scholarly journals YbcL of Uropathogenic Escherichia coli Suppresses Transepithelial Neutrophil Migration

2012 ◽  
Vol 80 (12) ◽  
pp. 4123-4132 ◽  
Author(s):  
Megan E. Lau ◽  
Jennifer A. Loughman ◽  
David A. Hunstad
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Immune Modulation ◽  
Neutrophil Migration ◽  
Single Amino Acid ◽  
Amino Acid Difference ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
K 12

ABSTRACTUropathogenicEscherichia coli(UPEC) strains suppress the acute inflammatory response in the urinary tract to ensure access to the intracellular uroepithelial niche that supports the propagation of infection. Our understanding of this initial cross talk between host and pathogen is incomplete. Here we report the identification of a previously uncharacterized periplasmic protein, YbcL, encoded by UPEC that contributes to immune modulation in the urinary tract by suppressing acute neutrophil migration. In contrast to wild-type UPEC, an isogenic strain lackingybcLexpression (UTI89 ΔybcL) failed to suppress transepithelial polymorphonuclear leukocyte (PMN) migrationin vitro, a defect complemented by expressingybcLepisomally. YbcL homologs are present in manyE. coligenomes; expression of the YbcL variant encoded by nonpathogenicE. coliK-12 strain MG1655 (YbcLMG) failed to complement the UTI89 ΔybcLdefect, whereas expression of the UPEC YbcL variant (YbcLUTI) in MG1655 conferred the capacity for suppressing PMN migration. This phenotypic difference was due to a single amino acid difference (V78T) between the two YbcL homologs, and a majority of clinical UPEC strains examined were found to encode the suppressive YbcL variant. Purified YbcLUTIprotein suppressed PMN migration in response to live or killed MG1655, and YbcLUTIwas detected in the supernatant during UPEC infection of bladder epithelial cells or PMNs. Lastly, early PMN influx to murine bladder tissue was augmented uponin vivoinfection with UTI89 ΔybcLcompared with wild-type UPEC. Our findings demonstrate a role for UPEC YbcL in suppression of the innate immune response during urinary tract infection.

scholarly journals RpoS Contributes to Phagocyte Oxidase-Mediated Stress Resistance during Urinary Tract Infection by Escherichia coli CFT073

mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Andrew J. Hryckowian ◽  
Rodney A. Welch
Keyword(s):  
Oxidative Stress ◽  
Urinary Tract ◽  
Wild Type ◽  
Upec Strain ◽  
Content Type ◽  
General Stress Response ◽  
E Coli ◽  
Phagocyte Oxidase ◽  
Strain Cft073 ◽  
K 12

ABSTRACTUropathogenicEscherichia coli(UPEC) is the most common causative agent of community-acquired urinary tract infection (UTI). In order to cause UTI, UPEC must endure stresses ranging from nutrient limitation to host immune components. RpoS (σS), the general stress response sigma factor, directs gene expression under a variety of inhibitory conditions. Our study ofrpoSin UPEC strain CFT073 began after we discovered anrpoS-frameshift mutation in one of our laboratory stocks of “wild-type” CFT073. We demonstrate that anrpoS-deletion mutation in CFT073 leads to a colonization defect during UTI of CBA/J mice at 48 hours postinfection (hpi). There is no difference between the growth rates of CFT073 and CFT073rpoSin urine. This indicates thatrpoSis needed for replication and survival in the host rather than being needed to address limitations imposed by urine nutrients. Consistent with previous observations inE. coliK-12, CFT073rpoSis more sensitive to oxidative stress than the wild type. We demonstrate that peroxide levels are elevated in voided urine from CFT073-infected mice compared to urine from mock-infected mice, which supports the notion that oxidative stress is generated by the host in response to UPEC. In mice that lack phagocyte oxidase, the enzyme complex expressed by phagocytes that produces superoxide, the competitive defect of CFT073rpoSin bladder colonization is lost. These results demonstrate that σSis important for UPEC survival under conditions of phagocyte oxidase-generated stress during UTI. Though σSaffects the pathogenesis of other bacterial species, this is the first work that directly implicates σSas important for UPEC pathogenesis.IMPORTANCEUPEC must cope with a variety of stressful conditions in the urinary tract during infection. RpoS (σS), the general stress response sigma factor, is known to direct the expression of many genes under a variety of stressful conditions in laboratory-adaptedE. coliK-12. Here, we show that σSis needed by the model UPEC strain CFT073 to cope with oxidative stress provided by phagocytes during infection. These findings represent the first report that implicates σSin the fitness of UPEC during infection and support the idea of the need for a better understanding of the effects of this global regulator of gene expression during UTI.

