Suppurative gastritis in BALB/c mice infected with Listeria monocytogenes via the intragastric route

Antilisterial efficacy of Lactobacillus brevis MF179529 from cow: an in vivo evidence

Background

Listeria monocytogenes is an opportunistic foodborne pathogen that causes human Listeriosis and high mortality particularly in immunocompromised individuals. Pregnant women are more prone to L. monocytogenes infection resulting in abortions.

In the present study, antilisterial activity of Lactobacillus brevis (LB) MF179529, a probiotic bacterial strain, was investigated in a murine model.

Methods

Initially a pilot study was conducted to determine the dose of L. monocytogenes required to cause symptomatic listeriosis. In the main trial, mice were divided into 4 groups. Group I was kept as negative control, group II was exposed to L. monocytogenes and maintained as positive control. Group III was fed with L. brevis only, while group IV received L. brevis for 3 days prior to L. monocytogenes infection. A volume of 200 μl of L. monocytogenes ATCC 19115 and L. brevis MF179529 bacterial suspension corresponding to cell density of 10⁹CFU/ml were given to respective groups by intragastric route. Progress of infection was monitored for 7 days including general health scoring, listeria dispersion in organs, bacterial load in intestine and blood biochemistry were recorded on 3rd, 5th and 7th days post infection (dpi).

Results

Clinical listeriosis was induced by 10⁹CFU/ml of L. monocytogenes ATCC 19115 in mice.

Animals of group IV displayed minor signs of infection. L. brevis supplementation resulted in significant reduction in dispersion and propagation of L. monocytogenes in liver, spleen and intestine. L. brevis MF179529 consumption led to a significant elevation of number of lactic acid bacteria and reduction of total plate count, anaerobic count and coliform population in intestine. Moreover, total leukocyte and neutrophil counts of treated animals were similar to the negative control while positive control group displayed higher number. Safety evaluation of L. brevis was performed by monitoring general health, hematological and serological parameters of L. brevis fed and negative control group (group III and I). No significant difference in feed intake, body temperature, body weight and blood picture could be detected in L. brevis supplemented and control groups.

Conclusion

Our results indicate ameliorative role of L. brevis in L. monocytogenes infection and suggest that L. brevis could be used for prophylactic measure.

Electronic supplementary material

The online version of this article (10.1186/s12906-019-2444-5) contains supplementary material, which is available to authorized users.

Inhibitory effects of the κ-casein macropeptide isolated from milk protein on the biofilm formation and virulence of Listeria monocytogenes

We demonstrate the inhibitory effects of κ-casein macropeptide (CMP) on the biofilm formation and virulence of Listeria monocytogenes Scott A. The inhibition of biofilm formation by CMP was initially investigated by using the protocol applied for the 96-well microtiter plate assay. Low concentrations of CMP (0.1, 0.2, 0.3, 0.4, and 0.5 mg/mL) that were tested resulted in a profound inhibitory effect on biofilm formation at a concentration of 0.4 mg/mL. CMP also significantly repressed the transcription of inlA (encoding internalin A) that was responsible for the initial adhesion and invasion event, and prolonged the survival of Caenorhabditis elegans infected by L. monocytogenes. Two-dimensional gel electrophoresis showed that newly identified proteins in the presence of CMP were involved in the stress response and metabolic processes that have important roles in developing listerial biofilms. Our results suggest that CMP from milk protein would be capable of eliminating biofilm formation and virulence by L. monocytogenes in the food industry.

New data, strategies, and insights for Listeria monocytogenes dose-response models: summary of an interagency workshop, 2011

Listeria monocytogenes is a leading cause of hospitalization, fetal loss, and death due to foodborne illnesses in the United States. A quantitative assessment of the relative risk of listeriosis associated with the consumption of 23 selected categories of ready-to-eat foods, published by the U.S. Department of Health and Human Services and the U.S. Department of Agriculture in 2003, has been instrumental in identifying the food products and practices that pose the greatest listeriosis risk and has guided the evaluation of potential intervention strategies. Dose-response models, which quantify the relationship between an exposure dose and the probability of adverse health outcomes, were essential components of the risk assessment. However, because of data gaps and limitations in the available data and modeling approaches, considerable uncertainty existed. Since publication of the risk assessment, new data have become available for modeling L. monocytogenes dose-response. At the same time, recent advances in the understanding of L. monocytogenes pathophysiology and strain diversity have warranted a critical reevaluation of the published dose-response models. To discuss strategies for modeling L. monocytogenes dose-response, the Interagency Risk Assessment Consortium (IRAC) and the Joint Institute for Food Safety and Applied Nutrition (JIFSAN) held a scientific workshop in 2011 (details available at http://foodrisk.org/irac/events/). The main findings of the workshop and the most current and relevant data identified during the workshop are summarized and presented in the context of L. monocytogenes dose-response. This article also discusses new insights on dose-response modeling for L. monocytogenes and research opportunities to meet future needs.

