scholarly journals Salmonella enterica Suppresses Pectobacterium carotovorum subsp. carotovorum Population and Soft Rot Progression by Acidifying the Microaerophilic Environment

mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Grace Kwan ◽  
Amy O. Charkowski ◽  
Jeri D. Barak
Keyword(s):  
Escherichia Coli ◽  
Disease Progression ◽  
Salmonella Enterica ◽  
Soft Rot ◽  
Pectobacterium Carotovorum ◽  
Human Pathogens ◽  
Bacterial Populations ◽  
Content Type ◽  
E Coli ◽  
The Impact

ABSTRACTAlthough enteric human pathogens are usually studied in the context of their animal hosts, a significant portion of their life cycle occurs on plants. Plant disease alters the phyllosphere, leading to enhanced growth of human pathogens; however, the impact of human pathogens on phytopathogen biology and plant health is largely unknown. To characterize the interaction between human pathogens and phytobacterial pathogens in the phyllosphere, we examined the interactions betweenPectobacterium carotovorumsubsp.carotovorumandSalmonella entericaorEscherichia coliO157:H7 with regard to bacterial populations, soft rot progression, and changes in local pH. The presence ofP. carotovorumsubsp.carotovorumenhanced the growth of bothS. entericaandE. coliO157:H7 on leaves. However, in a microaerophilic environment,S. entericareducedP. carotovorumsubsp.carotovorumpopulations and soft rot progression by moderating local environmental pH. Reduced soft rot was not due toS. entericaproteolytic activity. Limitations onP. carotovorumsubsp.carotovorumgrowth, disease progression, and pH elevation were not observed on leaves coinoculated withE. coliO157:H7 or when leaves were coinoculated withS. entericain an aerobic environment.S. entericaalso severely undermined the relationship between the phytobacterial population and disease progression of aP. carotovorumsubsp.carotovorum budBmutant defective in the 2,3-butanediol pathway for acid neutralization. Our results show thatS. entericaandE. coliO157:H7 interact differently with the enteric phytobacterial pathogenP. carotovorumsubsp.carotovorum.S. entericainhibition of soft rot progression may conceal a rapidly growing human pathogen population. Whereas soft rotted produce can alert consumers to the possibility of food-borne pathogens, healthy-looking produce may entice consumption of contaminated vegetables.IMPORTANCESalmonella entericaandEscherichia coliO157:H7 may use plants to move between animal and human hosts. Their populations are higher on plants cocolonized with the common bacterial soft rot pathogenPectobacterium carotovorumsubsp.carotovorum, turning edible plants into a risk factor for human disease. We inoculated leaves withP. carotovorumsubsp.carotovorumandS. entericaorE. coliO157:H7 to study the interactions between these bacteria. WhileP. carotovorumsubsp.carotovorumenhanced the growth of bothS. entericaandE. coliO157:H7, these human pathogens affectedP. carotovorumsubsp.carotovorumfundamentally differently.S. entericareducedP. carotovorumsubsp.carotovorumgrowth and acidified the environment, leading to less soft rot on leaves;E. coliO157:H7 had no such effects. As soft rot signals a food safety risk, the reduction of soft rot symptoms in the presence ofS. entericamay lead consumers to eat healthy-looking butS. enterica-contaminated produce.

scholarly journals Evaluation of Aerated Steam Treatment of Alfalfa and Mung Bean Seeds To Eliminate High Levels of Escherichia coli O157:H7 and O178:H12, Salmonella enterica, and Listeria monocytogenes

2013 ◽  
Vol 79 (15) ◽  
pp. 4613-4619 ◽  
Author(s):  
Patrick Studer ◽  
Werner E. Heller ◽  
Jörg Hummerjohann ◽  
David Drissner
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Mung Bean ◽  
Germination Rate ◽  
Steam Treatment ◽  
Heat Sensitivity ◽  
Human Pathogens ◽  
Content Type ◽  
E Coli

ABSTRACTSprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated withEscherichia coliO157:H7,Salmonella entericasubsp.entericaserovar Weltevreden, andListeria monocytogenesScott A. In addition, a recently collectedE. coliO178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations ofE. coliO157:H7 andS. entericaon alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies.L. monocytogenesandE. coliO178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA).

scholarly journals Occurrence of Antimicrobial-Resistant Escherichia coli and Salmonella enterica in the Beef Cattle Production and Processing Continuum

2014 ◽  
Vol 81 (2) ◽  
pp. 713-725 ◽  
Author(s):  
John W. Schmidt ◽  
Getahun E. Agga ◽  
Joseph M. Bosilevac ◽  
Dayna M. Brichta-Harhay ◽  
Steven D. Shackelford ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Generation Cephalosporin ◽  
Resistant Bacteria ◽  
Processing Plant ◽  
Cattle Production ◽  
Content Type ◽  
E Coli ◽  
Beef Processing ◽  
Tract Infections

ABSTRACTSpecific concerns have been raised that third-generation cephalosporin-resistant (3GCr)Escherichia coli, trimethoprim-sulfamethoxazole-resistant (COTr)E. coli, 3GCrSalmonella enterica, and nalidixic acid-resistant (NALr)S. entericamay be present in cattle production environments, persist through beef processing, and contaminate final products. The prevalences and concentrations of these organisms were determined in feces and hides (at feedlot and processing plant), pre-evisceration carcasses, and final carcasses from three lots of fed cattle (n= 184). The prevalences and concentrations were further determined for strip loins from 103 of the carcasses. 3GCrSalmonellawas detected on 7.6% of hides during processing and was not detected on the final carcasses or strip loins. NALrS. entericawas detected on only one hide. 3GCrE. coliand COTrE. coliwere detected on 100.0% of hides during processing. Concentrations of 3GCrE. coliand COTrE. colion hides were correlated with pre-evisceration carcass contamination. 3GCrE. coliand COTrE. coliwere each detected on only 0.5% of final carcasses and were not detected on strip loins. Five hundred and 42 isolates were screened for extraintestinal pathogenicE. coli(ExPEC) virulence-associated markers. Only two COTrE. coliisolates from hides were ExPEC, indicating that fed cattle products are not a significant source of ExPEC causing human urinary tract infections. The very low prevalences of these organisms on final carcasses and their absence on strip loins demonstrate that current sanitary dressing procedures and processing interventions are effective against antimicrobial-resistant bacteria.

scholarly journals Potentially Human-Pathogenic Escherichia coli O26 in Norwegian Sheep Flocks

2011 ◽  
Vol 77 (14) ◽  
pp. 4949-4958 ◽  
Author(s):  
C. Sekse ◽  
M. Sunde ◽  
B.-A. Lindstedt ◽  
P. Hopp ◽  
T. Bruheim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
Human Pathogens ◽  
Content Type ◽  
Representative Sampling ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
Close Relationship ◽  
Large Survey

ABSTRACTA national survey ofEscherichia coliO26 in Norwegian sheep flocks was conducted, using fecal samples to determine the prevalence. In total, 491 flocks were tested, andE. coliO26 was detected in 17.9% of the flocks. One hundred forty-twoE. coliO26 isolates were examined for flagellar antigens (H typing) and four virulence genes, includingstxandeae, to identify possible Shiga toxin-producingE. coli(STEC) and enteropathogenicE. coli(EPEC). Most isolates (129 out of 142) were identified asE. coliO26:H11. They possessedeaeand may have potential as human pathogens, although only a small fraction were identified as STEC O26:H11, giving a prevalence in sheep flocks of only 0.8%. Correspondingly, the sheep flock prevalence of atypical EPEC (aEPEC) O26:H11 was surprisingly high (15.9%). The genetic relationship between theE. coliO26:H11 isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA), identifying 63 distinct PFGE profiles and 22 MLVA profiles. Although the MLVA protocol was less discriminatory than PFGE and a few cases of disagreement were observed, comparison by partition mapping showed an overall good accordance between the two methods. A close relationship between a few isolates of aEPEC O26:H11 and STEC O26:H11 was identified, but all theE. coliO26:H11 isolates should be considered potentially pathogenic to humans. The present study consisted of a representative sampling of sheep flocks from all parts of Norway. This is the first large survey of sheep flocks focusing onE. coliO26 in general, including results of STEC, aEPEC, and nonpathogenic isolates.

