Background:There is increased demand for improved disinfection methods due to microorganisms resistant to multiple antimicrobial agents. Numerous types of disinfectants are available with different properties; but the proper disinfectant must be carefully selected for any specific application to obtain the desired antimicrobial effect.Objectives:Antimicrobial effect of a commercial nanosilver product, NanoCid® L2000, against some foodborne pathogens was evaluated.Materials and Methods:Minimum inhibitory concentrations (MIC) were determined by monitoring the growth of bacteria at 600 nm, after 24 hours incubation at 35°C. Minimum bactericidal concentrations (MBC) were determined based on 3 log decrease in the viable population of the pathogens after incubation of nutrient agar plates at 35°C for 24 hours. The required exposure time for 3 log reduction in the viable population of the tested pathogens was determined as the minimum exposure time for efficient bactericidal activity.Results:The MIC values of Ag NPs against tested pathogens were in the range of 3.12-6.25 µg/mL. While Listeria monocytogenes showed the MIC value of 6.25 µg/mL, Escherichia coli O157:H7, Salmonella typhimurium and Vibrio parahaemolyticus all showed the MIC values of 3.12 µg/mL. However, all the pathogens showed the same MBC value of 6.25 µg/mL. To obtain an efficient bactericidal activity against E. coli O157:H7 and S. typhimurium, the exposure time should be at least ca. 6 hours., while this time was ca. 5 hours for V. parahaemolyticus and ca. 7 hours for L. monocytogenes.Conclusions:Silver nanoparticles showed great antibacterial effectiveness on four important foodborne pathogens. Therefore, Ag NPs could be a good alternative for cleaning and disinfection of equipment and surfaces in food-related environments.

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Background: Meat contamination has been linked to consumer health problems, as proved by outbreaks and recalls from market places. Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella spp. are considered among the most important pathogens which can be spread through meat and meat products consumption. Objectives: The aim of the present study was to determine the prevalence of E. coli O157:H7, L. monocytogenes, and Salmonella spp. in different kinds of meat marketed in Ahvaz, South-west part of Iran. Materials and Methods: A total of 210 samples of beef, buffalo and lamb meats were collected from retail outlets and popular supermarkets. After each single pathogen and DNA extraction, multiplex PCR as a rapid and cost-effective method was carried out to determine the prevalence of the pathogens in the samples. Results: L. monocytogenes was detected in 2.8% of beef and buffalo samples and 4.3% of lamb samples. E. coli O157:H7 was detected in 2.8% of beef and 1.4% of buffalo samples. However, no contamination with this pathogen was found in lamb samples. The prevalence of Salmonella spp. in beef, buffalo and lamb samples was 4.3, 2.8 and 7.1%, respectively. Conclusions: Due to the presence and potential hazard of E. coli O157:H7, L. monocytogenes, and Salmonella spp. in meat samples, the detection of these pathogens in different kinds of meat is crucial to safeguard public health.

Background: Listeria monocytogenes has been isolated from various foods and environments in temperate areas, tropical countries and different parts of Iran. The bacterium as a psychrotrophic organism is capable of growth at refrigeration temperatures..Objective: The current study was conducted to determine the incidence of Listeria spp. on the surfaces of domestic refrigerators in Ahvaz city as a tropic area, to provide insights in to true burden of, and the risks posed by the bacterium in domestic refrigeration systems..Materials and Methods: During December 2009 – June 2010, 180 refrigerators located at student accommodations and private homes in Ahvaz, were sampled for the presence of Listeria spp. The temperature of each refrigerator was measured and owners were asked to fill out a questionnaire regarding the method of cleaning. All samples were tested by culture in Listeria enrichment broth (LEB), Oxford agar and PALCAM agar using standard methods. Suspected colonies were identified by biochemical tests..Results: L. monocytogenes was present in 1 domestic refrigerator out of the 180 investigated (0.5 %) and L. innocua was also isolated from 2 refrigerators (1.2%). It was demonstrated that a significant number of the investigated refrigerators were operating at a temperature that can compromise the safety of the foods stored inside them. Also, most owners used mixture of water and dishwasher and some of them used water alone to clean their refrigerators..Conclusions: Although the incidence of L. monocytogenes in domestic refrigerators in Ahvaz is low contamination of the stored food in refrigerator by the bacterium is still a concern. Two of the isolated Listeria were from student accommodations. It was found that most of the refrigerators used in student accommodations in comparison to private homes, were not cleaned in low frequency and had higher temperature

Morganella morganii was subjected to cold shock treatment at 10C for 2 h or heat shock treatment at 42C for 45 min. The effect of these shock treatments on the viability of M. morganii under adverse conditions was investigated. Viability of M. morganii cells during storage at 4C was slightly affected by cold shock treatment under the conditions tested (P > 0.05). However, a significant increase in the viable population of the cold-shocked cells was found in the subsequent challenge of -18C, as compared with the nonshocked cells (P < 0.05). In addition, coldshocked cells became more susceptible to high incubation temperature (P < 0.05). Nevertheless, cold shock treatment did not alter the susceptibility of this bacterium to 1.0 mM H2O2, 20% NaCl and low pH (pH, 3.5). On the contrary, heat shock treatment increased the susceptibility of M. morganii to low incubation temperatures and H2O2, while made the cells more resistant to high temperature. As in the cold shock treatment, heat shock treatment under the conditions tested did not affect the susceptibility of M. morganii to NaCl and low pH. PRACTICAL APPLICATIONSThese findings may be of significant importance with regard to food safety because cooling chains and heating regimes do exist in the food industry, which could potentially induce a cold or heat shock phenomenon.