Search

430 Background: The combination of cisplatin-based chemotherapy with immune checkpoint inhibitors is extensively investigated in urothelial carcinoma. Using this combination in the neoadjuvant setting for patients (pts) with MIUC might improve pathological response rate (PaR: 1 EFS at 2 years ≥ 65% compared to H0 EFS at 2 years ≤ 50%. We report the secondary endoints PaR, pathological complete remission (pCR: ypT0 N0), and safety on the full analysis set (FAS, received at least one dose of durva). Results: 61 pts were included between 7/18 and 9/19 at 12 sites. The FAS consists of 58 pts (79% male, median age 67.5 yrs) with bladder cancer (95%) or upper urinary tract/urethral cancer (5%). Clinical T2, T3, T4 stage were present at diagnosis in 69%, 21%, 10%, respectively, and 17% had cN1. 95% of pts received all 4 doses of neoadjuvant durva, 81% all 4 cycles of cis/gem and 17% switched to carboplatin. In total grade 3 and 4 adverse events (AE) during neoadjuvant treatment occurred in 48% and 27%, respectively. AEs related to durva were G3 in 7 pts (12%) and G4 in one patient (2%). Resection was performed in 53 pts (91%; 51 radical cystectomy, 2 nephroureterectomy), 4 pts refused surgery and one patient was irresectable due to a frozen pelvis. R0 resection was achieved in 52 pts (98%), one had R1. Postoperative complications included Clavien-Dindo III in 13 pts (24%) and IV in 5 pts (9%). PaR was found in 60% (95% CI 46.0%-73.5%) with 18 pts achieving pCR (34%; 95% CI 21.5%-48.3%) and 14 patients (26%) ypT1/ypTis. Conclusions: The first FAS results for neoadjuvant durvalumab in combination with cis/gem for operable MIUC confirm elevated pathological response rates and demonstrate acceptable safety. Postoperative morbidity is relevant but not exceeding the expected frequency or severity. Clinical trial information: NCT03406650.

To examine to what extent fresh vegetables imported into Switzerland represent carriers of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae , 169 samples of different types of fresh vegetables imported into Switzerland from the Dominican Republic, India, Thailand, and Vietnam were analyzed. Overall, 25.4% of the vegetable samples yielded one or more ESBL-producing Enterobacteriaceae , 78.3% of which were multidrug resistant. Sixty isolates were obtained: Escherichia coli , 26; Klebsiella pneumoniae , 26; Enterobacter cloacae , 6; Enterobacter aerogenes , 1; and Cronobacter sakazakii , 1. We found 29 isolates producing CTX-M-15, 8 producing CTX-M-14, 7 producing CTX-M-55, 3 producing CTX-M-65, 1 each producing CTX-M-1, CTX-M-3, CTX-M-27, and CTX-M-63, 5 producing SHV-2, 3 producing SHV-12, and 1 producing SHV-2a. Four of the E. coli isolates belonged to epidemiologically important clones: CTX-M-15-producing B2:ST131 (1 isolate), D:ST405 (1 isolate), and D:ST38 (2 isolates). One of the D:ST38 isolates belonged to the extraintestinal enteroaggregative E. coli (EAEC) D:ST38 lineage. Two of the K. pneumoniae isolates belonged to the epidemic clones sequence type 15 (ST15) and ST147. The occurrence of antibiotic-resistant pathogenic and commensal Enterobacteriaceae in imported agricultural foodstuffs constitutes a source of ESBL genes and a concern for food safety.

