Bacteriophage applications for fresh produce food safety.

Foodborne illnesses, mainly bacteria, are a major cause of morbidity and mortality worldwide. Pathogenic bacteria are involved in almost every step within the fresh produce chain compromising the companies' food safety programs and generating an ascending number of foodborne outbreaks in various regions of the world. Recently, bacteriophages return to the status of biocontrol agents. These bacteria-killing viruses are able to reduce or eliminate pathogenic bacterial load from raw and ready to eat foods. Phages are efficient, strain specific, easy to isolate and manipulate, and for that reasons, they have been used in pre and post harvest processes alone or mixed with antimicrobial agents for biocontrolling pathogenic bacteria. In this review, we focused on the feasibility of using lytic bacteriophage on fresh fruits and vegetables industry, considering challenges and perspectives mainly at industrial production level (packinghouses, supermarkets), where high volume of phage preparations and consequently high costs may be required.

Reduction of risk of Salmonella infection from kitchen cleaning clothes by use of sodium hypochlorite disinfectant cleaner.

UNLABELLED: The objective of this study was to evaluate the reduction of infection risk due to exposure to Salmonella sp. in kitchen cleaning clothes by the use of a bleach (sodium hypochlorite) cleaner utilizing a continuous-time dynamic exposure model. The only route of exposure considered was hand contamination during cloth use. The occurrence and numbers of Salmonella was studied in 60 homes over a 6-week period in which half disinfected kitchen cleaning clothes with a sodium hypochlorite based disinfectant cleaner. This study demonstrated that a significant risk exists for Salmonella infection from kitchen cleaning clothes in Mexican homes and that this risk can be reduced by almost 100-fold by soaking cleaning clothes in a bleach product. The risks of infection and illness could likely be further reduced by developing a more effective procedure for reducing Salmonella in cleaning clothes treated twice a day with a sodium hypochlorite disinfectant (i.e. longer soaking time) or using a greater concentration of the disinfectant. SIGNIFICANCE AND IMPACT OF THE STUDY: Hygiene intervention is a key strategy to reduce the potential risk of disease-causing micro-organisms in households. There is a lack of understanding of the human health risk associated with the use of contaminated kitchen cleaning cloths. The study used a quantitative microbial risk assessment to estimate the risk associated with the use of kitchen cleaning clothes by using disinfectant products. The results showed that the use of prescribe protocols can reduce the risk of Salmonella infections in household kitchens.

Irrigation water quality and the benefits of implementing good agricultural practices during tomato (Lycopersicum esculentum) production.

The implementation of good agricultural practices (GAP) from irrigation water to the tomato packaging process enhances the safety of fresh produce and its value throughout the food chain. The aim of the present study was to show that fresh produce farms that apply and enforce GAP could reduce the presence of Salmonella in finished produce. Samples were collected biweekly from six packing houses from the central region of Sinaloa, México, for the isolation of Salmonella spp by the ISO 6579:2002 method, and the isolated strains were serotyped and genotyped by the Kauffmman-White scheme and pulsed field gel electrophoresis (PFGE), respectively. Salmonella strains were detected in 13 (36.1 %) irrigation water samples, while only two tomato samples were positive (5.5 %). Eight different serotypes were identified in irrigation water, and Salmonella Oranienburg (34 %) was the most prevalent; however, only Salmonella Agona and Salmonella Weltevreden were present on tomatoes. Salmonella Oranienburg was the most widely dispersed and variable serotype, with 10 different PFGE profiles. Salmonella Weltevreden was isolated from both types of samples, albeit with distinct genetic profiles, implying that the sources of contamination differ. These results confirm the utility of implementing good agricultural practices to reduce Salmonella contamination in irrigation water and the packaging process.

Detection of pathogenic micro-organisms on children's hands and toys during play.

AIMS: This study aimed to determine if the children's leisure activities impact the presence of pathogens on their hands and toys. METHODS & RESULTS: To assess the microbiological hazard in playground areas, a pilot study that included 12 children was conducted. We then conducted an intervention study; children's hands and toys were washed before playing. Faecal coliforms, pathogenic bacteria and Giardia lamblia were quantified by membrane filtration, selective media and flotation techniques, respectively; rotavirus, hepatitis A and rhinovirus by RT-PCR. Pilot study results revealed faecal contamination on children's hands and toys after playing on sidewalks and in public parks. Pathogenic bacteria, hepatitis A and G. lamblia on children's hands were also found. In the intervention study, Staphylococcus aureus and Klebsiella pneumoniae were found on children's hands at concentrations up to 2·5 × 10(4) and 1 × 10(4) CFU hands(-1), respectively. E. coli and Kl. pneumoniae were detected on toys (2·4 × 10(3) and 2·7 × 10(4) CFU toy(-1), respectively). Salmonella spp, Serratia spp and G. lamblia cysts were also present on toys. CONCLUSION: Children's play activities influence microbial presence on hands and toys; the transfer seems to occur in both ways. SIGNIFICANCE AND IMPACT OF THE STUDY: Control strategy needs to be implemented to protect children from infectious diseases.

Impact of prescribed cleaning and disinfectant use on microbial contamination in the home.

AIMS: To identify and quantify the presence of Escherichia coli, Staphylococcus aureus, Salmonella, hepatitis A and norovirus in households and to assess the effect of chlorine and quaternary ammonium-based disinfectants following a prescribed use. METHODS AND RESULTS: Eleven sites distributed in kitchen, bathroom, pet and children's areas of two groups of 30 homes each: (i) a nonprescribed disinfectant user group and (ii) a disinfectant protocol user group. During the 6-week study, samples were collected once a week except for week one when sample collection occurred immediately before and after disinfectant application to evaluate the disinfectant protocol. The concentration and occurrence of bacteria were less in the households with prescribed use of disinfectants. The greatest reductions were for E. coli (99%) and Staph. aureus (99·9999%), respectively. Only two samples were positive for HAV, while norovirus was absent. Disinfection protocols resulted in a significant (P < 0·05) microbial reduction in all areas of the homes tested compared to homes not using a prescribed protocol. CONCLUSIONS: The study suggests that disinfectant product application under specific protocol is necessary to achieve greater microbial reductions. SIGNIFICANCE AND IMPACT OF THE STUDY: Prescribed protocols constitute an important tool to reduce the occurrence of potential disease-causing micro-organisms in households.

Detection and characterization of hepatitis A virus and Norovirus in estuarine water samples using ultrafiltration--RT-PCR integrated methods.

AIMS: Waterborne outbreaks of hepatitis A and Norovirus disease have been reported and associated with contaminated water supply in various countries. However, in Mexico, there are no studies that report HAV and NV presence in water. This study reports the application of ultrafiltration and RT-nested PCR methods to concentrate and identify these viruses. METHODS AND RESULTS: Forty estuarine water samples were collected from the Huizache Caimanero Lagunary Complex. Samples were concentrated by ultrafiltration system (UFS) and RT-nested PCR was performed for HAV and NV identification. These viruses were found in 80% and 70% of the samples collected respectively and both were present in 57.5%. The DNA sequences analysis showed that 21 estuarine water samples were associated with HAV and 13 with NV. Faecal coliforms were isolated in 48.57% of the samples, while Escherichia coli were found in 34.28%. CONCLUSIONS: DNA sequencing showed that the genotype IB for HAV and GII for NV were predominant in México. No significant relationships were detected between indicators and viruses (P < 0.05). SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that the UFS is adequate for viral concentration. This is the first study analysing the genetic sequence of HAV and NV isolated from Mexican estuarine water.