scholarly journals Genetic Analysis of the Role ofyfiRin the Ability of Escherichia coli CFT073 To Control Cellular Cyclic Dimeric GMP Levels and To Persist in the Urinary Tract

2013 ◽  
Vol 81 (9) ◽  
pp. 3089-3098 ◽  
Author(s):  
Erica L. Raterman ◽  
Daniel D. Shapiro ◽  
Daniel J. Stevens ◽  
Kevin J. Schwartz ◽  
Rodney A. Welch
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Cellulose Production ◽  
Content Type ◽  
E Coli ◽  
Successful Infection ◽  
Tract Infections

ABSTRACTDuring urinary tract infections (UTIs), uropathogenicEscherichia colimust maintain a delicate balance between sessility and motility to achieve successful infection of both the bladder and kidneys. Previous studies showed that cyclic dimeric GMP (c-di-GMP) levels aid in the control of the transition between motile and nonmotile states inE. coli. TheyfiRNBlocus inE. coliCFT073 contains genes for YfiN, a diguanylate cyclase, and its activity regulators, YfiR and YfiB. Deletion ofyfiRyielded a mutant that was attenuated in both the bladder and the kidneys when tested in competition with the wild-type strain in the murine model of UTI. A doubleyfiRNmutant was not attenuated in the mouse model, suggesting that unregulated YfiN activity and likely increased cytoplasmic c-di-GMP levels cause a survival defect. Curli fimbriae and cellulose production were increased in theyfiRmutant. Expression ofyhjH, a gene encoding a proven phosphodiesterase, in CFT073 ΔyfiRsuppressed the overproduction of curli fimbriae and cellulose and further verified that deletion ofyfiRresults in c-di-GMP accumulation. Additional deletion ofcsgDandbcsA, genes necessary for curli fimbriae and cellulose production, respectively, returned colonization levels of theyfiRdeletion mutant to wild-type levels. Peroxide sensitivity assays and iron acquisition assays displayed no significant differences between theyfiRmutant and the wild-type strain. These results indicate that dysregulation of c-di-GMP production results in pleiotropic effects that disableE. coliin the urinary tract and implicate the c-di-GMP regulatory system as an important factor in the persistence of uropathogenicE. coli in vivo.

scholarly journals Dissemination and Systemic Colonization of Uropathogenic Escherichia coli in a Murine Model of Bacteremia

mBio ◽  
2010 ◽  
Vol 1 (5) ◽  
Author(s):  
Sara N. Smith ◽  
Erin C. Hagan ◽  
M. Chelsea Lane ◽  
Harry L. T. Mobley
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Urinary Tract Infections ◽  
Murine Model ◽  
Systemic Disease ◽  
Content Type ◽  
E Coli ◽  
Bacterial Genes ◽  
Tract Infections ◽  
K 12