499 Background: Cisplatin-based neoadjuvant chemotherapy followed by surgery is the standard of care for patients (pts) with MIUC but relapse rates remain high. Immune checkpoint inhibitors have demonstrated efficacy in advanced urothelial carcinoma (UC). We hypothesize that the integration of the PD-L1 inhibitor durvalumab into perioperative management of MIUC improves outcome. Methods: SAKK 06/17 is an open label single arm phase II study including 61 pts. Operable MIUC cT2-T4a cN0-1 pts without contraindication for Cis were eligible. Four cycles of preoperative Cis/Gem q3w are administered in combination with 4 cycles Durva 1500mg q3w starting at cycle 2. Durva is continued after surgery q4w for 10 cycles. Primary endpoint is event free survival at 2 years. We report a preplanned interim analysis of the secondary endpoints safety, pathological complete remission ypT0 N0 (pCR,) and pathological response rate (PaR, defined as ≤ypT1N0) on the first 30 resected pts. Results: Among 34 eligible pts (27M, 7F; median age 70, range 41-81 years) included from 07/18 – 02/19, 33 pts (97%) had primary bladder cancer and 1 pt had upper tract UC. Clinical T2, T3, T4 and TxN1 stage were present at diagnosis in 68%, 18%, 15% and 15%, respectively. Four cycles of chemo-immunotherapy were completed per protocol in 34 pts (100%). No tumor progression was noted at preoperative restaging. AE related to Durvalumab were G3 in 5 pts (15%) and G4 in 3 pts (9%). Surgery was performed as planned in 30 pts (88%), 3 pts refused surgery and 1 pt had a frozen pelvis. Operation technique was open in 20 pts (67%) and laparoscopic/robot-assisted in 10 pts (33%). Postoperative complications included Clavien-Dindo III in 6 pts (20%) and IV in 2 pts (7%) with infections being most common (5 pts, 17%). pCR was found in 9 pts (30%) and additional 6 pts (20%) had ypT1/ypTis for a PaR of 50%. Conclusions: The combination of Cis/Gem and Durva as neoadjuvant treatment for MIUC is feasible with manageable toxicities and pCR and PaR rates in the expected range. The rate of postoperative complications warrants further close follow up. Clinical trial information: 2017-003565-10.

405 Background: Standard treatment options for stage IIA/B seminoma include either extensive paraaortal/pelvic radiotherapy or intensive chemotherapy with 3x BEP or 4x EP. Both treatment modalities are associated with excellent efficacy but also a high rate of acute and late toxicities. Therefore, de-escalation strategies appear warranted for this patient group aiming to minimize acute and long-term toxicities while maintaining efficacy. SAKK 01/10 is a joint project of the Swiss Group for Clinical Cancer Research and the German Testicular Cancer Study Group. Methods: Patients with stage IIA/B seminoma (de novo or relapse on active surveillance) were eligible for participation in this single arm phase II trial. A repeat scan was advised in patients with equivocal lymph node enlargement. Treatment consisted of one cycle carboplatin AUC7 followed by involved-node radiotherapy with 30 Gy in stage IIA and 36 Gy in stage IIB disease. The primary endpoint of the trial is 3-year progression free survival. We report on treatment compliance and early toxicity during treatment and within 30 days. Results: 120 patients with stage IIA/B seminoma were recruited from 10/12 until 06/18 in 20 study centers in Switzerland and Germany. 116 patients were eligible and initiated treatment per protocol (40% stage IIA, 60% stage IIB). All patients received chemotherapy (CT) with a median applied dose of 984 mg (range: 560-1920 mg). The median planning target volume (PTV) for radiotherapy (RT) was 297 cm3 (range: 24-1047 cm3). RT was delayed/interrupted in two patients due to adverse events. During CT, grade 2 and grade 3 adverse events were seen in 21% and 2% of all patients respectively (most common grade 2 events: neutropenia 6%, nausea 5%). During RT, grade 2 and grade 3 adverse events were seen in 26% and 6% of all patients respectively (most common grade 2 events: neutropenia 15%, nausea 6%). One case of transient creatinine increase was reported as a severe adverse event, resolving without sequelae. Conclusions: Treatment with one cycle carboplatin AUC7 and 30-36 Gy involved-node radiotherapy for stage IIA/B seminoma is feasible and demonstrates a very favorable early toxicity profile. Clinical trial information: NCT01593241.

