scholarly journals Protozoan Cysts Act as a Survival Niche and Protective Shelter for Foodborne Pathogenic Bacteria

2015 ◽  
Vol 81 (16) ◽  
pp. 5604-5612 ◽  
Author(s):  
Ellen Lambrecht ◽  
Julie Baré ◽  
Natascha Chavatte ◽  
Wim Bert ◽  
Koen Sabbe ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Acanthamoeba Castellanii ◽  
Bacterial Survival ◽  
Free Living ◽  
Active Growth ◽  
Content Type ◽  
Foodborne Pathogenic Bacteria ◽  
Adverse Environmental Conditions ◽  
Species Specific

ABSTRACTThe production of cysts, an integral part of the life cycle of many free-living protozoa, allows these organisms to survive adverse environmental conditions. Given the prevalence of free-living protozoa in food-related environments, it is hypothesized that these organisms play an important yet currently underinvestigated role in the epidemiology of foodborne pathogenic bacteria. Intracystic bacterial survival is highly relevant, as this would allow bacteria to survive the stringent cleaning and disinfection measures applied in food-related environments. The present study shows that strains of widespread and important foodborne bacteria (Salmonella enterica,Escherichia coli,Yersinia enterocolitica, andListeria monocytogenes) survive inside cysts of the ubiquitous amoebaAcanthamoeba castellanii, even when exposed to either antibiotic treatment (100 μg/ml gentamicin) or highly acidic conditions (pH 0.2) and resume active growth in broth media following excystment. Strain- and species-specific differences in survival periods were observed, withSalmonella entericasurviving up to 3 weeks inside amoebal cysts. Up to 53% of the cysts were infected with pathogenic bacteria, which were located in the cyst cytosol. Our study suggests that the role of free-living protozoa and especially their cysts in the persistence and epidemiology of foodborne bacterial pathogens in food-related environments may be much more important than hitherto assumed.

scholarly journals Behavior of Yersinia enterocolitica in the Presence of the Bacterivorous Acanthamoeba castellanii

2013 ◽  
Vol 79 (20) ◽  
pp. 6407-6413 ◽  
Author(s):  
E. Lambrecht ◽  
J. Baré ◽  
I. Van Damme ◽  
W. Bert ◽  
K. Sabbe ◽  
...  
Keyword(s):  
Yersinia Enterocolitica ◽  
Pathogenic Bacteria ◽  
Acanthamoeba Castellanii ◽  
Ecological Niches ◽  
Free Living ◽  
Content Type ◽  
Food Borne ◽  
Transmission Electron ◽  
Set Up ◽  
The Impact

ABSTRACTFree-living protozoa play an important role in the ecology and epidemiology of human-pathogenic bacteria. In the present study, the interaction betweenYersinia enterocolitica, an important food-borne pathogen, and the free-living amoebaAcanthamoeba castellaniiwas studied. Several cocultivation assays were set up to assess the resistance ofY. enterocoliticatoA. castellaniipredation and the impact of environmental factors and bacterial strain-specific characteristics. Results showed that allY. enterocoliticastrains persist in association withA. castellaniifor at least 14 days, and associations withA. castellaniienhanced survival ofYersiniaunder nutrient-rich conditions at 25°C and under nutrient-poor conditions at 37°C. Amoebae cultivated in the supernatant of oneYersiniastrain showed temperature- and time-dependent permeabilization. Intraprotozoan survival ofY. enterocoliticadepended on nutrient availability and temperature, with up to 2.8 log CFU/ml bacteria displaying intracellular survival at 7°C for at least 4 days in nutrient-rich medium. Transmission electron microscopy was performed to locate theYersiniacells inside the amoebae. AsYersiniaandAcanthamoebashare similar ecological niches, this interaction identifies a role of free-living protozoa in the ecology and epidemiology ofY. enterocolitica.

scholarly journals Increased Persistence of Salmonella enterica Serovar Typhi in the Presence of Acanthamoeba castellanii

