Integron-Associated DfrB4, a Previously Uncharacterized Member of the Trimethoprim-Resistant Dihydrofolate Reductase B Family, Is a Clinically Identified Emergent Source of Antibiotic Resistance

ABSTRACT Whole-genome sequencing of trimethoprim-resistant Escherichia coli clinical isolates identified a member of the trimethoprim-resistant type II dihydrofolate reductase gene family (dfrB). The dfrB4 gene was located within a class I integron flanked by multiple resistance genes. This arrangement was previously reported in a 130.6-kb multiresistance plasmid. The DfrB4 protein conferred a >2,000-fold increased trimethoprim resistance on overexpression in E. coli. Our results are consistent with the finding that dfrB4 contributes to clinical trimethoprim resistance.

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Vibrio cholerae Triggers SOS and Mutagenesis in Response to a Wide Range of Antibiotics: a Route towards Multiresistance

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01549-10 ◽

2011 ◽

Vol 55 (5) ◽

pp. 2438-2441 ◽

Cited By ~ 107

Author(s):

Zeynep Baharoglu ◽

Didier Mazel

Keyword(s):

Escherichia Coli ◽

Antibiotic Resistance ◽

Vibrio Cholerae ◽

Fluorescent Protein ◽

Resistance Development ◽

Content Type ◽

E Coli ◽

Wide Range ◽

Green Fluorescent ◽

Regulated Promoters

ABSTRACTAntibiotic resistance development has been linked to the bacterial SOS stress response. InEscherichia coli, fluoroquinolones are known to induce SOS, whereas other antibiotics, such as aminoglycosides, tetracycline, and chloramphenicol, do not. Here we address whether various antibiotics induce SOS inVibrio cholerae. Reporter green fluorescent protein (GFP) fusions were used to measure the response of SOS-regulated promoters to subinhibitory concentrations of antibiotics. We show that unlike the situation withE. coli, all these antibiotics induce SOS inV. cholerae.

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Spread of Antibiotic Resistance in Aquatic Environments: E. coli as a Case Study

Proceedings ◽

10.3390/proceedings2110693 ◽

2018 ◽

Vol 2 (11) ◽

pp. 693 ◽

Cited By ~ 1

Author(s):

Maria Adamantia Efstratiou ◽

Marina Bountouni ◽

Efthimios Kefalas

Keyword(s):

Escherichia Coli ◽

Drinking Water ◽

Antibiotic Resistance ◽

Rural Communities ◽

Ground Water ◽

Aquatic Environments ◽

Multiple Resistance ◽

E Coli ◽

Of Greece

The aim of this study was to gather information on the spread of antibiotic resistance in Escherichia coli isolates from wells, boreholes and untreated drinking water in islands of Greece. We analyzed for antibiotic resistance 235 E. coli strains isolated from untreated drinking water of small rural communities, and ground water from 4 islands. Resistance was tested against Norfloxacin, Ciprofloxacin, Levofloxacin, Amoxicillin and Cefaclor. More than half (54.9%) were resistant to at least one of the antibiotics tested. Of these 26.3% showed multiple resistance (to two or more antibiotics). Strains from drinking water sources were overall more sensitive. Frequent resistance was observed for Amoxicillin (38.3%) and Levofloxacin (28.5%), low for Norfloxacin (5.5%).

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Increased Survival of Antibiotic-Resistant Escherichia coli inside Macrophages

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01632-12 ◽

2012 ◽

Vol 57 (1) ◽

pp. 189-195 ◽

Cited By ~ 33

Author(s):

Migla Miskinyte ◽

Isabel Gordo

Keyword(s):

Escherichia Coli ◽

Antibiotic Resistance ◽

Bacterial Infections ◽

Resistance Mutation ◽

Fitness Cost ◽

Resistance Mutations ◽

Content Type ◽

E Coli ◽

Fitness Effects ◽

K 12

ABSTRACTMutations causing antibiotic resistance usually incur a fitness cost in the absence of antibiotics. The magnitude of such costs is known to vary with the environment. Little is known about the fitness effects of antibiotic resistance mutations when bacteria confront the host's immune system. Here, we study the fitness effects of mutations in therpoB,rpsL, andgyrAgenes, which confer resistance to rifampin, streptomycin, and nalidixic acid, respectively. These antibiotics are frequently used in the treatment of bacterial infections. We measured two important fitness traits—growth rate and survival ability—of 12Escherichia coliK-12 strains, each carrying a single resistance mutation, in the presence of macrophages. Strikingly, we found that 67% of the mutants survived better than the susceptible bacteria in the intracellular niche of the phagocytic cells. In particular, allE. colistreptomycin-resistant mutants exhibited an intracellular advantage. On the other hand, 42% of the mutants incurred a high fitness cost when the bacteria were allowed to divide outside of macrophages. This study shows that single nonsynonymous changes affecting fundamental processes in the cell can contribute to prolonged survival ofE. coliin the context of an infection.