Background Immune checkpoint inhibitors targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) have been recently approved for treatment of patients with metastatic melanoma and non-small cell lung cancer (NSCLC). Despite important clinical benefits, these therapies are associated with a diverse spectrum of immune-related adverse events (irAEs) that are typically transient, but occasionally severe or even fatal. Case presentation This autopsy case illustrates that clinically overt irAEs may represent only a fraction of the total spectrum of immune-related organ pathology in patients treated with immune checkpoint inhibitors. We report a comprehensive analysis of systemic irAE pathology based on the autopsy of a 35-year-old female patient with metastatic melanoma treated first with ipilimumab and then nivolumab. The clinical course was characterized by a mixed tumor response with regression of skin and lung metastases and fatal progression of metastatic disease in the small bowel, peritoneum and brain. During therapy with ipilimumab, radiographic features of immune-related pneumonitis were noted. The autopsy examination established a sarcoid-like granulomatous reaction of the lung, pulmonary fibrosis and diffuse alveolar damage. Importantly, a clinically unapparent but histologically striking systemic inflammation involving the heart, central nervous system, liver and bone marrow was identified. Severe immune-related end-organ damage due to lymphocytic myocarditis was found. Conclusions Autopsy studies are an important measure of quality control and may identify clinically unapparent irAEs in patients treated with immunotherapy. Pathologists and clinicians need to be aware of the broad spectrum of irAEs for timely management of treatment-related morbidity. Electronic supplementary material The online version of this article (doi:10.1186/s40425-016-0117-1) contains supplementary material, which is available to authorized users.

New biological strategies for the treatment ofSalmonellainfection are needed in response to the increase in antibiotic-resistant strains.Escherichia coliL1000 andBifidobacterium thermophilumRBL67 were previously shown to produce antimicrobial proteinaceous compounds (microcin B17 and thermophilicin B67, respectively) activein vitroagainst a panel ofSalmonellastrains recently isolated from clinical cases in Switzerland. In this study, two three-stage intestinal continuous fermentation models ofSalmonellacolonization inoculated with immobilized faeces of a two-year-old child were implemented to study the effects of the two bacteriocinogenic strains compared with a bacteriocin-negative mutant of strain L1000 onSalmonellagrowth, as well as gut microbiota composition and metabolic activity. ImmobilizedE. coliL1000 added to the proximal colon reactor showed a low colonization, and developed preferentially in the distal colon reactor independent of the presence of genetic determinants for microcin B17 production. Surprisingly,E. coliL1000 addition strongly stimulatedSalmonellagrowth in all three reactors. In contrast,B. thermophilumRBL67 added in a second phase stabilized at high levels in all reactors, but could not inhibitSalmonellaalready present at a high level (>107c.f.u. ml−1) when the probiotic was added. Inulin added at the end of fermentation induced a strong bifidogenic effect in all three colon reactors and a significant increase ofSalmonellacounts in the distal colon reactor. Our data show that under the simulated child colonic conditions, the microcin B17 production phenotype does not correlate with inhibition ofSalmonellabut leads to a better colonization ofE. coliL1000 in the distal colon reactor. We conclude thatin vitromodels with complex and complete gut microbiota are required to accurately assess the potential and efficacy of probiotics with respect toSalmonellacolonization in the gut.