ABSTRACTInfection with uropathogenicEscherichia coli(UPEC), the causative agent of most uncomplicated urinary tract infections, proceeds in an ascending manner and, if left untreated, may result in bacteremia and urosepsis. To examine the fate of UPEC after its entry into the bloodstream, we developed a murine model of sublethal bacteremia. CBA/J mice were inoculated intravenously with 1 × 106 CFU of pyelonephritis strainE. coliCFT073 carrying a bioluminescent reporter. Biophotonic imaging, used to monitor the infection over 48 h, demonstrated that the bacteria disseminated systemically and appeared to localize at discrete sites. UPEC was recovered from the spleen, liver, kidneys, lungs, heart, brain, and intestines as early as 20 min postinoculation, peaking at 24 h postinoculation. A nonpathogenicE. coliK-12 strain, however, disseminated at significantly lower levels (P< 0.01) and was cleared from the liver and cecum by 24 h postinoculation. Isogenic mutants lacking type 1 fimbriae, P fimbriae, capsule, TonB, the heme receptors Hma and ChuA, or particularly the sialic acid catabolism enzyme NanA were significantly outcompeted by wild-type CFT073 during bacteremia (P< 0.05), while flagellin and hemolysin mutants were not.IMPORTANCEE. coliis the primary cause of urinary tract infections. In severe cases of kidney infection, bacteria can enter the bloodstream and cause systemic disease. While the ability ofE. colito cause urinary tract infection has been extensively studied, the fate of these bacteria once they enter the bloodstream is largely unknown. Here we used an imaging technique to develop a mouse model ofE. colibloodstream infection and identify bacterial genes that are important for the bacteria to spread to and infect various organs. Understanding how urinary tract pathogens likeE. colicause disease after they enter the bloodstream may aid in the development of protective and therapeutic treatments.

scholarly journals Molecular Analysis of Asymptomatic Bacteriuria Escherichia coli Strain VR50 Reveals Adaptation to the Urinary Tract by Gene Acquisition

2015 ◽  
Vol 83 (5) ◽  
pp. 1749-1764 ◽  
Author(s):  
Scott A. Beatson ◽  
Nouri L. Ben Zakour ◽  
Makrina Totsika ◽  
Brian M. Forde ◽  
Rebecca E. Watts ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Mouse Model ◽  
Molecular Mechanisms ◽  
Asymptomatic Bacteriuria ◽  
Human Bladder ◽  
Content Type ◽  
E Coli ◽  
Tract Infections ◽  
K 12

Urinary tract infections (UTIs) are among the most common infectious diseases of humans, withEscherichia coliresponsible for >80% of all cases. One extreme of UTI is asymptomatic bacteriuria (ABU), which occurs as an asymptomatic carrier state that resembles commensalism. To understand the evolution and molecular mechanisms that underpin ABU, the genome of the ABUE. colistrain VR50 was sequenced. Analysis of the complete genome indicated that it most resemblesE. coliK-12, with the addition of a 94-kb genomic island (GI-VR50-pheV), eight prophages, and multiple plasmids. GI-VR50-pheVhas a mosaic structure and contains genes encoding a number of UTI-associated virulence factors, namely, Afa (afimbrial adhesin), two autotransporter proteins (Ag43 and Sat), and aerobactin. We demonstrated that the presence of this island in VR50 confers its ability to colonize the murine bladder, as a VR50 mutant with GI-VR50-pheVdeleted was attenuated in a mouse model of UTIin vivo. We established that Afa is the island-encoded factor responsible for this phenotype using two independent deletion (Afa operon and AfaE adhesin) mutants.E. coliVR50afaand VR50afaEdisplayed significantly decreased ability to adhere to human bladder epithelial cells. In the mouse model of UTI, VR50afaand VR50afaEdisplayed reduced bladder colonization compared to wild-type VR50, similar to the colonization level of the GI-VR50-pheVmutant. Our study suggests thatE. coliVR50 is a commensal-like strain that has acquired fitness factors that facilitate colonization of the human bladder.

scholarly journals Antimicrobial Activity Evaluation of Tebipenem (SPR859), an Orally Available Carbapenem, against a Global Set of Enterobacteriaceae Isolates, Including a Challenge Set of Organisms

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
S. J. Ryan Arends ◽  
Paul R. Rhomberg ◽  
Nicole Cotroneo ◽  
Aileen Rubio ◽  
Robert K. Flamm ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Broth Microdilution ◽  
Wild Type ◽  
Content Type ◽  
E Coli

