scholarly journals Salmonella entericasubsp.entericaSerovar Heidelberg Food Isolates Associated with a Salmonellosis Outbreak Have Enhanced Stress Tolerance Capabilities

2019 ◽  
Vol 85 (16) ◽  
Author(s):  
Andrea J. Etter ◽  
Alyssa M. West ◽  
John L. Burnett ◽  
Sophie Tongyu Wu ◽  
Deklin R. Veenhuizen ◽  
...  
Keyword(s):  
Heat Stress ◽  
Stress Tolerance ◽  
Heat Tolerance ◽  
Salmonella Enterica ◽  
Genetic Relationships ◽  
The United States ◽  
Intrinsic Stress ◽  
Transcriptomic Response ◽  
Content Type

ABSTRACTSalmonella entericaserovar Heidelberg is currently the 12th most common serovar ofSalmonella entericacausing salmonellosis in the United States and results in twice the average incidence of blood infections caused by nontyphoidal salmonellae. Multiple outbreaks of salmonellosis caused bySalmonellaHeidelberg resulted from the same poultry processor, which infected 634 people during 2013 and 2014. The hospitalization and invasive illness rates were 38% and 15%, respectively. We hypothesized that the outbreak strains ofSalmonellaHeidelberg had enhanced stress tolerance and virulence capabilities. We sourced nine food isolates collected during the outbreak investigation and three reference isolates to assess their tolerance to heat and sanitizers, ability to attach to abiotic surfaces, and invasivenessin vitro. We performed RNA sequencing on three isolates (two outbreak-associated isolates and a referenceSalmonellaHeidelberg strain) with various levels of heat tolerance to gain insight into the mechanism behind the isolates’ enhanced heat tolerance. We also performed genomic analyses to determine the genetic relationships among the outbreak isolates. Ultimately, we determined that (i) sixSalmonellaHeidelberg isolates associated with the foodborne outbreak had enhanced heat tolerance, (ii) one outbreak isolate with enhanced heat tolerance also had an enhanced biofilm-forming ability under stressful conditions, (iii) exposure to heat stress increased the expression ofSalmonellaHeidelberg multidrug efflux and virulence genes, and (iv) outbreak-associated isolates were likely transcriptionally primed to better survive processing stresses and, potentially, to cause illness.IMPORTANCEThis study provides a deep analysis of the intrinsic stress tolerance and virulence capabilities ofSalmonellaHeidelberg that may have contributed to the length and severity of a recent salmonellosis outbreak. Additionally, this study provides a comprehensive analysis of the transcriptomic response ofS. entericastrains to heat stress conditions and compares baseline stationary-phase gene expression among outbreak- and non-outbreak-associatedSalmonellaHeidelberg isolates. These data can be used in assay development to screen isolates for stress tolerance and subsequent survival. This study adds to our understanding of the strains associated with the outbreak and informs ongoing regulatory discussions onSalmonellain poultry.

scholarly journals Increased Resistance to Multiple Antimicrobials and Altered Resistance Gene Expression in CMY-2-Positive Salmonella enterica following a Simulated Patient Treatment with Ceftriaxone

2012 ◽  
Vol 78 (22) ◽  
pp. 8062-8066 ◽  
Author(s):  
Russell D. Hamilton ◽  
Holly J. Hulsebus ◽  
Samina Akbar ◽  
Jeffrey T. Gray
Keyword(s):  
Gene Expression ◽  
Antimicrobial Resistance ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Salmonella Enterica ◽  
The United States ◽  
Simulated Patient ◽  
Patient Treatment ◽  
Content Type

