Cultivation-Based Quantification and Identification of Bacteria at Two Hygienic Key Sides of Domestic Washing Machines

Abstract

Detergent drawer and door seal represent important sites for microbial life in domestic washing machines. Interestingly, quantitative data on the microbial contamination of these sites is scarce. Here, 10 domestic washing machines were swab-sampled for subsequent bacterial cultivation at four different sampling sites: detergent drawer and detergent drawer chamber, as well as the top and bottom part of the rubber door seal. The average bacterial load over all washing machines and sites was 2.1 ± 1.0 × 104 CFU cm−2 (average number of colony forming units ± standard error of the mean (SEM)). The top part of the door seal showed the lowest contamination (11.1 ± 9.2 × 101 CFU cm−2), probably due to less humidity. Out of 212 isolates, 178 (84%) were identified on the genus level, and 118 (56%) on the species level using matrix-assisted laser desorption/ionization (MALDI) Biotyping, resulting in 29 genera and 40 identified species across all machines. The predominant bacterial genera were Staphylococcus and Micrococcus, which were found at all sites. 22 out of 40 species were classified as opportunistic pathogens, emphasizing the need for regular cleaning of the investigated sites.

Metatranscriptomic Analysis of Bacterial Communities on Laundered Textiles: A Pilot Case Study

“…Based on the transcript counts, several bacterial genera known to be typical for washing machines and laundered textiles [ 7 , 10 , 13 ] were detected, such as Acinetobacter (48.5%, 51.7%), Aeromonas (26.1%, 21.6%), Rhizobium (6.0%, 6.5%), Agrobacterium (2.9%, 2.4%), Moraxella (1.8%, 2.1%) and Pseudomonas (0.4%, 0.4%) (the brackets show the relative abundances based on the Spades and Trinity assemblies, respectively, averaged over all of the samples). However, we also detected genera which were, to the best of our knowledge, previously not reported as being typical for washing machines or laundered textiles, such as Sphingorhabdus (9.9%, not detected), Anderseniella (2.1%, 12.1%), Epilithonimonas (0.9%, 1.0%), Haematobacter (0.5%, 0.6%) and Escherichia (0.04%, 0.3%).…”

“…Using the molecular approach of 16S rRNA gene pyrosequencing, we recently showed that the relatively most abundant sequence types in domestic washing machines were closely related to potentially pathogenic bacteria, such as Brevundimonas vesicularis or Pseudomonas aeruginosa inside the detergent drawer, and Moraxella osloensis or Acinetobacter parvus inside the door seal [ 7 ]. While this and other structural studies have looked at the microbial community composition of washing machines and laundry items [ 3 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ], studies on the metabolic activities of the laundry microbiota are often limited to distinct functionalities, such as the formation and prevention of malodor [ 2 , 15 , 16 ]. Malodor is often associated with a lack of hygiene, and can negatively affect the life cycle of a textile [ 17 ].…”

Pathogen Control in the Built Environment: A Probiotic-Based System as a Remedy for the Spread of Antibiotic Resistance

“…Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes were detected in private homes, including Propionibacterium, Bacteroides, and Staphylococcus genera [57]. Staphylococcus and Micrococcus genera were also detected in washing machines, half of which potential opportunistic pathogens, emphasizing the need for effective cleaning and control strategies [58].…”

Improvement of a microfiber filter for domestic washing machines

“…A self-cleaning of the filter is necessary for avoiding the built-up of a bio-film [38]. The sieve is a critical part to clean but the described usage to remove the microfibers together with the sieve solves this drawback.…”