scholarly journals Allosteric Activation of Escherichia coli Glucosamine-6-Phosphate Deaminase (NagB)In VivoJustified by Intracellular Amino Sugar Metabolite Concentrations

2016 ◽  
Vol 198 (11) ◽  
pp. 1610-1620 ◽  
Author(s):  
Laura I. Álvarez-Añorve ◽  
Isabelle Gaugué ◽  
Hannes Link ◽  
Jorge Marcos-Viquez ◽  
Dana M. Díaz-Jiménez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Sugar Metabolism ◽  
Fold Increase ◽  
Amino Sugar ◽  
Amino Sugars ◽  
High Concentration ◽  
Futile Cycle ◽  
Content Type ◽  
E Coli ◽  
The Impact

ABSTRACTWe have investigated the impact of growth on glucosamine (GlcN) andN-acetylglucosamine (GlcNAc) on cellular metabolism by quantifying glycolytic metabolites inEscherichia coli. Growth on GlcNAc increased intracellular pools of both GlcNAc6P and GlcN6P 10- to 20-fold compared to growth on glucose. Growth on GlcN produced a 100-fold increase in GlcN6P but only a slight increase in GlcNAc6P. Changes to the amounts of downstream glycolytic intermediates were minor compared to growth on glucose. The enzyme glucosamine-6P deaminase (NagB) is required for growth on both GlcN and GlcNAc. It is an allosteric enzyme inE. coli, displaying sigmoid kinetics with respect to its substrate, GlcN6P, and is allosterically activated by GlcNAc6P. The high concentration of GlcN6P, accompanied by the small increase in GlcNAc6P, drivesE. coliNagB (NagBEc) into its high activity state, as observed during growth on GlcN (L. I. Álvarez-Añorve, I. Bustos-Jaimes, M. L. Calcagno, and J. Plumbridge, J Bacteriol 191:6401–6407, 2009,http://dx.doi.org/10.1128/JB.00633-09). The slight increase in GlcNAc6P during growth on GlcN is insufficient to displace NagC, the GlcNAc6P-responsive repressor of thenaggenes, from its binding sites, so there is only a small increase innagBexpression. We replaced the gene for the allosteric NagBEcenzyme with that of the nonallosteric,B. subtilishomologue, NagBBs. We detected no effects on growth rates or competitive fitness on glucose or the amino sugars, nor did we detect any effect on the concentrations of central metabolites, thus demonstrating the robustness of amino sugar metabolism and leaving open the question of the role of allostery in the regulation of NagB.IMPORTANCEChitin, the polymer ofN-acetylglucosamine, is an abundant biomaterial, and both glucosamine andN-acetylglucosamine are valuable nutrients for bacteria. The amino sugars are components of numerous essential macromolecules, including bacterial peptidoglycan and mammalian glycosaminoglycans. Controlling the biosynthetic and degradative pathways of amino sugar metabolism is important in all organisms to avoid loss of nitrogen and energy via a futile cycle of synthesis and breakdown. The enzyme glucosamine-6P deaminase (NagB) is central to this control, andN-acetylglucosamine-6P is the key signaling molecule regulating amino sugar utilization inEscherichia coli. Here, we investigate how the metabolic status of the bacteria impacts on the activity of NagBEcand theN-acetylglucosamine-6P-sensitive transcriptional repressor, NagC.

scholarly journals Control of amino sugar metabolism in Escherichia coli and isolation of mutants unable to degrade amino sugars

1968 ◽  
Vol 106 (4) ◽  
pp. 847-858 ◽  
Author(s):  
R. J. White
Keyword(s):  
Escherichia Coli ◽  
Sugar Metabolism ◽  
Amino Sugar ◽  
Amino Sugars ◽  
Wild Type ◽  
Intracellular Accumulation ◽  
Uptake Mechanism ◽  
E Coli ◽  
Inhibition Of Growth

