Role of Clostridioides difficile in hospital environment and healthcare workers.

Clostridioides difficile infection (CDI) was traditionally considered to be transmitted within healthcare environment, from other patients or healthcare workers (HCW). Recently, this idea has been challenged. Our objective was to determine the extent of C. difficile contamination in hospital environment with a simplified method for C. difficile recovery. Environmental samples were taken from rooms of patients positive for CDI (Case) and negative for toxigenic C. difficile (Control). Environmental sampling was performed at the time a fecal sample was taken for CDI diagnosis, 48 h after, and 10 days after. HCW hands were also sampled. A total of 476 environmental samples were collected, 246 samples from "Case" rooms and 230 from "Control". Overall, 15.34% of environmental samples were positive for toxigenic C. difficile (TCD), 20.72% of "Case" rooms samples and 9.57% of the samples from "Control" rooms (p = 0.001). When samples from "Case" rooms were analyzed by sampling time, at diagnosis 52.94% were positive, 38.46% were positive at 48 h after symptom resolution and 23.07% were positive after course of treatment. Overall, the most contaminated site corresponded to the bathroom tap, followed by the toilet. We recovered TCD from alcohol-based dispensers and from 4.2% of HCW hands. We found a high proportion of surfaces contaminated with TCD, as well as hand colonization. Notably, even after isolation measures were terminated, there was still TCD contamination.

Clostridioides difficile contamination in a clinical microbiology laboratory?

OBJECTIVES: Clostridioides difficile infection has traditionally been considered to be transmitted predominantly within health-care settings. It is not recognized as a pathogen that presents a risk of laboratory acquisition. Data on laboratory contamination and acquisition by laboratory personnel are lacking. Our objective was to assess environmental contamination by C. difficile and its potential for transmission in a clinical microbiology laboratory. METHODS: Laboratory surfaces were screened for C. difficile. Samples were taken in areas that handle C. difficile isolates (high-exposure (HE) areas), areas adjacent to HE areas or those processing faecal samples (medium-exposure (ME) areas), and areas that do not process faecal samples or C. difficile isolates (low-exposure (LE) areas). We examined C. difficile carriage (hands/rectal samples) of laboratory workers. RESULTS: A total of 140 environmental samples were collected from two HE areas (n = 56), two ME areas (n = 56) and two LE areas (n = 28). Overall, 37.8% (37/98) of surfaces were contaminated with C. difficile, and 17.3% (17/98) with toxigenic C. difficile (TCD). HE areas were significantly more contaminated with TCD than LE areas (38.1% (16/42) versus 0.0% (0/14), p 0.005) and ME areas (38.1% (16/42) versus 2.4% (1/42), p <0.001). Hands were colonized with TCD in 11.8% (4/34) of cases. We found no rectal carriage of C. difficile. CONCLUSIONS: We found a significant proportion of laboratory surfaces to be contaminated with toxigenic C. difficile, as well as hand colonization of laboratory personnel. We recommend specific control measures for high-risk areas and laboratory personnel working in these areas.

Long-term administration of low doses of mycotoxins in poultry. 1. Residues of ochratoxin A in broilers and laying hens.

The occurrence and amount of residues of ochratoxin A (OA) in poultry tissues and organs were investigated in a trial aimed at measuring the effects of contamination approaching the patterns more frequently found in natural situations (i.e., small doses of OA in the diet for long periods). Hubbard male broilers and laying hens were treated with an OA-contaminated feed (50 ppb) from the 14th day of age onward. Both groups were further divided into subgroups, some of which underwent continual treatment (64 and 169 days, respectively) and others that were withdrawn from administration (maximum 28 and 82 days, respectively). Determination of residues was performed by high performance liquid chromatography. Residues in liver were higher in broilers (up to 11.0 ppb) than in hens (1.5 ppb), whereas the reverse occurred in kidney (up to .8 and 5.8 ppb, respectively). Residues (.8 ppb) were also in hen thigh muscle but not in breast muscle. Residues of OA in poultry appear to be of possible public health concern. Suggestions for monitoring are given.

Evaluation of allergenicity of genetically modified soybean protein extract in a murine model of oral allergen-specific sensitization.

BACKGROUND: With the development of genetically modified crop plants there has been a growing interest in the approaches available to assess the potential allergenicity of novel gene products. For additional assessment of the potential allergenicity of expressed proteins, informative data can be generated using animal models. Soybean is one of the major source of protein in human and animal nutrition, and has also been well characterized as a major allergenic source. Advances in biotechnology have resulted in an increasing number of genetically engineered foods, and among these soybean is one of the most widespread. OBJECTIVE: To develop and characterize a murine model of IgE-mediated soybean sensitization induced by intragastric immunization, in the presence of Cholera Toxin, with wild-type soybean extract (wt-SE) or with genetically modified soybean extract (gm-SE). METHODS: Balb/c mice born in our animal facilities, from females fed on soy-free food, were fed with the same soy-free food and used in all the experiments. Mice were sensitized by gavages with soybean extracts, and allergen-specific IgE and IgG responses were studied by direct ELISA and ELISA inhibition. Antigen-specific cell proliferation and cytokine production were evaluated in spleen cell cultures. Results Sensitization with both soybean extracts induced high levels of antigen-specific IgE and IgG1 and low levels of specific IgG2a. Both wt-SE and gm-SE were able to inhibit the binding of specific IgE from mice immunized with gm-SE to the same antigen used for the ELISA coating. A comparable proliferative response was obtained with the homologous as well as with the heterologous extracts. CONCLUSION: In sensitized mice, we observed a predominantly T-helper type 2 (Th2)-type immune response, with increased soybean-specific IgE and IgG1 antibodies and a concomitant increase of IL-4 and IL-5 production. RESULTS: obtained by specific IgE ELISA inhibition and by antigen-specific T cell proliferation demonstrated that wt-SE and gm-SE shared B and T epitopes. The present murine model of soybean sensitization established by the oral route should provide valuable information about risk assessment for food allergy from new proteins of genetically modified foods.

