Microbiological Safety of Kitchen Sponges Used in Food Establishments

Quantitation of Risk Reduction of E. coli Transmission After Using Antimicrobial Hand Soap

Handwashing with soap is an effective and economical means to reduce the likelihood of Escherichia coli infection from indirect contact with contaminated surfaces during food preparation. The purpose of this study was to conduct a quantitative microbial risk assessment (QMRA) to evaluate the risk of infection from indirect contact with fomites contaminated with E. coli after hand washing with antimicrobial hand soaps. A Monte Carlo simulation was done with a total of 10,000 simulations to compare the effectiveness of two antimicrobial and one control (non-antimicrobial) bar soaps in reducing the exposure and infection risk compared to no hand washing. The numbers of E. coli on several fomites commonly found in household kitchens, as well as the transfer rates between fomites and onto fingertips, were collected from the literature and experimental data. The sponsor company provided the E. coli survival on hands after washing with antimicrobial and control soaps. A number of scenarios were evaluated at two different exposure doses (high and low). Exposure scenarios included transfer of E. coli between meat-to-cutting board surface-to-hands, meat-to-knife surface-to-hands, and from a countertop surface-to-hands, kitchen sponge-to-hands, hand towel-to-hands, and dishcloth-to-hands. Results showed that the risks of illness after washing with the control soap was reduced approximately 5-fold compared to no handwashing. Washing with antimicrobial soap reduced the risk of E. coli infection by an average of about 40-fold compared with no handwashing. The antimicrobial soaps ranged from 3 to 32 times more effective than the non-antimicrobial soap, depending on the specific exposure scenario. Importance: The Centers for Disease Control and Prevention indicate the yearly incidence rate of Shiga Toxin producing E. coli infections is about 1.7/100,000, with about 10% of cases leading to life-threatening hemolytic uremic syndrome and 3–5% leading to death. Our findings confirm handwashing with soap reduces the risks associated with indirect transmission of E. coli infection from contact with fomites during food preparation. Further, in these exposure scenarios, antimicrobial soaps were more effective overall than the non-antimicrobial soap in reducing exposure to E. coli and risk of infection.

Microbiological quality of kitchens sponges used in university student dormitories

Background

Kitchen sponges are a major source of cross-contamination as they can transfer foodborne pathogens, infectious agents and spoilage causing microorganisms to food contact surfaces. Several studies have revealed that university students adopt poor practices regarding food safety, hygiene, and the handling of kitchen cleaning equipment.

Methods

A total of fifty kitchen sponges were collected along with a questionnaire addressing social demographics and kitchen sponge usage by students living at the University of Sharjah dormitories. The effect of storage (3 and 10 days) on the microbial population of kitchen sponges at room temperature (21 °C) was assessed. Enterobacteriaceae isolated from sponges were identified and their antibiotic resistance determined.

Results

Student responses revealed that kitchen sponges used to clean food contact surfaces were also used to clean the oven (32%), sink (26%), refrigerator (10%), and to clean spills on the floor (4%). Kitchen sponges contained high counts of mesophilic aerobic bacteria (7.9 log₁₀/cm³), coliform (7.2 log₁₀/cm³), Enterobacteriaceae (7.3 log₁₀/cm³) and yeasts and molds (7.0 log₁₀/cm³). After storage of the sponges at room temperature (21 °C) for 3 and 10 days, the number of mesophilic aerobic bacteria, coliform, Enterobacteriaceae and yeasts and molds decreased by 0.4 and 1.3 log₁₀/cm³, 0.7 and 1.4 log₁₀/cm³, 0.4 and 1.1 log₁₀/cm³, and 0.6 and 1.3 log₁₀/cm³, respectively. The most frequently isolated Enterobacteriaceae were Enterobacter cloacae (56%) and Klebsiella oxytoca (16%). All E. cloacae isolates were resistant to amoxicillin, cefalotin, cefoxitin and cefuroxime axetil.

Conclusions

This study showed that students living in dormitories lacked good hygienic practices and were at increased risk of food poisoning. Kitchen sponges were highly contaminated with potentially pathogenic bacteria which could be transferred from the general kitchen environment to food contact surfaces and consequently lead to food contamination.

Meat Safety in Northern Tanzania: Inspectors' and Slaughter Workers' Risk Perceptions and Management

Through a social scientific lens, this paper considers the risk perceptions and "risk-based decision-making" of two key groups in a northern Tanzanian context: (1) frontline government meat inspectors and health officers charged with ensuring that red meat sold commercially is safe for people to consume, and (2) the workers who slaughter and process cattle and red meat prior to its sale in rural butcheries. In contrast to techno-scientific understandings of disease risk and "rational" approaches to its management, this paper foregrounds the role of social, economic and institutional context in shaping the perceptions and practices around meat safety of these actors whose daily, close proximity to meat means they play a significant role in mitigating potential meat-borne disease. We show how limited resources, and a combination of scientific and local knowledge and norms result in "situated expertise" and particular forms of risk perception and practice which both enhance and compromise meat safety in different ways. Actors' shared concerns with what is visible, ensures that visibly unsafe or abnormal meat is excluded from sale, and that infrastructure and meat is kept "clean" and free of certain visible contaminants such as soil or, on occasion, feces. While such contaminants serve as a good proxy for pathogen presence, meat inspectors and especially slaughter workers were much less aware of or concerned with invisible pathogens that may compromise meat safety. The role of process and meat handling did not figure very strongly in their concerns. Microorganisms such as Salmonella and Campylobacter, which can easily be transferred onto meat and persist in slaughter and meat sale environments, went unacknowledged. Although health officers expressed more concern with hygiene and meat handling, their influence over slaughter process and butchery operations was unclear. Ultimately, recognizing the perceptions and practices of frontline actors who engage with meat, and the ways in which social, material and institutional realities shape these, is important for understanding how decisions about risk and meat safety are made in the complexity and context of everyday life, and thus for finding effective ways to support them to further enhance their work.

