Bacterial contamination investigation on communal washing machines in a university of Zhengzhou City

ObjectiveTo evaluate the contaminative level of communal washing machines in universities and help students to do healthy laundry with an effective method.

MethodsSource water in 100 communal turbine washing machines in a university in the city of Zhengzhou was detected to count their numbers of bacteria.Twenty heavily contaminated washing machines mentioned above were devided into 4 groups.And 5 washing machines in each group were numbered.The sterilizing effects of four kinds of bacteriostatic materials including ozone, 84 disinfectant, washing machine slot cleaning powder and washing powder used by the 4 groups of machines, were compared by counting the total number of bacteria with washing water before and after sterilizing.

ResultsNo bacterium was detected in the source water for the 100 washing machines.In washing water from the 100 washing machines, the total number was 5 500-31 250 CFU/mL (18 918 CFU/mL on average).Median (interquartile range) was 19 500 CFU/mL (15 500-22 125).The average sterilizing rates of the 4 sterilizing approaches using ozone, 84 disinfectant, washing machine slot cleaning powder and washing powder were 98.04%, 96.75%, 97.03% and 96.33% respectively.There was no significant difference found among the four methods (P>0.05).

ConclusionBacterial contamination of communal washing machines in the university is serious.Ordinary washing powder proved to be more convenient to use than washing machine slot cleaning powder, with the same sterilizing effect and at lower prices.