2011 ◽  
Vol 77 (21) ◽  
pp. 7640-7646 ◽  
Author(s):  
Frédéric Douesnard-Malo ◽  
France Daigle
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Systemic Disease ◽  
Acanthamoeba Castellanii ◽  
Selective Advantage ◽  
Viable Count ◽  
Physical Contact ◽  
Content Type ◽  
Contaminated Food ◽  
Cultured Bacteria

ABSTRACTSalmonella entericaserovar Typhi (S. Typhi) is the etiological agent of the systemic disease typhoid fever. Transmission occurs via ingestion of contaminated food or water.S. Typhi is specific to humans, and no animal or environmental reservoirs are known. As the free-living amoebaAcanthamoeba castellaniiis an environmental host for many pathogenic bacteria, this study investigates interactions betweenS. Typhi andA. castellaniiby using cocultures. Growth of both organisms was estimated by cell count, viable count, flow cytometry, and fluorescence microscopy. Results indicate thatS. Typhi can survive at least 3 weeks when grown withA. castellanii, as opposed to less than 10 days when grown as singly cultured bacteria under the same conditions. Interestingly, growth rates of amoebae after 14 days were similar in cocultures or when amoebae were singly cultured, suggesting thatS. Typhi is not cytotoxic toA. castellanii. Bacteria surviving in coculture were not intracellular and did not require a physical contact with amoebae for their survival. These results suggest thatS. Typhi may have a selective advantage when it is associated withA. castellaniiand that amoebae may contribute toS. Typhi persistence in the environment.

scholarly journals Mapping and Regulation of Genes within Salmonella Pathogenicity Island 12 That Contribute toIn VivoFitness of Salmonella enterica Serovar Typhimurium

2013 ◽  
Vol 81 (7) ◽  
pp. 2394-2404 ◽  
Author(s):  
Ana M. Tomljenovic-Berube ◽  
Brandyn Henriksbo ◽  
Steffen Porwollik ◽  
Colin A. Cooper ◽  
Brian R. Tuinema ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Pathogenicity Island ◽  
Bacterial Survival ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Serovar Typhimurium ◽  
Bacterial Fitness ◽  
Virulence Regulator

ABSTRACTSalmonellapathogenicity island 12 (SPI-12) ofSalmonella entericaserovar Typhimurium is a 15-kb region that encompasses genesSTM2230toSTM2245and encodes a remnant phage known to contribute to bacterial virulence. In mouse infection experiments and replication assays in macrophages, we demonstrated a role for four genes in SPI-12 for bacterial survival in the host. STM2239, a potential Q antiterminator, showed a prominent contribution to bacterial fitness. Transcriptional reporter experiments, quantitative reverse transcription-PCR (RT-PCR), and immunoblotting demonstrated that the virulence regulator SsrB and STM2239 contribute to transcriptional activation of genes in SPI-12. SsrB was found to indirectly regulate this locus by transcriptional read-through from thesspH2(STM2241) promoter. Chromatin immunoprecipitation showed that STM2239 copurified with the promoter regulatingSTM2237, suggesting that STM2239 may function as an antiterminator to activate adjacent genes. These results demonstrate that bacteriophage genes may be adapted by pathogenic bacteria to improve fitness in the host.

scholarly journals Antimicrobial Susceptibility Testing and Tentative Epidemiological Cutoff Values for FiveBacillusSpecies Relevant for Use as Animal Feed Additives or for Plant Protection

2018 ◽  
Vol 84 (19) ◽  
Author(s):  
Yvonne Agersø ◽  
Birgitte Stuer-Lauridsen ◽  
Karin Bjerre ◽  
Michelle Geervliet Jensen ◽  
Eric Johansen ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Resistance Genes ◽  
Pathogenic Bacteria ◽  
Animal Feed ◽  
Bacterial Species ◽  
Feed Additives ◽  
Content Type ◽  
Cutoff Values ◽  
Antimicrobial Resistance Genes ◽  
Species Specific

