Fecal Carriage and Molecular Epidemiology of mcr-1-Harboring Escherichia Coli from Children in Southern China.

Abstract Objective: The increase of multidrug resistant Enterobacteriaceae bacteria has led to reintroduction of colistin for clinical treatments, and colistin has become a last resort for infections caused by multidrug resistant bacteria. Enterobacteriaceae bacteria carrying the mcr-1 gene are majorly related to colistin resistance, which may be the main reason for continued increase in the colistin resistance rate of Enterobacteriaceae. The purpose of this study was to investigate the sequence type and prevalence of bacteria harboring mcr-1 gene in the gut flora of children in Southern China. Method: Fecal samples (n=2632) of children from 3 medical centers in Guangzhou were cultured for Escherichia coli (E. coli). The mcr-1-harboring isolates were screened by Polymerase chain reaction (PCR). The colistin resistance transfer frequency was studied by conjugation experiments. DNA sequencing of seven housekeeping genes were used for multi locus sequence typing analysis (MLST).Result: PCR indicated that 21 isolates from the 2632 E. coli (0.80%) were positive for mcr-1; these strains were resistant to colistin. Conjugation experiment indicated that 18 of the mcr-1-harboring isolates could transfer colistin resistance phenotypes to E. coli J53. MLST analysis revealed that the 21 isolates were divided into 18 sequence types (STs); ST69 was the most common (14.3%), followed by ST58 (9.5%). Conclusion: These results demonstrate the colonisation dynamics and molecular epidemiology of mcr-1-harboring E. coli in the gut flora of children in Southern China, and the mcr-1 gene can be horizontally transmitted within species, it is necessary to monitor the mcr-1-harboring bacteria in children.

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611. Fosfomycin Resistance of Multidrug-Resistant Escherichia coli and Mechanisms of Fosfomycin Resistance

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.680 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S285-S285

Author(s):

Hyeri Seok ◽

Ji Hoon Jeon ◽

Hee Kyoung Choi ◽

Won Suk Choi ◽

Dae Won Park ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Agents ◽

Multidrug Resistant ◽

Resistance Rate ◽

Coli Strain ◽

Resistant Bacteria ◽

E Coli ◽

Broth Microdilution Method ◽

Fosfomycin Resistance

Abstract Background Fosfomycin is one of the antibiotics that may be a candidate for the next-generation antimicrobial agents againt multidrug-resistant bacteria. To date, it is known that the resistance rate is not high for Escherichia coli. However, it is necessary to update the fosfomycin resistance rates in E. coli according to the studies that extended spectrum β-lactamase (ESBL) producing E. coli strains are highly resistance to fosfomycin. We evaluated the resistance rate of fosfomycin, the resistant mechanism of fosfomycin in E. coli, and the activity of fosfomycin against susceptible and resistant strains of E. coli. Methods A total of 283 clinical isolates was collected from patients with Escherichia coli species during the period of January 2018 to June 2018, in three tertiary hospitals of Republic of Korea. In vitro antimicrobial susceptibility tests were performed in all E. coli isolates using the broth microdilution method according to the Clinical and Laboratory Standard Institute (CLSI). Multilocus sequence typing (MLST) of the Oxford scheme was conducted to determine the genotypes of E. coli isolated. Fosfomycin genes were investigated for all fosfomycin-resistant E. coli strains. Results The overall resistance rate to fosfomycin was 10.2%, compared with 53.4%, 46.3%, 41.3%, 31.1%, 10.6%, 2.5%, and 2.1% for ciprofloxacin, cefixime, cefepime, piperacillin/tazobactam, colistin, ertapenem, and amikacin, respectively. The 29 fosfomycin-resistant isolates did not show a clonal pattern on the phylogenetic tree. MurA and glp genes were identified in all strains. FosA3 were identified in two strains and uhp gene were identified in 4 strains. In time-kill curve studies, fosfomycin was more bactericidal than cefixime against all sensitive E. coli strain. Morever, fosfomycin was more bactericidal than piperacillin/tazobactam against ESBL-producing E. coli strain. Conclusion The resistant rate of fosfomycin to E. coli is still low. Fosfomycin was active against E. coli including ESBL producing strains. Disclosures All authors: No reported disclosures.

