scholarly journals Listeria monocytogenes Strains Underrepresented during Selective Enrichment with an ISO Method Might Dominate during Passage through Simulated Gastric Fluid andIn VitroInfection of Caco-2 Cells

2016 ◽  
Vol 82 (23) ◽  
pp. 6846-6858 ◽  
Author(s):  
Evangelia Zilelidou ◽  
Christina-Vasiliki Karmiri ◽  
Georgia Zoumpopoulou ◽  
Eleni Mavrogonatou ◽  
Dimitris Kletsas ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Simultaneous Exposure ◽  
Relative Population ◽  
Content Type ◽  
Selective Enrichment ◽  
Outbreak Investigations ◽  
Multiple Strains

ABSTRACTVariousListeria monocytogenesstrains may contaminate a single food product, potentially resulting in simultaneous exposure of consumers to multiple strains. However, due to bias in strain recovery,L. monocytogenesstrains isolated from foods by selective enrichment (SE) might not always represent those that can better survive the immune system of a patient. We investigated the effect of cocultivation in tryptic soy broth with 0.6% yeast extract (TSB-Y) at 10°C for 8 days on (i) the detection ofL. monocytogenesstrains during SE with the ISO 11290-1:1996/Amd 1:2004 protocol and (ii) thein vitrovirulence of strains toward the Caco-2 human colon epithelial cancer cell line following exposure to simulated gastric fluid (SGF; pH 2.0)-HCl (37°C). We determined whether the strains which were favored by SE would be effective competitors under the conditions of challenges related to gastrointestinal passage of the pathogen. Interstrain competition ofL. monocytogenesin TSB-Y determined the relative population of each strain at the beginning of SE. This in turn impacted the outcome of SE (i.e., favoring survival of competitors with better fitness) and the levels exposed subsequently to SGF. However, strong growth competitors could be outcompeted after SGF exposure and infection of Caco-2 cells by strains outgrown in TSB-Y and underdetected (or even missed) during enrichment. Our data demonstrate a preferential selection of certainL. monocytogenesstrains during enrichments, often not reflecting a selective advantage of strains during infection. These findings highlight a noteworthy scenario associated with the difficulty of matching the source of infection (food) with theL. monocytogenesisolate appearing to be the causative agent during listeriosis outbreak investigations.IMPORTANCEThis report is relevant to understanding the processes involved in selection and prevalence of certainL. monocytogenesstrains in different environments (i.e., foods or sites of humans exposed to the pathogen). It highlights the occurrence of multiple strains in the same food as an important aspect contributing to mismatches between clinical isolates and infection sources during listeriosis outbreak investigations.

scholarly journals Liposome-Encapsulated Bacteriophages for Enhanced Oral Phage Therapy against Salmonella spp.

2015 ◽  
Vol 81 (14) ◽  
pp. 4841-4849 ◽  
Author(s):  
Joan Colom ◽  
Mary Cano-Sarabia ◽  
Jennifer Otero ◽  
Pilar Cortés ◽  
Daniel Maspoch ◽  
...  
Keyword(s):  
Intestinal Tract ◽  
Positive Charge ◽  
Phage Therapy ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Salmonella Spp ◽  
Content Type ◽  
The Difference ◽  
Over Time

