University dormitories represent densely populated environments, and washing machines are potential sites for the spread of bacteria and microbes. However, the extent of antibiotic resistance gene (ARG) variation in washing machines within university dormitories and their potential health risks are largely unknown. To disclose the occurrence of ARGs and antibiotic-resistant bacteria from university dormitories, we collected samples from washing machines in 10 dormitories and used metagenomic sequencing technology to determine microbial and ARG abundance. Our results showed abundant microbial diversity, with Proteobacteria being the dominant microorganism that harbors many ARGs. The majority of the existing ARGs were associated with antibiotic target alteration and efflux, conferring multidrug resistance. We identified tnpA and IS91 as the most abundant mobile genetic elements (MGEs) in washing machines and found that Micavibrio aeruginosavorus, Aquincola tertiaricarbonis, and Mycolicibacterium iranicum had high levels of ARGs. Our study highlights the potential transmission of pathogens from washing machines to humans and the surrounding environment. Pollution in washing machines poses a severe threat to public health and demands attention. Therefore, it is crucial to explore effective methods for reducing the reproduction of multidrug resistance.

Health and environmental protection are the development trend of household appliances, coupled with the impact of the COVID-19 epidemic in the past few years. Consumers have unprecedented concerns and expectations about the sterilization and disinfection functions of household appliances. As a washing and nursing equipment for household clothes, the anti-bacterial technology of washing machine has developed rapidly. The new models of washing machines in the market have basically added the function of sterilization. In order to thoroughly solve the problem of sterilization and bacteriostasis of washing machines from the source, the distribution of microbial contamination in washing machines should be fully investigated. At present, there is almost no systematic study on the microbial community structure in washing machines in China. Therefore, the purpose of this study is to analyze the bacterial community structure in Chinese household washing machines. To explore the key factors affecting the bacterial community structure of washing machines. Bacterial communities were comprehensively analyzed by high throughput sequencing. Using chao and shannon indexes as indicators, one-way ANOVA was used to explore the key factors affecting the bacterial community structure of washing machines. A total of 2,882,778 tags and 21,265 OTUs from 522 genera were sequenced from 56 washing machine samples. Genus Mycobacterium, Pseudomonas, Brevundimonas, Sphingomonas, Sphingobium, Enhydrobacter, Methylobacterium, Pseudoxanthomonas, Stenotrophomonas and Sphingopyxis were the top ten bacteria genera in abundance. The effects of sources, types, frequency of utilization, sampling locations and service life of washing machines on bacterial diversity in washing machine were systematically analyzed. The statistical analysis showed that service life was an important factor affecting bacterial diversity in washing machine. Our study lays a foundation for directional screening of characteristic microorganisms with targeted characters including malodor-producing, fouling, pathogenic and stress-resistance, the antibacterial evaluation, metabolic mechanism of key characteristic microorganisms as well as antibacterial materials development. At present, the sterilization technology of washing machines has not been fully in combination with the distribution survey of microorganisms in washing machines. According to the specific microorganism distribution condition of the washing machine, the key distribution positions and the types of specific microorganisms contained in different positions, conduct more targeted sterilization treatment. This will help to completely solve the problem of microbial growth in washing machines from the source.

OBJECTIVE: We aimed to develop a method to assess the virucidal performance of domestic laundry in a lab-scale washing machine (Rotawash) based on EN 17658.
RESULTS: For method development, virus recovery was investigated after drying on cotton carriers for three test viruses murine norovirus (MNV), modified vaccinia virus Ankara (MVA), and bovine coronavirus (BCoV), followed by washing simulations in flasks and Rotawash. MNV and MVA demonstrated sufficient recovery from carriers after drying and washing (up to 40°C and 60 min). BCoV exhibited lower recovery, indicating less relevance as a test virus. Rotawash efficacy tests conducted with MNV, a resistant, non-enveloped virus, showed limited efficacy of a bleach-free detergent, aligning with results from a domestic washing machine. Rotawash washes achieved higher reductions in infectious virus titers than suspension tests, indicating the role of washing mechanics in virus removal.
CONCLUSIONS: This study established a practical method to test the virucidal efficacy of laundry detergents in Rotawash, simulating domestic washing.

Streptococcus equi subsp. equi (S. equi) is transmitted via contact with infected horses or fomites such as equipment or surfaces of the stable environment. Effective cleaning and sanitation is essential to minimize risk of fomite-associated infections. This study assessed the effectiveness of cleaning and sanitation of experimentally S. equi contaminated materials and equipment found in stables. Wood, concrete, plastic, leather halters, leather gloves and polyester webbing halters were inoculated with a 24-hour culture S. equi laboratory strain. In addition, selected materials were inoculated with a clinical strain of S. equi. Three days post inoculation all materials were sampled for retention of viable S. equi and a subset of each material was cleaned and sanitized. After an additional 2 days all treated and untreated materials were sampled for continued retention of viable S. equi. Separate subsets of contaminated polyester halter material were washed at 40°C with or without drying at 70°C, or washed at 60°C. After cleaning and sanitation, all samples except polyester halters were culture negative. Even before cleaning and sanitation leather appears to poorly support survival of S. equi. After washing at 40°C and tumble drying, 14 of 16 halters were culture positive, however culture negative when washed at 60°C. Routine cleaning and sanitation of fomites contaminated with S. equi was generally effective to eliminate viable bacteria. However, survival between materials and strains differed, with leather poorly permissive to S. equi survival even without cleaning, whereas polyester webbing halters retained viable S. equi even after washing at temperatures of 40°C.