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Emergence of mobilized colistin resistance-1 in multidrug-resistant Klebsiella pneumoniae and Escherichia coli isolates from the Henan province in China: a multicentre study

10.21203/rs.3.rs-285784/v1 ◽

2021 ◽

Author(s):

Yi Li ◽

Wenjuan Yan ◽

Qi Zhang ◽

Nan Jing ◽

Youhua Yuan ◽

...

Keyword(s):

Escherichia Coli ◽

Klebsiella Pneumoniae ◽

Ethylenediaminetetraacetic Acid ◽

Multidrug Resistant ◽

Resistance Rate ◽

Henan Province ◽

Close Monitoring ◽

Colistin Resistance ◽

E Coli ◽

Carbapenem Resistant

Abstract Background The increased clinical use of polymyxin led to the emergence of polymyxin-resistant strains, especially those carrying plasmid-borne mobilized colistin resistance (mcr) gene variants. In this study, we aimed to evaluate the prevalence and characteristics of polymyxin-resistant Klebsiella pneumoniae and Escherichia coli isolates from the Henan province, China. Methods A total of 16 polymyxin-resistant isolates among 2301 E. coli and K. pneumoniae isolates collected in 6 local hospitals in the Henan province were studied. The isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and the minimum inhibitory concentrations (MICs) were determined using the microbroth dilution technique. Polymyxin-resistant isolates were further analysed for mcr-1 and carbapenemase-mediated resistance using the modified carbapenem inactivation method, the ethylenediaminetetraacetic acid-modified carbapenem inactivation method, and polymerase chain reaction. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were performed to disclose the phylogenetic relationships of the polymyxin-resistant isolates. The clinical characteristics of patients infected with the polymyxin-resistant isolates were also retrospectively analysed. Results 5/1499 (0.3%) and 11/802 (1.4%) E. coli and K. pneumoniae isolates, respectively, were polymyxin-resistant. The MICs of polymyxin were in the range of 4–64 µg/mL and all of the 16 polymyxin-resistant isolates were susceptible to tigecycline. Additionally, four of the five E. coli polymyxin-resistant isolates were mcr-1 positive; one of them was also carbapenem-resistant, carrying blaNDM−5. Conversely, only 1/11 K. pneumoniae isolates was mcr-1 positive, while 9 polymyxin-resistant isolates were also carbapenem-resistant (PRCRKP), carrying blaKPC−2 but not mcr-1. MLST results showed that the five E. coli isolates belonged to four sequence types (STs), including ST2, ST132, ST632, and ST983, while all PRCRKP isolates belonged to ST11. However, all 16 isolates showed different PFGE types using a genetic similarity of ≥ 95%. Furthermore, 33.3% (5/15) of the patients carrying polymyxin-resistant K. pneumoniae isolates showed a history of polymyxin use, and 10/15 (66.7%) patients displayed good clinical outcomes. Conclusion The polymyxin resistance rate of K. pneumoniae was slightly higher than that of E. coli in the Henan province; however, mcr-1 was only detected in one K. pneumoniae isolate. Thus, close monitoring is needed to prevent and control the spread of PRCRKP.

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Occurrence of KPC-Producing Escherichia coli in Psittaciformes Rescued from Trafficking in Paraíba, Brazil

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18010095 ◽

2020 ◽

Vol 18 (1) ◽

pp. 95

Author(s):

Gedean Galdino da Cruz Silva ◽

Eloiza Helena Campana ◽

Priscylla Carvalho Vasconcelos ◽

Núbia Michelle Vieira da Silva ◽

Lauro Santos Filho ◽

...

Keyword(s):