ABSTRACTSalmonellosis is one of the most common causes of food-borne disease in the United States. Increasing antimicrobial resistance and corresponding increases in virulence present serious challenges. Currently, empirical therapy for invasiveSalmonella entericainfection includes either ceftriaxone or ciprofloxacin (E. L. Hohmann, Clin. Infect. Dis. 32:263–269, 2001). TheblaCMY-2gene confers resistance to ceftriaxone, the antimicrobial of choice for pediatric patients with invasiveSalmonella entericainfections, making these infections especially dangerous (J. M. Whichard et al., Emerg. Infect. Dis. 11:1464–1466, 2005). We hypothesized thatblaCMY-2-positiveSalmonella entericawould exhibit increased MICs to multiple antimicrobial agents and increased resistance gene expression following exposure to ceftriaxone using a protocol that simulated a patient treatmentin vitro. SevenSalmonella entericastrains survived a simulated patient treatmentin vitroand, following treatment, exhibited a significantly increased ceftriaxone MIC. Not only would these isolates be less responsive to further ceftriaxone treatment, but because theblaCMY-2genes are commonly located on large, multidrug-resistant plasmids, increased expression of theblaCMY-2gene may be associated with increased expression of other drug resistance genes located on the plasmid (N. D. Hanson and C. C. Sanders, Curr. Pharm. Des. 5:881–894, 1999). The results of this study demonstrate that a simulated patient treatment with ceftriaxone can alter the expression of antimicrobial resistance genes, includingblaCMY-2andfloRinS. entericaserovar Typhimurium andS. entericaserovar Newport. Additionally, we have shown increased MICs following a simulated patient treatment with ceftriaxone for tetracycline, amikacin, ceftriaxone, and cefepime, all of which have resistance genes commonly located on CMY-2 plasmids. The increases in resistance observed are significant and may have a negative impact on both public health and antimicrobial resistance ofSalmonella enterica.

scholarly journals Whole-Genome Sequencing Analysis of Salmonella enterica Serovar Enteritidis Isolates in Chile Provides Insights into Possible Transmission between Gulls, Poultry, and Humans

2016 ◽  
Vol 82 (20) ◽  
pp. 6223-6232 ◽  
Author(s):  
Magaly Toro ◽  
Patricio Retamal ◽  
Sherry Ayers ◽  
Marlen Barreto ◽  
Marc Allard ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Genetic Relationships ◽  
The United States ◽  
Interspecies Transmission ◽  
Sequencing Analysis ◽  
Nucleotide Polymorphisms ◽  
Content Type ◽  
Published Evidence ◽  
Trace Back ◽  
The World

ABSTRACTSalmonella entericasubsp.entericaserotype Enteritidis is a major cause of human salmonellosis worldwide; however, little is known about the genetic relationships betweenS. Enteritidis clinical strains andS. Enteritidis strains from other sources in Chile. We compared the whole genomes of 30S. Enteritidis strains isolated from gulls, domestic chicken eggs, and humans in Chile, to investigate their phylogenetic relationships and to establish their relatedness to international strains. Core genome multilocus sequence typing (cgMLST) analysis showed that only 246/4,065 shared loci differed among these Chilean strains, separating them into two clusters (I and II), with cluster II being further divided into five subclusters. One subcluster (subcluster 2) contained strains from all surveyed sources that differed at 1 to 18 loci (of 4,065 loci) with 1 to 18 single-nucleotide polymorphisms (SNPs), suggesting interspecies transmission ofS. Enteritidis in Chile. Moreover, clusters were formed by strains that were distant geographically, which could imply that gulls might be spreading the pathogen throughout the country. Our cgMLST analysis, using otherS. Enteritidis genomes available in the National Center for Biotechnology Information (NCBI) database, showed thatS. Enteritidis strains from Chile and the United States belonged to different lineages, which suggests thatS. Enteritidis regional markers might exist and could be used for trace-back investigations.IMPORTANCEThis study highlights the importance of gulls in the spread ofSalmonellaEnteritidis in Chile. We revealed a close genetic relationship between some human and gullS. Enteritidis strains (with as few as 2 of 4,065 genes being different), and we also found that gull strains were present in clusters formed by strains isolated from other sources or distant locations. Together with previously published evidence, this suggests that gulls might be spreading this pathogen between different regions in Chile and that some of those strains have been transmitted to humans. Moreover, we discovered that ChileanS. Enteritidis strains clustered separately from most ofS. Enteritidis strains isolated throughout the world (in the GenBank database) and thus it might be possible to distinguish the geographical origins of strains based on specific genomic features. This could be useful for trace-back investigations of foodborne illnesses throughout the world.