ABSTRACTBacteriophages UAB_Phi20, UAB_Phi78, and UAB_Phi87 were encapsulated in liposomes, and their efficacy in reducingSalmonellain poultry was then studied. The encapsulated phages had a mean diameter of 309 to 326 nm and a positive charge between +31.6 and +35.1 mV (pH 6.1). In simulated gastric fluid (pH 2.8), the titer of nonencapsulated phages decreased by 5.7 to 7.8 log units, whereas encapsulated phages were significantly more stable, with losses of 3.7 to 5.4 log units. The liposome coating also improved the retention of bacteriophages in the chicken intestinal tract. When cocktails of the encapsulated and nonencapsulated phages were administered to broilers, after 72 h the encapsulated phages were detected in 38.1% of the animals, whereas the nonencapsulated phages were present in only 9.5%. The difference was significant. In addition, in anin vitroexperiment, the cecal contents of broilers promoted the release of the phages from the liposomes. In broilers experimentally infected withSalmonella, the daily administration of the two cocktails for 6 days postinfection conferred similar levels of protection againstSalmonellacolonization. However, once treatment was stopped, protection by the nonencapsulated phages disappeared, whereas that provided by the encapsulated phages persisted for at least 1 week, showing the enhanced efficacy of the encapsulated phages in protecting poultry againstSalmonellaover time. The methodology described here allows the liposome encapsulation of phages of different morphologies. The preparations can be stored for at least 3 months at 4°C and could be added to the drinking water and feed of animals.

Effect of Acid Adaptation on Growth during Storage at 10°C and Resistance to Simulated Gastric Fluid of Listeria monocytogenes Inoculated onto Bologna Formulated with or without Antimicrobials

2007 ◽  
Vol 70 (1) ◽  
pp. 65-69 ◽  
Author(s):  
GIOVANNI FORMATO ◽  
IFIGENIA GEORNARAS ◽  
IOANNA M. BARMPALIA ◽  
PANAGIOTIS N. SKANDAMIS ◽  
KEITH E. BELK ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Acid Adaptation ◽  
Treatment Groups ◽  
Cell Numbers ◽  
Product Formulation ◽  
Inhibition Of Growth ◽  
Control Samples

The fate of acid-adapted and nonadapted Listeria monocytogenes inoculated onto bologna slices (formulated with or without antimicrobials) was examined during storage and after exposure to in vitro gastric challenge. Bologna slices formulated with no antimicrobials (control), 3% sodium lactate (SL), or 1.8% SL plus 0.25% sodium diacetate (SD) were inoculated (2 log CFU/cm2) with a 10-strain composite of acid-adapted or nonadapted L. monocytogenes strains. Growth or survival of the two inocula on bologna was evaluated during vacuum-packaged storage (10°C) for up to 36 days. Survival of previously acid-adapted or nonadapted L. monocytogenes on stored bologna exposed to simulated gastric fluid (adjusted to pH 1.0 with HCl) for 20, 40, and 60 min also was determined. As expected, inclusion of antimicrobials in the product formulation inhibited growth of L. monocytogenes during storage of vacuum-packaged bologna compared with growth on control samples. Acid adaptation of L. monocytogenes prior to product inoculation did not affect subsequent survival or growth on bologna or resistance to simulated gastric fluid (P > 0.05). Survival of L. monocytogenes exposed to simulated gastric fluid during storage increased with product age, growth phase of the cells, and possibly age of the cells, particularly for control samples (no antimicrobials), in which the pathogen grew uninhibited to approximately 6 log CFU/cm2 by day 8 of storage. Inhibition of L. monocytogenes growth on product formulated with antimicrobials was associated with only sporadic and small numbers of survivors following exposure of these samples to simulated gastric fluid, especially in samples stored longer. However, cell numbers in these treatment groups before the gastric challenge did not exceed 3.8 log CFU/cm2. Inhibition of growth on product with antimicrobials precluded detection of survivors resistant to the effects of simulated gastric fluid.

scholarly journals Biofilm-isolated Listeria monocytogenes exhibits reduced systemic dissemination at the early (12–24 h) stage of infection in a mouse model

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xingjian Bai ◽  
Dongqi Liu ◽  
Luping Xu ◽  
Shivendra Tenguria ◽  
Rishi Drolia ◽  
...  
Keyword(s):  
Cell Culture ◽  
Listeria Monocytogenes ◽  
Early Stage ◽  
Intestinal Content ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Planktonic Cells ◽  
Cell Counts ◽  
Sessile Cells