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Whole-Genome Sequence of Phage-Resistant Strain Escherichia coli DH5α

Genome Announcements ◽

10.1128/genomea.00097-18 ◽

2018 ◽

Vol 6 (10) ◽

Cited By ~ 4

Author(s):

Jingchao Chen ◽

Yi Li ◽

Kun Zhang ◽

Hailei Wang

Keyword(s):

Escherichia Coli ◽

Comparative Analysis ◽

Genome Sequence ◽

Resistant Strain ◽

Resistance Mechanism ◽

Whole Genome Sequence ◽

Whole Genome ◽

Content Type ◽

E Coli ◽

T4 Bacteriophage

ABSTRACT The genomes of many strains of Escherichia coli have been sequenced, as this organism is a classic model bacterium. Here, we report the genome sequence of Escherichia coli DH5α, which is resistant to a T4 bacteriophage (CCTCC AB 2015375), while its other homologous E. coli strains, such as E. coli BL21, DH10B, and MG1655, are not resistant to phage invasions. Thus, understanding of the genome of the DH5α strain, along with comparative analysis of its genome sequence along with other sequences of E. coli strains, may help to reveal the bacteriophage resistance mechanism of E. coli .

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F Plasmids Are the Major Carriers of Antibiotic Resistance Genes in Human-Associated Commensal Escherichia coli

mSphere ◽

10.1128/msphere.00709-20 ◽

2020 ◽

Vol 5 (4) ◽

Author(s):

Craig Stephens ◽

Tyler Arismendi ◽

Megan Wright ◽

Austin Hartman ◽

Andres Gonzalez ◽

...

Keyword(s):

Escherichia Coli ◽

Antibiotic Resistance ◽

Transposable Elements ◽

Dna Sequencing ◽

Resistance Genes ◽

Bacterial Pathogens ◽

Acquired Resistance ◽

Antibiotic Resistance Genes ◽

Content Type ◽

E Coli

ABSTRACT The evolution and propagation of antibiotic resistance by bacterial pathogens are significant threats to global public health. Contemporary DNA sequencing tools were applied here to gain insight into carriage of antibiotic resistance genes in Escherichia coli, a ubiquitous commensal bacterium in the gut microbiome in humans and many animals, and a common pathogen. Draft genome sequences generated for a collection of 101 E. coli strains isolated from healthy undergraduate students showed that horizontally acquired antibiotic resistance genes accounted for most resistance phenotypes, the primary exception being resistance to quinolones due to chromosomal mutations. A subset of 29 diverse isolates carrying acquired resistance genes and 21 control isolates lacking such genes were further subjected to long-read DNA sequencing to enable complete or nearly complete genome assembly. Acquired resistance genes primarily resided on F plasmids (101/153 [67%]), with smaller numbers on chromosomes (30/153 [20%]), IncI complex plasmids (15/153 [10%]), and small mobilizable plasmids (5/153 [3%]). Nearly all resistance genes were found in the context of known transposable elements. Very few structurally conserved plasmids with antibiotic resistance genes were identified, with the exception of an ∼90-kb F plasmid in sequence type 1193 (ST1193) isolates that appears to serve as a platform for resistance genes and may have virulence-related functions as well. Carriage of antibiotic resistance genes on transposable elements and mobile plasmids in commensal E. coli renders the resistome highly dynamic. IMPORTANCE Rising antibiotic resistance in human-associated bacterial pathogens is a serious threat to our ability to treat many infectious diseases. It is critical to understand how acquired resistance genes move in and through bacteria associated with humans, particularly for species such as Escherichia coli that are very common in the human gut but can also be dangerous pathogens. This work combined two distinct DNA sequencing approaches to allow us to explore the genomes of E. coli from college students to show that the antibiotic resistance genes these bacteria have acquired are usually carried on a specific type of plasmid that is naturally transferrable to other E. coli, and likely to other related bacteria.

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Unstable Mechanisms of Resistance to Inhibitors of Escherichia coli Lipoprotein Signal Peptidase

mBio ◽

10.1128/mbio.02018-20 ◽

2020 ◽

Vol 11 (5) ◽

Cited By ~ 1

Author(s):

Homer Pantua ◽

Elizabeth Skippington ◽

Marie-Gabrielle Braun ◽

Cameron L. Noland ◽

Jingyu Diao ◽

...