Metagenomic Analysis of Regularly Microwave-Treated and Untreated Domestic Kitchen Sponges

Kitchen sponges massively absorb and spread microorganisms, leading to contamination of kitchen appliances, surfaces, and food. Microwaving as an effective and widespread technique can rapidly reduce the microbial load of kitchen sponges. However, long-term effects of such treatments are largely unknown. Notably, it has been speculated that regularly applied domestic cleaning and disinfection may select for microbial communities with a higher pathogenic potential and/or malodorous properties. In this study, we distributed newly purchased polyurethane kitchen sponges to 20 participants, with the instruction to use them under normal household conditions for four weeks. Ten of the participants sanitized their sponges regularly by a standardized microwaving protocol, while the remaining ten sponges remained untreated. Metagenomic sequence data evaluation indicated that, in addition to bacteria, viruses, eukaryotes, and archaea were also part of the kitchen sponge microbiome. Comparisons of sanitized and untreated kitchen sponges indicated a trend towards a reduced structural microbial diversity while functional diversity increased. Microwave sanitization appeared to alter composition and metabolic properties of the microbial communities. Follow-up studies will have to show whether these changes are more positive or negative in terms of domestic hygiene, human health, and well-being.

Characterization of Salmonella bacteriophages and their potential use in dishwashing materials

AIMS

The aims of this study were to isolate and characterize novel Salmonella phages and to evaluate the effectiveness of phage cocktails used as antibacterial agents in dishwashing materials.

METHODS AND RESULTS

The effective phages, vB_STy-RN5i1 and vB_STy-RN29, were isolated from drain water samples collected from open markets using Salmonella Typhimurium as the host strain. These phages were identified as members of Podoviridae and Siphoviridae, respectively. Both phages infected at least six Salmonella serovars and rapidly lysed their host within one hour. They were stable at 4-45°C and at pH 6-9 for at least an hour while being evaluated in this study. The phage application results indicated that bacterial cells were reduced by 3⋅1 and 2⋅7 log CFU per ml at room temperature when they encountered the phage cocktail on scouring pads (SPs) and dishwashing sponges (DSs), respectively.

CONCLUSIONS

The isolated Salmonella phages, vB_STy-RN5i1 and vB_STy-RN29, had potential against Salm. Typhimurium and could reduce the occurrence of bacterial-cross-contamination from dishwashing materials, which have been reported to be a source of bacteria, to other kitchen utensils and food.

SIGNIFICANCE AND IMPACT OF THE STUDY

The successful reduction of bacterial contamination in dishwashing materials by the phage cocktail consisting of vB_STy-RN5i1 and vB_STy-RN29 reveals its potential to be an alternative antimicrobial agent for SPs and DSs.

Condições higiênico-sanitárias e perfil da comunidade microbiana de utensílios e mesas higienizadas de um serviço de alimentação localizado no Rio de Janeiro

Resumo O objetivo deste estudo foi avaliar as condições higiênico-sanitárias e o perfil da comunidade microbiana dos utensílios e das mesas de um serviço de alimentação localizado no município do Rio de Janeiro. A caracterização do processo de higienização dos utensílios (pratos, bandejas e talheres) e das mesas foi realizada por observação sistemática. Verificou-se que os utensílios eram lavados em máquina de lavar e as mesas, manualmente. Após a higienização, os utensílios apresentavam umidade e resíduos de alimentos. Pelo método dependente de cultivo, foram analisadas 126 amostras higienizadas (utensílios: n=90 e mesas: n=36). Pesquisaram-se bactérias mesófilas, coliformes, Escherichia coli, Staphylococcus aureus e fungos. Das amostras analisadas, 100% dos utensílios e 80% das mesas apresentaram contagens microbianas superiores ao recomendado na literatura, estando em condições higiênico-sanitárias inadequadas. E. coli foi isolada nos utensílios e S. aureus, nas mesas. Pelos métodos independentes de cultivo (PCR-DGGE e sequenciamento da subunidade 16S do rRNA), foram analisadas 36 amostras (utensílios: n=27 e mesas: n=9). Klebsiella sp. e Acinetobacter sp. Foram detectadas em todas as amostras, Citrobacter sp. sobre as mesas e Aeromonas hydrophila, nos talheres. Houve falha no processo de higienização, que foi confirmada pelas análises realizadas, que evidenciaram a presença de microrganismos indicadores e patogênicos, que podem causar a perda da qualidade das refeições, assim como danos à saúde dos comensais. Desta forma, é necessário adequar o processo de higienização, a fim de minimizar o risco de contaminação e o surto de doenças transmitidas por alimentos (DTA).