scholarly journals Novel 5-Nitrofuran-Activating Reductase in Escherichia coli

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Vuong Van Hung Le ◽  
Ieuan G. Davies ◽  
Christina D. Moon ◽  
David Wheeler ◽  
Patrick J. Biggs ◽  
...  

ABSTRACT The global spread of multidrug-resistant enterobacteria warrants new strategies to combat these pathogens. One possible approach is the reconsideration of “old” antimicrobials, which remain effective after decades of use. Synthetic 5-nitrofurans such as furazolidone, nitrofurantoin, and nitrofurazone are such a class of antimicrobial drugs. Recent epidemiological data showed a very low prevalence of resistance to this antimicrobial class among clinical Escherichia coli isolates in various parts of the world, forecasting the increasing importance of its uses to battle antibiotic-resistant enterobacteria. However, although they have had a long history of clinical use, a detailed understanding of the 5-nitrofurans’ mechanisms of action remains limited. Nitrofurans are known as prodrugs that are activated in E. coli by reduction catalyzed by two redundant nitroreductases, NfsA and NfsB. Furazolidone, nevertheless, retains relatively significant antibacterial activity in the nitroreductase-deficient ΔnfsA ΔnfsB E. coli strain, indicating the presence of additional activating enzymes and/or antibacterial activity of the unreduced form. Using genome sequencing, genetic, biochemical, and bioinformatic approaches, we discovered a novel 5-nitrofuran-activating enzyme, AhpF, in E. coli. The discovery of a new nitrofuran-reducing enzyme opens new avenues for overcoming 5-nitrofuran resistance, such as designing nitrofuran analogues with higher affinity for AhpF or screening for adjuvants that enhance AhpF expression.

2017 ◽  
Vol 5 (18) ◽  
Author(s):  
Muhammad A. Rehman ◽  
Catherine Carrillo ◽  
François Malouin ◽  
Moussa S. Diarra

ABSTRACT Enterohemorrhagic Escherichia coli serotype O157:H7 is a major cause of foodborne outbreaks and hemolytic-uremic syndrome. Here, we report the draft genome sequences of three antibiotic-resistant E. coli O157:H7 strains isolated from feedlot cattle. These draft genome sequences will aid in the development of sequence-based tools for the detection of virulence and antimicrobial resistance genotypes.


mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Keiko C. Salazar ◽  
Li Ma ◽  
Sabrina I. Green ◽  
Jacob J. Zulk ◽  
Barbara W. Trautner ◽  
...  

ABSTRACT Extraintestinal pathogenic Escherichia coli (ExPEC), often multidrug resistant (MDR), is a leading cause of urinary tract and systemic infections. The crisis of emergent MDR pathogens has led some to propose bacteriophages as a therapeutic. However, bacterial resistance to phage is a concerning issue that threatens to undermine phage therapy. Here, we demonstrate that E. coli sequence type 131, a circulating pandemic strain of ExPEC, rapidly develops resistance to a well-studied and therapeutically active phage (ϕHP3). Whole-genome sequencing of the resisters revealed truncations in genes involved in lipopolysaccharide (LPS) biosynthesis, the outer membrane transporter ompA, or both, implicating them as phage receptors. We found ExPEC resistance to phage is associated with a loss of fitness in host microenvironments and attenuation in a murine model of systemic infection. Furthermore, we constructed a novel phage-bacterium bioreactor to generate an evolved phage isolate with restored infectivity to all LPS-truncated ExPEC resisters. This study suggests that although the resistance of pandemic E. coli to phage is frequent, it is associated with attenuation of virulence and susceptibility to new phage variants that arise by directed evolution. IMPORTANCE In response to the rising crisis of antimicrobial resistance, bacteriophage (phage) therapy has gained traction. In the United States, there have been over 10 cases of largely successful compassionate-use phage therapy to date. The resilience of pathogens allowing their broad antibiotic resistance means we must also consider resistance to therapeutic phages. This work fills gaps in knowledge regarding development of phage resisters in a model of infection and finds critical fitness losses in those resisters. We also found that the phage was able to rapidly readapt to these resisters.