Escherichia Coli ◽

Resistance Genes ◽

Clinical Importance ◽

Multidrug Resistant ◽

Resistance Rate ◽

Northeastern Brazil ◽

Resistant Bacteria ◽

Extended Spectrum Beta Lactamase ◽

E Coli ◽

Klebsiella Pneumoniae Carbapenemase

The emergence and spread of antimicrobial resistance pose a threat to public health globally. Antibiotic-resistant bacteria and genes can disseminate among environments, animals and humans. Therefore, investigation into potential reservoirs of multidrug-resistant bacteria is of great importance to the understanding of putative transmission routes of resistant bacteria and resistance genes. This study aimed to report the occurrence of Escherichia coli harboring the Klebsiella pneumoniae carbapenemase-producing gene (blaKPC) in Psittaciformes rescued from wildlife trafficking in Paraíba State, Brazil. Cloacal swabs were collected from thirty birds and cultured by conventional microbiology using MacConkey and serum tryptone glucose glycerol (STGG) media supplemented with selective antimicrobials. E. coli isolates (n = 43) were identified by phenotypic tests and confirmed by MALDI-TOF. Antimicrobial susceptibility profiles were determined by means of Kirby–Bauer test. All isolates were further screened for extended-spectrum beta-lactamase (ESBL) production, and putative genes encoding ESBL were investigated by PCR. Additionally, blaKPC-harboring strains were genotyped by REP-PCR. A total of 43 E. coli phenotypically resistant isolates were recovered. The highest resistance rate was observed against ciprofloxacin. Among the resistance genes, only blaKPC was found in seven different birds from three species. According to the genotyping, these seven isolates belonged to four different strains. To date, this is the first report on the occurrence of KPC-E. coli in Psittaciformes rescued from trafficking in Northeastern Brazil. Due to the high clinical importance of KPC-E. coli, our findings suggest that wild animals in captivity at wildlife rescue centers can play a role as reservoirs of bacteria that are resistance to Critically Important antimicrobials in human medicine.

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Three-Year Trend in Escherichia coli Antimicrobial Resistance among Children’s Urine Cultures in an Italian Metropolitan Area

Children ◽

10.3390/children8070597 ◽

2021 ◽

Vol 8 (7) ◽

pp. 597

Author(s):

Luca Pierantoni ◽

Laura Andreozzi ◽

Simone Ambretti ◽

Arianna Dondi ◽

Carlotta Biagi ◽

...

Keyword(s):

Escherichia Coli ◽

Metropolitan Area ◽

Bacterial Infections ◽

Asymptomatic Bacteriuria ◽

Multidrug Resistant ◽

Resistance Rate ◽

First Line ◽

E Coli ◽

First Line Therapy ◽

Tract Infections

Urinary tract infections (UTIs) are among the most common bacterial infections in children, and Escherichia coli is the main pathogen responsible. Several guidelines, including the recently updated Italian guidelines, recommend amoxicillin-clavulanic acid (AMC) as a first-line antibiotic therapy in children with febrile UTIs. Given the current increasing rates of antibiotic resistance worldwide, this study aimed to investigate the three-year trend in the resistance rate of E. coli isolated from pediatric urine cultures (UCs) in a metropolitan area of northern Italy. We conducted a retrospective review of E. coli-positive, non-repetitive UCs collected in children aged from 1 month to 14 years, regardless of a diagnosis of UTI, catheter colonization, urine contamination, or asymptomatic bacteriuria. During the study period, the rate of resistance to AMC significantly increased from 17.6% to 40.2% (p < 0.001). Ciprofloxacin doubled its resistance rate from 9.1% to 16.3% (p = 0.007). The prevalence of multidrug-resistant E. coli rose from 3.9% to 9.2% (p = 0.015). The rate of resistance to other considered antibiotics remained stable, as did the prevalence of extended spectrum beta-lactamases and extensively resistant E. coli among isolates. These findings call into question the use of AMC as a first-line therapy for pediatric UTIs in our population, despite the indications of recent Italian guidelines.

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In vitro activity of antimicrobial peptide CDP-B11 alone and in combination with colistin against colistin-resistant and multidrug-resistant Escherichia coli

Scientific Reports ◽

10.1038/s41598-021-81140-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kaitlin S. Witherell ◽

Jason Price ◽

Ashok D. Bandaranayake ◽

James Olson ◽

Douglas R. Call

Keyword(s):

Escherichia Coli ◽

Antimicrobial Peptide ◽

Membrane Integrity ◽

Antibiotic Resistance Genes ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Multidrug Resistant Bacteria ◽