scholarly journals rpoS-Regulated Core Genes Involved in the Competitive Fitness of Salmonella enterica Serovar Kentucky in the Intestines of Chickens

2014 ◽  
Vol 81 (2) ◽  
pp. 502-514 ◽  
Author(s):  
Ying Cheng ◽  
Adriana Ayres Pedroso ◽  
Steffen Porwollik ◽  
Michael McClelland ◽  
Margie D. Lee ◽  
...  
Keyword(s):  
United States ◽  
Salmonella Enterica ◽  
The United States ◽  
Differential Regulation ◽  
Metabolic Adaptation ◽  
Content Type ◽  
Metabolic Genes ◽  
Core Genes

ABSTRACTSalmonella entericaserovar Kentucky has become the most frequently isolated serovar from poultry in the United States over the past decade. Despite its prevalence in poultry, it causes few human illnesses in the United States. The dominance ofS. Kentucky in poultry does not appear to be due to single introduction of a clonal strain, and its reduced virulence appears to correlate with the absence of virulence genesgrvA,sseI,sopE, andsodC1. S. Kentucky's prevalence in poultry is possibly attributable to its metabolic adaptation to the chicken cecum. While there were no difference in the growth rate ofS. Kentucky andS. Typhimurium grown microaerophilically in cecal contents,S. Kentucky persisted longer when chickens were coinfected withS. Typhimurium. Thein vivoadvantage thatS. Kentucky has overS. Typhimurium appears to be due to differential regulation of coreSalmonellagenes via the stationary-phase sigma factorrpoS. Microarray analysis ofSalmonellagrown in cecal contentsin vitroidentified several metabolic genes and motility and adherence genes that are differentially activated inS. Kentucky. The contributions of four of these operons (mgl,prp,nar, andcsg) toSalmonellacolonization in chickens were assessed. Deletion ofmglandcsgreducedS. Kentucky persistence in competition studies in chickens infected with wild-type or mutant strains. Subtle mutations affecting differential regulation of coreSalmonellagenes appear to be important inSalmonella's adaptation to its animal host and especially forS. Kentucky's emergence as the dominant serovar in poultry.

scholarly journals Development of an in vitro Microtuberization and Temporary Immersion Bioreactor System to Evaluate Heat Stress Tolerance in Potatoes (Solanum tuberosum L.)

2021 ◽  
Vol 12 ◽  
Author(s):  
Sanjeev Gautam ◽  
Nora Solis-Gracia ◽  
Megan K. Teale ◽  
Kranthi Mandadi ◽  
Jorge A. da Silva ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Stress Tolerance ◽  
Heat Tolerance ◽  
Potato Variety ◽  
Temporary Immersion Bioreactor ◽  
Temporary Immersion ◽  
Bioreactor System ◽  
Heat Tolerant