Keyword(s):

Escherichia Coli ◽

Antibiotic Susceptibility ◽

Pathogenic Bacteria ◽

Susceptibility Testing ◽

Regulatory Elements ◽

Signal Peptidase ◽

Type Ii ◽

Mechanisms Of Resistance ◽

Content Type ◽

E Coli

ABSTRACT Clinical development of antibiotics with novel mechanisms of action to kill pathogenic bacteria is challenging, in part, due to the inevitable emergence of resistance. A phenomenon of potential clinical importance that is broadly overlooked in preclinical development is heteroresistance, an often-unstable phenotype in which subpopulations of bacterial cells show decreased antibiotic susceptibility relative to the dominant population. Here, we describe a new globomycin analog, G0790, with potent activity against the Escherichia coli type II signal peptidase LspA and uncover two novel resistance mechanisms to G0790 in the clinical uropathogenic E. coli strain CFT073. Building on the previous finding that complete deletion of Lpp, the major Gram-negative outer membrane lipoprotein, leads to globomycin resistance, we also find that an unexpectedly modest decrease in Lpp levels mediated by insertion-based disruption of regulatory elements is sufficient to confer G0790 resistance and increase sensitivity to serum killing. In addition, we describe a heteroresistance phenotype mediated by genomic amplifications of lspA that result in increased LspA levels sufficient to overcome inhibition by G0790 in culture. These genomic amplifications are highly unstable and are lost after as few as two subcultures in the absence of G0790, which places amplification-containing resistant strains at high risk of being misclassified as susceptible by routine antimicrobial susceptibility testing. In summary, our study uncovers two vastly different mechanisms of resistance to LspA inhibitors in E. coli and emphasizes the importance of considering the potential impact of unstable and heterogenous phenotypes when developing antibiotics for clinical use. IMPORTANCE Despite increasing evidence suggesting that antibiotic heteroresistance can lead to treatment failure, the significance of this phenomena in the clinic is not well understood, because many clinical antibiotic susceptibility testing approaches lack the resolution needed to reliably classify heteroresistant strains. Here we present G0790, a new globomycin analog and potent inhibitor of the Escherichia coli type II signal peptidase LspA. We demonstrate that in addition to previously known mechanisms of resistance to LspA inhibitors, unstable genomic amplifications containing lspA can lead to modest yet biologically significant increases in LspA protein levels that confer a heteroresistance phenotype.

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Identification of Escherichia coli and Shigella Species from Whole-Genome Sequences

Journal of Clinical Microbiology ◽

10.1128/jcm.01790-16 ◽

2016 ◽

Vol 55 (2) ◽

pp. 616-623 ◽

Cited By ~ 49

Author(s):

Marie A. Chattaway ◽

Ulf Schaefer ◽

Rediat Tewolde ◽

Timothy J. Dallman ◽

Claire Jenkins

Keyword(s):

Escherichia Coli ◽

Clonal Complex ◽

Shigella Flexneri ◽

Bacterial Species ◽

Whole Genome ◽

Content Type ◽

E Coli ◽

Shigella Species ◽

Close Phylogenetic Relationship ◽

Initial Identification

ABSTRACTEscherichia coliandShigellaspecies are closely related and genetically constitute the same species. Differentiating between these two pathogens and accurately identifying the four species ofShigellaare therefore challenging. The organism-specific bioinformatics whole-genome sequencing (WGS) typing pipelines at Public Health England are dependent on the initial identification of the bacterial species by use of a kmer-based approach. Of the 1,982Escherichia coliandShigellasp. isolates analyzed in this study, 1,957 (98.4%) had concordant results by both traditional biochemistry and serology (TB&S) and the kmer identification (ID) derived from the WGS data. Of the 25 mismatches identified, 10 were enteroinvasiveE. coliisolates that were misidentified asShigella flexneriorS. boydiiby the kmer ID, and 8 wereS. flexneriisolates misidentified by TB&S asS. boydiidue to nonfunctionalS. flexneriO antigen biosynthesis genes. Analysis of the population structure based on multilocus sequence typing (MLST) data derived from the WGS data showed that the remaining discrepant results belonged to clonal complex 288 (CC288), comprising bothS. boydiiandS. dysenteriaestrains. Mismatches between the TB&S and kmer ID results were explained by the close phylogenetic relationship between the two species and were resolved with reference to the MLST data.Shigellacan be differentiated fromE. coliand accurately identified to the species level by use of kmer comparisons and MLST. Analysis of the WGS data provided explanations for the discordant results between TB&S and WGS data, revealed the true phylogenetic relationships between different species ofShigella, and identified emerging pathoadapted lineages.