AbstractEnvironmental cues promote microbial biofilm formation and physiological and genetic heterogeneity. In food production facilities, biofilms produced by pathogens are a major source for food contamination; however, the pathogenesis of biofilm-isolated sessile cells is not well understood. We investigated the pathogenesis of sessile Listeria monocytogenes (Lm) using cell culture and mouse models. Lm sessile cells express reduced levels of the lap, inlA, hly, prfA, and sigB and show reduced adhesion, invasion, translocation, and cytotoxicity in the cell culture model than the planktonic cells. Oral challenge of C57BL/6 mice with food, clinical, or murinized-InlA (InlAm) strains reveals that at 12 and 24 h post-infection (hpi), Lm burdens are lower in tissues of mice infected with sessile cells than those infected with planktonic cells. However, these differences are negligible at 48 hpi. Besides, the expressions of inlA and lap mRNA in sessile Lm from intestinal content are about 6.0- and 280-fold higher than the sessle inoculum, respectively, suggesting sessile Lm can still upregulate virulence genes shortly after ingestion (12 h). Similarly, exposure to simulated gastric fluid (SGF, pH 3) and intestinal fluid (SIF, pH 7) for 13 h shows equal reduction in sessile and planktonic cell counts, but induces LAP and InlA expression and pathogenic phenotypes. Our data show that the virulence of biofilm-isolated Lm is temporarily attenuated and can be upregulated in mice during the early stage (12–24 hpi) but fully restored at a later stage (48 hpi) of infection. Our study further demonstrates that in vitro cell culture assay is unreliable; therefore, an animal model is essential for studying the pathogenesis of biofilm-isolated bacteria.

scholarly journals Formulation of Quaternized Aminated Chitosan Nanoparticles for Efficient Encapsulation and Slow Release of Curcumin

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 449
Author(s):  
Ahmed M. Omer ◽  
Zyta M. Ziora ◽  
Tamer M. Tamer ◽  
Randa E. Khalifa ◽  
Mohamed A. Hassan ◽  
...  
Keyword(s):  
Slow Release ◽  
Sodium Tripolyphosphate ◽  
Chitosan Nanoparticles ◽  
Gastric Fluid ◽  
Release Profile ◽  
Simulated Gastric Fluid ◽  
Maximum Value ◽  
Structure Surface ◽  
Drug Encapsulation Efficiency

An effective drug nanocarrier was developed on the basis of a quaternized aminated chitosan (Q-AmCs) derivative for the efficient encapsulation and slow release of the curcumin (Cur)-drug. A simple ionic gelation method was conducted to formulate Q-AmCs nanoparticles (NPs), using different ratios of sodium tripolyphosphate (TPP) as an ionic crosslinker. Various characterization tools were employed to investigate the structure, surface morphology, and thermal properties of the formulated nanoparticles. The formulated Q-AmCs NPs displayed a smaller particle size of 162 ± 9.10 nm, and higher surface positive charges, with a maximum potential of +48.3 mV, compared to native aminated chitosan (AmCs) NPs (231 ± 7.14 nm, +32.8 mV). The Cur-drug encapsulation efficiency was greatly improved and reached a maximum value of 94.4 ± 0.91%, compared to 75.0 ± 1.13% for AmCs NPs. Moreover, the in vitro Cur-release profile was investigated under the conditions of simulated gastric fluid [SGF; pH 1.2] and simulated colon fluid [SCF; pH 7.4]. For Q-AmCs NPs, the Cur-release rate was meaningfully decreased, and recorded a cumulative release value of 54.0% at pH 7.4, compared to 73.0% for AmCs NPs. The formulated nanoparticles exhibited acceptable biocompatibility and biodegradability. These findings emphasize that Q-AmCs NPs have an outstanding potential for the delivery and slow release of anticancer drugs.

scholarly journals Complete Genome Sequences of Three Bacillus amyloliquefaciens Strains That Inhibit the Growth of Listeria monocytogenes In Vitro

