putative plasmids from long-read hybrid assemblies and predicted the plasmid backbones of non-long-read sequencing isolates to elucidate mcr transmission patterns. The mcr-1 and mcr-3 genes are transmitted on similar high-risk clones (sequence type 34 [ST34]) but through plasmids of various replicon types. Furthermore, the ban on colistin use in food animals can lead to a decrease in the mcr-positive Salmonella prevalence among diarrheal patients, related mainly to IncHI2A_IncHI2 plasmids. We provide a framework for plasmid data incorporation into genomic surveillance systems, contributing to a better understanding of mcr spread and transmission. IMPORTANCE Nontyphoidal Salmonella is one of four major causative agents of diarrheal diseases globally, with most cases of salmonellosis being mild. Antimicrobial treatments are required for cases of life-threatening infections, and colistin is one of the last-line antibiotics for the treatment of multidrug-resistant Salmonella infections. However, the efficacy of colistin has been compromised by the emergence of various mcr genes. To elucidate the transmission of mcr genes in Salmonella isolates, our study analyzed 7,106 Salmonella strains from 29 provinces in China from 2011 to 2020. The results showed that mcr genes are transmitted on similar high-risk clones (ST34) but through plasmids of various replicon types. In addition, our data illustrated that the ban on the use of colistin in food animals led to a significant decrease in mcr-positive isolates. Our findings offer an essential step toward a more comprehensive understanding of the spread and transmission of mcr genes.

Dataset Information

Clonal spread of mcr-1 in PMQR-carrying ST34 Salmonella isolates from animals in China.

Publications

Clonal spread of mcr-1 in PMQR-carrying ST34 Salmonella isolates from animals in China.

Similar Datasets

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