scholarly journals Colonization of Arabidopsis thaliana with Salmonella enterica and Enterohemorrhagic Escherichia coli O157:H7 and Competition by Enterobacter asburiae

2003 ◽  
Vol 69 (8) ◽  
pp. 4915-4926 ◽  
Author(s):  
Michael B. Cooley ◽  
William G. Miller ◽  
Robert E. Mandrell
Keyword(s):  
Escherichia Coli ◽  
Arabidopsis Thaliana ◽  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Enterohemorrhagic Escherichia Coli ◽  
Plant Responses ◽  
Human Pathogens ◽  
E Coli ◽  
Green Fluorescent ◽  
Enterobacter Asburiae

ABSTRACT Enteric pathogens, such as Salmonella enterica and Escherichia coli O157:H7, have been shown to contaminate fresh produce. Under appropriate conditions, these bacteria will grow on and invade the plant tissue. We have developed Arabidopsis thaliana (thale cress) as a model system with the intention of studying plant responses to human pathogens. Under sterile conditions and at 100% humidity, S. enterica serovar Newport and E. coli O157:H7 grew to 109 CFU g−1 on A. thaliana roots and to 2 × 107 CFU g−1 on shoots. Furthermore, root inoculation led to contamination of the entire plant, indicating that the pathogens are capable of moving on or within the plant in the absence of competition. Inoculation with green fluorescent protein-labeled S. enterica and E. coli O157:H7 showed invasion of the roots at lateral root junctions. Movement was eliminated and invasion decreased when nonmotile mutants of S. enterica were used. Survival of S. enterica serovar Newport and E. coli O157:H7 on soil-grown plants declined as the plants matured, but both pathogens were detectable for at least 21 days. Survival of the pathogen was reduced in unautoclaved soil and amended soil, suggesting competition from indigenous epiphytes from the soil. Enterobacter asburiae was isolated from soil-grown A. thaliana and shown to be effective at suppressing epiphytic growth of both pathogens under gnotobiotic conditions. Seed and chaff harvested from contaminated plants were occasionally contaminated. The rate of recovery of S. enterica and E. coli O157:H7 from seed varied from undetectable to 19% of the seed pools tested, depending on the method of inoculation. Seed contamination by these pathogens was undetectable in the presence of the competitor, Enterobacter asburiae. Sampling of 74 pools of chaff indicated a strong correlation between contamination of the chaff and seed (P = 0.025). This suggested that contamination of the seed occurred directly from contaminated chaff or by invasion of the flower or silique. However, contaminated seeds were not sanitized by extensive washing and chlorine treatment, indicating that some of the bacteria reside in a protected niche on the seed surface or under the seed coat.

scholarly journals Impact of Extended-Spectrum β-Lactamase Production on Treatment Outcomes of Acute Pyelonephritis Caused by Escherichia coli in Patients without Health Care-Associated Risk Factors

2015 ◽  
Vol 59 (4) ◽  
pp. 1962-1968 ◽  
Author(s):  
Sun Hee Park ◽  
Su-Mi Choi ◽  
Dong-Gun Lee ◽  
Sung-Yeon Cho ◽  
Hyo-Jin Lee ◽  
...  
Keyword(s):  
Risk Factors ◽  
Escherichia Coli ◽  
Health Care ◽  
Treatment Outcomes ◽  
Acute Pyelonephritis ◽  
Esbl Production ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
The Impact

