Genetic analysis of the first mcr-1 positive Escherichia coli isolate collected from an outpatient in Chile

Isolation of an Extensively Drug-Resistant Pseudomonas aeruginosa exoS+/O4 Strain Belonging to the "High-Risk" Clone ST654 and Coproducer of NDM-1 and the Novel VIM-80

The aim of this study was to investigate the genomic features of an extensively drug-resistant (XDR) Pseudomonas aeruginosa isolate (P-469) emerging in Chile. Antibiotic susceptibility was determined by disk diffusion and "colistin agar" test. Whole-genome sequencing (WGS) was performed by the Illumina NextSeq 2000 platform, and epidemiologically and clinically relevant data (i.e., sequence-type, serotype, mobile genetic elements, virulome, resistome, plasmidome, prophages, and CRISPR-Cas systems) were retrieved using multiple bioinformatic tools. The P-469 strain displayed an XDR profile, remaining susceptible to colistin. Genomic analysis revealed that this isolate belonged to the "high-risk" clone ST654 (CC654), serotype O4, and genotype exoS⁺. Strikingly, two CRISPR-Cas systems, five intact prophages sequences, and a broad resistome that included bla_NDM-1 and the novel bla_VIM-80 carbapenemase genes were predicted. Our results revealed the genomic characteristics of P. aeruginosa belonging to the high-risk clone ST654/O4 coproducing NDM-1 and VIM-80 in Chile, supporting that genomic surveillance is necessary to track the emergence and spread of epidemiologically successful WHO's critical priority pathogens in order to prevent their rapid dissemination.

Rapid Detection of Multi-Resistance Strains Carrying mcr-1 Gene Using Recombinase-Aided Amplification Directly on Clinical Samples

With the increasingly severe problem of bacterial resistance, colistin, as the last line of defense, has attracted attention again. Mobile colistin resistance (mcr-1) gene is involved in the horizontal transmission of colistin resistance in Gram-negative bacteria (GNB), which is a serious threat to human health. Therefore, rapid detection of mcr-1 gene presence in clinical samples is crucial. In this study, a Recombinase-aided amplification(RAA) method for mcr-1 was successfully constructed, with sensitivity of 20 copies/reaction. In addition, amplification signal could only be detected in the strain containing mcr-1 gene among 14 different bacterial species. The method was then used to test a total of 672 clinical samples from a pediatric hospital in Beijing. Five strains harbored mcr-1 genes were isolated from mcr-1-positive clinical samples and identified as Escherichia coli. Multi-locus sequence typing (MLST) analysis showed that the five E. coli belonged to different ST types. Notably, the mcr-1 gene from the isolates could be transferred conjugately to the recipient strain E. coli J53, with highest transfer efficiency up to 57–58%, suggesting that the mcr-1 gene was located on the plasmid. These findings showed that the RAA assay has potential to be a rapid and sensitive mcr-1 gene screening test for clinical samples, and mcr-1 could be transmitted vertically and horizontally between and within bacterial species in a plasmid-mediated manner.

Updates on the global dissemination of colistin-resistant Escherichia coli: An emerging threat to public health

Colistin drug resistance is an emerging public health threat worldwide. The adaptability, existence and spread of colistin drug resistance in multiple reservoirs and ecological environmental settings is significantly increasing the rate of occurrence of multidrug resistant (MDR) bacteria such as Escherichia coli (E. coli). Here, we summarized the reports regarding molecular and biological characterization of mobile colistin resistance gene (mcr)-positive E. coli (MCRPEC), originating from diverse reservoirs, including but not limited to humans, environment, waste water treatment plants, wild, pets, and food producing animals. The MCRPEC revealed the abundance of clinically important resistance genes, which are responsible for MDR profile. A number of plasmid replicon types such as IncI2, IncX4, IncP, IncX, and IncFII with a predominance of IncI2 were facilitating the spread of colistin resistance. This study concludes the distribution of multiple sequence types of E. coli carrying mcr gene variants, which are possible threat to "One Health" perspective. In addition, we have briefly explained the newly known mechanisms of colistin resistance i.e. plasmid-encoded resistance determinant as well as presented the chromosomally-encoded resistance mechanisms. The transposition of ISApl1 into the chromosome and existence of intact Tn6330 are important for transmission and stability for mcr gene. Further, genetic environment of co-localized mcr gene with carbapenem-resistance or extended-spectrum β-lactamases genes has also been elaborated, which is limiting human beings to choose last resort antibiotics. Finally, environmental health and safety control measures along with spread mechanisms of mcr genes are discussed to avoid further propagation and environmental hazards of colistin resistance.