ABSTRACT The antimicrobial activity of tebipenem and other carbapenem agents were tested in vitro against a set of recent clinical isolates responsible for urinary tract infection (UTI), as well as against a challenge set. Isolates were tested by reference broth microdilution and included Escherichia coli (101 isolates), Klebsiella pneumoniae (208 isolates), and Proteus mirabilis (103 isolates) species. Within each species tested, tebipenem showed equivalent MIC50/90 values to those of meropenem (E. coli MIC50/90, ≤0.015/0.03 mg/liter; K. pneumoniae MIC50/90, 0.03/0.06 mg/liter; and P. mirabilis MIC50/90, 0.06/0.12 mg/liter) and consistently displayed MIC90 values 8-fold lower than imipenem. Tebipenem and meropenem (MIC50, 0.03 mg/liter) showed equivalent MIC50 results against wild-type, AmpC-, and/or extended-spectrum β-lactamase (ESBL)-producing isolates. Tebipenem also displayed MIC50/90 values 4- to 8-fold lower than imipenem against the challenge set. All carbapenem agents were less active (MIC50, ≥8 mg/liter) against isolates carrying carbapenemase genes. These data confirm the in vitro activity of the orally available agent tebipenem against prevalent UTI Enterobacteriaceae species, including those producing ESBLs and/or plasmid AmpC enzymes.

scholarly journals mhpTEncodes an Active Transporter Involved in 3-(3-Hydroxyphenyl)Propionate Catabolism by Escherichia coli K-12

2013 ◽  
Vol 79 (20) ◽  
pp. 6362-6368 ◽  
Author(s):  
Ying Xu ◽  
Bing Chen ◽  
Hongjun Chao ◽  
Ning-Yi Zhou
Keyword(s):  
Escherichia Coli ◽  
Wild Type Strain ◽  
Fluorescent Protein ◽  
Gene Knockout ◽  
Transport Activity ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
Green Fluorescent ◽  
K 12

ABSTRACTEscherichia coliK-12 utilizes 3-(3-hydroxyphenyl)propionate (3HPP) as a sole carbon and energy source. Among the genes in its catabolic cluster in the genome,mhpTwas proposed to encode a hypothetical transporter. Since no transporter for 3HPP uptake has been identified, we investigated whether MhpT is responsible for 3HPP uptake. MhpT fused with green fluorescent protein was found to be located at the periphery of cells by confocal microscopy, consistent with localization to the cytoplasmic membrane. Gene knockout and complementation studies clearly indicated thatmhpTis essential for 3HPP catabolism inE. coliK-12 W3110 at pH 8.2. Uptake assays with14C-labeled substrates demonstrated that strain W3110 and strain W3110ΔmhpTcontaining recombinant MhpT specifically transported 3HPP but not benzoate, 3-hydroxybenzoate, or gentisate into cells. Energy dependence assays suggested that MhpT-mediated 3HPP transport was driven by the proton motive force. The change of Ala-272 of MhpT to a histidine, surprisingly, resulted in enhanced transport activity, and strain W3110ΔmhpTcontaining the MhpT A272H mutation had a slightly higher growth rate than the wild-type strain at pH 8.2. Hence, we demonstrated that MhpT is a specific 3HPP transporter and vital forE. coliK-12 W3110 growth on this substrate under basic conditions.

scholarly journals Enzymatically Active and Inactive Phosphodiesterases and Diguanylate Cyclases Are Involved in Regulation of Motility or Sessility in Escherichia coli CFT073

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Rachel R. Spurbeck ◽  
Rebecca J. Tarrien ◽  
Harry L. T. Mobley
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Biofilm Formation ◽  
Second Messenger ◽  
Content Type ◽  
E Coli ◽  
Diguanylate Cyclases ◽  
Genes Encoding ◽  
K 12 ◽  
Messenger Molecule