E Coli ◽

Minimal Media

AbstractMultidrug-resistant bacteria are a growing global concern, and with increasingly prevalent resistance to last line antibiotics such as colistin, it is imperative that alternative treatment options are identified. Herein we investigated the mechanism of action of a novel antimicrobial peptide (CDP-B11) and its effectiveness against multidrug-resistant bacteria including Escherichia coli #0346, which harbors multiple antibiotic-resistance genes, including mobilized colistin resistance gene (mcr-1). Bacterial membrane potential and membrane integrity assays, measured by flow cytometry, were used to test membrane disruption. Bacterial growth inhibition assays and time to kill assays measured the effectiveness of CDP-B11 alone and in combination with colistin against E. coli #0346 and other bacteria. Hemolysis assays were used to quantify the hemolytic effects of CDP-B11 alone and in combination with colistin. Findings show CDP-B11 disrupts the outer membrane of E. coli #0346. CDP-B11 with colistin inhibits the growth of E. coli #0346 at ≥ 10× lower colistin concentrations compared to colistin alone in Mueller–Hinton media and M9 media. Growth is significantly inhibited in other clinically relevant strains, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. In rich media and minimal media, the drug combination kills bacteria at a lower colistin concentration (1.25 μg/mL) compared to colistin alone (2.5 μg/mL). In minimal media, the combination is bactericidal with killing accelerated by up to 2 h compared to colistin alone. Importantly, no significant red blood hemolysis is evident for CDP-B11 alone or in combination with colistin. The characteristics of CDP-B11 presented here indicate that it can be used as a potential monotherapy or as combination therapy with colistin for the treatment of multidrug-resistant infections, including colistin-resistant infections.

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Molecular survey of mcr1 and mcr2 plasmid mediated colistin resistance genes in Escherichia coli isolates of animal origin in Iran

BMC Research Notes ◽

10.1186/s13104-021-05519-6 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Kayhan Ilbeigi ◽

Mahdi Askari Badouei ◽

Hossein Vaezi ◽

Hassan Zaheri ◽

Sina Aghasharif ◽

...

Keyword(s):

Escherichia Coli ◽

Resistance Genes ◽

Companion Animals ◽

Multidrug Resistant ◽

Animal Origin ◽

Colistin Resistance ◽

E Coli ◽

High Level ◽

Farming Industry

Abstract Objectives The emergence of colistin-resistant Enterobacteriaceae from human and animal sources is one of the major public health concerns as colistin is the last-resort antibiotic for treating infections caused by multidrug-resistant Gram-negative bacteria. We aimed to determine the prevalence of the prototype widespread colistin resistance genes (mcr-1 and mcr-2) among commensal and pathogenic Escherichia coli strains isolated from food-producing and companion animals in Iran. Results A total of 607 E. coli isolates which were previously collected from different animal sources between 2008 and 2016 used to uncover the possible presence of plasmid-mediated colistin resistance genes (mcr-1 and mcr-2) by PCR. Overall, our results could not confirm the presence of any mcr-1 or mcr-2 positive E. coli among the studied isolates. It is concluded that despite the important role of food-producing animals in transferring the antibiotic resistance, they were not the main source for carriage of mcr-1 and mcr-2 in Iran until 2016. This study suggests that the other mcr variants (mcr-3 to mcr-9) might be responsible for conferring colistin resistance in animal isolates in Iran. The possible linkage between pig farming industry and high level of mcr carriage in some countries needs to be clarified in future prospective studies.

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Surveillance of antimicrobial-resistant Escherichia coli in Sheltered dogs in the Kanto Region of Japan

Scientific Reports ◽

10.1038/s41598-021-04435-w ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Akihisa Hata ◽

Noboru Fujitani ◽

Fumiko Ono ◽

Yasuhiro Yoshikawa

Keyword(s):