ABSTRACTBacillus megaterium(n= 29),Bacillus velezensis(n= 26),Bacillus amyloliquefaciens(n= 6),Bacillus paralicheniformis(n= 28), andBacillus licheniformis(n= 35) strains from different sources, origins, and time periods were tested for the MICs for nine antimicrobial agents by the CLSI-recommended method (Mueller-Hinton broth, 35°C, for 18 to 20 h), as well as with a modified CLSI method (Iso-Sensitest [IST] broth, 37°C [35°C forB. megaterium], 24 h). This allows a proposal of species-specific epidemiological cutoff values (ECOFFs) for the interpretation of antimicrobial resistance in these species. MICs determined by the modified CLSI method were 2- to 16-fold higher than with the CLSI-recommended method for several antimicrobials. The MIC distributions differed between species for five of the nine antimicrobials. Consequently, use of the modified CLSI method and interpretation of resistance by use of species-specific ECOFFs is recommended. The genome sequences of all strains were determined and used for screening for resistance genes against the ResFinder database and for multilocus sequence typing. A putative chloramphenicol acetyltransferase (cat) gene was found in oneB. megateriumstrain with an elevated chloramphenicol MIC compared to the otherB. megateriumstrains. InB. velezensisandB. amyloliquefaciens, a putative tetracycline efflux gene,tet(L), was found in all strains (n= 27) with reduced tetracycline susceptibility but was absent in susceptible strains. AllB. paralicheniformisand 23% ofB. licheniformisstrains had elevated MICs for erythromycin and harboredermD. The presence of these resistance genes follows taxonomy suggesting they may be intrinsic rather than horizontally acquired. Reduced susceptibility to chloramphenicol, streptomycin, and clindamycin could not be explained in all species.IMPORTANCEWhen commercializing bacterial strains, likeBacillusspp., for feed applications or plant bioprotection, it is required that the strains are free of acquired antimicrobial resistance genes that could potentially spread to pathogenic bacteria, thereby adding to the pool of resistance genes that may cause treatment failures in humans or animals. Conversely, if antimicrobial resistance is intrinsic to a bacterial species, the risk of spreading horizontally to other bacteria is considered very low. Reliable susceptibility test methods and interpretation criteria at the species level are needed to accurately assess antimicrobial resistance levels. In the present study, tentative ECOFFs for fiveBacillusspecies were determined, and the results showed that the variation in MICs followed the respective species. Moreover, putative resistance genes, which were detected by whole-genome sequencing and suggested to be intrinsic rather that acquired, could explain the resistance phenotypes in most cases.

scholarly journals Cellular Response of the Amoeba Acanthamoeba castellanii to Chlorine, Chlorine Dioxide, and Monochloramine Treatments

2011 ◽  
Vol 77 (14) ◽  
pp. 4974-4980 ◽  
Author(s):  
Emerancienne Mogoa ◽  
Charles Bodet ◽  
Franck Morel ◽  
Marie-Hélène Rodier ◽  
Bernard Legube ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Flow Cytometry ◽  
Chlorine Dioxide ◽  
Mode Of Action ◽  
Cellular Response ◽  
Acanthamoeba Castellanii ◽  
Size Reduction ◽  
Resistant Bacteria ◽  
Free Living ◽  
Content Type

ABSTRACTAcanthamoeba castellaniiis a free-living amoebae commonly found in water systems. Free-living amoebae might be pathogenic but are also known to bear phagocytosis-resistant bacteria, protecting these bacteria from water treatments. The mode of action of these treatments is poorly understood, particularly on amoebae. It is important to examine the action of these treatments on amoebae in order to improve them. The cellular response to chlorine, chlorine dioxide, and monochloramine was tested onA. castellaniitrophozoites. Doses of disinfectants leading to up to a 3-log reduction were compared by flow cytometry and electron microscopy. Chlorine treatment led to size reduction, permeabilization, and retraction of pseudopods. In addition, treatment with chlorine dioxide led to a vacuolization of the cytoplasm. Monochloramine had a dose-dependent effect. At the highest doses monochloramine treatment resulted in almost no changes in cell size and permeability, as shown by flow cytometry, but the cell surface became smooth and dense, as seen by electron microscopy. We show that these disinfectants globally induced size reduction, membrane permeabilization, and morphological modifications but that they have a different mode of action onA. castellanii.