2018 ◽  
Vol 6 (25) ◽  
Author(s):  
Thao D. Tran ◽  
Steven Huynh ◽  
Craig T. Parker ◽  
Robert Hnasko ◽  
Lisa Gorski ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Secondary Metabolites ◽  
Growth Inhibition ◽  
Complete Genome ◽  
Bacillus Amyloliquefaciens ◽  
Gene Clusters ◽  
Genome Sequences ◽  
Multiple Gene ◽  
Content Type

ABSTRACT Here, we report the complete genome sequences of three Bacillus amyloliquefaciens strains isolated from alfalfa, almond drupes, and grapes that inhibited the growth of Listeria monocytogenes strain 2011L-2857 in vitro. We also report multiple gene clusters encoding secondary metabolites that may be responsible for the growth inhibition of L. monocytogenes.

scholarly journals Safety Assessment of Nano-Hydroxyapatite as an Oral Care Ingredient according to the EU Cosmetics Regulation

Cosmetics ◽  
2018 ◽  
Vol 5 (3) ◽  
pp. 53 ◽  
Author(s):  
Joana Ramis ◽  
Catarina Coelho ◽  
Alba Córdoba ◽  
Paulo Quadros ◽  
Marta Monjo
Keyword(s):  
Oral Care ◽  
Gastric Fluid ◽  
Gingival Tissue ◽  
Simulated Gastric Fluid ◽  
Tem Analysis ◽  
Consumer Safety ◽  
Transmission Electron ◽  
Dissolution Behaviour ◽  
Gingival Epithelium

Hydroxyapatite nanoparticles (HAP-NP) are incorporated in oral care products such as toothpastes and mouthwashes to treat dental sensitivity or to promote enamel remineralisation. Despite the good performance of HAP-NP in this application, it is important to ensure its safety for consumers. For that reason, the Scientific Committee on Consumer Safety (SCCS) evaluated the safety of HAP-NP as an oral care ingredient, but the issued opinion was not completely conclusive and the SCCS recommended that additional tests should be performed. Here, we used a commercially available human gingival epithelium (HGE) as a non-animal alternative and MTT cell viability, LDH activity, and IL-1alpha production were evaluated after 3.1% HAP-NP treatment for 10 min, 1 h, and 3 h. Moreover, the absorption of HAP-NP in the gingival tissue was assessed by transmission electron microscopy (TEM) analysis. Finally, the dissolution behaviour of HAP-NP in simulated gastric fluid was also investigated. No deleterious effect was observed for HGE tissues incubated with HAP-NP for all time-points and parameters evaluated. Moreover, a complete dissolution of 3.1% HAP-NP in simulated gastric fluid was observed after 7.5 min at 37 °C. In conclusion, our results evidence the safety of HAP-NP for oral care products with the use of an in vitro replacement alternative for human gingival epithelium and a simulated gastric fluid assay.

scholarly journals Mutant and Recombinant Phages Selected from In Vitro Coevolution Conditions Overcome Phage-Resistant Listeria monocytogenes

2020 ◽  
Vol 86 (22) ◽  
Author(s):  
Tracey Lee Peters ◽  
Yaxiong Song ◽  
Daniel W. Bryan ◽  
Lauren K. Hudson ◽  
Thomas G. Denes
Keyword(s):  
Listeria Monocytogenes ◽  
Host Range ◽  
Foodborne Pathogen ◽  
Resistant Bacteria ◽  
Phage Resistance ◽  
Short Term ◽  
Content Type ◽  
Life Threatening ◽  
The Impact

