Persistence of specialized bacteria during disinfectant challenge in a new swimming pool

Abstract

Swimming pools represent a unique aquatic environment, with continuous bacterial inoculation from swimmers and high disinfectant levels to control microbial growth. Whether, how, and which groups of bacteria can survive this strong disinfectant stress and pose a potential threat to swimmer health remain poorly understood. This study leveraged the unique opportunity of a newly opened swimming pool to address these questions. Analysis of bacterial community structures in water revealed that disinfectants substantially and temporarily simplified bacterial communities, with only a few dominant specialized groups surviving under disinfectant stress. Among the culturable pathogens, such as Escherichia coli, Staphylococcus, and Acinetobacter, only specific strains possessing genetic adaptations, such as stress-tolerant plasmids, persisted. Although most of the isolated strains did not exhibit high levels of antibiotic resistance, the presence of resistant pathogens was confirmed, one of which carried a unique complex Class I integron. This study demonstrates how bacteria emerge and persist in heavily managed, disinfected aquatic environments, such as swimming pools. Consequently, there is an urgent need to shift focus from merely reducing bacterial populations to developing sustainable strategies for managing persistent bacteria to protect public health.

Keywords

Swimming pool / Bacterial community structure / Whole genome sequencing / Disinfectant resistance / Plasmids / Complex class I integron

Data availability statement

The sequencing data generated in this study are available in the GenBank database under accession number PRJNA1211488.

Declaration of competing interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Given his role as Editor-in-Chief, Dr. Youming Zhang had no involvement in the peer-review of this article and has no access to information regarding its peer-review. Full responsibility for the editorial process for this article was delegated to Dr. Biao Tang. Mingyu Wang reports financial support was provided by National Key Research and Development Program of China. Mingyu Wang reports financial support was provided by Qingdao Science and Technology Wellness Promotion Demonstration Program. Mingyu Wang reports financial support was provided by National Natural Science Foundation of China. Mingyu Wang reports financial support was provided by SKLMT Frontiers and Challenges Project. Ling Li reports financial support was provided by Shandong Provincial Natural Science Foundation. Ling Li reports financial support was provided by Qingdao Natural Science Foundation. Xueyun Geng reports financial support was provided by Opening Project of Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP). If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Ziyu Wan: Investigation, Formal analysis. Wanzhen Guo: Software, Investigation. Kaiyue Zhang: Investigation. Lianfeng Tang: Conceptualization. Youming Zhang: Supervision. Hai Xu: Supervision. Mengge Zhang: Methodology. Xueyun Geng: Methodology, Funding acquisition. Ling Li: Funding acquisition. Wenjia Wang: Writing – review & editing, Methodology. Mingyu Wang: Writing – original draft, Funding acquisition.

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