1. Growth of Escherichia coli on glucosamine results in an induction of glucosamine 6-phosphate deaminase [2-amino-2-deoxy-d-glucose 6-phosphate ketol-isomerase (deaminating), EC 5.3.1.10] and a repression of glucosamine 6-phosphate synthetase (l-glutamine–d-fructose 6-phosphate aminotransferase, EC 2.6.1.16); glucose abolishes these control effects. 2. Growth of E. coli on N-acetylglucosamine results in an induction of N-acetylglucosamine 6-phosphate deacetylase and glucosamine 6-phosphate deaminase, and in a repression of glucosamine 6-phosphate synthetase; glucose diminishes these control effects. 3. The synthesis of amino sugar kinases (EC 2.7.1.8 and 2.7.1.9) is unaffected by growth on amino sugars. 4. Glucosamine 6-phosphate synthetase is inhibited by glucosamine 6-phosphate. 5. Mutants of E. coli that are unable to grow on N-acetylglucosamine have been isolated, and lack either N-acetylglucosamine 6-phosphate deacetylase (deacetylaseless) or glucosamine 6-phosphate deaminase (deaminaseless). Deacetylaseless mutants can grow on glucosamine but deaminaseless mutants cannot. 6. After growth on glucose, deacetylaseless mutants have a repressed glucosamine 6-phosphate synthetase and a super-induced glucosamine 6-phosphate deaminase; this may be related to an intracellular accumulation of acetylamino sugar that also occurs under these conditions. In one mutant the acetylamino sugar was shown to be partly as N-acetylglucosamine 6-phosphate. Deaminaseless mutants have no abnormal control effects after growth on glucose. 7. Addition of N-acetylglucosamine or glucosamine to cultures of a deaminaseless mutant caused inhibition of growth. Addition of N-acetylglucosamine to cultures of a deacetylaseless mutant caused lysis, and secondary mutants were isolated that did not lyse; most of these secondary mutants had lost glucosamine 6-phosphate deaminase and an uptake mechanism for N-acetylglucosamine. 8. Similar amounts of 14C were incorporated from [1−14C]-glucosamine by cells of mutants and wild-type growing on broth. Cells of wild-type and a deaminaseless mutant incorporated 14C from N-acetyl[1−14C]glucosamine more efficiently than from N[1−14C]-acetylglucosamine, incorporation from the latter being further decreased by acetate; cells of a deacetylaseless mutant showed a poor incorporation of both types of labelled N-acetylglucosamine.

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.

scholarly journals Impact of Ralstonia eutropha's Poly(3-Hydroxybutyrate) (PHB) Depolymerases and Phasins on PHB Storage in Recombinant Escherichia coli

2014 ◽  
Vol 80 (24) ◽  
pp. 7702-7709 ◽  
Author(s):  
Jessica Eggers ◽  
Alexander Steinbüchel
Keyword(s):  
Escherichia Coli ◽  
Ralstonia Eutropha ◽  
Model Organism ◽  
Dry Weight ◽  
Growth Behavior ◽  
Carbon Limitation ◽  
Content Type ◽  
Phb Depolymerase ◽  
E Coli ◽  
The Impact

ABSTRACTThe model organism for polyhydroxybutyrate (PHB) biosynthesis,Ralstonia eutrophaH16, possesses multiple isoenzymes of granules coating phasins as well as of PHB depolymerases, which degrade accumulated PHB under conditions of carbon limitation. In this study, recombinantEscherichia coliBL21(DE3) strains were used to study the impact of selected PHB depolymerases ofR. eutrophaH16 on the growth behavior and on the amount of accumulated PHB in the absence or presence of phasins. For this purpose, 20 recombinantE. coliBL21(DE3) strains were constructed, which harbored a plasmid carrying thephaCABoperon fromR. eutrophaH16 to ensure PHB synthesis and a second plasmid carrying different combinations of the genes encoding a phasin and a PHB depolymerase fromR. eutrophaH16. It is shown in this study that the growth behavior of the respective recombinantE. colistrains was barely affected by the overexpression of the phasin and PHB depolymerase genes. However, the impact on the PHB contents was significantly greater. The strains expressing the genes of the PHB depolymerases PhaZ1, PhaZ2, PhaZ3, and PhaZ7 showed 35% to 94% lower PHB contents after 30 h of cultivation than the control strain. The strain harboringphaZ7reached by far the lowest content of accumulated PHB (only 2.0% [wt/wt] PHB of cell dry weight). Furthermore, coexpression of phasins in addition to the PHB depolymerases influenced the amount of PHB stored in cells of the respective strains. It was shown that the phasins PhaP1, PhaP2, and PhaP4 are not substitutable without an impact on the amount of stored PHB. In particular, the phasins PhaP2 and PhaP4 seemed to limit the degradation of PHB by the PHB depolymerases PhaZ2, PhaZ3, and PhaZ7, whereas almost no influence of the different phasins was observed ifphaZ1was coexpressed. This study represents an extensive analysis of the impact of PHB depolymerases and phasins on PHB accumulation and provides a deeper insight into the complex interplay of these enzymes.

scholarly journals Amino Sugars Enhance the Competitiveness of Beneficial Commensals with Streptococcus mutans through Multiple Mechanisms

2016 ◽  
Vol 82 (12) ◽  
pp. 3671-3682 ◽  
Author(s):  
Lin Zeng ◽  
Tanaz Farivar ◽  
Robert A. Burne
Keyword(s):  
Dental Caries ◽  
Streptococcus Mutans ◽  
Sugar Metabolism ◽  
Amino Sugar ◽  
Amino Sugars ◽  
Mrna Levels ◽  
Oral Streptococci ◽  
Streptococcus Gordonii ◽  
Carbohydrate Source ◽  
Content Type