Animal models of listeriosis: a comparative review of the current state of the art and lessons learned

Listeriosis is a leading cause of hospitalization and death due to foodborne illness in the industrialized world. Animal models have played fundamental roles in elucidating the pathophysiology and immunology of listeriosis, and will almost certainly continue to be integral components of the research on listeriosis. Data derived from animal studies helped for example characterize the importance of cell-mediated immunity in controlling infection, allowed evaluation of chemotherapeutic treatments for listeriosis, and contributed to quantitative assessments of the public health risk associated with L. monocytogenes contaminated food commodities. Nonetheless, a number of pivotal questions remain unresolved, including dose-response relationships, which represent essential components of risk assessments. Newly emerging data about species-specific differences have recently raised concern about the validity of most traditional animal models of listeriosis. However, considerable uncertainty about the best choice of animal model remains. Here we review the available data on traditional and potential new animal models to summarize currently recognized strengths and limitations of each model. This knowledge is instrumental for devising future studies and for interpreting current data. We deliberately chose a historical, comparative and cross-disciplinary approach, striving to reveal clues that may help predict the ultimate value of each animal model in spite of incomplete data.

In vivo study on the effectiveness of pediocin PA-1 and Pediococcus acidilactici UL5 at inhibiting Listeria monocytogenes

The anti-listerial effect of pediocin PA-1 and its producing strain, Pediococcus acidilactici UL5, was investigated in vivo using an ICR mouse model. The effect of intra-gastric administration of a single dose of P. acidilactici UL5 (4 x 10(10) CFU/animal) on the propagation of Listeria monocytogenes LSD348 in intestine, liver and spleen was negligible. P. acidilactici UL5 did not appear competitive with the mouse intestinal flora and was not detectable in fecal samples collected two days after administration. However, double-agar-layer activity assay showed the ability of P. acidilactici UL5 colonies recovered from fecal samples one day after administration to produce pediocin PA-1 and inhibit L. monocytogenes. Moreover, repeated doses (250 microg/day for three consecutive days) of purified pediocin PA-1 provided up to 2-log reductions in fecal listerial counts compared to the infected control group and slowed pathogen translocation into the liver and spleen, leading to the disappearance of L. monocytogenes infection in these two organs within six days. Neither P. acidilactici UL5 nor ingested purified pediocin PA-1 had any negative effect on feed intake or body weight development. Pediocin PA-1 did not affect the composition of the mouse intestinal flora, suggesting a potential advantage over other inhibitory agents as a prophylactic measure against L. monocytogenes.

The anti-inflammatory non-antibiotic helper compound diclofenac: an antibacterial drug target

Diclofenac sodium (Dc) was found to possess antibacterial activity against both drug-sensitive and drug-resistant clinical isolates of Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Mycobacterium spp., in addition to its potent anti-inflammatory activity. The time-kill curve study indicates that this non-steroidal drug exhibits bactericidal activity against Listeria, E. coli, and M. tuberculosis. The antibacterial activity of Dc comes, in part, from its ability to inhibit the DNA synthesis of E. coli and L. monocytogenes. Dc could protect murine listeriosis, salmonellosis, and tuberculosis at doses ranged within its maximum recommended human or non-toxic ex-vivo dose. Dc possesses anti-plasmid activity and acts as a 'helper compound' in synergistic combination with streptomycin against E. coli and Mycobacterium or gentamicin against Listeria. This review focuses on the possible use of Dc, a non-antibiotic helper compound, in infections and inflammatory conditions, rationalized on the basis of the activities of the compounds.

In vitro and in vivo efficacies of amlodipine against Listeria monocytogenes

Listeria monocytogenes causes suppurative gastritis in BALB/c mice. We investigated the effect of the antihypertensive drug amlodipine (Aml) on the growth of L. monocytogenes in vitro and in vivo. Aml showed noteworthy inhibitory action (minimum inhibitory concentration, MIC(90) 32 microg/ml) against Listeria strains and demonstrated cidal (minimum bactericidal concentration, MBC 64 microg/ml) activity. Aml administered orally at 2.5 microg/g in female BALB/c mice for 7 days, commencing 4 days before oral challenge (1 x 10(8) CFU/ml with L. monocytogenes ATCC 51774), significantly reduced bacterial counts in the stomach (P < 0.01), liver (P < 0.01), and spleen (P < 0.05), and decreased (P < 0.05) gastric lesions, neutrophilic infiltration, edema, vascular degeneration, and necrosis of gastric tissues. It caused the down-regulation of expression of inflammatory cytokines (IFN-gamma, IL-1 beta, and TNF-alpha) compared to drug-free control. Aml may be used in the presence of an antibiotic as adjunct therapy that boosts the host immunity against Listeria. Further, QSAR studies might contribute in manipulating it as a lead compound for the synthesis of new, more effective non-antibiotics (helper compounds), perhaps devoid of side-effects, that could be recommended as compassionate therapy for listeriosis.