ABSTRACT Bacteriophages (phages) are currently available for use by the food industry to control the foodborne pathogen Listeria monocytogenes. Although phage biocontrols are effective under specific conditions, their use can select for phage-resistant bacteria that repopulate phage-treated environments. Here, we performed short-term coevolution experiments to investigate the impact of single phages and a two-phage cocktail on the regrowth of phage-resistant L. monocytogenes and the adaptation of the phages to overcome this resistance. We used whole-genome sequencing to identify mutations in the target host that confer phage resistance and in the phages that alter host range. We found that infections with Listeria phages LP-048, LP-125, or a combination of both select for different populations of phage-resistant L. monocytogenes bacteria with different regrowth times. Phages isolated from the end of the coevolution experiments were found to have gained the ability to infect phage-resistant mutants of L. monocytogenes and L. monocytogenes strains previously found to be broadly resistant to phage infection. Phages isolated from coinfected cultures were identified as recombinants of LP-048 and LP-125. Interestingly, recombination events occurred twice independently in a locus encoding two proteins putatively involved in DNA binding. We show that short-term coevolution of phages and their hosts can be utilized to obtain mutant and recombinant phages with adapted host ranges. These laboratory-evolved phages may be useful for limiting the emergence of phage resistance and for targeting strains that show general resistance to wild-type (WT) phages. IMPORTANCE Listeria monocytogenes is a life-threatening bacterial foodborne pathogen that can persist in food processing facilities for years. Phages can be used to control L. monocytogenes in food production, but phage-resistant bacterial subpopulations can regrow in phage-treated environments. Coevolution experiments were conducted on a Listeria phage-host system to provide insight into the genetic variation that emerges in both the phage and bacterial host under reciprocal selective pressure. As expected, mutations were identified in both phage and host, but additionally, recombination events were shown to have repeatedly occurred between closely related phages that coinfected L. monocytogenes. This study demonstrates that in vitro evolution of phages can be utilized to expand the host range and improve the long-term efficacy of phage-based control of L. monocytogenes. This approach may also be applied to other phage-host systems for applications in biocontrol, detection, and phage therapy.

scholarly journals THE USE OF CLINOPTILOLITES AS CARRIER OF METFORMIN HYDROCHLORIDE IN DRUG DELIVERY SYSTEM: IN VITRO DRUG RELEASE STUDY

2018 ◽  
Vol 11 (11) ◽  
pp. 285
Author(s):  
Putra Imwa ◽  
Kusumawati Igaw
Keyword(s):  
Drug Release ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Metformin Hydrochloride ◽  
Simulated Intestinal Fluid ◽  
In Vitro Drug Release ◽  
Encapsulation Process ◽  
N2 Sorption ◽  
Metformin Hcl

Objective: As an antidiabetic drug, metformin hydrochloride (HCl) has been well known to possess low oral bioavailability and short half-life. In this study, we prepared the drug delivery system (DDS) of metformin HCl and clinoptilolite as its carrier. The in vitro drug release profile was further investigated.Methods: DDS was made by encapsulating metformin HCl on clinoptilolite using the wet impregnation method at various pH and initial concentration of metformin HCl. Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), and N2 Sorption Analyzer were used to characterize the as-synthesized DDS. Drug release study was conducted by stirring the DDS in simulated gastric fluid and simulated intestinal fluid over 12 h.Results: The encapsulation process was achieved optimally at pH 7.0 and initial concentration of metformin HCl of 300 mg/l (CLI2-300 denoted DDS). The results of FTIR and N2 sorption analyzer confirmed the existence of metformin HCl on clinoptilolites. Meanwhile, the XRD result showed that the crystallinity of clinoptilolites remained unchanged after the encapsulation process. The cumulative drug release in the simulated gastric fluid was found to be higher than that in the simulated intestinal fluid, which indicated the potent influence of pH on the release properties of the drugs. The drug release kinetics of metformin HCl from clinoptilolite was best fitted into the Korsmeyer-Peppas model with non-Fickian transport mechanism.Conclusion: We found that clinoptilolite was suitable for DDS application, particularly as a carrier of metformin HCl.

scholarly journals Preparation, Characterization, and In Vitro Evaluation of Resveratrol-Loaded Cellulose Aerogel