Global Prevalence and Molecular Epidemiology of mcr-Mediated Colistin Resistance in Escherichia coli Clinical Isolates: A Systematic Review

BACKGROUND AND AIM

The continuing rise in infections caused by multi-drug resistant (MDR) bacteria is one of the most serious public health issues in today's societies. Colistin is a last-resort antimicrobial medication used to treat infections caused by MDR gram-negative bacteria; therefore resistance to this antibiotic is extremely hazardous. The current study aimed to evaluate the global prevalence and distribution of colistin resistance genes among human clinical isolates of Escherichia coli (E. coli) as a systematic review.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched. For further evaluation, all original English-language articles that demonstrated colistin resistance in E. coli clinical isolates published between 2000 and 2020 were examined.

RESULTS

Out of 4857 initial articles, after various stages of review and evaluation, 190 related articles were selected. More than 79 % of the publications selected in this research were published from 2014 to 2020. In Asia, Europe, America, Africa, and Oceania, the prevalence of mobilized colistin resistance (mcr) producing colistin-resistant E. coli was 66.72%, 25.48%, 5.19%, 2.27%, and 0.32 %, respectively.

CONCLUSION

The recent widespread spreading of E. coli strains harboring mcr conferring colistin resistance, especially in Asia and Europe, is concerning and needs more attention.

Global colistin use: A review of the emergence of resistant Enterobacterales and the impact on their genetic basis

The dramatic global rise of MDR and XDR Enterobacterales in human medicine forced clinicians to the reintroduction of colistin as last-resort drug. Meanwhile, colistin is used in the veterinary medicine since its discovery, leading to a steadily increasing prevalence of resistant isolates in the livestock and meat-based food sector. Consequently, transmission of resistant isolates from animals to humans, acquisition via food and exposure to colistin in the clinic are reasons for the increased prevalence of colistin-resistant Enterobacterales in humans in the last decades. Initially, resistance mechanisms were caused by mutations in chromosomal genes. However, since the discovery in 2015, the focus has shifted exclusively to mobile colistin resistances (mcr). This review will advance the understanding of chromosomal-mediated resistance mechanisms in Enterobacterales. We provide an overview about genes involved in colistin resistance and the current global situation of colistin-resistant Enterobacterales. A comparison of the global colistin use in veterinary and human medicine highlights the effort to reduce colistin sales in veterinary medicine under the One Health approach. In contrast, it uncovers the alarming rise in colistin consumption in human medicine due to the emergence of MDR Enterobacterales, which might be an important driver for the increasing emergence of chromosome-mediated colistin resistance.

