Emerging carbapenemases: a global perspective.

The clinical importance of the genus Enterococcus is directly related to its antibiotic resistance, which contributes to the risk of colonization and infection. The species of the greatest clinical importance are Enterococcus faecalis and Enterococcus faecium. Although the resistance characteristics of these two species differ in important ways, they can generally be categorized as intrinsic resistance, acquired resistance, and tolerance.Relative to the streptococci, enterococci are intrinsically resistant to many commonly used antimicrobial agents. All enterococci exhibit decreased susceptibility to penicillin and ampicillin, as well as high-level resistance to most cephalosporins and all semi-synthetic penicillins, as the result of expression of low-affinity penicillin-binding proteins. For many strains, their level of resistance to ampicillin does not preclude the clinical use of this agent. In fact, ampicillin remains the treatment of choice for enterococcal infections that lack other mechanisms for high-level resistance. Enterococci are also intrinsically resistant to clindamycin, which is mediated by the product of the lsa gene, although the mechanism remains poorly defined. Trimethoprim-sulfamethoxazole appears to be active against enterococci when tested in vitro on folate-deficient media, but fails in animal models, presumably because enterococci can absorb folate from the environment (Zervos & Schaberg, 1985). Enterococci also have a native resistance to clinically achievable concentrations of aminoglycosides, which precludes their use as single agents. Although E. faecalis is naturally resistant to quinupristin-dalfopristin, this combination is highly active against E. faecium strains that lack specific resistance determinants.Enterococci are tolerant to the (normally) bactericidal activity of cell-wall active agents, such as β–lactam antibiotics and vancomycin. Tolerance implies that the bacteria can be inhibited by clinically achievable concentrations of the antibiotic, but will only be killed by concentrations far in excess of the inhibitory concentration. Enterococcal tolerance can be overcome by combining cell-wall active agents with an aminoglycoside. The mechanism by which β–lactam-aminoglycoside combinations yield synergistic bactericidal activity remains a mystery, but in vitro data indicate that a higher concentration of aminoglycoside enters cells that are also treated with agents that inhibit cell wall synthesis, which suggests that the cell wall active agents promote uptake of the aminoglycoside (Mohr, Friedrich, Yankelev, & Lamp, 2009).Tolerance is normally detected in vitro by plotting survival in kill curves, and can be observed for a number of antibiotic-bacteria combinations. In vitro tolerance has an important impact on therapy for treating enterococcal infections. The treatment of endocarditis requires bactericidal therapy, due to the inaccessibility of the bacteria within the cardiac vegetations to the mammalian immune system. Recognition of synergism between penicillin-streptomycin led to an improvement in cure rates for enterococcal endocarditis, from approximately 40% to greater than 80% (Jensen, Frimodt-Moller, & Aarestrup, 1999; Rice & Carias, 1998). Despite considerable effort, investigators have yet to find other combinations of antibiotics that are synergistically bactericidal against enterococci.In addition to intrinsic resistance and tolerance, enterococci have been extraordinarily successful at rapidly acquiring resistance to virtually any antimicrobial agent put into clinical use. Introduction of chloramphenicol, erythromycin and tetracyclines was quickly followed by the emergence of resistance, in some cases reaching a prevalence that precluded their empirical use. While the occurrence of ampicillin resistance in E. faecalis has been quite rare, there is now widespread, high-level resistance to ampicillin among clinical E. faecium isolates. High-level aminoglycoside resistance, which negates the synergism between cell-wall active agents and aminoglycosides, has been recognized for several decades. Vancomycin resistance is widely prevalent in E. faecium, although it remains relatively rare in E. faecalis. In response to the growing problem of vancomycin resistance in enterococci, the pharmaceutical industry has developed a number of newer agents that have activity against vancomycin-resistant enterococci (VRE). However, none of these newly licensed agents (quinupristin-dalfopristin, linezolid, daptomycin, tigecycline) has been entirely free of resistance. Thus, the widespread resistance of enterococci has had a substantial impact on our use of both empirical and definitive antibiotics for the treatment of enterococcal infections, a situation that is likely to persist for the foreseeable future.

