Diversity of Listeria monocytogenes strains of clinical and food chain origins in Belgium between 1985 and 2014

Listeriosis is a rare but severe disease, mainly caused by Listeria monocytogenes. This study shows the results of the laboratory-based surveillance of Listeriosis in Belgium over the period 1985-2014. Besides the incidence and some demographic data we present also more detailed microbiological and molecular characteristics of human strains isolated since 2000. The strains from the latter period were compared to food and animal strains from the same period. Our study shows that different food matrices were commonly contaminated with L. monocytogenes presenting the same PFGE profile as in patient's isolates. Since 1985, we observed a significant decrease in incidence of the Materno-Neonatal cases (from 0.15 to 0.04 cases /100,000 inhabitants-year), which is probably to be attributed to active prevention campaigns targeting pregnant women. Despite the strengthening of different control measures by the food industry, the incidence of non-Materno-Neonatal listeriosis increased in Belgium (from 0.3 to 0.7 cases /100,000 inhabitants-year), probably due to the rise of highly susceptible patients in an aging population. This significant increase found in non-Materno-Neonatal cases (slope coefficient 7.42%/year, P< 0.0001) can be attributed to significant increase in incidence of isolates belonging to serovars 1/2a (n = 393, slope coefficient 6.62%/year, P< 0.0001). Although resistance to antimicrobials is rare among L. monocytogenes isolates, a trend to increasing MIC values is evident with chloramphenicol, amoxicillin, tetracycline and ciprofloxacin. We show that fluoroquinolone resistance is not linked to chromosomal mutations, but caused by a variety of efflux pumps. Our study also shows that huge majority of known underlying pathologies (426 out of 785 cases) were cancers (185/426, 43.1%) and haematological malignancies (75/185, 40.5%). Moreover the risk population is susceptible to low levels of contamination in food stressing the need of prevention campaigns specifically targeting these persons

Inhibition of Salmonella Typhimurium by medium chain fatty acids in an in vitro simulation of the porcine caecum

To lower the contamination of pork meat with Salmonella, feed additives such as medium chain fatty acids (MCFA\u27s) can be applied at the primary production level. An in vitro continuous culture system, simulating the porcine caecum, was developed for investigating the effect of MCFAs on the pig intestinal microbial community. The system was monitored by plating on selective media, 16S rDNA PCR denaturing gradient gel electrophoresis (PCR-DGGE) and HPLC analysis of fermentation products. In a simulation of the porcine caecum without MCFA treatment, with Salmonella Typhimurium added after stabilization of the microbial community, the strain could establish itself at a stable population size of about 5 log cfu/ml. The effect of selected MCFAs was observed from all monitored parameters and depended on chain length and concentration applied. At a dose of 15 mM, caproate and caprinate did not show any pronounced effect, while a clear Salmonella inhibiting effect (3 log units reduction) was found for caprylate. Doubling the caprylate dose did not result in enhanced Salmonella inhibition

Drosophila Apc2 Is a Cytoskeletally-Associated Protein That Regulates Wingless Signaling in the Embryonic Epidermis

The tumor suppressor adenomatous polyposis coli (APC) negatively regulates Wingless (Wg)/Wnt signal transduction by helping target the Wnt effector β-catenin or its Drosophila homologue Armadillo (Arm) for destruction. In cultured mammalian cells, APC localizes to the cell cortex near the ends of microtubules. Drosophila APC (dAPC) negatively regulates Arm signaling, but only in a limited set of tissues. We describe a second fly APC, dAPC2, which binds Arm and is expressed in a broad spectrum of tissues. dAPC2's subcellular localization revealed colocalization with actin in many but not all cellular contexts, and also suggested a possible interaction with astral microtubules. For example, dAPC2 has a striking asymmetric distribution in neuroblasts, and dAPC2 colocalizes with assembling actin filaments at the base of developing larval denticles. We identified a dAPC2 mutation, revealing that dAPC2 is a negative regulator of Wg signaling in the embryonic epidermis. This allele acts genetically downstream of wg, and upstream of arm, dTCF, and, surprisingly, dishevelled. We discuss the implications of our results for Wg signaling, and suggest a role for dAPC2 as a mediator of Wg effects on the cytoskeleton. We also speculate on more general roles that APCs may play in cytoskeletal dynamics

Exposure assessment of foodborne pathogens in pork in Belgium

The aim of this study was to assess the exposure of the most incident foodborne pathogens in the Belgian meat production chain. The prevalence of Salmonella, Campylobacter and Listeria monocytogenes were evaluated in carcasses (swabs), retail cuts, minced meat and meat products of pork. The investigation was made each year since 1997, using official methods from the Ministry of Public Health for Salmonella and Campylobacter and the Vidas Listeria monocytogenes method. More than 10 % of each matrix were contaminated with Salmonella. For minced meat and meat products, the contamination rate were respectively round 20 % and 3 – 6 % for Listeria monocytogenes. Under 5 % of minced meat samples were positive for Campylobacter. For minced meat, the contamination has also been assessed according to the location of sampling (agreed, low capacity establishments or retail level). The characterisation of bacterial species allows the comparison between meat and human isolates