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Comparative Genomics of an IncA/C Multidrug Resistance Plasmid from Escherichia coli and Klebsiella Isolates from Intensive Care Unit Patients and the Utility of Whole-Genome Sequencing in Health Care Settings

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02573-14 ◽

2014 ◽

Vol 58 (8) ◽

pp. 4814-4825 ◽

Cited By ~ 16

Author(s):

Tracy H. Hazen ◽

LiCheng Zhao ◽

Mallory A. Boutin ◽

Angela Stancil ◽

Gwen Robinson ◽

...

Keyword(s):

Escherichia Coli ◽

Health Care ◽

Intensive Care Unit ◽

Intensive Care ◽

Comparative Genomics ◽

Resistance Genes ◽

Whole Genome ◽

Content Type ◽

Health Care Settings ◽

E Coli

ABSTRACTThe IncA/C plasmids have been implicated for their role in the dissemination of β-lactamases, including gene variants that confer resistance to expanded-spectrum cephalosporins, which are often the treatment of last resort against multidrug-resistant, hospital-associated pathogens. AblaFOX-5gene was detected in 14Escherichia coliand 16Klebsiellaisolates that were cultured from perianal swabs of patients admitted to an intensive care unit (ICU) of the University of Maryland Medical Center (UMMC) in Baltimore, MD, over a span of 3 years. Four of the FOX-encoding isolates were obtained from subsequent samples of patients that were initially negative for an AmpC β-lactamase upon admission to the ICU, suggesting that the AmpC β-lactamase-encoding plasmid was acquired while the patient was in the ICU. The genomes of fiveE. coliisolates and sixKlebsiellaisolates containingblaFOX-5were selected for sequencing based on their plasmid profiles. An ∼167-kb IncA/C plasmid encoding the FOX-5 β-lactamase, a CARB-2 β-lactamase, additional antimicrobial resistance genes, and heavy metal resistance genes was identified. Another FOX-5-encoding IncA/C plasmid that was nearly identical except for a variable region associated with the resistance genes was also identified. To our knowledge, these plasmids represent the first FOX-5-encoding plasmids sequenced. We used comparative genomics to describe the genetic diversity of a plasmid encoding a FOX-5 β-lactamase relative to the whole-genome diversity of 11E. coliandKlebsiellaisolates that carry this plasmid. Our findings demonstrate the utility of whole-genome sequencing for tracking of plasmid and antibiotic resistance gene distribution in health care settings.

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bla OXA-48-like genome architecture among carbapenemase-producing Escherichia coli and Klebsiella pneumoniae in the Netherlands

Microbial Genomics ◽

10.1099/mgen.0.000512 ◽

2021 ◽

Vol 7 (5) ◽

Author(s):

Antoni P. A. Hendrickx ◽

Fabian Landman ◽

Angela de Haan ◽

Sandra Witteveen ◽

Marga G. van Santen-Verheuvel ◽

...

Keyword(s):