mBio ◽  
2012 ◽  
Vol 3 (6) ◽  
Author(s):  
Sarah L. Warnes ◽  
Callum J. Highmore ◽  
C. William Keevil

ABSTRACTHorizontal gene transfer (HGT) is largely responsible for increasing the incidence of antibiotic-resistant infections worldwide. While studies have focused on HGTin vivo, this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role.Escherichia coli, virulent clone ST131, andKlebsiella pneumoniaeharboring extended-spectrum-β-lactamase (ESBL)blaCTX-M-15and metallo-β-lactamaseblaNDM-1, respectively, exhibited prolonged survival on stainless steel, with approximately 104viable cells remaining from an inoculum of 107 CFU per cm2after 1 month at 21°C. HGT ofblato an antibiotic-sensitive but azide-resistant recipientE. colistrain occurred on stainless steel dry touch surfaces and in suspension but not on dry copper. The conjugation frequency was approximately 10 to 50 times greater and occurred immediately, and resulting transconjugants were more stable with ESBLE. colias the donor cell than withK. pneumoniae, butblaNDM-1transfer increased with time. Transconjugants also exhibited the same resistance profile as the donor, suggesting multiple gene transfer. Rapid death, inhibition of respiration, and destruction of genomic and plasmid DNA of both pathogens occurred on copper alloys accompanied by a reduction inblacopy number. NakedE. coliDNA degraded on copper at 21°C and 37°C but slowly at 4°C, suggesting a direct role for the metal. Persistence of viable pathogenic bacteria on touch surfaces may not only increase the risk of infection transmission but may also contribute to the spread of antibiotic resistance by HGT. The use of copper alloys as antimicrobial touch surfaces may help reduce infection and HGT.IMPORTANCEHorizontal gene transfer (HGT) conferring resistance to many classes of antimicrobials has resulted in a worldwide epidemic of nosocomial and community infections caused by multidrug-resistant microorganisms, leading to suggestions that we are in effect returning to the preantibiotic era. While studies have focused on HGTin vivo, this work investigates whether the ability of pathogens to persist in the environment, particularly on touch surfaces, may also play an important role. Here we show prolonged (several-week) survival of multidrug-resistantEscherichia coliandKlebsiella pneumoniaeon stainless steel surfaces. Plasmid-mediated HGT of β-lactamase genes to an azide-resistant recipientE. colistrain occurred when the donor and recipient cells were mixed together on stainless steel and in suspension but not on copper surfaces. In addition, rapid death of both antibiotic-resistant strains and destruction of plasmid and genomic DNA were observed on copper and copper alloy surfaces, which could be useful in the prevention of infection spread and gene transfer.


Author(s):  
Nahla Omer Eltai ◽  
Hadi M. Yassine ◽  
Sara H. Al-Hadidi ◽  
Tahra ElObied ◽  
Asmaa A. Al Thani ◽  
...  

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.


2017 ◽  
Vol 83 (6) ◽  
Author(s):  
James R. Johnson ◽  
Stephen B. Porter ◽  
Brian Johnston ◽  
Paul Thuras ◽  
Sarah Clock ◽  
...  

