Microbial contamination status of swimming places for infants and young children in Shijia-zhuang City and comparison with other public places, 2021–2022

Background At present, China's Public places health management regulations list 7 categories and 28 sub-categories of public places, but infant and young child swimming places are not in the list yet.

Objective To understand the microbial pollution status in commercial infant and young child swimming places in Shijiazhuang City, compare with the microbial pollution in other five types of public places, and find the potential safety hazards in infant and young child swimming places.

Methods A total of 3438 microbial samples were collected from the environment of infant and young child swimming places and 5 types of public places (hotels, barber stores, waiting rooms, shopping malls and supermarkets, and conventional swimming places) in Shijiazhuang City from 2021 to 2022. Sampling and monitoring were carried out according to the requirements of Examination methods for public places—Part 6: Technical specifications of health monitoring (GB/T 18204.6-2013). Chi-square test was used to compare hygiene qualification by microbial indicators, and Kruskal-Wallis H test was used to compare overall distributions of total bacterial counts on the surface of public articles.

Results From 2021 to 2022, the highest qualified rate of microbial indicators on the surface of public articles was Staphylococcus aureus (100%) for all tested public places in Shijiazhuang City, followed by coliforms (99.44%), and that of total bacterial count was relative low (92.83%). The qualified rate of total bacterial count on the surface of public articles in the swimming places for infants and young children was 87.76%, and the qualified rates in hotels, barber stores, waiting rooms, shopping malls and supermarkets were all above 92%, and the difference among the 5 types of places was statistically significant (P<0.001). The highest value of total bacterial count on the surface of public articles in the swimming places for infants and young children was 80000 CFU·(25 cm²)⁻¹ 100 CFU·(25 cm²)⁻¹=4 CFU·cm⁻²; that in 4 types of public places such as hotels (except mouthwash cups), barber stores, waiting rooms, and shopping malls or supermarkets was 2500 CFU·(25 cm²)⁻¹. The difference of total bacteria count on the surface of public articles was statistically significant in comparing infant and young child swimming places with hotels (except mouthwash cups) or barber stores (H=5.432, H=2.997, both Ps<0.05); but the difference was not significant in comparing with waiting rooms and shopping malls or supermarkets (P>0.05). The qualified rates of total bacteria count and coliforms in pool water of infant and young child swimming places were 45.99% and 74.69% respectively, and the two indicators in pool water of conventional swimming places were 94.57% and 98.91% respectively; both showed significant differences between the two types of public places (χ²=162.532, χ²=71.910, both Ps<0.001).

Conclusion Compared to conventional swimming places, hotels, barber stores, waiting rooms, and shopping malls or supermarkets, the infant and young child swimming places are not optimistic in hygiene condition; therefore, there is an urgent need to formulate national health standards for infants and young child swimming places, and include them in standard management to further improve their hygiene condition.