Grape seed extract against Aichi virus infectivity in model foods and contact surfaces.

Aichi virus (AiV) is an enteric virus that affects humans and is prevalent in sewage waters. Effective strategies to control its spread need to be explored. This study evaluated grape seed extract (GSE) for: a) antiviral potential towards AiV infectivity at 37 °C and room temperature (RT); b) antiviral behavior in model foods (apple juice (AJ) and 2% fat milk) and also simulated gastric environments; and c) potential application as a wash solution on stainless steel surfaces. GSE at 0.5 mg/mL decreased AiV suspensions containing ~4.75 log PFU/mL to titer levels that were not detected after 30 s at both 37 °C and RT. Infectious AiV titers were not detected after 5 min treatment with 1 mg/mL GSE at 37 °C in AJ. GSE at 2 mg/mL and 4 mg/mL in 2% fat milk decreased AiV after 24 h by 1.18 and 1.57 log PFU/mL (4.75 log PFU/mL to 2.86 and 3.25 log PFU/mL), respectively. As a surface wash, GSE at 1 mg/mL after 30 s decreased AiV to undetectable levels under clean conditions. With organic load (mimicking unclean conditions), 2 and 4 mg/mL GSE reduced AiV after 5 min by 1.13 and 1.71 log PFU/mL, respectively. Overall, GSE seems to be a promising antiviral agent against AiV at low concentrations and short contact times.

Antimicrobial activity of copper surfaces against biofilm formation by Salmonella Enteritidis and its potential application in the poultry industry.

As a consequence of developing antimicrobial resistance to disinfectants, copper, which exhibits antimicrobial activity, has been studied as a possible alternative to the use of stainless steel surfaces. The aim was to evaluate the antimicrobial activity of copper surfaces in preventing biofilm formation by Salmonella Enteritidis and to determine their corrosive capacity. Strains of S. Enteritidis were incubated at 4 °C, 12 °C, and 25 °C with 1 cm2 coupons of electrolytic copper (99.9% Cu), brass (70% Cu), copper coated with tin, and stainless steel (control). A planktonic cell-suspension assay was used, followed by serial dilutions and bacterial counts. The corrosion test was performed with two disinfectants: benzalkonium chloride and sodium hypochlorite (100, 200, and 400 ppm). There was a significant reduction in biofilm production (log10 CFU cm-2) on the copper (2.64 at 4 °C, 4.20 at 12 °C, 4.56 at 25 °C) and brass (2.79 at 4 °C, 3.49 at 12 °C, 4.55 at 25 °C) surfaces compared to the control (5.68 at 4 °C, 5.89 at 12 °C, 6.01 at 25 °C). The antimicrobial surfaces showed uniform corrosion similar to that of surfaces generally used. These results demonstrated the effectiveness of copper surfaces in reducing S. Enteritidis and suggest they can be used as a complementary antimicrobial to control for this pathogen.

Influence of physical variables on the transfer of Salmonella Typhimurium LT2 between potato (Solanum tuberosum) and stainless steel via static and dynamic contact.

Bacterial cross-contamination between foods and contact surfaces can increase food safety risk; however, these processes are not well described in terms of fundamental variables. The objective was to determine the effect of sliding speed (3.75, 5.00, or 7.75 mm/s), contact time (5 or 40 s), normal pressure (~1217 to 8869 Pa), and number of sequential contacts on bacterial transfer to/from potato samples and stainless steel surfaces. Potato samples (~11 g, 3 × 3 × 1 cm) were either pulled across a stainless steel plate inoculated with Salmonella Typhimurium LT2 (~6.23 Log CFU/cm2) (dynamic contact) or placed on the inoculated plate for multiple sequential contacts on uninoculated squares (static contact). Salmonella on the potato and steel plate then were quantified by plating on modified trypticase soy agar. Bacterial transfer increased with increasing sliding speed (P = 0.0098) in dynamic tests and with contact time (P < 0.0001) in static tests. Salmonella on the inoculated potatoes decreased (P < 0.0001) from ~6.5 to ~5.5 Log CFU after 18 sequential static contacts with stainless steel. Reporting transfer results based on fundamental variables will improve the overall impact of bacterial transfer research on equipment design, cleaning/sanitation strategies, and overall food safety.

Efficacy of oregano and rosemary essential oils to affect morphology and membrane functions of noncultivable sessile cells of Salmonella Enteritidis 86 in biofilms formed on stainless steel.

AIMS: This study evaluated the efficacy of essential oil from Origanum vulgare L. (oregano; OVEO) and Rosmarinus officinalis L. (rosemary; ROEO) to inactivate sessile cells of Salmonella enterica serovar Enteritidis 86 (SE86) in young and mature biofilms formed on stainless steel. METHODS AND RESULTS: Ultrastructural alterations and damage in different physiological functions caused by OVEO and ROEO in noncultivable sessile cells of SE86 were investigated using scanning electron microscopy and flow cytometry. OVEO (2·5 µl ml-1 ) and ROEO (40 µl ml-1 ) were effective to eradicate young and mature biofilms formed by SE86 sessile cells on stainless steel surfaces; however, the efficacy varied with exposure time. OVEO and ROEO caused alterations in morphology of SE86 sessile cells, inducing the occurrence of bubbles or spots on cell surface. OVEO and ROEO compromised membrane polarization, permeability and efflux activity in noncultivable SE86 sessile cells. These findings show that OVEO and ROEO act by a multitarget mechanism on SE86 membrane functions. CONCLUSIONS: ROEO and OVEO showed efficacy to eradicate SE86 sessile cells in preformed biofilms on stainless steel, displaying a time-dependent effect and multitarget action mode on bacterial cell membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides for the first time the effects of OVEO and ROEO on morphology and physiological functions of noncultivable sessile cells of S. Enteritidis biofilms preformed on stainless steel surfaces.