High temperature (heat) stress reduces tuber yield and quality of potatoes. Screening potatoes for heat tolerance is increasingly important, considering the climate change scenario and expansion of potatoes to countries where heat stress is an issue. In vitro screening for tolerance to abiotic stresses offers several advantages, including quick evaluation of numerous genotypes (clones) in reduced space, controlled environmental conditions (temperature and photoperiod), and free from confounding variables inherent to greenhouse and field conditions. In this study, we explored the feasibility of using a temporary immersion bioreactor system for heat tolerance screening of potatoes. We determined the best hormone-free microtuberizing media for this system (MSG with 8% sucrose) to enhance microtuber number and size. Comparisons of microtubers produced at 30°C as heat treatment, with 16°C as normal condition, allowed to identify heat tolerant and susceptible potato clones. The use of bioreactors allowed distinguishing well-formed (non-deformed) from deformed microtubers. Heat stress increased the total biomass of plant tissues in all the clones. However, the effect of heat stress on microtuber number and weight varied among the clones. Incubation at 30°C decreased the weight and number of non-deformed microtubers in all the clones except for Reveille Russet in which the weight of non-deformed microtubers was significantly increased and the count of non-deformed microtubers was not affected. The potato variety Reveille Russet, which was selected under high-temperature field conditions in Texas, had many non-deformed microtubers per explant and the highest microtuber weight among four clones evaluated under heat stress. We described a faster and reliable in vitro microtuberization system for abiotic stress tolerance screening, identified Reveille Russet as a promising heat-tolerant potato variety, and confirmed Russet Burbank and Atlantic as susceptible heat-tolerant checks.

scholarly journals From (p)ppGpp to (pp)pGpp: Characterization of Regulatory Effects of pGpp Synthesized by the Small Alarmone Synthetase of Enterococcus faecalis

2015 ◽  
Vol 197 (18) ◽  
pp. 2908-2919 ◽  
Author(s):  
Anthony O. Gaca ◽  
Pavel Kudrin ◽  
Cristina Colomer-Winter ◽  
Jelena Beljantseva ◽  
Kuanqing Liu ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Enterococcus Faecalis ◽  
Second Messengers ◽  
Stringent Response ◽  
Synthetase Activity ◽  
Protective Effects ◽  
Content Type ◽  
Regulatory Effects ◽  
Complex Target

ABSTRACTThe bacterial stringent response (SR) is a conserved stress tolerance mechanism that orchestrates physiological alterations to enhance cell survival. This response is mediated by the intracellular accumulation of the alarmones pppGpp and ppGpp, collectively called (p)ppGpp. InEnterococcus faecalis, (p)ppGpp metabolism is carried out by the bifunctional synthetase/hydrolaseE. faecalisRel (RelEf) and the small alarmone synthetase (SAS) RelQEf. Although Rel is the main enzyme responsible for SR activation inFirmicutes, there is emerging evidence that SASs can make important contributions to bacterial homeostasis. Here, we showed that RelQEfsynthesizes ppGpp more efficiently than pppGpp without the need for ribosomes, tRNA, or mRNA. In addition to (p)ppGpp synthesis from GDP and GTP, RelQEfalso efficiently utilized GMP to form GMP 3′-diphosphate (pGpp). Based on this observation, we sought to determine if pGpp exerts regulatory effects on cellular processes affected by (p)ppGpp. We found that pGpp, like (p)ppGpp, strongly inhibits the activity ofE. faecalisenzymes involved in GTP biosynthesis and, to a lesser extent, transcription ofrrnBbyEscherichia coliRNA polymerase. Activation ofE. coliRelA synthetase activity was observed in the presence of both pGpp and ppGpp, while RelQEfwas activated only by ppGpp. Furthermore, enzymatic activity of RelQEfis insensitive to relacin, a (p)ppGpp analog developed as an inhibitor of “long” RelA/SpoT homolog (RSH) enzymes. We conclude that pGpp can likely function as a bacterial alarmone with target-specific regulatory effects that are similar to what has been observed for (p)ppGpp.IMPORTANCEAccumulation of the nucleotide second messengers (p)ppGpp in bacteria is an important signal regulating genetic and physiological networks contributing to stress tolerance, antibiotic persistence, and virulence. Understanding the function and regulation of the enzymes involved in (p)ppGpp turnover is therefore critical for designing strategies to eliminate the protective effects of this molecule. While characterizing the (p)ppGpp synthetase RelQ ofEnterococcus faecalis(RelQEf), we found that, in addition to (p)ppGpp, RelQEfis an efficient producer of pGpp (GMP 3′-diphosphate).In vitroanalysis revealed that pGpp exerts complex, target-specific effects on processes known to be modulated by (p)ppGpp. These findings provide a new regulatory feature of RelQEfand suggest that pGpp may represent a new member of the (pp)pGpp family of alarmones.