Ipsilateral humerus and forearm fractures, or \'floating elbow,\' are high-energy injuries, uncommon in children and usually due to falls or motor vehicle accidents. Early models of washing machines were associated with various reports of upper extremity injuries in children, mostly occurring when the child attempted to remove clothes from a spinning machine. Some of these accidents resulted in serious injuries, including amputation, but have become considerably less common with the introduction of improved safety features in modern appliances. We describe the successful management of a child with multiple complex upper limb fractures caused by a modern washing machine.

Microorganisms are an important factor in the wash-and-use cycle of textiles since they can cause unwanted aesthetic effects, such as malodour formation, and even pose health risks. In this regard, a comprehensive view of the microbial communities in washing machines and consideration of the microbial contamination of used textiles is needed to understand the formation of malodour and evaluate the infection risk related to laundering. So far, neither the compositions of washing machine biofilms leading to the formation of or protection against malodour have been investigated intensively, nor have microbial communities on used towels been analysed after normal use. Our results link the qualitative and quantitative analysis of microbial communities in washing machines and on used towels with the occurrence of malodour and thus not only allow for a better risk evaluation but also suggest bacterial colonizers of washing machines that might prevent malodour formation. It was shown that soil bacteria such as Rhizobium, Agrobacterium, Bosea, and Microbacterium in particular are found in non-odourous machines, and that Rhizobium species are able to prevent malodour formation in an in vitro model.

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.

Microplastic fibres released in synthetic cloth washing have been shown to be a source of microplastics into the environment. The annual emission of polyester fibres from household washing machines has earlier been estimated to be 150,000 kg in a country with a population of 5.5 × 106 (Finland). The objectives of this study were (1) to quantify the emissions of synthetic textile fibres discharged from five sequential machine washes (fibre number and length) and tumble dryings (fibre mass) and (2) to determine the collection efficiency of two commercial fibre traps. The synthetic fabrics were five types of polyester textiles, one polyamide and one polyacryl. The number of fibres released from the test fabrics in the first wash varied in the range from 1.0 × 105 to 6.3 × 106 kg-1. The fibre lengths showed that the fleece fabrics released, on average, longer fibres than the technical sports t-shirts. The mass of fibres ranged from 10 to 1700 mg/kg w/w in the first drying. Fibre emissions showed a decreasing trend both in sequential washes and dryings. The ratio of the fibre emissions in machine wash to tumble drying varied between the fabrics: the ratio was larger than one to polyester and polyamide technical t-shirts whereas it was much lower to the other tested textiles. GuppyFriend washing bag and Cora Ball trapped 39% and 10% of the polyester fibres discharged in washings, respectively.

In horizontal-axis washing machines, the front gasket as well as the damping system are crucial owing to the possible collision of the tub with the housing during the transient period. However, most dynamic models for predicting tub motion focus on the steady state and consider only the suspension system without including the gasket. We conducted an experimental study to analyze the effect of the gasket on the transient motion of the tub. The results obtained indicate the necessity of implementing the gasket in the multibody model of a washing machine to accurately predict the tub behavior during this period. The gasket model is formed by a combination of Voigt elements. Stiffness parameters are determined using a load cell, and damping factors are estimated using a process that integrates Adams/View, Matlab optimization algorithms, and displacement measurements that are taken using accelerometers. A D-optimal design used to predict the effect of the gasket parameters reveals that the tub displacement is most sensitive to the changes in linear stiffness in the transversal direction. Finally, the model of the gasket provides a better approach for predicting the tub movement during resonance that can be used in the design phase to avoid tub collision.

Pathogenic bacteria on abiotic surfaces such as fabrics, bedding, patient wears, and surgical tools are known to increase the risk of bacterial diseases in infants and the elderly. The desiccation tolerance of bacteria affects their viability in cotton. Thus, washing and drying machines are required to use conditions that ensure the sterilization of bacteria in cotton. The objective of this study is to determine the effects of various sterilization conditions of washing and drying machines on the survival of three pathogenic bacteria (Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus) commonly presented in contaminated cotton and two non-pathogenic bacteria (Bacillus subtilis and Escherichia coli) in cotton. High survival rates of A. baumannii and S. aureus in desiccated cotton were observed based on scanning electron microscope and replicate organism direct agar contact assay. The survival rates of A. baumannii and S. aureus exposed in desiccated cotton for 8 h were higher (14.4 and 5.0%, respectively) than those of other bacteria (< 0.5%). All tested bacteria were eradicated at low-temperature (< 40°C) washing with activated oxygen bleach (AOB). However, bacterial viability was shown in low temperature washing without AOB. High-temperature (> 60°C) washing was required to achieve 99.9% of the sterilization rate in washing without AOB. The sterilization rate was 93.2% using a drying machine at 60°C for 4 h. This level of sterilization was insufficient in terms of time and energy efficiency. High sterilization efficiency (> 99.9%) at 75°C for 3 h using a drying machine was confirmed. This study suggests standard conditions of drying machines to remove bacterial contamination in cotton by providing practical data.