Bacterial Exchange in Household Washing Machines

Abstract

Household washing machines (WMs) launder soiled clothes and textiles, but do not sterilize them. We investigated the microbial exchange occurring in five household WMs. Samples from a new cotton T-shirt were laundered together with a normal laundry load. Analyses were performed on the influent water and the ingoing cotton samples, as well as the greywater and the washed cotton samples. The number of living bacteria was generally not lower in the WM effluent water as compared to the influent water. The laundering process caused a microbial exchange of influent water bacteria, skin-, and clothes-related bacteria and biofilm-related bacteria in the WM. A variety of biofilm-producing bacteria were enriched in the effluent after laundering, although their presence in the cotton sample was low. Nearly all bacterial genera detected on the initial cotton sample were still present in the washed cotton samples. A selection for typical skin- and clothes-related microbial species occurred in the cotton samples after laundering. Accordingly, malodour-causing microbial species might be further distributed to other clothes. The bacteria on the ingoing textiles contributed for a large part to the microbiome found in the textiles after laundering.

Laundry hygiene-how to get more than clean

“…; Callewaert et al . ). Table compiles some typical genera present on textiles and in the washing machine.…”

“…; Callewaert et al . ; Nix et al . ), it appears likely that biofilm‐forming organisms cause malodour when distributed onto the textiles after the main wash (Bellante et al .…”

“…Some studies investigating the composition of the microbiota on textiles and in washing machines, have suggested that a mixture of skin-associated bacteria and ubiquitous micro-organisms from the environment and from machine biofilms may comprise the relevant microbial community associated with laundry (Blaser et al 1984;Smith et al 1987;Gattlen et al 2010;Babic et al 2015;Callewaert et al 2015;Nix et al 2015). In this regard, it can be assumed that the laundering process causes a shift in the microbial community on the textiles from primary contaminants (e.g.…”

“…skin bacteria) to secondary contaminants (e.g. biofilm-associated environmental bacteria) (Bellante et al 2011;Callewaert et al 2015). Table 1 compiles some typical genera present on textiles and in the washing machine.…”

“…The possible sources were assigned based on the microbial genera and locations described in the referenced articles. Selected from indicated references: 1 (Callewaert et al 2015); 2 (Nix et al 2015); 3 (Gattlen et al 2010);4 (Smith et al 1987); 5 (Blaser et al 1984 assumed that contaminations with dermatophytes, viruses and faecal pathogens may occur when family members suffer from the respective diseases.…”