〔Abstract〕 Objective To explore the microbial contamination status of household washing machines and evaluate the improvement effect of professional washing machine cleaning on microbial contamination.Methods Before and after cleaning,samples were collected asepticly from the outer wall of the inner cylinder,filter,sealing ring,detergent drawer box and washing water of 15 household washing machines,thus,a total of 150 samples were obtained.The total number of bacteria,fungi and coliform were detected to reflect the hygiene status of the washing machine.At the same time,Salmonella,Shigella and Candida albicans were isolated and cultured to reflect the contamination status of pathogenic bacteria.According to the detection and clearance rate of microorganisms,the cleaning effects of washing machine were comprehensively analyzed.Results Before washing,the total number of bacteria in the washing machine ranged from 1.25 × 103 to 1.19 × 106 CFU/cm2.After washing,the total number of bacteria in the washing machine ranged from 0.01 to 375 CFU/cm2.The bacterial clearance rates of the outer wall of the inner cylinder,the filter,the sealing ring,the washing water and the detergent drawer box were 99.93%,99.99%,99.99%,99.74% and 99.86%,respectively.Before washing,the total number of fungi in the washing machine ranged from 8.5 to 9.45 × 103CFU/cm2.After washing,the total number of fungi in the washing machine ranged from 0 to 49.22 CFU/cm2.The fungal clearance rates of the outer wall of the inner cylinder,filter screen,seal ring,washing water and detergent drawer box were 99.36%,99.74%,99.76%,99.51% and 99.64%,respectively.Before washing,the coliforms in the washing machine ranged from 0 to 4.6 × 104MPN/100 ml.After washing,the number of coliform bacteria was close to 0.Before washing,the average detection rate of Salmonella in the washing machine was 5.33%,the average detection rate of Shigella was 2.67%,and no Candida albicans was detected.After washing,Salmonella,Shigella and Candida albicans were not detected.Conclusion There are a large number of bacteria and fungi in the household washing machine before cleaning,and there are Salmonella and Shigella contamination.After professional cleaning,the hygiene condition of the washing machine is significantly improved.