ABSTRACT Chicken meat products are hypothesized to be vehicles for transmitting antimicrobial-resistant and extraintestinal pathogenic Escherichia coli (ExPEC) to consumers. To reassess this hypothesis in the current era of heightened concerns about antimicrobial use in food animals, we analyzed 175 chicken-source E. coli isolates from a 2013 Consumer Reports national survey. Isolates were screened by PCR for ExPEC-defining virulence genes. The 25 ExPEC isolates (12% of 175) and a 2:1 randomly selected set of 50 non-ExPEC isolates were assessed for their phylogenetic/clonal backgrounds and virulence genotypes for comparison with their resistance profiles and the claims on the retail packaging label (“organic,” “no antibiotics,” and “natural”). Compared with the findings for non-ExPEC isolates, the group of ExPEC isolates had a higher prevalence of phylogroup B2 isolates (44% versus 4%; P < 0.001) and a lower prevalence of phylogroup A isolates (4% versus 30%; P = 0.001), a higher prevalence of multiple individual virulence genes, higher virulence scores (median, 11 [range, 4 to 16] versus 8 [range, 1 to 14]; P = 0.001), and higher resistance scores (median, 4 [range, 0 to 8] versus 3 [range, 0 to 10]; P < 0.001). All five isolates of sequence type 131 (ST131) were ExPEC (P = 0.003), were as extensively resistant as the other isolates tested, and had higher virulence scores than the other isolates tested (median, 12 [range, 11 to 13] versus 8 [range, 1 to 16]; P = 0.005). Organic labeling predicted lower resistance scores (median, 2 [range, 0 to 3] versus 4 [range, 0 to 10]; P = 0.008) but no difference in ExPEC status or virulence scores. These findings document a persisting reservoir of extensively antimicrobial-resistant ExPEC isolates, including isolates from ST131, in retail chicken products in the United States, suggesting a potential public health threat. IMPORTANCE We found that among Escherichia coli isolates from retail chicken meat products purchased across the United States in 2013 (many of these isolates being extensively antibiotic resistant), a minority had genetic profiles suggesting an ability to cause extraintestinal infections in humans, such as urinary tract infection, implying a risk of foodborne disease. Although isolates from products labeled “organic” were less extensively antibiotic resistant than other isolates, they did not appear to be less virulent. These findings suggest that retail chicken products in the United States, even if they are labeled “organic,” pose a potential health threat to consumers because they are contaminated with extensively antibiotic-resistant and, presumably, virulent E. coli isolates.


mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Yingbo Shen ◽  
Zuowei Wu ◽  
Yang Wang ◽  
Rong Zhang ◽  
Hong-Wei Zhou ◽  
...  

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.


2011 ◽  
Vol 77 (20) ◽  
pp. 7104-7112 ◽  
Author(s):  
Maria Karczmarczyk ◽  
Yvonne Abbott ◽  
Ciara Walsh ◽  
Nola Leonard ◽  
Séamus Fanning

ABSTRACTIn this study, we examined molecular mechanisms associated with multidrug resistance (MDR) in a collection ofEscherichia coliisolates recovered from hospitalized animals in Ireland. PCR and DNA sequencing were used to identify genes associated with resistance. Class 1 integrons were prevalent (94.6%) and contained gene cassettes recognized previously and implicated mainly in resistance to aminoglycosides, β-lactams, and trimethoprim (aadA1,dfrA1-aadA1,dfrA17-aadA5,dfrA12-orfF-aadA2,blaOXA-30-aadA1,aacC1-orf1-orf2-aadA1,dfr7). Class 2 integrons (13.5%) contained thedfrA1-sat1-aadA1gene array. The most frequently occurring phenotypes included resistance to ampicillin (97.3%), chloramphenicol (75.4%), florfenicol (40.5%), gentamicin (54%), neomycin (43.2%), streptomycin (97.3%), sulfonamide (98.6%), and tetracycline (100%). The associated resistance determinants detected includedblaTEM,cat,floR,aadB,aphA1,strA-strB,sul2, andtet(B), respectively. TheblaCTX-M-2gene, encoding an extended-spectrum β-lactamase (ESβL), andblaCMY-2, encoding an AmpC-like enzyme, were identified in 8 and 18 isolates, respectively. The mobility of the resistance genes was demonstrated using conjugation assays with a representative selection of isolates. High-molecular-weight plasmids were found to be responsible for resistance to multiple antimicrobial compounds. The study demonstrated that animal-associated commensalE. coliisolates possess a diverse repertoire of transferable genetic determinants. Emergence of ESβLs and AmpC-like enzymes is particularly significant. To our knowledge, theblaCTX-M-2gene has not previously been reported in Ireland.


2013 ◽  
Vol 79 (23) ◽  
pp. 7502-7509 ◽  
Author(s):  
Camilla Sekse ◽  
Marianne Sunde ◽  
Petter Hopp ◽  
Torkjel Bruheim ◽  
Kofitsyo Sewornu Cudjoe ◽  
...  

