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Imprint
Microbial contamination of kitchen sponges
Project
Project code: BfR-BIOS-08-1322-708
Contract period: 01.01.2018
- 31.12.2019
Purpose of research: Experimental development
Foodborne illnesses are most commonly caused by microorganisms. Bacteria can enter the kitchen via contaminated food (of animal and plant origin), materials or be introduced by family members or pets. A health risk arises when people are exposed to a certain amount of the pathogens that is required to cause an infection (infectious dose). It is therefore of utmost importance that microorganisms that have entered the kitchen are not distributed in the kitchen, cannot multiply and are not transferred to food (e.g., during preparation). This requires, inter alia, a thorough and regular cleaning of work surfaces and kitchen utensils, which is usually performed by the use of kitchen sponges and dishcloths (in addition to dishwashers). Different studies have shown that especially sponges and dishcloths are often heavily contaminated with bacteria. The colonization of kitchen sponges is not homogeneous. Instead, dense, biofilm-like bacterial clusters are detectable especially on the sponge surface. Such clusters have been visualized in previous studies by electron microscopy and FISH hybridization. Sponges from different households often contain a similar microbiota. Cardinale et al. investigated the incidence and frequency of bacteria in 14 sponges from different households by means of metagenome analysis. Gammaproteobacteria dominated within the sponge microbiota and five of the ten most abundant taxonomic units were closely related to risk group 2 species (e.g., Chryseobacterium sp., Moraxella sp., Acinetobacter sp.). In the 14 sponges from different households, the most common operational taxonomic units (OTU) were found to be highly related to Moraxella osloensis, Chryseobacterium hominis, Acinetobacter johnsonii, Acinetobacter pitii, Acinetobacter ursingii, Pseudomonas cremoricolorata, Agrobacterium tumefaciens, Sphingobium yanoikuyae, Brevundimonas diminuta and Chryseobacterium haifense. These OTUs were identified in different combinations in all or almost all sponges tested. Interestingly, bacterial pathogens associated with food-borne diseases were rarely found (eg Enterobacteriaceae, Staphylococcus sp., And Streptococcus sp.) or not detected at all (eg, Salmonella sp., Proteus sp., And Campylobacter sp., Listeria sp.). In several culture-based studies, however, these classical bacterial pathogens have been found in kitchen sponges as well as in dishcloths. Kitchen sponges not only provide an ideal habitat for the colonization and multiplication of bacteria, but also contribute to their spread within the kitchen. In experimental settings it has been shown that the use of contaminated sponges for cleaning kitchen surfaces leads to cross-contamination. In particular, the preparation of raw chicken meat often represents a risk for entry and transmission of food-associated pathogens within the kitchen. The Zoonoses monitoring report 2016 showed that chicken meat was often associated with Campylobacter sp. (47.2%), ESBL- / AmpC-producing E. coli (49.8%) and methicillin-resistant Staphylococcus aureus (13%), respectively. Salmonella was detected in 4.7% of the samples studied. During this project, the colonization and proliferation of relevant food-associated pathogens in the sponge habitat shall be examined, taking into account the following aspects: a. General possibility of colonization and survivability as a function of time (FISH-CLSM) b. Local distribution in the sponge as a function of time (FISH-CLSM) c. Changes in the quantitative composition of the microbiota over a longer colonization period (metagenome analysis) In addition, the potential transmission of bacterial infectious agents through the use of contaminated kitchen sponges during the cleaning of surfaces shall be investigated.
Section overview
Subjects
- Biotechnology
- Food microbiology
- Toxicology