ABSTRACTIntracellular concentration of cyclic diguanylate monophosphate (c-di-GMP), a second messenger molecule, is regulated in bacteria by diguanylate cyclases (DGCs) (synthesizing c-di-GMP) and phosphodiesterases (PDEs) (degrading c-di-GMP). c-di-GMP concentration ([c-di-GMP]) affects motility and sessility in a reciprocal fashion; high [c-di-GMP] typically inhibits motility and promotes sessility. A c-di-GMP sensor domain, PilZ, also regulates motility and sessility. UropathogenicEscherichia coliregulates these processes during infection; motility is necessary for ascending the urinary tract, while sessility is essential for colonization of anatomical sites. Here, we constructed and screened 32 mutants containing deletions of genes encoding each PDE (n= 11), DGC (n= 13), PilZ (n= 2), and both PDE and DGC (n= 6) domains for defects in motility, biofilm formation, and adherence for the prototypical pyelonephritis isolateE. coliCFT073. Three of 32 mutations affected motility, all of which were in genes encoding enzymatically inactive PDEs. Four PDEs, eight DGCs, four PDE/DGCs, and one PilZ regulated biofilm formation in a medium-specific manner. Adherence to bladder epithelial cells was regulated by [c-di-GMP]. Four PDEs, one DGC, and three PDE/DGCs repress adherence and four DGCs and one PDE/DGC stimulate adherence. Thus, specific effectors of [c-di-GMP] and catalytically inactive DGCs and PDEs regulate adherence and motility in uropathogenicE. coli.IMPORTANCEUropathogenicEscherichia coli(UPEC) contains several genes annotated as encoding enzymes that increase or decrease the abundance of the second messenger molecule, c-di-GMP. While this class of enzymes has been studied in anE. coliK-12 lab strain, these proteins have not been comprehensively examined in UPEC. UPEC utilizes both swimming motility and adherence to colonize and ascend the urinary tract; both of these processes are hypothesized to be regulated by the concentration of c-di-GMP. Here, for the first time, in a uropathogenic strain,E. coliCFT073, we have characterized mutants lacking each protein and demonstrated that the uropathogen has diverged fromE. coliK-12 to utilize these enzymes to regulate adherence and motility by distinct mechanisms.

scholarly journals Functional Analysis ofycfRandycfQin Escherichia coli O157:H7 Linked to Outbreaks of Illness Associated with Fresh Produce

2011 ◽  
Vol 77 (12) ◽  
pp. 3952-3959 ◽  
Author(s):  
Kaiping Deng ◽  
Siyun Wang ◽  
Xiaoqian Rui ◽  
Wei Zhang ◽  
Mary Lou Tortorello
Keyword(s):  
Escherichia Coli ◽  
Fresh Produce ◽  
The United States ◽  
Sublethal Concentration ◽  
Wild Type ◽  
Chloramphenicol Resistance ◽  
Content Type ◽  
E Coli ◽  
K 12 ◽  
Postharvest Processing

ABSTRACTFresh produce has been associated with multiple outbreaks of illness caused byEscherichia coliO157:H7. The mechanism ofE. coliO157:H7 survival through postharvest processing of fresh produce needs to be understood to help develop more effective interventions. In our recent transcriptomic study of strain Sakai, an isolate from the 1996 sprout outbreak in Japan, and strain TW14359, an isolate from the 2006 spinach outbreak in the United States, we showed thatycfRwas the most significantly upregulated gene in response to chlorine-based oxidative stress. YcfR is known to be a multiple stress resistance protein and a biofilm regulator inE. coliK-12 strains; however, its role in the pathogenicE. coliO157:H7 has not been clearly defined. In this study,ycfRwas replaced with a chloramphenicol resistance cassette oriented in two different directions to construct polar and nonpolarycfR::catmutants of Sakai and TW14359. Chlorine resistance and survival on spinach leaf surfaces were assessed in the wild-type strains and theycfRmutants. Both polar and nonpolarycfRmutants of Sakai showed significantly less chlorine resistance than their parent strain. In contrast, deletion ofycfRin TW14359 did not change chlorine resistance, indicating thatycfRin these two outbreak-relatedE. coliO157:H7 strains may function differently. In addition, after a 24-h incubation on spinach leaves in a sublethal concentration of chlorine, the Sakai nonpolarycfRmutant exhibited lower survival compared to the wild type. The results suggest a role forycfRin survival of Sakai during chlorine exposure. We also found that the upstreamycfQ, which is annotated as a DNA-binding regulator, acted as a repressor ofycfR. These findings suggest that gene regulation may be a mechanism by whichE. coliO157:H7 strain Sakai could survive in the postharvest processing environment.