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1624
Author(s):  
Lili Qin ◽  
Xinyu Zhao ◽  
Yiwei He ◽  
Hongqiang Wang ◽  
Hanjing Wei ◽  
...  
Keyword(s):  
High Speed ◽  
Drug Carrier ◽  
Phosphate Buffer Solution ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Oxidized Cellulose ◽  
Buffer Solution ◽  
Aggregation State ◽  
Cellulose Aerogel

Resveratrol is a natural active ingredient found in plants, which is a polyphenolic compound and has a variety of pharmaceutical uses. Resveratrol-loaded TEMPO-oxidized cellulose aerogel (RLTA) was prepared using a freeze-drying method, employing high speed homogenization followed by rapid freezing with liquid nitrogen. RLTAs were designed at varying drug–cellulose aerogel ratios (1:2, 2:3, 3:2, and 2:1). It could be seen via scanning electron microscopy (SEM) that Res integrated into TEMPO-oxidized cellulose (TC) at different ratios, which changed its aggregation state and turned it into a short rod-like structure. Fourier transform infrared (FTIR) spectra confirmed that the RLTAs had the characteristic peaks of TC and Res. In addition, X-ray diffraction (XRD) demonstrated that the grain size of RLTA was obviously smaller than that of pure Res. RLTAs also had excellent stability in both simulated gastric fluid and phosphate buffer solution. The drug release rate was initially completed within 5 h under a loading rate of 30.7 wt%. The results of an MTT assay showed the low toxicity and good biocompatibility of the RLTAs. TC aerogel could be a promising drug carrier that may be widely used in designing and preparing novel biomedicine.

scholarly journals Mutations of the Listeria monocytogenes PeptidoglycanN-Deacetylase andO-Acetylase Result in Enhanced Lysozyme Sensitivity, Bacteriolysis, and Hyperinduction of Innate Immune Pathways

2011 ◽  
Vol 79 (9) ◽  
pp. 3596-3606 ◽  
Author(s):  
Chris S. Rae ◽  
Aimee Geissler ◽  
Paul C. Adamson ◽  
Daniel A. Portnoy
Keyword(s):  
Listeria Monocytogenes ◽  
Transcriptional Responses ◽  
Gram Positive ◽  
Content Type ◽  
Growth Defects ◽  
Gram Positive Bacteria ◽  
Host Cell Death

ABSTRACTListeria monocytogenesis a Gram-positive intracellular pathogen that is naturally resistant to lysozyme. Recently, it was shown that peptidoglycan modification by N-deacetylation or O-acetylation confers resistance to lysozyme in various Gram-positive bacteria, includingL. monocytogenes.L. monocytogenespeptidoglycan is deacetylated by the action ofN-acetylglucosamine deacetylase (Pgd) and acetylated byO-acetylmuramic acid transferase (Oat). We characterized Pgd−, Oat−, and double mutants to determine the specific role ofL. monocytogenespeptidoglycan acetylation in conferring lysozyme sensitivity during infection of macrophages and mice. Pgd−and Pgd−Oat−double mutants were attenuated approximately 2 and 3.5 logs, respectively,in vivo. In bone-marrow derived macrophages, the mutants demonstrated intracellular growth defects and increased induction of cytokine transcriptional responses that emanated from a phagosome and the cytosol. Lysozyme-sensitive mutants underwent bacteriolysis in the macrophage cytosol, resulting in AIM2-dependent pyroptosis. Each of thein vitrophenotypes was rescued upon infection of LysM−macrophages. The addition of extracellular lysozyme to LysM−macrophages restored cytokine induction, host cell death, andL. monocytogenesgrowth inhibition. This surprising observation suggests that extracellular lysozyme can access the macrophage cytosol and act on intracellular lysozyme-sensitive bacteria.

Sign in / Sign up

Export Citation Format

Share Document