ABSTRACTThe investigation of an outbreak of hemorrhagic-uremic syndrome in Norway in 2006 indicated that the outbreak strainEscherichia coliO103:H25 could originate from sheep. A national survey of the Norwegian sheep population was performed, with the aim of identifying and describing a possible reservoir of potentially human-pathogenicE. coliO103, in particular of the H types 2 and 25. The investigation of fecal samples from 585 sheep flocks resulted in 1,222E. coliO103 isolates that were analyzed for the presence ofeaeandstxgenes, while a subset of 369 isolates was further examined for flagellar antigens (H typing),stxsubtypes,bfpA,astA, and molecular typing by pulsed-field gel electrophoresis (PFGE). The total ovineE. coliO103 serogroup was genetically diverse by numbers of H types, virulotypes, and PFGE banding patterns identified, although a tendency of clustering toward serotypes was seen. The flocks positive for potentially human-pathogenicE. coliO103 were geographically widely distributed, and no association could be found with county or geographical region. The survey showed thateae-negative,stx-negativeE. coliO103, probably nonpathogenic to humans, is very common in sheep, with 27.5% of flocks positive. Moreover, the study documented a low prevalence (0.7%) of potentially human-pathogenic Shiga toxin-producingE. coliO103:H2, while STEC O103:H25 was not detected. However, 3.1% and 5.8% of the flocks were positive for enteropathogenicE. coliO103 belonging to H types 2 and 25, respectively. These isolates are of concern as potential human pathogens by themselves but more importantly as possible precursors for human-pathogenic STEC.


2012 ◽  
Vol 56 (7) ◽  
pp. 3898-3904 ◽  
Author(s):  
Joanne L. Platell ◽  
Darren J. Trott ◽  
James R. Johnson ◽  
Peter Heisig ◽  
Anke Heisig ◽  
...  

ABSTRACTFluoroquinolone (FQ)-resistant extraintestinal pathogenicEscherichia coli(FQrExPEC) strains from phylogenetic group B2 are undergoing epidemic spread. Isolates belonging to phylogenetic group B2 are generally more virulent than otherE. coliisolates; therefore, resistance to FQs among group B2 isolates is concerning. Although clonal expansion of sequence type 131 (ST131) is a major factor, the contribution of additional clonal groups has not been quantified. Group B2 FQrExPEC isolates from humans (n= 250) and dogs (n= 12) in Australia were screened for ST131, a recently recognized and rapidly emerging multidrug-resistant and virulent clonal group that is important in both human and companion animal medicine. Non-ST131 isolates underwent virulence genotyping, PCR-based O typing, partial multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and FQ resistance mechanism analysis. Of 49 non-ST131 isolates (45 human, 4 canine), 49% (24 human, 2 canine) represented O-type O75 and exhibited conserved virulence genotypes (F10papAallele,iha,fimH,sat,vat,fyuA,iutA,kpsMII,usp,ompT,malX, K1/K5 capsule) and MLST allele profiles corresponding with clonal complex CC14. Two clusters, each containing canine and human isolates, were identified by PFGE (differentiated by K1 and K5 capsules). Australian FQrO75 isolates exhibited commonality with an historical FQ-susceptible O75 urosepsis isolate (also CC14). The isolation from humans and dogs of highly similar FQrderivatives of the classic O75:K1/K5 (CC14) ExPEC lineage suggests recent acquisition of FQ resistance and potential cross-host-species transfer. This lineage should be targeted with ST131 in future epidemiological investigations of FQrExPEC.


2011 ◽  
Vol 55 (6) ◽  
pp. 3005-3007 ◽  
Author(s):  
Ivan Literak ◽  
Radim Petro ◽  
Monika Dolejska ◽  
Erika Gruberova ◽  
Hana Dobiasova ◽  
...  

ABSTRACTThe study was performed in the Czech Republic during 2007 to 2009. OfEscherichia coliisolates from 275 children aged 6 weeks, 36% (n= 177) were resistant to 1 to 7 antibiotics. Of isolates from 253 children aged 6 to 17 years, 24% (n= 205) were resistant to 1 to 5 antibiotics. There was no significant difference in the prevalences of antibiotic-resistantE. coliisolates between these groups of children, even though the consumptions of antibiotics were quite different.


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