ABSTRACTExtended-spectrum β-lactamase-producingEscherichia coli(ESBL-EC) is increasingly identified as a cause of acute pyelonephritis (APN) among patients without recent health care contact, i.e., community-associated APN. This case-control study compared 75 cases of community-associated ESBL-EC APN (CA-ESBL) to 225 controls of community-associated non-ESBL-EC APN (CA-non-ESBL) to identify the risk factors for ESBL-EC acquisition and investigate the impact of ESBL on the treatment outcomes of community-associated APN (CA-APN) caused byE. coliat a Korean hospital during 2007 to 2013. The baseline characteristics were similar between the cases and controls; the risk factors for ESBL-EC were age (>55 years), antibiotic use within the previous year, and diabetes with recurrent APN. The severity of illness did not differ between CA-ESBL and CA-non-ESBL (Acute Physiology and Chronic Health Evaluation [APACHE] II scores [mean ± standard deviation], 7.7 ± 5.9 versus 6.4 ± 5.3;P= 0.071). The proportions of clinical (odds ratio [OR], 1.76; 95% confidence interval [CI], 0.57 to 5.38;P= 0.323) and microbiological (OR, 1.16; 95% CI, 0.51 to 2.65;P= 0.730) cures were similar, although the CA-ESBL APN patients were less likely to receive appropriate antibiotics within 48 h. A multivariable Cox proportional hazards analysis of the prognostic factors for CA-APN caused byE. colishowed that ESBL production was not a significant factor for clinical (hazard ratio [HR], 0.39; 95% CI, 0.12 to 1.30;P= 0.126) or microbiological (HR, 0.49; 95% CI, 0.21 to 1.12;P= 0.091) failure. The estimates did not change after incorporating weights calculated using propensity scores for acquiring ESBL-EC. Therefore, ESBL production did not negatively affect treatment outcomes among patients with community-associatedE. coliAPN.

scholarly journals Impact of UV and Peracetic Acid Disinfection on the Prevalence of Virulence and Antimicrobial Resistance Genes in Uropathogenic Escherichia coli in Wastewater Effluents

2014 ◽  
Vol 80 (12) ◽  
pp. 3656-3666 ◽  
Author(s):  
Basanta Kumar Biswal ◽  
Ramzi Khairallah ◽  
Kareem Bibi ◽  
Alberto Mazza ◽  
Ronald Gehr ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Resistance Genes ◽  
Peracetic Acid ◽  
Content Type ◽  
E Coli ◽  
Antimicrobial Resistance Genes ◽  
Antimicrobial Resistance Gene ◽  
Municipal Wastewaters ◽  
The Impact

ABSTRACTWastewater discharges may increase the populations of pathogens, includingEscherichia coli, and of antimicrobial-resistant strains in receiving waters. This study investigated the impact of UV and peracetic acid (PAA) disinfection on the prevalence of virulence and antimicrobial resistance genes in uropathogenicEscherichia coli(UPEC), the most abundantE. colipathotype in municipal wastewaters. Laboratory disinfection experiments were conducted on wastewater treated by physicochemical, activated sludge, or biofiltration processes; 1,766E. coliisolates were obtained for the evaluation. The target disinfection level was 200 CFU/100 ml, resulting in UV and PAA doses of 7 to 30 mJ/cm2and 0.9 to 2.0 mg/liter, respectively. The proportions of UPECs were reduced in all samples after disinfection, with an average reduction by UV of 55% (range, 22% to 80%) and by PAA of 52% (range, 11% to 100%). Analysis of urovirulence genes revealed that the decline in the UPEC populations was not associated with any particular virulence factor. A positive association was found between the occurrence of urovirulence and antimicrobial resistance genes (ARGs). However, the changes in the prevalence of ARGs in potential UPECs were different following disinfection, i.e., UV appears to have had no effect, while PAA significantly reduced the ARG levels. Thus, this study showed that both UV and PAA disinfections reduced the proportion of UPECs and that PAA disinfection also reduced the proportion of antimicrobial resistance gene-carrying UPEC pathotypes in municipal wastewaters.

scholarly journals In VivoTransmission of an IncA/C Plasmid in Escherichia coli Depends on Tetracycline Concentration, and Acquisition of the Plasmid Results in a Variable Cost of Fitness

2015 ◽  
Vol 81 (10) ◽  
pp. 3561-3570 ◽  
Author(s):  
Timothy J. Johnson ◽  
Randall S. Singer ◽  
Richard E. Isaacson ◽  
Jessica L. Danzeisen ◽  
Kevin Lang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Dose ◽  
Broad Host Range ◽  
Antibiotic Administration ◽  
Dose Administration ◽  
Content Type ◽  
E Coli ◽  
The Impact ◽  
Selection Of