Escherichia Coli ◽

Antibiotic Resistance ◽

The Netherlands ◽

Resistance Genes ◽

Type Species ◽

Antibiotic Resistance Genes ◽

Gene Content ◽

Content Type ◽

E Coli ◽

Link Type

Carbapenem-hydrolysing enzymes belonging to the OXA-48-like group are encoded by bla OXA-48-like alleles and are abundant among Enterobacterales in the Netherlands. Therefore, the objective here was to investigate the characteristics, gene content and diversity of the bla OXA-48-like carrying plasmids and chromosomes of Escherichia coli and Klebsiella pneumoniae collected in the Dutch national surveillance from 2014 to 2019 in comparison with genome sequences from 29 countries. A combination of short-read genome sequencing with long-read sequencing enabled the reconstruction of 47 and 132 complete bla OXA-48-like plasmids for E. coli and K. pneumoniae , respectively. Seven distinct plasmid groups designated as pOXA-48-1 to pOXA-48-5, pOXA-181 and pOXA-232 were identified in the Netherlands which were similar to internationally reported plasmids obtained from countries from North and South America, Europe, Asia and Oceania. The seven plasmid groups varied in size, G+C content, presence of antibiotic resistance genes, replicon family and gene content. The pOXA-48-1 to pOXA-48-5 plasmids were variable, and the pOXA-181 and pOXA-232 plasmids were conserved. The pOXA-48-1, pOXA-48-2, pOXA-48-3 and pOXA-48-5 groups contained a putative conjugation system, but this was absent in the pOXA-48-4, pOXA-181 and pOXA-232 plasmid groups. pOXA-48 plasmids contained the PemI antitoxin, while the pOXA-181 and pOXA-232 plasmids did not. Furthermore, the pOXA-181 plasmids carried a virB2-virB3-virB9-virB10-virB11 type IV secretion system, while the pOXA-48 plasmids and pOXA-232 lacked this system. A group of non-related pOXA-48 plasmids from the Netherlands contained different resistance genes, non-IncL-type replicons or no replicons. Whole genome multilocus sequence typing revealed that the bla OXA-48-like plasmids were found in a wide variety of genetic backgrounds in contrast to chromosomally encoded bla OXA-48-like alleles. Chromosomally localized bla OXA-48 and bla OXA-244 alleles were located on genetic elements of variable sizes and comprised regions of pOXA-48 plasmids. The bla OXA-48-like genetic element was flanked by a direct repeat upstream of IS1R, and was found at multiple locations in the chromosomes of E. coli . Lastly, K. pneumoniae isolates carrying bla OXA-48 or bla OXA-232 were mostly resistant for meropenem, whereas E. coli bla OXA-48, bla OXA-181 and chromosomal bla OXA-48 or bla OXA-244 isolates were mostly sensitive. In conclusion, the overall bla OXA-48-like plasmid population in the Netherlands is conserved and similar to that reported for other countries, confirming global dissemination of bla OXA-48-like plasmids. Variations in size, presence of antibiotic resistance genes and gene content impacted pOXA-48, pOXA-181 and pOXA-232 plasmid architecture.

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Distinct Requirements for Tail-Anchored Membrane Protein Biogenesis in Escherichia coli

mBio ◽

10.1128/mbio.01580-19 ◽

2019 ◽

Vol 10 (5) ◽

Cited By ~ 1

Author(s):

Markus Peschke ◽

Mélanie Le Goff ◽

Gregory M. Koningstein ◽

Norbert O. Vischer ◽

Abbi Abdel-Rehim ◽

...

Keyword(s):

Escherichia Coli ◽

Membrane Proteins ◽

Transmembrane Domain ◽

Signal Recognition Particle ◽

Membrane Insertion ◽

Type Ii ◽

Content Type ◽

E Coli ◽

C Terminus

ABSTRACT Tail-anchored membrane proteins (TAMPs) are a distinct subset of inner membrane proteins (IMPs) characterized by a single C-terminal transmembrane domain (TMD) that is responsible for both targeting and anchoring. Little is known about the routing of TAMPs in bacteria. Here, we have investigated the role of TMD hydrophobicity in tail-anchor function in Escherichia coli and its influence on the choice of targeting/insertion pathway. We created a set of synthetic, fluorescent TAMPs that vary in the hydrophobicity of their TMDs and corresponding control polypeptides that are extended at their C terminus to create regular type II IMPs. Surprisingly, we observed that TAMPs have a much lower TMD hydrophobicity threshold for efficient targeting and membrane insertion than their type II counterparts. Using strains conditional for the expression of known membrane-targeting and insertion factors, we show that TAMPs with strongly hydrophobic TMDs require the signal recognition particle (SRP) for targeting. Neither the SecYEG translocon nor YidC appears to be essential for the membrane insertion of any of the TAMPs studied. In contrast, corresponding type II IMPs with a TMD of sufficient hydrophobicity to promote membrane insertion followed an SRP- and SecYEG translocon-dependent pathway. Together, these data indicate that the capacity of a TMD to promote the biogenesis of E. coli IMPs is strongly dependent upon the polypeptide context in which it is presented. IMPORTANCE A subset of membrane proteins is targeted to and inserted into the membrane via a hydrophobic transmembrane domain (TMD) that is positioned at the very C terminus of the protein. The biogenesis of these so-called tail-anchored proteins (TAMPs) has been studied in detail in eukaryotic cells. Various partly redundant pathways were identified, the choice for which depends in part on the hydrophobicity of the TMD. Much less is known about bacterial TAMPs. The significance of our research is in identifying the role of TMD hydrophobicity in the routing of E. coli TAMPs. Our data suggest that both the nature of the TMD and its role in routing can be very different for TAMPs versus “regular” membrane proteins. Elucidating these position-specific effects of TMDs will increase our understanding of how prokaryotic cells face the challenge of producing a wide variety of membrane proteins.

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