Bacterial levels and diversity in kitchen sponges and dishwashing brushes used by consumers.

AIMS: The purpose of the work was to investigate bacterial levels and diversity as well as survival of Salmonella in used dish washing sponges and brushes and identify consumer practices that can potentially explain bacterial status of these items. METHODS AND RESULTS: Used washing up utensils were collected from consumers. The bacterial numbers (TVC) were very variable with an extremely high median level (10.3 log cfu/item) in Portuguese sponges and lower levels in Norwegian items (7.3 and 7.0 cfu/item for sponges and brushes). No self-reported practices or household composition could explain differences found in TVC levels among the collected sponges. Lower mean TVC levels were found in unworn brushes and brushes regularly cleaned with soap, but the differences were modest (1.5 log or less). A common set of bacteria was found in brushes and sponges, dominated by Acinetobacter, Chryseobacterium, Enhydrobacter, Enterobacteriaceae and Pseudomonas. There was no difference in TVC or bacterial diversity between conventional and antimicrobial sponges containing silver after 4 weeks of use. For used brushes inoculated with Salmonella and allowed to dry overnight, a significant reduction in Salmonella numbers was observed. No reduction was observed for brushes stored in humid conditions (in a plastic bag) or for sponges regardless of storing conditions. CONCLUSIONS: Overall, lower bacterial levels were observed in used brushes than in sponges, and Salmonella died more rapidly in brushes. A common set of non-pathogenic bacteria dominated in brushes and sponges. SIGNIFICANCE AND IMPACT OF STUDY: The study demonstrates that the use of brushes may be more hygienic than the use of sponges.

Dishwashing sponges and brushes: Consumer practices and bacterial growth and survival.

Sponges are frequently used in kitchens and have been shown to harbor large numbers of bacteria, occasionally also pathogens. Less is known about kitchen brushes regarding usage and presence of bacteria. In the present study, the use of sponges and brushes was studied in a survey among 9966 European consumers in ten countries, and growth and survival of bacteria in sponges and brushes were examined in laboratory experiments. Sponges were the preferred hand-cleaning utensils for washing-up in the majority of countries, while brushes were most frequently used in Denmark and Norway. Consumers mostly change their sponges at regular times, but also sensory cues (looks dirty, smelly, slimy) and usage occurrences such as wiping up meat juices may trigger replacement. Besides cleaning the dishes, over a quarter of the dish brush users also use it to clean a chopping board after soilage from chicken meat juices. The water uptake and drying rate varied considerably, both between different sponges and between brushes and sponges, where brushes dried fastest. Campylobacter survived one day in all sponges and Salmonella more than seven days in two of three types of sponges. In the type of sponge that dried slowest, Salmonella grew on the first day and was always found in higher levels than in the other sponges. Non-pathogenic bacteria grew in the sponges and reached levels around 9 log CFU/sponge. In brushes all types of bacteria died over time. Campylobacter and Salmonella were reduced by more than 2.5 log to below the detection limit after one and three days, respectively. Bacteriota studies revealed a tendency for a dominance by Gram-negative bacteria and a shift to high relative prevalence of Pseudomonas over time in sponges. Both enumeration by agar plating and bacteriota analysis confirmed that the pathogens were in a minority compared to the other bacteria. Treatments of sponges and brushes with chlorine, boiling or in the dishwasher were effective to reduce Salmonella. We conclude that brushes are more hygienic than sponges and that their use should be encouraged. Contaminated sponges or brushes should be replaced or cleaned when they may have been in contact with pathogenic microorganisms, e.g. used on raw food spills. Cleaning of sponges and brushes with chlorine, boiling or dishwasher may be a safe alternative to replacing them with new ones.

Consumer practices and prevalence of Campylobacter, Salmonella and norovirus in kitchens from six European countries.

About 40% of foodborne infections are acquired in the home. The aim of the present study was to track contamination of pathogens during domestic food preparation and link the contamination to preparation practices. Research participants from 87 households in six European countries were observed and interviewed during shopping and preparation of a chicken and vegetable meal. The presence of Salmonella spp., Campylobacter spp. and norovirus on raw chicken, kitchen surfaces, cloths and sponges was determined. The prevalence of Campylobacter on raw chicken varied from 8.3% in Norway (NO) to 80% in France (FR) and Portugal (PT), with a mean prevalence of 57%. Campylobacter was found on half of the products that had been frozen and appeared to be less prevalent on chicken from supermarkets than other sources. Salmonella was found in 8.6% of raw chicken samples, exclusively from Hungary (HU). A relationship between observed practices and spread of pathogens to kitchen surfaces was found only for the use of cutting boards for chicken and/or vegetables. After food preparation, Campylobacter and Salmonella were isolated from 23% (samples derived from HU, RO, UK) and 8.7% (HU), respectively of cutting boards. Research participants in France and Portugal were more likely to buy products that fitted their recipe, with less need for using cutting boards. Using the same board and knife for vegetables after using it for chicken and without washing with detergent was common in Portugal and Romania, but not in the other countries. Contamination with Campylobacter to other kitchen surfaces or washing utensils were found in five households (UK, RO, PT). Rinsing chicken in sinks was common in three countries (PT, HU, RO), and washing vegetables in the same sink was also usual. Prevalence of Norovirus was low, with detection in one out of 451 samples. The participants' awareness of the risk posed by pathogens from raw chicken differed among the six countries, with higher awareness in Norway and the UK than the other countries studied. In conclusion, practices intended to avoid cross-contamination from chicken to kitchen surfaces and washing utensils are not established among consumers in all European countries. Nevertheless, cross-contamination events that disseminate infectious doses of pathogens seems to be rare, probably due to the relatively low levels of pathogens in food combined with food preferences. Food safety interventions must consider the national food culture, preferences, practices and the prevalence and levels of pathogens in food. Emphasis should be on providing and promoting chicken products with lower risk (prevalence of pathogens, ready-to-cook) and safe use of cutting boards.