ABSTRACTIncA/C plasmids are broad-host-range plasmids enabling multidrug resistance that have emerged worldwide among bacterial pathogens of humans and animals. Although antibiotic usage is suspected to be a driving force in the emergence of such strains, few studies have examined the impact of different types of antibiotic administration on the selection of plasmid-containing multidrug resistant isolates. In this study, chlortetracycline treatment at different concentrations in pig feed was examined for its impact on selection and dissemination of an IncA/C plasmid introduced orally via a commensalEscherichia colihost. Continuous low-dose administration of chlortetracycline at 50 g per ton had no observable impact on the proportions of IncA/C plasmid-containingE. colifrom pig feces over the course of 35 days. In contrast, high-dose administration of chlortetracycline at 350 g per ton significantly increased IncA/C plasmid-containingE. coliin pig feces (P< 0.001) and increased movement of the IncA/C plasmid to other indigenousE. colihosts. There was no evidence of conjugal transfer of the IncA/C plasmid to bacterial species other thanE. coli.In vitrocompetition assays demonstrated that bacterial host background substantially impacted the cost of IncA/C plasmid carriage inE. coliandSalmonella.In vitrotransfer and selection experiments demonstrated that tetracycline at 32 μg/ml was necessary to enhance IncA/C plasmid conjugative transfer, while subinhibitory concentrations of tetracyclinein vitrostrongly selected for IncA/C plasmid-containingE. coli. Together, these experiments improve our knowledge on the impact of differing concentrations of tetracycline on the selection of IncA/C-type plasmids.

scholarly journals Impact of Ceftiofur Injection on Gut Microbiota and Escherichia coli Resistance in Pigs

2015 ◽  
Vol 59 (9) ◽  
pp. 5171-5180 ◽  
Author(s):  
M. A. Fleury ◽  
G. Mourand ◽  
E. Jouy ◽  
F. Touzain ◽  
L. Le Devendec ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gut Microbiota ◽  
Treated Group ◽  
Conjugative Plasmid ◽  
Health Concern ◽  
Pcr Analysis ◽  
Contamination Level ◽  
Content Type ◽  
E Coli ◽  
The Impact

ABSTRACTResistance to extended-spectrum cephalosporins (ESCs) is an important health concern. Here, we studied the impact of the administration of a long-acting form of ceftiofur on the pig gut microbiota and ESC resistance inEscherichia coli. Pigs were orally inoculated with an ESC-resistantE. coliM63 strain harboring a conjugative plasmid carrying a gene conferring resistance,blaCTX-M-1. On the same day, they were given or not a unique injection of ceftiofur. Fecal microbiota were studied using quantitative PCR analysis of the main bacterial groups and quantification of short-chain fatty acids.E. coliand ESC-resistantE. coliwere determined by culture methods, and the ESC-resistantE. coliisolates were characterized. The copies of theblaCTX-M-1gene were quantified. After ceftiofur injection, the main change in gut microbiota was the significant but transitory decrease in theE. colipopulation. Acetate and butyrate levels were significantly lower in the treated group. In all inoculated groups,E. coliM63 persisted in most pigs, and theblaCTX-M-1gene was transferred to otherE. coli. Culture and PCR results showed that the ceftiofur-treated group shed significantly more resistant strains 1 and 3 days after ESC injection. Thereafter, on most dates, there were no differences between the groups, but notably, one pig in the nontreated group regularly excreted very high numbers of ESC-resistantE. coli, probably leading to a higher contamination level in its pen. In conclusion, the use of ESCs, and also the presence of high-shedding animals, are important features in the spread of ESC resistance.

scholarly journals The Impact of Plasma Membrane Lipid Composition on Flagellum-Mediated Adhesion of Enterohemorrhagic Escherichia coli

mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Hélène Cazzola ◽  
Laurine Lemaire ◽  
Sébastien Acket ◽  
Elise Prost ◽  
Luminita Duma ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Linolenic Acid ◽  
Lipid Rafts ◽  
Bacterial Adhesion ◽  
Human Pathogen ◽  
Content Type ◽  
E Coli ◽  
The Impact