Aims: To evaluate the survival of Pediococcus acidilactici UL5 and its ability to produce pediocin PA-1 during transit in an artificial gastrointestinal tract (GIT). To investigate the physicochemical and biological stability of purified pediocin PA-1 under GIT conditions. Methods and Results: Skim milk culture of Ped. acidilactici UL5 was fed to a dynamic gastrointestinal (GI) model known as TIM-1, comprising four compartments connected by computer-controlled peristaltic valves and simulating the human stomach, duodenum, jejunum and ileum. This strain tolerated a pH of 2·7 in the gastric compartment, while lower pH reduced its viability. Bile salts in the duodenal compartment brought a further 4-log reduction after 180 min of digestion, while high viable counts (up to 5 × 107 CFU ml−1 fermented milk) of Ped. acidilactici were found in both the jejunal and ileal compartments. Pediococcus acidilactici recovered from all four compartments was able to produce pediocin at the same level as unstressed cells. The activity of the purified pediocin in the gastric compartment was slightly reduced after 90 min of gastric digestion, while no detectable activity was found in the duodenal, jejunal and ileal compartments during 5 h of digestion. HPLC analysis showed partial degradation of the pediocin peptide in the duodenal compartment and massive breakdown in the jejunal and ileal compartments. Conclusions: Pediococcus acidilactici UL5 showed high resistance to GIT conditions, and its ability to produce pediocin was not affected, suggesting its potential as a probiotic candidate. The physicochemical and biological stability of pediocin was significantly poor under GIT conditions. Significance and Impact of the Study: Pediococcus acidilactici UL5 appears to be a potential probiotic candidate because its capacity to produce pediocin PA-1 is not affected by the GI conditions as well as the strain shows an acceptable survival rate. Meanwhile, purified pediocin PA-1 losses activity during GIT transit; microcapsules could be used to deliver it to the target site.

The antimicrobial activities of the class IIa bacteriocin divergicin M35 and several types of chitosan against Listeria monocytogenes were quantified by agar diffusion, critical micro-dilution, and viable count and observed by electron microscopy. Antimicrobial activity of chitosan depended on its molecular mass (MM) and the pH. Three chitosans with MM values of 2, 20, and 100 kDa and 87.4% degree of deacetylation (DDA) were chosen for further study, based on high anti-listerial activity at pH 4.5. Electron microscopy suggested that the mechanism of anti-listerial activity also varied with the MM. Low-MM chitosan appeared to inhibit L. monocytogenes by affecting cell permeability and growth, whereas medium- and high-MM chitosan may form a barrier on the cell surface that prevents entry of nutrients. The minimum inhibitory concentrations (MICs) of 2, 20, and 100 kDa chitosan and divergicin M35 against a divergicin-resistant strain of L. monocytogenes (LSD 535) were 2.5, 2.5, 0.625, and 0.25 mg/mL, respectively. The combination of any of these 3 chitosans and divergicin M35 appeared to have an additive effect against L. monocytogenes, as determined by fractional inhibitory concentration (FIC) index. This study provides useful data for the development of chitosan films incorporating divergicin M35 for inhibiting L. monocytogenes in foods.

In this study, a new in vitro continuous colonic fermentation model of Salmonella infection with immobilized child fecal microbiota and Salmonella serovar Typhimurium was developed for the proximal colon. This model was then used to test the effects of two amoxicillin concentrations (90 and 180 mg day−1) on the microbial composition and metabolism of the gut microbiota and on Salmonella serovar Typhimurium during a 43-day fermentation. Addition of gel beads (2%, v/v) colonized with Salmonella serovar Typhimurium in the reactor resulted in a high and stable Salmonella concentration (log 7.5 cell number mL−1) in effluent samples, and a concomitant increase of Enterobacteriaeceae, Clostridium coccoides–Eubacterium rectale and Atopobium populations and a decrease of bifidobacteria. During amoxicillin treatments, Salmonella concentrations decreased while microbial balance and activity were modified in agreement with in vivo data, with a marked decrease in C. coccoides–E. rectale and an increase in Enterobacteriaceae. After interruption of antibiotic addition, Salmonella concentration again increased to reach values comparable to that measured before antibiotic treatments, showing that our model can be used to simulate Salmonella shedding in children as observed in vivo. This in vitro model could be a useful tool for developing and testing new antimicrobials against enteropathogens.

