Ready-to-eat sandwiches as source of pathogens endowed with antibiotic resistance and other virulence factors

The aim of this study was to evaluate and characterize the bacterial load present in twenty-four Ready-To-Eat (RTE) sandwiches, purchased at refrigerated vending machines and supermarkets in the province of Modena (Italy). We isolated 54 bacterial strains, including pathogens of interest in food safety, such as Listeria, Staphylococcus, Enterococcus, Yersinia, Aeromonas and Acinetobacter spp. Phenotypic tests have been performed on these pathogens to detect the presence of virulence factors, such as gelatinase production and hemolytic capability. To test their antibiotic resistance features, the minimum inhibitory concentration (MIC) against eight commonly used antibiotics (Amikacin, Ciprofloxacin, Ampicillin, Oxacillin, Imipenem, Tetracycline, Erythromycin and Vancomycin) was also evaluated. The results showed that among the 54 isolates, fifty percent (50%) belonged to harmless microorganisms (Leuconostoc and Lactococcus), whereas the remaining fifty percent (50%) included pathogenic bacteria (Listeria ivanovii, Listeria monocytogenes, Staphylococcus aureus, Yersinia, and Citrobacter spp.), species responsible for pathologies often difficult to treat due to the presence of antibiotic resistance features. This study demonstrates the importance of thorough controls, both during the production and marketing of RTE food like sandwiches, to avoid reaching the infectious load and the onset of pathologies, particularly dangerous for old and immunocompromised patients

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Effects of a blend of essential oils on some end products of in vitro rumen fermentation

This study was designed to evaluate effects of increasing doses of a blend of essential oils (EO; oregano, cinnamon, thyme, orange peel) on in vitro rumen fermentation in rumen liquor from dairy cows and fattening bulls, as influenced by acidity at the start of the fermentation. Two in vitro fermentation experiments, which differed only in the origin of rumen liquor (i.e., dairy cows [DC] or fattening bulls [FB]), were conducted in duplicate runs in 100 ml glass tubes containing 50 ml of diluted rumen fluid and 500 mg of a mixed ration substrate. The pH of the diluted rumen liquor at the beginning of each fermentation was adjusted to 7.0 with 5N NaOH or 5.5 with 3N HCl. The EO blend was added to each fermentation tube at doses of 8, 16, 24 and 32 \u3bcl/tube, equivalent to 160, 320, 480 and 640 \u3bcl/l, using 3 tubes for each dosage level plus 3 tubes without EO as controls (i.e., 30 tubes in total/run). After 24 h of incubation, fermentation liquor was collected and analyzed for volatile fatty acids (VFA), ammonia N and pH. In both experiments, pH and ammonia N concentration of the fermentation liquor were lower (P<0.01) at the initial pH of 5.5. The reduction of initial pH from 7.0 to 5.5 depressed VFA yield (138 mM versus 120 mM and 132 mM versus 111 mM, P<0.01, respectively, for DC and FB rumen liquors), and modified end products of fermentation by lowering the acetate:propionate ratio (4.3 versus 3.6 and 3.2 versus 2.5, P<0.01, respectively, for DC and FB rumen liquors). Butyrate concentration was higher at the lower pH in the DC rumen liquor fermentation (22.4 mM/100 mM versus 16.2 mM/100 mM, P<0.01), but not in the FB fermentation. In both experiments, addition of the EO blend did not depress total VFA concentrations, except at the highest dose in the experiment with rumen fluid from DC (122 mM versus 128 mM, P<0.01). In both experiments, there was an interaction (P<0.01) between EO addition and initial pH on acetate proportion; at the initial pH of 5.5, EO addition decreased acetate from 65.0 to 63.9 and from 62.6 to 61.8 mM/100 mM, respectively, for DC and FB rumen liquors, while there were no effects of EO at the initial pH of 7.0. In the experiment with DC rumen liquid, EO addition tended (P<0.08) to increase propionate proportion (from 16.1 to 16.6 mM/100 mM), while there was no effect in FB rumen liquid. In the FB experiment, EO decreased (P<0.05) the acetate:propionate ratio, while in the DC experiment it decreased only at low pH (interaction 'EO addition 7initial pH': P<0.01). A moderate shift in end products of fermentation occurred with both types of rumen liquor, but mainly at low ruminal pH (i.e., 5.5), suggesting a selective toxicity of these EO against rumen bacterial strains that grow at low rumen pH

Effect of milk replacers added with microencapsulated organic acids or essential oils on the performance of weaning calves

The use of antibiotics as feed additives in animal nutrition has been banned in the EU countries and alternative substances are required to control the development of the intestinal microbial communities. Organic acids (OA) have been demonstrated to improve performance in young growing animals, while essential oils extracted from plants (EO) are known to have antimicrobial effects. The aim of present experiment was to compare the effects of two microencapsulated feed additives based on OA and EO on the in vivo performance and health status of weaning calves. The trial was conducted using a total of 36 Friesian male calves, reared from 20 to 52 d of age at the Agricultural Experimental Station "Servadei" of Udine University. The experiment was split in three consecutive randomised blocks of 12 animals, which were divided in three groups and fed with the same milk replacer (diluted at 10.5% in 40\ub0C water) containing no additives (control, C) or added (1% w/w) with commercial microencapsulated supplements based on OA ("ERASE Feed", containing 50% OA) or EO ("RepaXol calves2%", containing 0.8 % EO). Animals were weighted at the beginning (51.3, 50.7 and 50.5 kg, respectively for C, OA and EO; RSD: 5.7 kg), after 20 d and at the end of the trial (at 32 d) and a grab faecal sample was individually collected from the rectum to be analysed for DM content and pH. The faecal samples collected at the start and at the end of the trial were also analysed for the presence of Escherichia coli, Salmonella typhimurium and Clostridium perfrigens. Within each block, a fraction of the third faecal sample was bulked to obtain a mixed sample for each dietary treatment and to be used as inoculum for an in vitro fermentation (gas production technique). 220 mg of air dried milk replacer C were weighted in graduated 100 ml syringes, which were added with 30 ml of diluted faecal material. Three syringes were used for each type of inoculum (C, OA and EO) plus three syringes without substrate as blanks and gas production was recorded at 2, 4, 6, 21 and 24 h from the beginning of the fermentation. One animal of the OA group was excluded from the trial for respiratory disease. The individual DM consumption during the trial was equal to 21.5 kg, without any refusal. The live weight gain was higher and the feed conversion was better (P=0.11 and P=0.07, respectively) for OA and EO groups with respect to the control (369 and 355 vs 287 g/d, respectively and 2.00 and 2.00 vs 2.92 kg/kg respectively). Dietary treatments did not affect the DM content, the pH and the presence of pathogenic microbial strains of the faecal samples, while produced inoculums with different fermentation capacity. In fact, gas volumes recorded at all the incubation times considered, were from 18 to 37 % higher (P<0.01) for calves which received the C milk replacer than those fed the milk added with OA or EO. The trial showed that inoculum from calves fed both the additives studied reduced the in vitro fermentation capacity of substrate in the syringes, as a probable consequence of a lower faecal microbial activity. This positive effect on the intestinal ecological environment could be the reason of the slight improvement in the in vivo performances showed by animals fed the additives