Escherichia Coli ◽

Multidrug Resistant ◽

Quinolone Resistance ◽

Resistant Bacteria ◽

Animal Shelters ◽

E Coli ◽

Chiba Prefecture ◽

Shelter Dogs ◽

Kanagawa Prefecture ◽

Kanto Region

AbstractThere is a lack of an established antimicrobial resistance (AMR) surveillance system in animal welfare centers. Therefore, the AMR prevalence in shelter dogs is rarely known. Herein, we conducted a survey in animal shelters in Chiba and Kanagawa prefectures, in the Kanto Region, Japan, to ascertain the AMR status of Escherichia coli (E. coli) prevalent in shelter dogs. E. coli was detected in the fecal samples of all 61 and 77 shelter dogs tested in Chiba and Kanagawa, respectively. The AMR was tested against 20 antibiotics. E. coli isolates derived from 16.4% and 26.0% of samples from Chiba and Kanagawa exhibited resistance to at least one antibiotic, respectively. E. coli in samples from Chiba and Kanagawa prefectures were commonly resistant to ampicillin, piperacillin, streptomycin, kanamycin, tetracycline, and nalidixic acid; that from the Kanagawa Prefecture to cefazolin, cefotaxime, aztreonam, ciprofloxacin, and levofloxacin and that from Chiba Prefecture to chloramphenicol and imipenem. Multidrug-resistant bacteria were detected in 18 dogs from both regions; β-lactamase genes (blaTEM, blaDHA-1, blaCTX-M-9 group CTX-M-14), quinolone-resistance protein genes (qnrB and qnrS), and mutations in quinolone-resistance-determining regions (gyrA and parC) were detected. These results could partially represent the AMR data in shelter dogs in the Kanto Region of Japan.

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Retail Chicken Carcasses as a Reservoir of Antimicrobial- Resistant Escherichia coli

University of the Future: Re-Imagining Research and Higher Education ◽

10.29117/quarfe.2020.0115 ◽

2020 ◽

Author(s):

Nahla Omer Eltai ◽

Hadi M. Yassine ◽

Sara H. Al-Hadidi ◽

Tahra ElObied ◽

Asmaa A. Al Thani ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Resistance ◽

Growth Promotion ◽

Multidrug Resistant ◽

Chicken Meat ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

E Coli ◽

Inappropriate Use ◽

Esbl Producers

The dissemination of antimicrobial resistance (AMR) bacteria has been associated with the inappropriate use of antibiotics in both humans and animals and with the consumption of food contaminated with resistant bacteria. In particular, the use of antibiotics as prophylactic and growth promotion purposes in food-producing animals has rendered many of the antibiotics ineffective. The increased global prevalence of AMR poses a significant threat to the safety of the world’s food supply. Objectives: This study aims at determining the prevalence of antibiotic-resistant Escherichia coli (E. coli) isolated from local and imported retail chicken meat in Qatar. Methodology: A total of 270 whole chicken carcasses were obtained from three different hypermarket stores in Qatar. A total of 216 E. coli were isolated and subjected to antibiotic susceptibility testing against 18 relevant antibiotics using disc diffusion and micro- dilution methods. Furthermore, extended-spectrum β-lactamase (ESBL) production was determined via a double-disc synergetic test. Isolates harboring colistin resistance were confirmed using multiplex-PCR and DNA sequencing. Results: Nearly 89% (192/216) of the isolates were resistant to at least one antibiotics. In general, isolates showed relatively higher resistance to sulfamethoxazole (62%), tetracycline (59.7%), ampicillin and trimethoprim (52.3%), ciprofloxacin (47.7%), cephalothin, and colistin (31.9%). On the other hand, less resistance was recorded against amoxicillin/clavulanic acid (6%), ceftriaxone (5.1%), nitrofurantoin (4.2%) and piperacillin/tazobactam (4.2%), cefepime (2.3%), meropenem (1.4%), ertapenem (0.9%), and amikacin (0.9%). Nine isolates (4.2%) were ESBL producers. Furthermore, 63.4% were multidrug-resistant (MDR). The percentage of MDR, ESBL producers, and colistin-resistant isolates was significantly higher among local isolates compared to imported chicken samples. Conclusion: We reported a remarkably high percentage of the antibiotic-resistant E. coli in chicken meat sold at retail in Qatar. The high percentage of MDR and colistin isolates is troublesome to the food safety of raw chicken meat and the potential of antibiotic resistance spread to public health. Our findings support the need for the implementation of one health approach to address the spread of antimicrobial resistance and the need for a collaborative solution.

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Extraintestinal pathogenic Escherichia coli in Saudi Arabia: A review of antimicrobial resistance and molecular epidemiology

Tropical Journal of Pharmaceutical Research ◽

10.4314/tjpr.v19i2.30 ◽

2020 ◽

Vol 19 (2) ◽

pp. 447-453

Author(s):

Abdulaziz Alqasim

Keyword(s):