Laboratory studies. Data on differential blood counts, renal function, liver function tests and thyroid function during each treatment cycle (dacarbazine, ipilimumab, nivolumab) are provided. (DOCX 16 kb)

Antibodies and staining protocols. All stains were performed on a Leica BOND III / max autostainer platform (Leica Bioystems, Muttenz, Switzerland). Information on antibody clones, pretreatment and staining protocols is provided. (DOCX 18 kb)

Autoimmune serology. Table showing the screening results of autoimmune serology including systemic antibodies, anti-neutrophil cytoplasmic antibodies (ANCA) and anti-neuronal antibodies. (DOCX 16.8 kb)

Immunohistochemical stains. Systematic overview of the immunohistochemical stains performed for each organ and tumor specimen. (DOCX 21.3 kb)

Expression of cytotoxic granule-associated RNA binding protein (TIA-1) and programmed cell death protein 1 (PD-1, nivolumab). Frequent expression of PD-1 and TIA-1 in tumor infiltrating T-cells (A, B) and in lymphocytic infiltrates in the peripheral organs including the meninges (C, D); scale bars as indicated. (PPTX 4.8 mb)

Aims: To evaluate the sensitivity of 21 common intestinal bacteria to six antibiotics and three broad-spectrum bacteriocins (nisins Z and A and pediocin PA-1). Methods and Results: Neutralized cell-free culture supernatants containing active bacteriocins, and antibiotics were tested with the agar diffusion test and the disc-diffusion method, respectively. The tested intestinal strains showed high sensitivity to most antibiotics except for streptomycin and oxacillin. Nisins A and Z (8 μg per well) had similar activity spectra and inhibited all Gram-positive intestinal bacteria at different levels (except Streptococcus salivarius), with bifidobacteria (except Bifidobacterium breve and Bif. catenulatum), Collinsella aerofaciens and Eubacterium biforme being the most sensitive strains, but they were not active against Gram-negative bacteria. Surprisingly, none of the tested strains were inhibited by pediocin PA-1 (16 μg per well). Conclusion: Pediocin PA-1 which is very active against Listeria spp. and other food pathogens did not inhibit major intestinal species in the human intestine in contrast to both nisins A and Z. Significance and Impact of the Study: Our data suggest that pediocin PA-1 has potential to inhibit Listeria within the intestinal microbiota without altering commensal bacteria.

To clarify which immunohistochemical markers could be helpful in distinguishing between classical Hodgkin's lymphoma (cHL) and primary mediastinal B-cell lymphoma (PMBCL) to more narrowly define 'B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and cHL'.Two hundred and 83 cHLs and 51 PMBCLs were analysed on validated tissue microarray platforms with antibodies to BOB.1, CD15, CD20, CD23, CD30, CD79a, cyclin E, LMP-1, MUM1p, p63 and Oct2. The marker cut-off scores were calculated using receiver-operating characteristic curves. Markers with the highest positive predictive value for cHL were: CD15, cyclin E, LMP-1 (all 100%), MUM1p (93%) and CD30 (83%). High sensitivity was achieved only by CD30 (92%) and cyclin E (79%). Nineteen percent of PMBCLs were also positive for CD30, which led to a lower specificity of CD30 as regards cHL (81%) compared with cyclin E (100%). The antibodies with the highest positive predictive value for PMBCL were: CD23 (98%), p63 (96%), BOB.1 (94%) and CD79a (90%), with high sensitivity for BOB.1 (100%), CD79a (89%) and p63 (82%).The use of at least three of the most accurate immunohistochemical markers, cyclin E, CD79a and BOB.1, may be helpful in the differential diagnosis of cHL and PMBCL.