HPLC determination of the total content of aflatoxins in naturally contaminated eggs in free and conjugate forms.

A study was undertaken to evaluate the total aflatoxin content in naturally contaminated eggs. Two pools of eggs from laying hens were collected after 2 and 7 days of treatment with aflatoxin B1 (AFB1). An HPLC method has been developed for the determination of AFB1, aflatoxin M1 (AFM1), aflatoxin B2a (AFB2a) and aflatoxicol (Ro) both in free form and after release from water-soluble conjugates. The bound form was cleaned up after acid hydrolysis of the aqueous phase. Eggs collected after 2 days of treatment revealed residues of AFB1, AFB2a and Ro in the organic phase, but none in the aqueous portion. After 7 days of treatment both AFB1 and its hydroxy derivative were found in the organic phase but the aqueous portion showed only hydroxylated metabolites accounting for 35% of the total aflatoxin content.

Contamination of human milk with ochratoxin A.

Ochratoxin A is a mycotoxin frequently found as a contaminant both in food and in animal feed. It can reach humans through the food chain and can then be excreted in biological fluids, one of which is human milk; it can therefore be transmitted from mother to child during breast-feeding. This fact prompted us to carry out the present study, aimed at the determination of ochratoxin A in human milk in Italy, as done elsewhere. Fifty samples of human milk were collected randomly over one year and analysed by a high-performance liquid chromatography method. Nine samples were found to contain levels in the range of 1.7-6.6 ng/ml.

Evaluation of lead, cadmium, chromium, copper and zinc by atomic absorption spectroscopy in durum wheat milling products in relation to the percentage of extraction.

36 samples representative of the 1981 Italian durum wheat crop were separated by an industrial Italian milling process and the products obtained analyzed by AAS for their Pb, Cd, Cr, Cu, Zn content. The results obtained were: Pb ranging from 0.04 to 0.80 ppm, Cd from 0.02 to 1.39 ppm, Cr from 0.05 to 1.60 ppm, Cu from 1.8 to 39.7 ppm and Zn from 8.8 to 117.6 ppm. Although Cr content was relatively homogeneous, Pb, Cd, Cu and Zn distribution in the various mill products proved to be rather inhomogeneous. Maximum contamination for Pb, Cd and Cr, was appreciably lower than in previous studies.

Long term administration of low doses of mycotoxins in poultry. 2. Residues of ochratoxin A and aflatoxins in broilers and laying hens after combined administration of ochratoxin A and aflatoxin B1.

The effects of combined administration of ochratoxin A (OA) and aflatoxin B1 (AFB1) on the occurrence and the levels of residues of mycotoxins in poultry have been investigated. Male broilers and laying hens were fed from 14 days old with standard diets contaminated with 50 micrograms/kg OA and 50 micrograms/kg AFB1. Two groups of broilers and hens were withdrawn from contaminated feed at 37 and 88 days, respectively. At the time of sacrifice no significant lesions were found. Residues were compared with those found after administration of either toxin alone in former trials. Combined treatment resulted in higher content of OA in broiler livers (40 versus 5.0 micrograms/kg) and, to a lesser extent, in kidneys and skin, and of AFB1 in broiler liver and kidney (0.15 versus 0.02 microgram/kg and 0.40 versus 0.05 microgram/kg respectively). Laying hens showed smaller differences (0.20 versus 0.10 microgram/kg in liver and 0.32 versus 0.08 in kidneys). Withdrawal from treatment led to the almost complete disappearance of OA residues in broilers and in hens. These results show a synergistic effect of OA and AFB1, particularly in broilers.

Long-term administration of low doses of mycotoxins to poultry. 1. Residues of aflatoxin B1 and its metabolites in broilers and laying hens.

A study was performed to determine aflatoxin residues in tissues and organs of male broilers and hens that had been fed a diet contaminated with 50 micrograms/kg aflatoxin B1 (AFB1). Residue levels of AFB1, aflatoxicol (Ro), aflatoxin M1 (AFM1) and aflatoxin B2a (AFB2a) were determined by an HPLC method and, with the exception of AFB2a, were detected in the liver, kidney and thigh of both male broilers and hens. The highest levels found were for Ro in liver (1.10 and 0.60 micrograms/kg for male broilers and hens, respectively). On the other hand no detectable amounts of aflatoxins were found in any tissue after withdrawal periods of 14 and 33 days for male broilers and laying hens respectively.