scholarly journals A Single B-Repeat of Staphylococcus epidermidis Accumulation-Associated Protein Induces Protective Immune Responses in an Experimental Biomaterial-Associated Infection Mouse Model

2014 ◽  
Vol 21 (9) ◽  
pp. 1206-1214 ◽  
Author(s):  
Lin Yan ◽  
Lei Zhang ◽  
Hongyan Ma ◽  
David Chiu ◽  
James D. Bryers
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Porous Scaffold ◽  
The United States ◽  
Protein Vaccine ◽  
Weight Changes ◽  
Biofilm Inhibition ◽  
Content Type ◽  
Accumulation Associated Protein

ABSTRACTNosocomial infections are the fourth leading cause of morbidity and mortality in the United States, resulting in 2 million infections and ∼100,000 deaths each year. More than 60% of these infections are associated with some type of biomedical device.Staphylococcus epidermidisis a commensal bacterium of the human skin and is the most common nosocomial pathogen infecting implanted medical devices, especially those in the cardiovasculature.S. epidermidisantibiotic resistance and biofilm formation on inert surfaces make these infections hard to treat. Accumulation-associated protein (Aap), a cell wall-anchored protein ofS. epidermidis, is considered one of the most important proteins involved in the formation ofS. epidermidisbiofilm. A small recombinant protein vaccine comprising a single B-repeat domain (Brpt1.0) ofS. epidermidisRP62A Aap was developed, and the vaccine's efficacy was evaluatedin vitrowith a biofilm inhibition assay andin vivoin a murine model of biomaterial-associated infection. A high IgG antibody response againstS. epidermidisRP62A was detected in the sera of the mice after two subcutaneous immunizations with Brpt1.0 coadministered with Freund's adjuvant. Sera from Brpt1.0-immunized mice inhibitedin vitroS. epidermidisRP62A biofilm formation in a dose-dependent pattern. After receiving two immunizations, each mouse was surgically implanted with a porous scaffold disk containing 5 × 106CFU ofS. epidermidisRP62A. Weight changes, inflammatory markers, and histological assay results after challenge withS. epidermidisindicated that the mice immunized with Brpt1.0 exhibited significantly higher resistance toS. epidermidisRP62A implant infection than the control mice. Day 8 postchallenge, there was a significantly lower number of bacteria in scaffold sections and surrounding tissues and a lower residual inflammatory response to the infected scaffold disks for the Brpt1.0-immunized mice than for of the ovalbumin (Ova)-immunized mice.

scholarly journals A Salmonella Virulence Factor Activates the NOD1/NOD2 Signaling Pathway

mBio ◽  
2011 ◽  
Vol 2 (6) ◽  
Author(s):  
A. Marijke Keestra ◽  
Maria G. Winter ◽  
Daisy Klein-Douwel ◽  
Mariana N. Xavier ◽  
Sebastian E. Winter ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Intestinal Inflammation ◽  
Inflammatory Responses ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Content Type ◽  
Type Iii