Escherichia Coli ◽

Saudi Arabia ◽

Antimicrobial Resistance ◽

Molecular Epidemiology ◽

Bloodstream Infections ◽

Epidemiological Studies ◽

Colistin Resistance ◽

E Coli ◽

Extended Spectrum ◽

Pathogenic Escherichia Coli

Extra-intestinal pathogenic Escherichia coli (ExPEC) is commonly associated with causing urinary tract and bloodstream infections. Over the past two decades, the antimicrobial resistance of ExPEC has increasingly been reported [1]. Given that Saudi Arabia annually hosts mass religious events, such as Hajj, this review investigated several aspects of antimicrobial resistance of ExPEC in this country including the current prevalence of resistance and molecular epidemiology of ExPEC isolates. Generally, the overall prevalence of antibiotic resistance of ExPEC in Saudi Arabia is on increase. The current emergence of colistin resistance in ExPEC represents a major challenge to public health. Local molecular epidemiological studies have shown the dominance of E. coli sequence type 131 (E. coli ST131) over other major ExPEC STs. This is an important observation given that this clone has been associated with high multidrug resistance and extended-spectrum β-lactamases carriage. To reduce the burden of this resistance in the future, it would be crucial to avoid uncontrolled use of antibiotics in either clinical settings or animal food industry. Keywords: Extra-intestinal pathogenic Escherichia coli, Antimicrobial resistance, ST131, Saudi Arabia, Colistin resistance, Extended-spectrum β-lactamases

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Heterogeneous and Flexible Transmission ofmcr-1in Hospital-AssociatedEscherichia coli

mBio ◽

10.1128/mbio.00943-18 ◽

2018 ◽

Vol 9 (4) ◽

Cited By ~ 23

Author(s):

Yingbo Shen ◽

Zuowei Wu ◽

Yang Wang ◽

Rong Zhang ◽

Hong-Wei Zhou ◽

...

Keyword(s):

Escherichia Coli ◽

Genomic Analysis ◽

Multidrug Resistant ◽

Fluoroquinolone Resistance ◽

Gram Negative Bacteria ◽

Colistin Resistance ◽

Gram Negative ◽

Content Type ◽

E Coli ◽

Genes Encoding

ABSTRACTThe recent emergence of a transferable colistin resistance mechanism, MCR-1, has gained global attention because of its threat to clinical treatment of infections caused by multidrug-resistant Gram-negative bacteria. However, the possible transmission route ofmcr-1amongEnterobacteriaceaespecies in clinical settings is largely unknown. Here, we present a comprehensive genomic analysis ofEscherichia coliisolates collected in a hospital in Hangzhou, China. We found thatmcr-1-carrying isolates from clinical infections and feces of inpatients and healthy volunteers were genetically diverse and were not closely related phylogenetically, suggesting that clonal expansion is not involved in the spread ofmcr-1. Themcr-1gene was found on either chromosomes or plasmids, but in most of theE. coliisolates,mcr-1was carried on plasmids. The genetic context of the plasmids showed considerable diversity as evidenced by the different functional insertion sequence (IS) elements, toxin-antitoxin (TA) systems, heavy metal resistance determinants, and Rep proteins of broad-host-range plasmids. Additionally, the genomic analysis revealed nosocomial transmission ofmcr-1and the coexistence ofmcr-1with other genes encoding β-lactamases and fluoroquinolone resistance in theE. coliisolates. These findings indicate thatmcr-1is heterogeneously disseminated in both commensal and pathogenic strains ofE. coli, suggest the high flexibility of this gene in its association with diverse genetic backgrounds of the hosts, and provide new insights into the genome epidemiology ofmcr-1among hospital-associatedE. colistrains.IMPORTANCEColistin represents one of the very few available drugs for treating infections caused by extensively multidrug-resistant Gram-negative bacteria. The recently emergentmcr-1colistin resistance gene threatens the clinical utility of colistin and has gained global attention. Howmcr-1spreads in hospital settings remains unknown and was investigated by whole-genome sequencing ofmcr-1-carryingEscherichia coliin this study. The findings revealed extraordinary flexibility ofmcr-1in its spread among genetically diverseE. colihosts and plasmids, nosocomial transmission ofmcr-1-carryingE. coli, and the continuous emergence of novel Inc types of plasmids carryingmcr-1and newmcr-1variants. Additionally,mcr-1was found to be frequently associated with other genes encoding β-lactams and fluoroquinolone resistance. These findings provide important information on the transmission and epidemiology ofmcr-1and are of significant public health importance as the information is expected to facilitate the control of this significant antibiotic resistance threat.

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