Resistance patterns of Campylobacter spp. strains isolated from poultry carcasses in a big Swiss poultry slaughterhouse

The aim of this study was to determine resistance patterns of strains of Campylobacter spp. isolated from poultry carcasses in one of the two big Swiss poultry slaughterhouses. A variety of antibiotics with clinical relevance in human and/or in veterinary medicine was tested. In addition, the results of the disc diffusion method, E-test and microdilution broth methods were compared. Of the 195 Campylobacter jejuni strains isolated from 195 poultry carcasses from 21 flocks, 134 strains were susceptible in vitro to all tested antibiotics. Sixty-one strains (31.3%, from eight flocks) showed resistance. Forty-one strains were resistant to a single antibiotic-34 to streptomycin, 6 to ampicillin and 1 to ciprofloxacin. Eighteen strains (from two flocks) showed combined resistance to erythromycin and streptomycin, two strains to ciprofloxacin and streptomycin. None of the isolates was resistant to tetracycline. The data of this first study in Switzerland show a favourable resistance situation for C. jejuni strains against erythromycin, tetracycline and ciprofloxacin. The disc diffusion method was found to be a reliable and easy tool for monitoring the prevalence of resistant C. jejuni strains. For surveillance of changes in the susceptibility concentration levels to antimicrobial agents, however, a MIC method should be used. Further investigations along the whole poultry production chain (farm, slaughterhouse and retail levels) are now necessary in order to confirm the resistance situation.     

Distribution and identification of culturable airborne microorganisms in a Swiss milk processing facility

Airborne communities (mainly bacteria) were sampled and characterized (concentration levels and diversity) at 1 outdoor and 6 indoor sites within a Swiss dairy production facility. Air samples were collected on 2 sampling dates in different seasons, one in February and one in July 2012 using impaction bioaerosol samplers. After cultivation, isolates were identified by mass spectrometry (matrix-assisted laser desorption/ionization-time-of-flight) and molecular (sequencing of 16S rRNA and rpoB genes) methods. In general, total airborne particle loads and total bacterial counts were higher in winter than in summer, but remained constant within each indoor sampling site at both sampling times (February and July). Bacterial numbers were generally very low (<100 cfu/m³ of air) during the different steps of milk powder production. Elevated bacterial concentrations (with mean values of 391 ± 142 and 179 ± 33 cfu/m³ of air during winter and summer sampling, respectively; n = 15) occurred mainly in the “logistics area,” where products in closed tins are packed in secondary packaging material and prepared for shipping. However, total bacterial counts at the outdoor site varied, with a 5- to 6-fold higher concentration observed in winter compared with summer. Twenty-five gram-positive and gram-negative genera were identified as part of the airborne microflora, with Bacillus and Staphylococcus being the most frequent genera identified. Overall, the culturable microflora community showed a composition typical and representative for the specific location. Bacterial counts were highly correlated with total airborne particles in the size range 1 to 5 µm, indicating that a simple surveillance system based upon counting of airborne particles could be implemented. The data generated in this study could be used to evaluate the effectiveness of the dairy plant’s sanitation program and to identify potential sources of airborne contamination, resulting in increased food safety.     

Germin-like protein Cit s 1 and profilin Cit s 2 are major allergens in orange (Citrus sinensis) fruits

Oranges are clinically relevant allergenic foods. To date, orange allergens have not been characterized in detail. The study is aimed at analyzing the sensitization profile in orange-sensitized subjects with and without clinical allergy, and to identify orange allergens. Fifty-six sensitized subjects with self-reported reactions to orange were grouped into reactors (anaphylaxis or multiple episodes of immediate reactions and/or positive challenge tests) and non-reactors (negative open food challenge tests). Allergens were characterized by IgE immunoblotting, N-terminal sequencing, IgE-inhibition assays, and mediator release assays were performed to determine the allergenic potency of orange profilin. Of 56 subjects, 23 were classified as orange allergic showing mainly an oral allergy syndrome. Of 23 subjects classified as orange allergic, 22 were sensitized to profilin, Cit s 2. In patients with mono-sensitization to profilin in vitro histamine releases up to 75% from basophils were induced using orange extract and purified plant profilins. Of the allergic patients 78% were sensitized to germin-like protein, Cit s 1. Both allergens showed retained IgE reactivity in heat-processed orange juice. Interestingly, subjects with and without clinical allergy showed a comparable sensitization profile. Profilin and germin-like proteins are major orange allergens. The potential clinical relevance of orange profilin was indicated by its strong capacity to release histamine from basophils. However, a predominant sensitization to both allergens in subjects without symptoms also indicates a high frequency of clinically insignificant sensitization.     

Development and validation of two dipstick type immunoassays for determination of trace amounts of peanut and hazelnut in processed foods

Two dipstick-type sandwich-ELISAs were developed allowing the detection of trace amounts of peanut and hazelnut in processed foods. The detection limit of both assays was about 10 ng/ml of hazelnut or peanut protein, equivalent to 1 ppm protein in a food sample. The dipstick format allows a fast and cost-effective screening of foods because no specific instrumentation, such as microplate reader and washer, is necessary. The tests can be performed within 3 and 4 hours respectively. Various commercial food samples were tested and the results were compared with previously described and validated quantitative ELISAs for peanut and hazelnut. Results of the dipstick assays and the corresponding microplate ELISAs were in complete concordance. Our results indicated that the dipstick format could be a useful tool for fast and convenient monitoring of food production with regard to the labelling of allergens in food products. This would contribute to improve the protection of consumers from severe allergic reactions.     