ABSTRACTThe invasion-associated type III secretion system (T3SS-1) ofSalmonella entericaserotype Typhimurium (S. Typhimurium) activates the transcription factor NF-κB in tissue culture cells and induces inflammatory responses in animal models through unknown mechanisms. Here we show that bacterial delivery or ectopic expression of SipA, a T3SS-1-translocated protein, led to the activation of the NOD1/NOD2 signaling pathway and consequent RIP2-mediated induction of NF-κB-dependent inflammatory responses. SipA-mediated activation of NOD1/NOD2 signaling was independent of bacterial invasionin vitrobut required an intact T3SS-1. In the mouse colitis model, SipA triggered mucosal inflammation in wild-type mice but not in NOD1/NOD2-deficient mice. These findings implicate SipA-driven activation of the NOD1/NOD2 signaling pathway as a mechanism by which the T3SS-1 induces inflammatory responsesin vitroandin vivo.IMPORTANCESalmonella entericaserotype Typhimurium (S. Typhimurium) deploys a type III secretion system (T3SS-1) to induce intestinal inflammation and benefits from the ensuing host response, which enhances growth of the pathogen in the intestinal lumen. However, the mechanisms by which the T3SS-1 triggers inflammatory responses have not been resolved. Here we show that the T3SS-1 effector protein SipA induces NF-κB activation and intestinal inflammation by activating the NOD1/NOD2 signaling pathway. These data suggest that the T3SS-1 escalates innate responses through a SipA-mediated activation of pattern recognition receptors in the host cell cytosol.

scholarly journals Complete Genome Sequence of Lactococcus lactis subsp. lactis Strain 14B4, Which Inhibits the Growth of Salmonella enterica Serotype Poona In Vitro

2018 ◽  
Vol 7 (19) ◽  
Author(s):  
Thao D. Tran ◽  
Steven Huynh ◽  
Craig T. Parker ◽  
Ruyang Han ◽  
Robert Hnasko ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Salmonella Enterica ◽  
Complete Genome ◽  
Northern California ◽  
Content Type ◽  
Lactococcus Lactis Subsp ◽  
Lactis Strain

We present here the complete genome sequence of Lactococcus lactis strain 14B4, isolated from almond drupes in northern California. This strain was observed to inhibit the growth of Salmonella enterica serotype Poona strain RM3363 in vitro.

scholarly journals Antimicrobial Susceptibility to Azithromycin among Salmonella enterica Isolates from the United States

2011 ◽  
Vol 55 (9) ◽  
pp. 3985-3989 ◽  
Author(s):  
Maria Sjölund-Karlsson ◽  
Kevin Joyce ◽  
Karen Blickenstaff ◽  
Takiyah Ball ◽  
Jovita Haro ◽  
...  
Keyword(s):  
United States ◽  
Antimicrobial Susceptibility ◽  
Salmonella Enterica ◽  
Antimicrobial Agents ◽  
The United States ◽  
Outcome Data ◽  
Content Type ◽  
Susceptibility Data ◽  
Retail Meat ◽  
Clinical Breakpoints

ABSTRACTDue to emerging resistance to traditional antimicrobial agents, such as ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol, azithromycin is increasingly used for the treatment of invasiveSalmonellainfections. In the present study, 696 isolates of non-TyphiSalmonellacollected from humans, food animals, and retail meats in the United States were investigated for antimicrobial susceptibility to azithromycin. Seventy-twoSalmonella entericaserotype Typhi isolates from humans were also tested. For each isolate, MICs of azithromycin and 15 other antimicrobial agents were determined by broth microdilution. Among the non-TyphiSalmonellaisolates, azithromycin MICs among human isolates ranged from 1 to 32 μg/ml, whereas the MICs among the animal and retail meat isolates ranged from 2 to 16 μg/ml and 4 to 16 μg/ml, respectively. AmongSalmonellaserotype Typhi isolates, the azithromycin MICs ranged from 4 to 16 μg/ml. The highest MIC observed in the present study was 32 μg/ml, and it was detected in three human isolates belonging to serotypes Kentucky, Montevideo, and Paratyphi A. Based on our findings, we propose an epidemiological cutoff value (ECOFF) for wild-typeSalmonellaof ≤16 μg/ml of azithromycin. The susceptibility data provided could be used in combination with clinical outcome data to determine tentative clinical breakpoints for azithromycin andSalmonella enterica.

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