scholarly journals Quinazoline-Based Antivirulence Compounds Selectively Target Salmonella PhoP/PhoQ Signal Transduction System

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
María Ayelén Carabajal ◽  
Christopher R. M. Asquith ◽  
Tuomo Laitinen ◽  
Graham J. Tizzard ◽  
Lucía Yim ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Catalytic Domain ◽  
Kinase Inhibitor ◽  
Adaptive Responses ◽  
Antibacterial Compounds ◽  
Content Type ◽  
Two Component ◽  
Serovar Typhimurium

ABSTRACT The rapid emergence of multidrug resistance among bacterial pathogens has become a significant challenge to human health in our century. Therefore, development of next-generation antibacterial compounds is an urgent need. Two-component signal transduction systems (TCS) are stimulus-response coupling devices that allow bacteria to sense and elaborate adaptive responses to changing environmental conditions, including the challenges that pathogenic bacteria face inside the host. The differential presence of TCS, present in bacteria but absent in the animal kingdom, makes them attractive targets in the search for new antibacterial compounds. In Salmonella enterica, the PhoP/PhoQ two-component system controls the expression of crucial phenotypes that define the ability of the pathogen to establish infection in the host. We now report the screening of 686 compounds from a GlaxoSmithKline published kinase inhibitor set in a high-throughput whole-cell assay that targets Salmonella enterica serovar Typhimurium PhoP/PhoQ. We identified a series of quinazoline compounds that showed selective and potent downregulation of PhoP/PhoQ-activated genes and define structural attributes required for their efficacy. We demonstrate that their bioactivity is due to repression of the PhoQ sensor autokinase activity mediated by interaction with its catalytic domain, acting as competitive inhibitors of ATP binding. While noncytotoxic, the hit molecules exhibit antivirulence effect by blockage of S. Typhimurium intramacrophage replication. Together, these features make these quinazoline compounds stand out as exciting leads to develop a therapeutic intervention to fight salmonellosis.

scholarly journals Specific Discrimination of Three Pathogenic Salmonella enterica subsp. enterica Serotypes bycarB-Based Oligonucleotide Microarray

2013 ◽  
Vol 80 (1) ◽  
pp. 366-373 ◽  
Author(s):  
Hwa Hui Shin ◽  
Byeong Hee Hwang ◽  
Jeong Hyun Seo ◽  
Hyung Joon Cha
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Detection System ◽  
Large Subunit ◽  
Cross Reactivity ◽  
Oligonucleotide Microarray ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Content Type ◽  
Contaminated Food

ABSTRACTIt is important to rapidly and selectively detect and analyze pathogenicSalmonella entericasubsp.entericain contaminated food to reduce the morbidity and mortality ofSalmonellainfection and to guarantee food safety. In the present work, we developed an oligonucleotide microarray containing duplicate specific capture probes based on thecarBgene, which encodes the carbamoyl phosphate synthetase large subunit, as a competent biomarker evaluated by genetic analysis to selectively and efficiently detect and discriminate threeS. entericasubsp.entericaserotypes: Choleraesuis, Enteritidis, and Typhimurium. Using the developed microarray system, three serotype targets were successfully analyzed in a range as low as 1.6 to 3.1 nM and were specifically discriminated from each other without nonspecific signals. In addition, the constructed microarray did not have cross-reactivity with other common pathogenic bacteria and even enabled the clear discrimination of the targetSalmonellaserotype from a bacterial mixture. Therefore, these results demonstrated that our novelcarB-based oligonucleotide microarray can be used as an effective and specific detection system forS. entericasubsp.entericaserotypes.