Gastric lesions and immune responses caused by long-term infection with Helicobacter heilmannii in C57BL/6 mice

Helicobacter heilmannii is a gastric micro-organism that can induce gastritis and B-cell MALT (mucosa-associated lymphoid tissue) lymphoma in mice, in a host-dependent manner. The present study was designed to examine gastric lesions and immune responses caused by intragastric H. heilmannii infection of an inbred mouse strain, C57BL/6. Long-term infection led to the formation of gastric nodules and increased mucosal thickness of the stomach, due to gastric epithelial proliferation. Infection also induced the formation of lymphoid follicles in the corpus mucosa and submucosa. The follicular cells were mainly CD45R+ cells that did not produce immunoglobulin. However, scattered in the lamina propria and corpus submucosa, numerous IgA+ cells were found in infected mice, but not in control mice. RT-PCR results showed that H. heilmannii infection led to increased mRNA expression for IFN-gamma (a Th1 cytokine) and IL-10 (a Th2 cytokine) in the mouse stomach, suggesting that both Th1 and Th2 responses are associated with H. heilmannii infection. The mRNA of other cytokines and chemokines (IL-1beta, IL-12p40, TNF-alpha, MCP-1, KC and MIP-2) was also increased by infection.

The anti-inflammatory drug Diclofenac retains anti-listerial activity in vivo

AIMS

The interactions between nonsteroidal anti-inflammatory drugs (NSAID) and Listeria monocytogenes have not been sufficiently documented to date. The aim of this study was to investigate the possible effects of Diclofenac (Dc) in a murine listerial infection model.

METHODS AND RESULTS

Dc was administered orally at 2.5 mug g(-1) to female albino strain of laboratory mouse (BALB/c) thrice postinfection (1 x 10(8) CFU ml(-1) oral challenge with L. monocytogenes ATCC 51774), which resulted in significantly (P < 0.01) reduced bacterial counts in liver and spleen, decreased (10-fold, P < 0.05) hepatic colonization and necrosis, and caused up-regulation of the expression of inflammatory cytokines (interferon-gamma, interleukin-1beta, tumour necrosis factor-alpha), compared with drug-free control.

CONCLUSIONS

Dc may be useful as a promising adjuvant to the existing therapies in controlling systemic listerial infection. Further, quantitative structure-activity relationship studies might contribute in manipulating it as a lead compound for the synthesis of new, more effective nonantibiotics, perhaps, devoid of side-effects that could be recommended as a compassionate therapy for listeriosis.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first in vivo study designed to evaluate the antilisterial effect of the NSAID Dc with special emphasis on the immunological mechanism of action of the drug.

Characteristics of the gastritis induced by Listeria monocytogenes in mice: microbiology, histopathology, and mRNA expression of inflammatory mediators with time course of infection

Listeria monocytogenes induces the suppurative gastritis in some mice strains. In this study, characteristics of the gastritis caused by L. monocytogenes infection in mice were examined with time course of infection. Mice were administered intragastrically with 1.8 x 10(8) CFU of L. monocytogenes. Each three mice were sacrificed by cervical dislocation at 1, 3, 5, 7, 10, 14, 17, 21, and 28 days postinoculation (pi), respectively. Bacterial colonization in the stomachs reached the peak at 3 days pi, maintained over 4.3 log10 CFU/g tissue until 14 days pi, and was cleared by 28 days pi. However, in the spleens and livers, the bacteria could not be detected after 7 days pi. The gastric lesions were the most prominent at between 3 and 7 days pi. The lesions consisted of marked neutrophilic infiltration, edema, vacuolar degeneration and necrosis of muscle cells and were more severe in the nonglandular region and fundus than in the pylorus, and were in submucosa, lamina muscularis, and serosa than in mucosa. mRNA expression of several cytokines (INF-gamma, IL-1beta, IL-5, IL-6, IL-12, and TNF-alpha) and chemokines (KC, MCP-1) increased in the gastric tissue of infected mice at 1-7 days pi and slightly decreased at 14 days pi. These findings would be useful for studying the pathological mechanism of human febrile gastroenteritis due to L. monocytogenes infection.