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major cause of foodborne gastrointestinal illness. The adhesion of EHEC to host tissues is the first step enabling bacterial colonization. Adhesins such as fimbriae and flagella mediate this process. Here, we studied the interaction of the bacterial flagellum with the host cell’s plasma membrane using giant unilamellar vesicles (GUVs) as a biologically relevant model. Cultured cell lines contain many different molecular components, including proteins and glycoproteins. In contrast, with GUVs, we can characterize the bacterial mode of interaction solely with a defined lipid part of the cell membrane. Bacterial adhesion on GUVs was dependent on the presence of the flagellar filament and its motility. By testing different phospholipid head groups, the nature of the fatty acid chains, or the liposome curvature, we found that lipid packing is a key parameter to enable bacterial adhesion. Using HT-29 cells grown in the presence of polyunsaturated fatty acid (α-linolenic acid) or saturated fatty acid (palmitic acid), we found that α-linolenic acid reduced adhesion of wild-type EHEC but not of a nonflagellated mutant. Finally, our results reveal that the presence of flagella is advantageous for the bacteria to bind to lipid rafts. We speculate that polyunsaturated fatty acids prevent flagellar adhesion on membrane bilayers and play a clear role for optimal host colonization. Flagellum-mediated adhesion to plasma membranes has broad implications for host-pathogen interactions. IMPORTANCE Bacterial adhesion is a crucial step to allow bacteria to colonize their hosts, invade tissues, and form biofilm. Enterohemorrhagic Escherichia coli O157:H7 is a human pathogen and the causative agent of diarrhea and hemorrhagic colitis. Here, we use biomimetic membrane models and cell lines to decipher the impact of lipid content of the plasma membrane on enterohemorrhagic E. coli flagellum-mediated adhesion. Our findings provide evidence that polyunsaturated fatty acid (α-linolenic acid) inhibits E. coli flagellar adhesion to the plasma membrane in a mechanism separate from its antimicrobial and anti-inflammatory functions. In addition, we confirm that cholesterol-enriched lipid microdomains, often called lipid rafts, are important in bacterial adhesion. These findings demonstrate that plasma membrane adhesion via bacterial flagella play a significant role for an important human pathogen. This mechanism represents a promising target for the development of novel antiadhesion therapies.

scholarly journals mcr-1 Gene Expression Modulates the Inflammatory Response of Human Macrophages to Escherichia coli

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Giorgio Mattiuz ◽  
Sabrina Nicolò ◽  
Alberto Antonelli ◽  
Tommaso Giani ◽  
Ilaria Baccani ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lipid A ◽  
Nuclear Translocation ◽  
Interleukin 12 ◽  
Bacterial Survival ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Human Macrophages ◽  
E Coli ◽  
The Impact

ABSTRACT MCR-1 is a plasmid-encoded phosphoethanolamine transferase able to modify the lipid A structure. It confers resistance to colistin and was isolated from human, animal, and environmental strains of Enterobacteriaceae, raising serious global health concerns. In this paper, we used recombinant mcr-1-expressing Escherichia coli to study the impact of MCR-1 products on E. coli-induced activation of inflammatory pathways in activated THP-1 cells, which was used as a model of human macrophages. We found that infection with recombinant mcr-1-expressing E. coli significantly modulated p38-MAPK and Jun N-terminal protein kinase (JNK) activation and pNF-κB nuclear translocation as well as the expression of genes for the relevant proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-12 (IL-12), and IL-1β compared with mcr-1-negative strains. Caspase-1 activity and IL-1β secretion were significantly less activated by mcr-1-positive E. coli strains than the mcr-1-negative parental strain. Similar results were obtained with clinical isolates of mcr-1-positive E. coli, suggesting that, in addition to colistin resistance, the expression of mcr-1 allows the escape of early host innate defenses and may promote bacterial survival.

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