Modulating the gut microbiota via dietary interventions is a common strategy to enhance the natural defence mechanisms of the host. Several in vitro studies have highlighted the probiotic potential of Bifidobacterium thermophilum RBL67 (RBL67) selected for its anti-Salmonella effects. The present study aimed to investigate the impact of RBL67 alone and combined with fructo-oligosaccharides (FOS) on the gut microbiota of Göttingen minipigs. Minipigs were fed a basal diet supplemented with 8 g/d probiotic powder (1×109 CFU/g in skim milk matrix) (probiotic diet (PRO)), 8 g/d probiotic powder plus 8 g/d FOS (synbiotic diet (SYN)) or 8 g/d skim milk powder (control), following a cross-sectional study design. Faecal and caecal microbiota compositions were analysed with pyrosequencing of 16S rRNA genes and quantitative PCR. Metabolic activity in the caecum and colon was measured by HPLC. 16S rRNA gene amplicon sequencing revealed that minipig faeces show close similarity to pig microbiota. During the treatments and at the time of killing of animals, RBL67 was consistently detected in faeces, caecum and colon at numbers of 105–106 16S rRNA copies/g content after feeding PRO and SYN diets. At the time of killing of animals, significantly higher Bifidobacterium numbers in the caecum and colon of SYN-fed minipigs were measured compared with PRO. Our data indicate that the Göttingen minipig may be a suitable model for gut microbiota research in pigs. Data from this first in vivo study of RBL67 colonisation suggest that the combination with FOS may represent a valuable symbiotic strategy to increase probiotic bacteria levels and survival in gastrointestinal tracts for feed and food applications.

Infectious gastroenteritis caused by non-typhoidal serovars of Salmonella is usually self-limiting but life-threatening complications may require appropriate antibiotic therapies. Probiotics have evolved as potential alternatives to antibiotics in response to an increasing prevalence of resistant strains, but there are no studies comparing the effectiveness of both treatment strategies on the same intestinal microbiota. We used an in vitro intestinal fermentation system with immobilized fecal microbiota to model enteric Salmonella infection in children. The effects of antibiotics, amoxicillin/clavulanic acid at two dosages, and a probiotic candidate, Bifidobacterium thermophilum RBL67, on Salmonella counts, intestinal microbiota composition, and metabolic activity were compared. Antibiotic therapy, in agreement with current clinical reports, produced only a transient decrease of Salmonella concentrations but strongly modified bacterial population profiles and metabolic activity, confirming the suitability of the model. B. thermophilum RBL67 grew in the intestinal environment and exerted a strong inhibition on Salmonella when added before or after infection and was able to rebalance the metabolic activity of gut microbiota after antibiotic treatments. Our study revealed a high potential of B. thermophilum RBL67 for prevention and treatment of Salmonella infection. The exact mechanism has to be further elucidated.

In vitro gut fermentation modeling offers a useful platform for ecological studies of the intestinal microbiota. In this study we describe a novel Polyfermentor Intestinal Model (PolyFermS) designed to compare the effects of different treatments on the same complex gut microbiota. The model operated in conditions of the proximal colon is composed of a first reactor containing fecal microbiota immobilized in gel beads, and used to continuously inoculate a set of parallel second-stage reactors. The PolyFermS model was validated with three independent intestinal fermentations conducted for 38 days with immobilized human fecal microbiota obtained from three child donors. The microbial diversity of reactor effluents was compared to donor feces using the HITChip, a high-density phylogenetic microarray targeting small subunit rRNA sequences of over 1100 phylotypes of the human gastrointestinal tract. Furthermore, the metabolic response to a decrease of pH from 5.7 to 5.5, applied to balance the high fermentative activity in inoculum reactors, was studied. We observed a reproducible development of stable intestinal communities representing major taxonomic bacterial groups at ratios similar to these in feces of healthy donors, a high similarity of microbiota composition produced in second-stage reactors within a model, and a high time stability of microbiota composition and metabolic activity over 38 day culture. For all tested models, the pH-drop of 0.2 units in inoculum reactors enhanced butyrate production at the expense of acetate, but was accompanied by a donor-specific reorganization of the reactor community, suggesting a concerted metabolic adaptation and trigger of community-specific lactate or acetate cross-feeding pathways in response to varying pH. Our data showed that the PolyFermS model allows the stable cultivation of complex intestinal microbiota akin to the fecal donor and can be developed for the direct comparison of different experimental conditions in parallel reactors continuously inoculated with the exact same microbiota. ISSN:1932-6203