Genomic features of a high-risk mcr-1.1-positive Escherichia coli ST10 isolated from cattle farm environment

The environment plays an important role in the dissemination of clinically relevant antimicrobial-resistant bacteria and genes. In this study, we described genomic features of a plasmid-mediated colistin-resistant mcr-1-positive Escherichia coli strains (PK-3225) isolated from a dairy farm wastewater sample. After initial isolation and PCR detection of mcr-1-positive E. coli, whole-genome sequencing was performed using Illumina Hiseq 2500 followed by in silico analysis. Genetic context surrounding the mcr-1 gene was determined and SNP-based phylogenomic analysis was performed. Furthermore, plasmid analysis and conjugation assays were performed to determine transferability of mcr-1. E. coli PK-3225 belonged to ST10 and carried a broad resistome that included colistin (mcr-1), beta-lactam (bla_TEM-IB), tetracycline (tetB), phenicol (catA1), macrolide (mdfA), trimethoprim (dfrA17), aminoglycosides (aadA5, aph(3")-Ib, aph(6)-Id), and sulphonamide (sul2) resistance genes. The draft genome of E. coli calculated as 4.9 Mbp. Conjugation experiment showed successful transfer of the mcr-1 gene to E. coli recipient strain J53. In silico analysis showed that mcr-1 was located on IncI2 plasmid of > 59 kb in length, with the nikB-mcr-1-pap2 gene array, and lack ISApl1. The phylogenomic analysis revealed that the PK-3225 was closely related to human ST10 E. coli from Brazil and USA. To our knowledge, this is the first draft genome sequence of mcr-1 carrying E. coli isolated from the farm environment in Pakistan. Considering the high burden of colistin resistance in Pakistan, presence of pandemic high-risk E. coli clones in the environment requires strict surveillance.

Polymyxin resistance in Enterobacterales: overview and epidemiology in the Americas

The worldwide spread of carbapenem- and polymyxin-resistant Enterobacterales represents an urgent public-health threat. However, for most countries in the Americas, the available data are limited, although Latin America has been suggested as a silent spreading reservoir for isolates carrying plasmid-mediated polymyxin resistance mechanisms. This work provides an overall update on polymyxin and polymyxin resistance and focuses on uses, availability and susceptibility testing. Moreover, a comprehensive review of the current polymyxin resistance epidemiology in the Americas is provided. We found that reports in the English and Spanish literature show widespread carbapenemase-producing and colistin-resistant Klebsiella pneumoniae in the Americas determined by the clonal expansion of the pandemic clone ST258 and mgrB-mediated colistin resistance. In addition, widespread IncI2 and IncX4 plasmids carrying mcr-1 in Escherichia coli come mainly from human sources; however, plasmid-mediated colistin resistance in the Americas is underreported in the veterinary sector. These findings demonstrate the urgent need for the implementation of polymyxin resistance surveillance in Enterobacterales as well as appropriate regulatory measures for antimicrobial use in veterinary medicine.

Global trends and current status in colistin resistance research: a bibliometric analysis (1973-2019)

Background: Colistin resistance is a major breach in our last line of defense and without urgent action, we are heading for a post-antibiotic era, in which common infections and minor injuries can once again kill. To the best of our knowledge, the use of the bibliometric analytical technique for examining colistin resistance-related research does not exist in the literature. Methods: Here, we analyze and present bibliometric indicators of the global literature in colistin resistance research. The Scopus database was searched for articles on colistin resistance. The articles retrieved were analyzed using the bibliometrix R-package. Results: A total of 1105 publications were retrieved. There was a noticeable increase in the number of publications on colistin resistance research in the past decade. Six journals made up the core zone in colistin research and produced 35.83% of the published articles. The analysis across time-intervals revealed several keywords that had increased or decreased in usage when comparing the interval between 1973-2009 and 2010-2019. Authors' keywords "Acinetobacter baumanii", and " Pseudomonas aeruginosa" were the most frequent encountered during the period of 1973-2009, while " mcr-1", " Enterobacteriaceae", " Escherichia coli", and " Klebsiella pneumoniae" emerged in the past decade. Conclusions: There has been a significant growth in publications on colistin resistance in the past decade, suggesting an urgent need for action by different stakeholders to contain this threat of colistin resistance. Keyword analysis revealed temporal changes in the types of keywords used across time-intervals. These findings summarize a general vision on colistin resistance research and will serve as baseline data for future comparative purposes.