No abstract

Listeria monocytogenes contaminated processing equipment and the general packing environment have been implicated in deadly foodborne listeriosis outbreaks, highlighting the significance of proper sanitization and disinfection of food contact surfaces. This study aims to comprehensively evaluate antimicrobial efficacy of commercially available, economical sanitizers at practical concentrations against L. monocytogenes biofilm formed on polystyrene surfaces under different conditions. Ozonated water 1-min treatment at 1.0, 2.0, and 4.0 ppm resulted in ∼0.9, 3.4, and 4.1 log reduction of L. monocytogenes single strain biofilm grown on polystyrene surfaces, respectively. However, its efficacy was dramatically diminished in multi-strain L. monocytogenes biofilm and was further compromised by aged biofilm and in the presence of organic matter. Quaternary ammonium compounds (QAC) at 100/400 ppm, chlorine at 100/200 ppm, chlorine dioxide at 2.5/5.0 ppm and peroxyacetic acid (PAA) at 80/160 ppm resulted in 2.4/3.6, 2.0/3.1, 2.4/3.8, and 3.6/4.8 log reduction of L. monocytogenes single strain biofilm, respectively. Antimicrobial efficacies of all tested sanitizers against 7-day-old biofilm were much lower when compared to 2-day-old biofilm, with PAA being the least influenced by the age of the biofilm. Organic matter conditioning with diluted milk or apple juice dramatically impacted the antimicrobial efficacy of all sanitizers. PAA treatment of 1 min at 160–200 ppm resulted in a 3.2–3.5 log reduction against 7-day-old biofilm in the presence of organic matter, thus showing its effectiveness in eradicating L. monocytogenes biofilm on polystyrene surface. Collectively, data highlight the importance of timely and thoroughly cleaning food contact surfaces before disinfection and provides practical information and guidance for the food industry in selecting the most effective sanitizer in their sanitizing regimes to eliminate L. monocytogenes biofilm.

A total of 150 samples of raw milk, ice cream and yogurt (50 of each) were collected randomly in their packages from different localities in Beni‐Suef governorate, Egypt, to study the presence of Bacillus cereus in these products. B. cereus could be detected in 30, 48 and 2% of examined raw milk, ice cream and yogurt samples with a mean count of 9.11 × 102 ± 4.87 × 102, 6.37 × 103 ± 2.83 × 103 and 6 ± 5.9 cells/mL or g, respectively. All B. cereus isolates showed hemolytic activity; 95% of isolates showed vero cell toxicity and 27.5% of them killed adult mice. B. cereus could not be detected in artificially inoculated yogurt after 24 and 48 h. B. cereus was sensitive to pefloxacin, gentamycin, chloramphenicol and nalidixic acid, whereas all isolates were resistant to colistin sulfate. Public health significance and suggestive control measures are discussed. PRACTICAL APPLICATIONS The incidence of contamination of raw milk and ice cream by Bacillus cereus is fairly high, and nearly all of the isolates showed hemolysin and cytotoxic toxin activities, so the risk of food poisoning caused by B. cereus in such products should not be neglected. B. cereus rapidly dies in yogurt, so acidification is a common method of preservation, and as the acidity of fermented milk increased, B. cereus fails to survive. Pefloxacin, gentamicin and chloramphenicol are effective antibiotics against B. cereus infection. B. cereus is highly resistant to colistin sulfate.

This is the first report on nasal carriage of pvl-positive MRSA among Egyptian health care personnel. High carriage rate of MRSA among health care personnel has been attributed mainly to poor hand hygiene compliance and non-judicious use of antibiotics. Improving compliance, reducing antibiotic overuse, screening for carriers, and decolonization are recommended strategies for reducing the spread of MRSA. Multiplex PCR could be used for confirmation of results obtained by conventional phenotypic methods.

Seventy-five randomly collected samples of ice-cream, rice with milk and mehallabeia (25, each) from different localities in Beni-Suef city, Egypt, were bacteriologically examined. The mean values of aerobic plate, Coliforms, Fecal coliforms, E. coli, Enterococci, Bacillus cereus and Staphylococcus aureus counts/g in the examined ice-cream samples were 7.02×10 5 ±4.93×10 5 , 1.45×10 5 ±3.21×10 4 , 9.58×10 2 ±4.6×10 2 , 1.35×10 2 ±66, 8.12×10 4 ±4.61×10 4 , 1.17×10 4 ±4.59×10 3 and 1.51×10 4 ±9.13×10 3 , while, in rice with milk samples they were 5.52×10 4 ±2.78×10 4 , 3.52× 10 3 ±1.94 ×10 3 , 1.66×10 2 ±1.56×10 2 ,4.8±3.1, 1.28×10 4 ±6.25×10 3 , 2.38×10 5 ±1.4×10 5 and 6.32×10 2 ±2.96×10 2 , respectively. In mehallabeia samples, the counts were 6.07×10 4 ±3.6×10 4 , 6.59×10 3 ±2.6×10 3 , 1.6×10 2 ±89, 9.48±8, 2.6×10 4 ±1.64×10 4 , 3.83×10 5 ±3.27×10 5 and 4.89×10 2 ±3.28×10 2 , respectively. Amplification of enterotoxigenic associated genes using multiplex PCR, showed that sea and see genes were detected in all the examined coagulase positive S. aureus isolates. In conclusion, strict hygienic measures should be followed during production and handling of milk products with health educational programs for producers and handlers.