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.

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 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 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 Effect of Gaseous Ozone on Listeria monocytogenes Planktonic Cells and Biofilm: An In Vitro Study

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1484
Author(s):  
Felice Panebianco ◽  
Selene Rubiola ◽  
Francesco Chiesa ◽  
Tiziana Civera ◽  
Pierluigi Aldo Di Ciccio
Keyword(s):  
Listeria Monocytogenes ◽  
In Vitro Study ◽  
Planktonic Cells ◽  
Free Living ◽  
Biofilm Inhibition ◽  
Additional Tool ◽  
Complete Inactivation ◽  
Gaseous Ozone ◽  
Food Borne

Among food-borne pathogens, Listeria monocytogenes continues to pose concerns to food business operators due to its capacity to form biofilm in processing environments. Ozone may be an eco-friendly technology to control microbial contaminations, but data concerning its effect on Listeria monocytogenes biofilm are still limited. In this study, the effect of gaseous ozone at 50 ppm on planktonic cells and biofilm of reference and food-related Listeria monocytogenes strains was evaluated. Ozone caused a reduction in microbial loads of 3.7 ± 0.4 and 3.9 ± 0.4 Log10 CFU/mL after 10 and 30 min, respectively. A complete inactivation of planktonic cells after 6 h of treatment was observed. Biofilm inhibition and eradication treatments (50 ppm, 6 h) resulted in a significant decrease of the biofilm biomass for 59% of the strains tested, whilst a slight dampening of live cell loads in the biofilm state was observed. In conclusion, gaseous ozone is not sufficient to completely counteract Listeria monocytogenes biofilm, but it may be useful as an additional tool to contrast Listeria monocytogenes free-living cells and to improve the existing sanitization procedures in food processing environments.

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 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 Vertical Transmission of Listeria monocytogenes: Probing the Balance between Protection from Pathogens and Fetal Tolerance

Pathogens ◽  
2018 ◽  
Vol 7 (2) ◽  
pp. 52 ◽  
Author(s):  
Nicole Lamond ◽  
Nancy Freitag
Keyword(s):  
Cell Culture ◽  
Listeria Monocytogenes ◽  
Animal Models ◽  
Vertical Transmission ◽  
Surface Proteins ◽  
Placental Barrier ◽  
Bacterial Surface ◽  
Organ Models ◽  
The Many

Protection of the developing fetus from pathogens is one of the many critical roles of the placenta. Listeria monocytogenes is one of a select number of pathogens that can cross the placental barrier and cause significant harm to the fetus, leading to spontaneous abortion, stillbirth, preterm labor, and disseminated neonate infection despite antibiotic treatment. Such severe outcomes serve to highlight the importance of understanding how L. monocytogenes mediates infiltration of the placental barrier. Here, we review what is currently known regarding vertical transmission of L. monocytogenes as a result of cell culture and animal models of infection. In vitro cell culture and organ models have been useful for the identification of L. monocytogenes virulence factors that contribute to placental invasion. Examples include members of the Internalin family of bacterial surface proteins such as Interalin (Inl)A, InlB, and InlP that promote invasion of cells at the maternal-fetal interface. A number of animal models have been used to interrogate L. monocytogenes vertical transmission, including mice, guinea pigs, gerbils, and non-human primates; each of these models has advantages while still not providing a comprehensive understanding of L. monocytogenes invasion of the human placenta and/or fetus. These models do, however, allow for the molecular investigation of the balance between fetal tolerance and immune protection from L. monocytogenes during pregnancy.

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.

Survival of Listeria monocytogenes Strain H7762 and Resistance to Simulated Gastric Fluid following Exposure to Frankfurter Exudate†

2004 ◽  
Vol 67 (6) ◽  
pp. 1170-1176 ◽  
Author(s):  
LAURA D. WONDERLING ◽  
DARRELL O. BAYLES
Keyword(s):  
Listeria Monocytogenes ◽  
Brain Heart Infusion ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Time Of Death ◽  
Nonlinear Regression Analysis ◽  
Underlying Distribution ◽  
Acid Sensitivity ◽  
The Mean ◽  
Mean Time

Listeria monocytogenes strain H7762, a frankfurter isolate, was tested to determine whether it was able to survive at 4°C in frankfurter pack fluid (exudate) and to determine whether food exposure affects its acid sensitivity. Cultures were sampled and tested for acid sensitivity by challenge with simulated gastric fluid (SGF). SGF challenges performed immediately after inoculation revealed that between 20 and 26% of the cells survived the full 30 min of SGF challenge regardless of whether the cells were inoculated into brain heart infusion broth (BHI) or exudate. After 2 days of incubation, cells exposed to both exudate and BHI had significantly decreased SGF resistance; however, the cells exposed to exudate were significantly more SGF resistant than cells exposed to BHI (after 15 min of SGF treatment, 33% of the exudate-exposed cells survived and 12% of the BHI-exposed cells survived). L. monocytogenes exposed to exudate had greater SGF resistance at all challenge times compared with BHI-exposed cells from day 2 through day 4. From days 8 to 15, exudate-exposed cells continued to have greater SGF resistance than BHI-exposed cells up to 10 min of SGF challenge but were as sensitive as the BHI-exposed cells at 20 to 30 min of challenge. By day 25, cells exposed to exudate were significantly more sensitive to SGF challenge than BHI-exposed cells. The survivor data generated from SGF challenges were modeled by a nonlinear regression analysis to calculate the underlying distribution of SGF resistance found in the challenged populations. These analyses indicated that L. monocytogenes exposed to exudate at 48C had a broader distribution of resistance to SGF compared with cells exposed to BHI at 4°C. In addition, the mean time of death during SGF treatment was greater after exposure to exudate, indicating that cells exposed to exudate were more resistant to killing by SGF. These data suggest that exposure to frankfurter exudate might render L. monocytogenes more able to survive the stomach environment during the initial stages of infection.

scholarly journals The Antioxidant Properties of Pectin Fractions Isolated from Vegetables Using a Simulated Gastric Fluid

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Vasily V. Smirnov ◽  
Victoria V. Golovchenko ◽  
Fedor V. Vityazev ◽  
Olga A. Patova ◽  
Nikolay Yu. Selivanov ◽  
...  
Keyword(s):  
Xanthine Oxidase ◽  
Antioxidant Properties ◽  
Sweet Pepper ◽  
Structural Features ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Oxygen Species ◽  
Pectic Polysaccharides ◽  
White Cabbage

The antioxidant properties of vegetable pectin fractions against intraluminal reactive oxygen species were elucidated in vitro in conjunction with their structural features. The pectin fractions were isolated using a simulated gastric fluid (pH 1.5, pepsin 0.5 g/L, 37°C, 4 h) from fresh white cabbage, carrot, onion, and sweet pepper. The fraction from onion was found to inhibit the production of superoxide radicals by inhibiting the xanthine oxidase. The high molecular weight of onion pectin and a large number of galactose residues in its side chains appeared to participate in interaction with xanthine oxidase. All the isolated pectic polysaccharides were found to be associated with protein (2–9%) and phenolics (0.5–0.7%) as contaminants; these contaminants were shown to be responsible for the antioxidant effect of vegetable pectin fractions against the hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals.

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