Biological safety of Electroacupuncture with STS316 needles.

BACKGROUND: Electroacupuncture (EA) is often used in clinical settings due to its analgesic effect, but its safety has not been verified due to the lack of clear criteria. This study examined the critical range of the corrosion of stainless steel types STS304 and STS316, which have been used clinically, and the relationship between needle corrosion and cell necrosis. METHOD: The critical point of corrosion for STS304 and STS316 was identified by varying the time, frequency, and stimulation intensity. In a tissue necrosis experiment, EA stimulation was applied to rats using STS316 needles with different thicknesses at maximum intensity for 60 min, and the presence of corrosion and tissue necrosis was determined. A cytotoxicity experiment was also conducted and assessed the needles and tissue necrosis. RESULTS: The results showed that STS316 was more stable than STS304 and that only coated needles corroded. Furthermore, tissue necrosis was observed regardless of corrosion, and slight cell necrosis was associated with needles with corrosion. CONCLUSIONS: This study demonstrated that non-coated STS316 was the most stable for EA stimulation and that corrosion byproducts and cell necrosis were not directly related.

Effect of green tea extract on enteric viruses and its application as natural sanitizer.

In this work, the effect of green tea extract (GTE) was assessed against murine norovirus (MNV) and hepatitis A virus (HAV) at different temperatures, exposure times and pH conditions. Initially, GTE at 0.5 and 5 mg/ml were individually mixed with each virus at 5 log TCID50/ml and incubated 2 h at 37 °C at different pHs (from 5.5 to 8.5). GTE affected both viruses depending on pH with higher reductions observed in alkaline conditions. Secondly, different concentrations of GTE (0.5 and 5 mg/ml) were mixed with viral suspensions and incubated for 2 or 16 h at 4, 25 and 37 °C at pH 7.2. A concentration-, temperature- and exposure time-dependent response was showed by GTE in suspension tests, where complete inactivation was achieved after overnight exposure at 37 °C for both viruses and also at 25 °C for HAV. In addition, antiviral effect of GTE proved efficient in the surface disinfection tests since 1.5 log reduction and complete inactivation were recorded for MNV and HAV on stainless steel and glass surfaces treated with 10 mg/ml GTE for 30 min, analyzed in accordance with ISO 13697:2001. GTE was also evaluated as a natural disinfectant of produce, showing 10 mg/ml GTE reduced MNV and HAV titers in lettuce and spinach by more than 1.5 log after 30 min treatment. The results show a potential of GTE as natural disinfectant able to limit enteric viral (cross-)contaminations conveyed by food and food-contact surfaces.

Antibiofilm effect of plant derived antimicrobials on Listeria monocytogenes.

The present study investigated the efficacy of sub-inhibitory concentrations (SICs, concentrations not inhibiting bacterial growth) and bactericidal concentrations (MBCs) of four, generally recognized as safe (GRAS), plant-derived antimicrobials (PDAs) in inhibiting Listeria monocytogenes (LM) biofilm formation and inactivating mature LM biofilms, at 37, 25 and 4 °C on polystyrene plates and stainless-steel coupons. In addition, the effect of SICs of PDAs on the expression of LM genes critical for biofilm synthesis was determined by real-time quantitative PCR. The PDAs and their SICs used for inhibition of biofilm were trans-cinnamaldehyde (TC 0.50, 0.75 mM), carvacrol (CR 0.50, 0.65 mM), thymol (TY 0.33, 0.50 mM), and eugenol (EG 1.8, 2.5 mM), whereas the PDA concentrations used for inactivating mature biofilms were 5.0 and 10.0 mM (TC, CR), 3.3 and 5.0 mM (TY), 18.5 and 25.0 mM (EG). All PDAs inhibited biofilm synthesis and inactivated fully formed LM biofilms on both matrices at three temperatures tested (P < 0.05). Real-time quantitative PCR data revealed that all PDAs down-regulated critical LM biofilm-associated genes (P < 0.05). Results suggest that TC, CR, TY, and EG could potentially be used to control LM biofilms in food processing environments, although further studies under commercial settings are necessary.

Biotherapeutic formulation factors affecting metal leachables from stainless steel studied by design of experiments.

Trace amounts of metals are inevitably present in biotherapeutic products. They can arise from various sources. The impact of common formulation factors such as protein concentration, antioxidant, metal chelator concentration and type, surfactant, pH, and contact time with stainless steel on metal leachables was investigated by a design of experiments approach. Three major metal leachables, iron, chromium, and nickel were monitored by inductively coupled plasma-mass spectrometry. It was observed that among all the tested factors, contact time, metal chelator concentration, and protein concentration were statistically significant factors with higher temperature resulting in higher levels of leached metals. Within a pH range of 5.5-6.5, solution pH played a minor role for chromium leaching at 25°C. No statistically significant difference was observed due to type of chelator, presence of antioxidant, or surfactant. In order to optimize a biotherapeutic formulation to achieve a target drug product shelf life with acceptable quality, each formulation component must be evaluated for its impact.