Triclosan: occurrence and fate of a widely used biocide in the aquatic environment: field measurements in wastewater treatment plants,surface waters,and lake sediments

Triclosan is used as an antimicrobial agent in a wide range of medical and consumer care products. To investigate the occurrence and fate of triclosan in the aquatic environment, analytical methods for the quantification of triclosan in surface water and wastewater, sludge, and sediment were developed. Furthermore, the fate of triclosan in a wastewater treatment plant (biological degradation, 79%; sorption to sludge, 15%; input into the receiving surface water, 6%) was measured during a field study. Despite the high overall removal rate, the concentration in the wastewater effluents were in the range of 42-213 ng/L leading to concentrations of 11-98 ng/L in the receiving rivers. Moreover, a high removal rate of 0.03 d(-1) for triclosan in the epilimnion of the lake Greifensee was observed. This is due to photochemical degradation. The measured vertical concentration profile of triclosan in a lake sediment core of lake Greifensee reflects its increased use over 30 years. As the measured concentrations in surface waters are in the range of the predicted no effect concentration of 50 ng/L, more measurements and a detailed investigation of the degradation processes are needed.     

Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations

Arsenic removal by passive treatment, in which naturally present Fe(II) is oxidized by aeration and the forming iron(III) (hydr)oxides precipitate with adsorbed arsenic, is the simplest conceivable water treatment option. However, competing anions and low iron concentrations often require additional iron. Application of Fe(II) instead of the usually applied Fe(III) is shown to be advantageous, as oxidation of Fe(II) by dissolved oxygen causes partial oxidation of As(III) and iron(III) (hydr)oxides formed from Fe(II) have higher sorption capacities. In simulated groundwater (8.2 mM HCO3(-), 2.5 mM Ca2+, 1.6 mM Mg2+, 30 mg/L Si, 3 mg/L P, 500 ppb As(III), or As(V), pH 7.0 +/- 0.1), addition of Fe(II) clearly leads to better As removal than Fe(III). Multiple additions of Fe(II) further improved the removal of As(II). A competitive coprecipitation model that considers As(III) oxidation explains the observed results and allows the estimation of arsenic removal under different conditions. Lowering 500 microg/L As(III) to below 50 microg/L As(tot) in filtered water required > 80 mg/L Fe(III), 50-55 mg/L Fe(II) in one single addition, and 20-25 mg/L in multiple additions. With As(V), 10-12 mg/L Fe(II) and 15-18 mg/L Fe(III) was required. In the absence of Si and P, removal efficiencies for Fe(II) and Fe(III) were similar: 30-40 mg/L was required for As(II), and 2.0-2.5 mg/L was required for As(V). In a field study with 22 tubewells in Bangladesh, passive treatment efficiently removed phosphate, but iron contents were generally too low for efficient arsenic removal.     

Microbiological, epidemiological, and food safety aspects of Enterobacter sakazakii

Enterobacter sakazakii is considered to be an opportunistic pathogen and has been implicated in foodborne diseases causing meningitis or enteritis, especially in neonates and infants. The U.S FoodNet 2002 survey rate of invasive infections with this organism in infants under 1 year of age was 1 per 100,000 infants. Severity of the disease is a matter of concern. In a recent study on the occurrence of E. sakazakii in production environments from food (milk powder, chocolate, cereal, potato, and pasta) factories and households, this organism was isolated with varying frequency from nearly all environments examined, strongly indicating that it is widespread. Stationary phase E. sakazakii cells are remarkably resistant to osmotic and drying stresses compared with other species of the Enterobacteriacae. In this article, we review the literature on this organism with special respect to the information relevant for food safety.     

Structural changes of casein micelles in a rennin gradient film with simultaneous consideration of the film morphology

The effect of rennin on the micelle structure and microstructure of casein films was investigated with micro-beam grazing incidence small angle X-ray scattering and optical microscopy. Size distributions of casein micelles and colloidal calcium phosphate particles were determined as a function of rennin concentration within a rennin gradient film. While the size of the casein micelles decreased with increasing rennin concentration, the size of the colloidal calcium phosphate clusters remained constant. In accordance with a first-order enzyme reaction mechanism, the rennin-induced decay of the micellar sizes could be well described by an exponential function. Two distinct film morphologies at high and low rennin concentration were observed. At intermediate rennin concentration a two-phase surface structure was found, in which both film morphologies coexisted. The conclusions drawn on the behaviour of casein micelles in films can generally be applied to the rennin-induced changes in casein micelles in bulk solutions.     

Electrolyzed water and its application in the food industry

Electrolyzed water (EW) is gaining popularity as a sanitizer in the food industries of many countries. By electrolysis, a dilute sodium chloride solution dissociates into acidic electrolyzed water (AEW), which has a pH of 2 to 3, an oxidation-reduction potential of >1,100 mV, and an active chlorine content of 10 to 90 ppm, and basic electrolyzed water (BEW), which has a pH of 10 to 13 and an oxidation-reduction potential of -800 to -900 mV. Vegetative cells of various bacteria in suspension were generally reduced by > 6.0 log CFU/ml when AEW was used. However, AEW is a less effective bactericide on utensils, surfaces, and food products because of factors such as surface type and the presence of organic matter. Reductions of bacteria on surfaces and utensils or vegetables and fruits mainly ranged from about 2.0 to 6.0 or 1.0 to 3.5 orders of magnitude, respectively. Higher reductions were obtained for tomatoes. For chicken carcasses, pork, and fish, reductions ranged from about 0.8 to 3.0, 1.0 to 1.8, and 0.4 to 2.8 orders of magnitude, respectively. Considerable reductions were achieved with AEW on eggs. On some food commodities, treatment with BEW followed by AEW produced higher reductions than did treatment with AEW only. EW technology deserves consideration when discussing industrial sanitization of equipment and decontamination of food products. Nevertheless, decontamination treatments for food products always should be considered part of an integral food safety system. Such treatments cannot replace strict adherence to good manufacturing and hygiene practices.