Microorganism levels in spray from warm-water bidet toilet seats: factors affecting total viable and heterotrophic plate counts, and examination of the fluctuations and origins of Pseudomonas aeruginosa

Toru Iyo, Keiko Asakura, Makiko Nakano, Kazuyuki Omae

Research output: Contribution to journalArticle

Abstract

The objectives of this study were to conduct an appropriate microbial evaluation of warm-water bidet toilet seats. Health-related advantages and disadvantages have been associated with using warm-water bidet toilet seats, which are classified according to the tank type, including tanks equipped with reservoir water heaters and on-demand tankless systems equipped with an instantaneous water heater. However, related bacterial research is sparse. Here, we performed a long-term survey of the behavior of microorganisms (i.e., the total viable count (TVC), heterotrophic plate counts (HPCs), and Pseudomonas aeruginosa count) in a university campus. We also examined the differences between the tank and on-demand types, and the origins of P. aeruginosa. A low TVC (1/mL) in the spray waters from both on-demand and tank-type warm-water bidet toilet seats showed low bacterial contamination, although there was an increase in HPC, i.e., growth of biofilms, inside in the warm-water bidet toilet seats. When P. aeruginosa was detected in spray water over an extended duration, the P. aeruginosa origin was considered as either from feces or tap water. Collectively our findings demonstrate that hygienic safety of warm-water bidet toilet seats is being maintained overall.

Original languageEnglish
Pages (from-to)346-358
Number of pages13
JournalJournal of Water and Health
Volume16
Issue number3
DOIs
Publication statusPublished - 2018 Jun

Keywords

  • Bidet toilet
  • Heterotrophic plate count
  • Multidrug-resistant Pseudomonas aeruginosa (MDRP)
  • PCR-based ORF typing (POT) classification
  • Pseudomonas aeruginosa
  • Residual chlorine

ASJC Scopus subject areas

  • Water Science and Technology
  • Waste Management and Disposal
  • Public Health, Environmental and Occupational Health
  • Microbiology (medical)
  • Infectious Diseases

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