Hi all…in my quest to find new and interesting topics in drinking water research this is the first study I’ve come across on dishwashers. No municipality that I’m aware of is responsible for appliances connected to distributed networks. Nonetheless, aren’t you a bit interested? What should come as no surprise is that opportunistic pathogens were identified. The authors do make an astute statement in that such “appliances can present a source of domestic cross-contamination that leads to broader medical impacts.”
“IMPORTANCE…The harsh conditions in household dishwashers should prevent the growth of most microorganisms. However, our research shows that persisting polyextremotolerant groups of microorganisms in household appliances are well established under these unfavorable conditions and supported by the biofilm mode of growth. The significance of our research is in identifying the microbial composition of biofilms formed on dishwasher rubber seals, how diverse abiotic conditions affect microbiota, and which key microbial members were represented in early colonization and contamination of dishwashers, as these appliances can present a source of domestic cross-contamination that leads to broader medical impacts.”
Bill
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Microbial Diversity and Putative Opportunistic Pathogens in Dishwasher Biofilm Communities
Prem Krishnan Raghupathi, Jerneja Zupancˇic, Asker Daniel Brejnrod, Samuel Jacquiod, Kurt Houf, Mette Burmolle, Nina Gunde-Cimerman, Soren J. Sorensena
Applied and Environmental Microbiology March 2018 Volume 84 Issue 5
http://aem.asm.org/content/84/5/e02755-17.abstract?etoc
ABSTRACT
“Extreme habitats are not only limited to natural environments, but also exist in manmade systems, for instance, household appliances such as dishwashers. Limiting factors, such as high temperatures, high and low pHs, high NaCl concentrations, presence of detergents, and shear force from water during washing cycles, define microbial survival in this extreme system. Fungal and bacterial diversity in biofilms isolated from rubber seals of 24 different household dishwashers was investigated using next-generation sequencing. Bacterial genera such as Pseudomonas, Escherichia, and Acinetobacter, known to include opportunistic pathogens, were represented in most samples. The most frequently encountered fungal genera in these samples belonged to Candida, Cryptococcus, and Rhodotorula, also known to include opportunistic pathogenic representatives. This study showed how specific conditions of the dishwashers impact the abundance of microbial groups and investigated the inter-kingdom and intra-kingdom interactions that shape these biofilms. The age, usage frequency, and hardness of incoming tap water of dishwashers had significant impact on bacterial and fungal community compositions. Representatives of Candida spp. were found at the highest prevalence (100%) in all dishwashers and are assumed to be one of the first colonizers in recently purchased dishwashers. Pairwise correlations in tested microbiomes showed that certain bacterial groups co-occur, as did the fungal groups. In mixed bacterial-fungal biofilms, early adhesion, contact, and interactions were vital in the process of biofilm formation, where mixed complexes of bacteria and fungi could provide a preliminary biogenic structure for the establishment of these biofilms.”
