Dataset Information

Emergence of a Hybrid IncI1-Iα Plasmid-Encoded bla_CTX-M-101 Conferring Resistance to Cephalosporins in Salmonella enterica Serovar Enteritidis.

ABSTRACT: The increasing resistance to cephalosporins in Salmonella poses a serious threat to public health. In our previous study, the bla_CTX-M-101 gene, a new bla_CTX-M variant, was first reported in Salmonella enterica serovar Enteritidis (S. Enteritidis). Here, we further analyzed the genome characterization, transferability, and resistance mechanism of one S. Enteritidis isolate (SJTUF14523) carrying bla_CTX-M-101 from an outpatient in 2016 in Xinjiang, China. This strain was a multidrug resistance (MDR) isolate and exhibited resistance to ceftazidime (MIC = 64 μg/mL), cefotaxime (MIC = 256 μg/mL), and cefepime (MIC = 16 μg/mL). Phylogenetic analysis revealed that SJTUF14523 had a close relationship to another S. Enteritidis isolate from the United States. In the presence of plasmid p14523A, there were 8- and 2133-fold increases in the MICs of cephalosporins in Escherichia coli C600 in the conjugation. Gene cloning results indicated that bla_CTX-M-101 was the decisive mechanism leading to ceftazidime and cefotaxime resistance that could make the MICs break through the resistance breakpoint. Plasmid sequencing revealed that the bla_CTX-M-101 gene was located on an IncI1-Iα transferable plasmid (p14523A) that was 85,862 bp in length. Sequence comparison showed that p14523A was a novel hybrid plasmid that might have resulted from the interaction between a homologous region. Furthermore, we found a composite transposon unit composed of ISEcp1, bla_CTX-M-101, and orf477 in p14523A. ISEcp1-mediated transposition was likely to play a key role in the horizontal transfer of bla_CTX-M-101 among plasmids in S. Enteritidis. Collectively, these findings underline further challenges in the prevention and control of antibiotic resistance posed by new CTX-M-101-like variants in Salmonella.

SUBMITTER: Qin X

PROVIDER: S-EPMC10222410 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature

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Emergence of a Hybrid IncI1-Iα Plasmid-Encoded blaCTX-M-101 Conferring Resistance to Cephalosporins in Salmonella enterica Serovar Enteritidis.

Qin Xiaojie X Zhang Zengfeng Z

Microorganisms 20230512 5

The increasing resistance to cephalosporins in Salmonella poses a serious threat to public health. In our previous study, the blaCTX-M-101 gene, a new blaCTX-M variant, was first reported in Salmonella enterica serovar Enteritidis (S. Enteritidis). Here, we further analyzed the genome characterization, transferability, and resistance mechanism of one S. Enteritidis isolate (SJTUF14523) carrying blaCTX-M-101 from an ...[more]

PMID: 37317249

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Project description:In this study, we investigated the pattern of antimicrobial resistance in Salmonella enterica serotype Enteritidis isolates in Shanghai, China from 2005 to 2014. We found the first isolates with resistance to the fourth-generation cephalosporin cefepime starting in 2010. Furthermore, we analyzed the epidemic characteristics and mechanisms of underlying cefepime resistance in S. Enteritidis isolates found from 2010. In total, 38 of 2,914 (1.30%) isolates were identified as cefepime-resistant S. Enteritidis (CRSE) isolates by Kirby-Bauer disk diffusion. Two isolates were from animal derived food sources; 36 isolates were from fecal samples of human patients with salmonellosis. Antimicrobial susceptibility testing using the agar dilution method revealed that all CRSE isolates showed additional resistances at least to ceftazidime, cefotaxime, and ampicillin. Additionally, pulsed-field gel electrophoresis (PFGE) profiles indicated that 89.47% of CRSE isolates also displayed similar PFGE patterns. Five types of β-lactamase genes, bla CTX-M (100.00%, 38/38), bla SHV (65.79%, 25/38), bla TEM (52.63%, 20/38), bla ACC (18.42%, 7/38), and bla PSE (5.26%, 2/38) were detected by PCR and sequencing. Among bla CTX-M genes, bla CTX-M-55 was the dominant type (84.21%, 32/38). Conjugation and transformation experiments along with plasmid replicon typing revealed that bla CTX-M-55 was located on plasmids of various replicon types with sizes ranging from 76.8 to 138.9 kb. Plasmid sequence analysis also showed that the bla CTX-M-55 gene was mobilized mainly by the ISEcp1-bla CTX-M-55-ORF477 transposition unit and had its own ISEcp1-based promoter, which accelerated the expression and transmission of bla CTX-M-55. Analysis of whole genome sequences (Illumina) of one selected transformant SH12G706-C showed high similarity of the bla CTX-M-55 carrying plasmid with the IncI1 plasmid backbone p628-CTX-M of Klebsiella pneumoniae detected in 2010 in China. The present study demonstrated that the bla CTX-M-55 gene mobilized by ISEcp1- bla CTX-M-55-ORF477 was the main feature shared by CRSE isolates and seems to play an important role for transmission of cefepime resistance. The number of CRSE isolates is rising annually, and the strong dissemination ability of ISEcp1-bla CTX-M-55-ORF477-harboring plasmids among different species represents an important threat to the therapeutic effectiveness of cefepime.

Dataset Information

Emergence of a Hybrid IncI1-Iα Plasmid-Encoded bla_CTX-M-101 Conferring Resistance to Cephalosporins in Salmonella enterica Serovar Enteritidis.

Publications

Emergence of a Hybrid IncI1-Iα Plasmid-Encoded <i>bla</i><sub>CTX-M-101</sub> Conferring Resistance to Cephalosporins in <i>Salmonella enterica</i> Serovar Enteritidis.

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