Enterococcal Infection—Treatment and Antibiotic Resistance

Broad-spectrum β-lactamase genes (coding for extended-spectrum β-lactamases and AmpC β-lactamases) have been frequently demonstrated in the microbiota of food-producing animals. This may pose a human health hazard as these genes may be present in zoonotic bacteria, which would cause a direct problem. They can also be present in commensals, which may act as a reservoir of resistance genes for pathogens causing disease both in humans and in animals. Broad-spectrum β-lactamase genes are frequently located on mobile genetic elements, such as plasmids, transposons and integrons, which often also carry additional resistance genes. This could limit treatment options for infections caused by broad-spectrum β-lactam-resistant microorganisms. This review addresses the growing burden of broad-spectrum β-lactam resistance among Enterobacteriaceae isolated from food, companion and wild animals worldwide. To explore the human health hazard, the diversity of broad-spectrum β-lactamases among Enterobacteriaceae derived from animals is compared with respect to their presence in human bacteria. Furthermore, the possibilities of the exchange of genes encoding broad-spectrum β-lactamases – including the exchange of the transposons and plasmids that serve as vehicles for these genes – between different ecosystems (human and animal) are discussed.

https://biblio.ugent.be/publication/910573/file/924121.pdf

Broad-spectrum β-lactamases among Enterobacteriaceae of animal origin: molecular aspects, mobility and impact on public health

Antibiotic resistant enterococci-tales of a drug resistance gene trafficker.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1469-0691.12275

A nosocomial outbreak of KPC-2-producing Klebsiella pneumoniae in a Chinese hospital: dissemination of ST11 and emergence of ST37, ST392 and ST395

Four isolates of Klebsiella pneumoniae and one isolate of Enterobacter cloacae exhibiting resistance to most β-lactam antibiotics, including oxyimino-cephalosporins and carbapenems, were obtained from different patients among four hospitals in China. Pulsed-field gel electrophoresis demonstrated that all the K. pneumoniae isolates belonged to two clone patterns. Multilocus sequence typing showed that the four isolates of K. pneumoniae belonged to two sequence types: ST 23 and ST 351. Conjugation studies with Escherichia coli (EC600) resulted in the transfer of reduced carbapenem susceptibility compared with that of the original isolates. Plasmid restriction analysis and hybridization experiment showed that the five isolates of Enterobacteriaceae carried a common 50 kb blaKPC-2-encoding plasmid.

Detection of a Common Plasmid Carrying blaKPC-2 in Enterobacteriaceae Isolates from Distinct Cities in China

Objectives: The multiresistance plasmid pKP96 from Klebsiella pneumoniae was sequenced completely and analysed concerning its genetic environment and distributing of antimicrobial resistance genes. Methods: The complete sequence of the plasmid was determined using a whole-genome shotgun approach. MICs of 13 antimicrobial agents were determined using Etests. A conjugation experiment was performed in liquid medium. Results: pKP96 is a circularly closed 67 850 bp multiresistance plasmid with an IncN incompatibility group. Seventy putative genes were identified according to the annotation of the finished sequence. The backbone region of the plasmid, comprising the conjugal transfer and plasmid replication regions, showed 91% identity to the IncN plasmid R46. Several mobile elements were found to be inserted into pKP96 together with antimicrobial resistance genes, including qnrA1, aac(6 0 )-Ib-cr and blaCTX-M-24. Conclusions: Plasmid pKP96 is a chimera that has acquired its multiple antimicrobial resistance determinants horizontally from different sources. It may have evolved from an ancestor plasmid similar to R46 through the stepwise events of integration or recombination.

Complete nucleotide sequence of pKP96, a 67850 bp multiresistance plasmid encoding qnrA1, aac(6 0 )-Ib-cr and blaCTX-M-24 from

Forty-seven vancomycin-resistant Enterococcus (VRE) strains were isolated from clinical samples in 13 Zhejiang hospitals and fecal samples from ICU patients in a large teaching hospital in China No VRE isolates were detected in healthy human subjects CC17 was the main clonal complex in clinical Enterococcus faecium isolates but not in isolates from healthy human subjects Novel vancomycin-resistance transposons were detected among VRE strains This is the first report demonstrating insertion of tnpA and fosB genes in the vanRS–vanH intergenic region of Tn1546 leading to coresistance to vancomycin and fosfomycin The four plasmid replicon types (pRUM, pRE25, pEF418, and pB82) were more common in VRE isolates, suggesting their association with vancomycin resistance and nosocomial transmission The prevalence rate of vancomycin-resistant Staphylococcus aureus–related Inc18-like plasmid, pIP501, in VRE was 213% The prevalence of the esp gene among VRE isolates was high (766%) In several VRE strains, the

Novel Vancomycin-Resistance Transposon, Plasmid Replicon Types, and Virulence Factors of Vancomycin-Resistant Enterococci in Zhejiang, China

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Ping Shen

Author Tools

Chat about Author

Papers

Detection of a Common Plasmid Carrying blaKPC-2 in Enterobacteriaceae Isolates from Distinct Cities in China

Complete nucleotide sequence of pKP96, a 67850 bp multiresistance plasmid encoding qnrA1, aac(6 0 )-Ib-cr and blaCTX-M-24 from

Novel Vancomycin-Resistance Transposon, Plasmid Replicon Types, and Virulence Factors of Vancomycin-Resistant Enterococci in Zhejiang, China