ABSTRACTBiochemical and genetic aspects of the metabolism of the amino sugarsN-acetylglucosamine (GlcNAc) and glucosamine (GlcN) by commensal oral streptococci and the effects of these sugars on interspecies competition with the dental caries pathogenStreptococcus mutanswere explored. MultipleS. mutanswild-type isolates displayed long lag phases when transferred from glucose-containing medium to medium with GlcNAc as the primary carbohydrate source, but commensal streptococci did not. Competition in liquid coculture or dual-species biofilms betweenS. mutansandStreptococcus gordoniishowed thatS. gordoniiwas particularly dominant when the primary carbohydrate was GlcN or GlcNAc. Transcriptional and enzymatic assays showed that the catabolic pathway for GlcNAc was less highly induced inS. mutansthan inS. gordonii. Exposure to H2O2, which is produced byS. gordoniiand antagonizes the growth ofS. mutans, led to reduced mRNA levels ofnagAandnagBinS. mutans. When the gene for the transcriptional regulatory NagR was deleted inS. gordonii, the strain produced constitutively high levels ofnagA(GlcNAc-6-P deacetylase),nagB(GlcN-6-P deaminase), andglmS(GlcN-6-P synthase) mRNA. Similar to NagR ofS. mutans(NagRSm), theS. gordoniiNagR protein (NagRSg) could bind to consensus binding sites (dre) in thenagA,nagB, andglmSpromoter regions ofS. gordonii. Notably, NagRSgbinding was inhibited by GlcN-6-P, but G-6-P had no effect, unlike for NagRSm. This study expands the understanding of amino sugar metabolism and NagR-dependent gene regulation in streptococci and highlights the potential for therapeutic applications of amino sugars to prevent dental caries.IMPORTANCEAmino sugars are abundant in the biosphere, so the relative efficiency of particular bacteria in a given microbiota to metabolize these sources of carbon and nitrogen might have a profound impact on the ecology of the community. Our investigation reveals that several oral commensal bacteria have a much greater capacity to utilize amino sugars than the dental pathogenStreptococcus mutansand that the ability of the model commensalStreptococcus gordoniito compete againstS. mutansis substantively enhanced by the presence of amino sugars commonly found in the oral cavity. The mechanisms underlying the greater capacity and competitive enhancements of the commensal are shown to depend on how the genes for the catabolic enzymes are regulated, the role of the allosteric modulators affecting such regulation, and the ability of amino sugars to enhance certain activities of the commensal that are antagonistic toS. mutans.

scholarly journals A Large, Refractory Nosocomial Outbreak of Klebsiella pneumoniae Carbapenemase-Producing Escherichia coli Demonstrates Carbapenemase Gene Outbreaks Involving Sink Sites Require Novel Approaches to Infection Control

2018 ◽  
Vol 62 (12) ◽  
Author(s):  
V. Decraene ◽  
H. T. T. Phan ◽  
R. George ◽  
D. H. Wyllie ◽  
O. Akinremi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Control Measures ◽  
Effective Control ◽  
Infection Prevention And Control ◽  
Content Type ◽  
E Coli ◽  
Incidence Trends ◽  
Carbapenemase Gene ◽  
The Impact

ABSTRACT Carbapenem-resistant Enterobacteriaceae (CRE) represent a health threat, but effective control interventions remain unclear. Hospital wastewater sites are increasingly being highlighted as important potential reservoirs. We investigated a large Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli outbreak and wider CRE incidence trends in the Central Manchester University Hospital NHS Foundation Trust (CMFT) (United Kingdom) over 8 years, to determine the impact of infection prevention and control measures. Bacteriology and patient administration data (2009 to 2017) were linked, and a subset of CMFT or regional hospital KPC-producing E. coli isolates (n = 268) were sequenced. Control interventions followed international guidelines and included cohorting, rectal screening (n = 184,539 screens), environmental sampling, enhanced cleaning, and ward closure and plumbing replacement. Segmented regression of time trends for CRE detections was used to evaluate the impact of interventions on CRE incidence. Genomic analysis (n = 268 isolates) identified the spread of a KPC-producing E. coli outbreak clone (strain A, sequence type 216 [ST216]; n = 125) among patients and in the environment, particularly on 2 cardiac wards (wards 3 and 4), despite control measures. ST216 strain A had caused an antecedent outbreak and shared its KPC plasmids with other E. coli lineages and Enterobacteriaceae species. CRE acquisition incidence declined after closure of wards 3 and 4 and plumbing replacement, suggesting an environmental contribution. However, ward 3/ward 4 wastewater sites were rapidly recolonized with CRE and patient CRE acquisitions recurred, albeit at lower rates. Patient relocation and plumbing replacement were associated with control of a clonal KPC-producing E. coli outbreak; however, environmental contamination with CRE and patient CRE acquisitions recurred rapidly following this intervention. The large numbers of cases and the persistence of blaKPC in E. coli, including pathogenic lineages, are of concern.

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