Background: The effect of age and gender on left ventricular (LV) size, muscle mass, and systolic function as determined by two-dimensional echocardiography has not yet been investigated in a large population. Methods: Normal transthoracic two-dimensional echocardiography studies of 5307 subjects (47% males) performed between March 1990 and December 2011 were analyzed. LV end-diastolic volume index (LVEDVI), LV muscle mass index (LVMMI), LV ejection fraction (LVEF), and LV fractional shortening (LVFS) were compared in different age groups. Results: LVMMI increased in females from 66.4 1.3 g/m 2 (7–20 years) to 76.3 0.9 g/m 2 (60–80 years; P < 0.0001) and in males from 81.9 1.7 g/m 2 (7–20 years) to 94.6 1.3 g/m 2 (60–80 years; P < 0.0001). LVEDVI decreased in females from 49.8 0.9 mL/m 2 (7–20 years) to 42.8 0.6 mL/m 2 (60–80 years; P < 0.0001) and in males from 56.6 0.8 mL/m 2 (7–20 years) to 49.0 0.7 mL/m 2 (60–80 years; P < 0.0001). A significant increase in LVEF was observed with age (P < 0.0001 for both genders), but it was more pronounced in females (62 0.5% [age 7–20 years] vs. 65 0.3% [age 60–80 years]) than in males (62 0.5% [age 7–20 years] vs. 64 0.3% [age 60–80 years]). Similarly, LVFS increased in females from 37.7 0.5% (7–20 years) to 42.4 0.4% (60–80 years; P < 0.001) and in males from 37.3 0.5% (7–20 years) to 39.4 0.5% (60–80 years; P < 0.001). Conclusions: LVEF, LVFS, and LVMMI increase with advancing age, in particular in females. In contrast, LVEDVI decreases with age. These findings indicate that the LV undergoes a lifelong remodeling. (Echocardiography 2013;0:1-8)

Human intestinal cell models are widely used to study host-enteric pathogen interactions, with different cell lines exhibiting specific characteristics and functions in the gut epithelium. In particular, the presence of mucus may play an important role in adhesion and invasion of pathogens. The aim of this study was to evaluate the suitability of the mucus-secreting HT29-MTX intestinal epithelial cell model to test adhesion and invasion of Salmonella strains and compare with data obtained with the more commonly used Caco-2 and HT-29 models. Adhesion of Salmonella to HT29-MTX cell model was significantly higher, likely due to high adhesiveness to mucins present in the native human mucus layer covering the whole cell surface, compared to the non- and low-mucus producing Caco-2 and HT-29 cell models, respectively. In addition, invasion percentages of some clinical Salmonella strains to HT29-MTX cultures were remarkably higher than to Caco-2 and HT-29 cells suggesting that these Salmonellae have subverted the mucus to enhance pathogenicity. The transepithelial electrical resistances of the infected HT29-MTX cell model decreased broadly and were highly correlated with invasion ability of the strain. Staining of S. Typhimurium-infected cell epithelium confirmed the higher invasion by Salmonella and subsequent disruption of tight junctions of HT29-MTX cell model compared with the Caco-2 and HT-29 cell models. Data from this study suggest that the HT29-MTX cell model, with more physiologically relevant characteristics with the mucus layer formation, could be better suited for studying cells-pathogens interactions.