scholarly journals The Small RNA RyhB Contributes to Siderophore Production and Virulence of Uropathogenic Escherichia coli

2014 ◽  
Vol 82 (12) ◽  
pp. 5056-5068 ◽  
Author(s):  
Gaëlle Porcheron ◽  
Rima Habib ◽  
Sébastien Houle ◽  
Mélissa Caza ◽  
François Lépine ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Urinary Tract ◽  
Type Strain ◽  
Iron Homeostasis ◽  
Wild Type Strain ◽  
Iron Acquisition ◽  
Wild Type ◽  
Content Type ◽  
E Coli

ABSTRACTInEscherichia coli, the small regulatory noncoding RNA (sRNA) RyhB and the global ferric uptake regulator (Fur) mediate iron acquisition and storage control. Iron is both essential and potentially toxic for most living organisms, making the precise maintenance of iron homeostasis necessary for survival. While the roles of these regulators in iron homeostasis have been well studied in a nonpathogenicE. colistrain, their impact on the production of virulence-associated factors is still unknown for a pathogenicE. colistrain. We thus investigated the roles of RyhB and Fur in iron homeostasis and virulence of the uropathogenicE. coli(UPEC) strain CFT073. In a murine model of urinary tract infection (UTI), deletion offuralone did not attenuate virulence, whereas a ΔryhBmutant and a ΔfurΔryhBdouble mutant showed significantly reduced bladder colonization. The Δfurmutant was more sensitive to oxidative stress and produced more of the siderophores enterobactin, salmochelins, and aerobactin than the wild-type strain. In contrast, while RyhB was not implicated in oxidative stress resistance, the ΔryhBmutant produced lower levels of siderophores. This decrease was correlated with the downregulation ofshiA(encoding a transporter of shikimate, a precursor of enterobactin and salmochelin biosynthesis) andiucD(involved in aerobactin biosynthesis) in this mutant grown in minimal medium or in human urine.iucDwas also downregulated in bladders infected with the ΔryhBmutant compared to those infected with the wild-type strain. Our results thus demonstrate that the sRNA RyhB is involved in production of iron acquisition systems and colonization of the urinary tract by pathogenicE. coli.

scholarly journals Genotype and Phenotypes of an Intestine-Adapted Escherichia coli K-12 Mutant Selected by Animal Passage for Superior Colonization

2011 ◽  
Vol 79 (6) ◽  
pp. 2430-2439 ◽  
Author(s):  
Andrew J. Fabich ◽  
Mary P. Leatham ◽  
Joe E. Grissom ◽  
Graham Wiley ◽  
Hongshing Lai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Carbon Sources ◽  
Genomic Analysis ◽  
Metabolic Efficiency ◽  
Spontaneous Mutant ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
Expression Of Genes ◽  
K 12

ABSTRACTWe previously isolated a spontaneous mutant ofEscherichia coliK-12, strain MG1655, following passage through the streptomycin-treated mouse intestine, that has colonization traits superior to the wild-type parent strain (M. P. Leatham et al., Infect. Immun.73:8039–8049, 2005). This intestine-adapted strain (E. coliMG1655*) grew faster on several different carbon sources than the wild type and was nonmotile due to deletion of theflhDgene. We now report the results of several high-throughput genomic analysis approaches to further characterizeE. coliMG1655*. Whole-genome pyrosequencing did not reveal any changes on its genome, aside from the deletion at theflhDClocus, that could explain the colonization advantage ofE. coliMG1655*. Microarray analysis revealed modest yet significant induction of catabolic gene systems across the genome in bothE. coliMG1655* and an isogenicflhDmutant constructed in the laboratory. Catabolome analysis with Biolog GN2 microplates revealed an enhanced ability of bothE. coliMG1655* and the isogenicflhDmutant to oxidize a variety of carbon sources. The results show that intestine-adaptedE. coliMG1655* is more fit than the wild type for intestinal colonization, because loss of FlhD results in elevated expression of genes involved in carbon and energy metabolism, resulting in more efficient carbon source utilization and a higher intestinal population. Hence, mutations that enhance metabolic efficiency confer a colonization advantage.

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