scholarly journals ElyC and Cyclic Enterobacterial Common Antigen Regulate Synthesis of Phosphoglyceride-Linked Enterobacterial Common Antigen

mBio ◽  
2021 ◽  
Author(s):  
Ashutosh K. Rai ◽  
Joseph F. Carr ◽  
David E. Bautista ◽  
Wei Wang ◽  
Angela M. Mitchell
Keyword(s):  
Klebsiella Pneumoniae ◽  
Yersinia Pestis ◽  
Outer Membrane ◽  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Permeability Barrier ◽  
Common Antigen ◽  
Content Type ◽  
Enterobacterial Common Antigen ◽  
The Many

Enterobacterial common antigen (ECA) is a conserved polysaccharide present on the surface of the outer membrane (OM) and in the periplasm of the many pathogenic bacteria belonging to Enterobacterales , including Klebsiella pneumoniae , Salmonella enterica , and Yersinia pestis . As the OM is a permeability barrier that excludes many antibiotics, synthesis pathways for OM molecules are promising targets for antimicrobial discovery.

scholarly journals (p)ppGpp-dependent regulation of the nucleotide hydrolase PpnN confers complement resistance in Salmonella enterica serovar Typhimurium

2020 ◽  
Author(s):  
N. Y Elizabeth Chau ◽  
Deyanira Pérez-Morales ◽  
Wael Elhenawy ◽  
Víctor H. Bustamante ◽  
Yong E. Zhang ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Stringent Response ◽  
Metabolic Reprogramming ◽  
Bacterial Survival ◽  
Complement Resistance ◽  
Serovar Typhimurium ◽  
Bacterial Fitness ◽  
Host Infection

The stringent response is an essential mechanism of metabolic reprogramming during environmental stress that is mediated by the nucleotide alarmones, guanosine tetraphosphate and pentaphosphate ((p)ppGpp). In addition to physiological adaptations, (p)ppGpp also regulates virulence programs in pathogenic bacteria including Salmonella enterica serovar Typhimurium. S. Typhimurium is a common cause of acute gastroenteritis, but it may also spread to systemic tissues resulting in severe clinical outcomes. During infection, S. Typhimurium encounters a broad repertoire of immune defenses that it must evade for successful host infection. Here, we examined the role of the stringent response in S. Typhimurium resistance to complement-mediated killing and found that the (p)ppGpp synthetase-hydrolase, SpoT, is required for bacterial survival in human serum. We identified the nucleotide hydrolase, PpnN, as a target of the stringent response that is required to promote bacterial fitness in serum. Using chromatography and mass spectrometry, we show that PpnN hydrolyzes purine and pyrimidine monophosphates to generate free nucleobases and ribose 5′-phosphate, and that this metabolic activity is required for conferring resistance to complement killing. In addition to PpnN, we show that (p)ppGpp is required for the biosynthesis of the very long and long O-antigen in the outer membrane known to be important for complement resistance. Our results provide new insights into the role of the stringent response in mediating evasion of the innate immune system by pathogenic bacteria.

scholarly journals Survival and Heat Resistance of Salmonella enterica and Escherichia coli O157:H7 in Peanut Butter

2011 ◽  
Vol 77 (23) ◽  
pp. 8434-8438 ◽  
Author(s):  
Yingshu He ◽  
Dongjing Guo ◽  
Jingyun Yang ◽  
Mary Lou Tortorello ◽  
Wei Zhang
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Bacterial Resistance ◽  
Incubation Temperature ◽  
Peanut Butter ◽  
Survival Rates ◽  
Escherichia Coli O157 ◽  
Bacterial Survival ◽  
Content Type ◽  
Resistance To Heat

ABSTRACTSignificant differences (P< 0.05) were found between the survival rates ofSalmonella entericaandEscherichia coliO157:H7 in peanut butter with different formulations and water activity. High carbohydrate content in peanut butter and low incubation temperature resulted in higher levels of bacterial survival during storage but lower levels of bacterial resistance to heat treatment.

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