Background Accurate assessment of probiotics with targeted anti-Salmonella activity requires suitable models accounting for both, microbe-microbe and host-microbe interactions in gut environments. Here we report the combination of two original in vitro intestinal models closely mimicking the complex in vivo conditions of the large intestine. Effluents from continuous in vitro three-stage fermentation colonic models of Salmonella Typhimurium infection inoculated with immobilized child microbiota and Salmonella were directly applied to confluent mucus-secreting HT29-MTX cell layers. The effects of Salmonella, addition of two bacteriocinogenic strains, Bifidobacterium thermophilum RBL67 (thermophilicin B67) and Escherichia coli L1000 (microcin B17), and inulin were tested on Salmonella growth and interactions with epithelial cell layers. Salmonella adhesion and invasion were investigated and epithelial integrity assessed by transepithelial electrical resistance (TER) measurements and confocal microscopy observation. Data from complex effluents were compared with pure Salmonella cultures. Results Salmonella in effluents of all reactors of the colonic fermentation model stabilized at mean values of 5.3 ± 0.8 log10 cfu/ml effluent. Invasion of cell-associated Salmonella was up to 50-fold lower in complex reactor samples compared to pure Salmonella cultures. It further depended on environmental factors, with 0.2 ± 0.1% being measured with proximal, 0.6 ± 0.2% with transverse and 1.3 ± 0.7% with distal reactor effluents, accompanied by a similar high decrease of TER across cell monolayers (minus 45%) and disruption of tight junctions. Subsequent addition of E. coli L1000 stimulated Salmonella growth (6.4 ± 0.6 log10 cfu/ml effluent of all 3 reactors) and further decreased TER, but led to 10-fold decreased invasion efficiency when tested with distal reactor samples. In contrast, presence of B. thermophilum RBL67 revealed a protective effect on epithelial integrity compared to previous E. coli L1000 periods, as reflected by a significant mean increase of TER by 58% in all reactors. Inulin addition enhanced Salmonella growth and invasion when tested with distal and proximal reactor samples, respectively, but induced a limited decrease of TER (minus 18%) in all reactors. Conclusions Our results highlight the benefits of combining suitable cellular and colonic fermentation models to assess strain-specific first-level host protection properties of probiotics during Salmonella infection, providing an efficient system biology tool for preclinical development of new antimicrobials.

The gut microbiota is a highly specialized organ containing host-specific assemblages of microbes whereby metabolic activity directly impacts human health and disease. In vitro gut fermentation models present an unmatched opportunity of performing studies frequently challenged in humans and animals owing to ethical concerns. Multidisciplinary systems biology analyses supported by ‘-omics' platforms remain widely neglected in the field of in vitro gut fermentation modeling but are key to advancing the significance of these models. Model-driven experimentation using a combination of in vitro gut fermentation and in vitro human cell models represent an advanced approach in identifying complex host–microbe interactions and niches central to gut fermentation processes. The aim of this review is to highlight the advances and challenges exhibited by in vitro human gut fermentation modeling.

The definitive version is available at ww3.interscience.wiley.com; International audience; Aims: To compare in vitro the inhibitory activity of four bacteriocin-producing Escherichia coli to a well-characterized panel of Salmonella strains, recently isolated from clinical cases in Switzerland. Methods and Results: A panel of 68 nontyphoidal Salmonella strains was characterized by pulsed-field gel electrophoresis analysis and susceptibility to antibiotics. The majority of tested strains were genetically different, with 40% resistant to at least one antibiotic. E. coli Mcc24 showed highest in vitro activity against Salmonella (100%, microcin 24), followed by E. coli L1000 (94%, microcin B17), E. coli 53 (49%, colicin H) and E. coli 52 (21%, colicin G) as revealed using a cross-streak activity assay. Conclusions: Escherichia coli Mcc24, a genetically modified organism producing microcin 24, and E. coli L1000, a natural strain isolated from human faeces carrying the mcb-operon for microcin B17-production, were the most effective strains in inhibiting in vitro both antibiotic resistant and sensitive Salmonella isolates. Significance and Impact of the Study: Due to an increasing prevalence of antibiotic resistant Salmonella strains, alternative strategies to fight these foodborne pathogens are needed. E. coli L1000 appears to be a promising candidate in view of developing biotechnological alternatives to antibiotics against Salmonella infections.

FEMS Microbiology Ecology, 67 (2), ISSN:0168-6496, ISSN:1574-6941

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.