title: Evaluation of disinfective potential of reactivated free chlorine in pooled tap water by electrolysis.
abstract: Tap water is one of the causative factors of hospital infections. We examined the disinfective potential of electrolysis and mechanism of disinfection, and clarified the disinfective effect of electrolysis on tap water contaminated with bacteria, and discussed its clinical applications. Tap waters artificially contaminated with Pseudomonas aeruginosa, Escherichia coli, Legionella pneumophila, and Staphylococcus aureus could be sterilized by electrolysis at 20-30 mA for 5 min. A high-density suspension (10(6) CFU/ml) of a spore forming bacterium, Bacillus subtilis was not completely sterilized by electrolysis at 50 mA up to 30 min, but a low-density suspension (10(5) CFU/ml) was totally sterilized by electrolysis at 50 mA for 5 min. Electrolyzed P. aeruginosa changed morphologically, that is, there was bleb formation on the cell wall and irregular aggregation of cytoplasmic small granules. Moreover, cytoplasmic enzyme, nitrate reductase, was inactivated by the electrolysis. On the other hand, genomic DNA of the electrolyzed bacteria was not degenerated, therefore, their DNA polymerase activity was not completely inactivated. Consequently, the major agent in electrolysis for bactericidal action was considered to be free chlorine, and the possible bactericidal mechanism was by destruction of bacterial membranes, followed by the aggregation of peripheral cytoplasmic proteins. Electrolysis of tap water for both disinfecting contaminating bacteria and increasing the disinfectant capacity was considered effective with some limitations, particularly against high-density contamination by spore-forming bacteria. In clinical settings, electrolysis of tap water is considered effective to disinfect water for hand washing in operation theatres, and bathing water for immunocompromised hosts.
authors.affiliation: Department of Microbiology, Osaka Medical College, 2-7 Daigaku-machi Takatsuki, Osaka 569-8686, Japan.
authors.forename: Norihito
authors.initials: N
authors.lastname: Nakajima
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
authors.forename: Fumiue
authors.initials: F
authors.lastname: Harada
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Taniguchi
authors.forename: Isao
authors.initials: I
authors.lastname: Yokoyama
authors.forename: Jun
authors.initials: J
authors.lastname: Hirose
authors.forename: Eriko
authors.initials: E
authors.lastname: Daikoku
authors.forename: Kouichi
authors.initials: K
authors.lastname: Sano
mesh_terms: D001412:Bacillus subtilis / Q000166:cytology / Q000254:growth & development; D002713:Chlorine / Q000494:pharmacology; D015169:Colony Count, Microbial; D003428:Cross Infection / Q000517:prevention & control; D004269:DNA, Bacterial / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004202:Disinfectants / Q000494:pharmacology; D004203:Disinfection / Q000379:methods*; D004572:Electrolysis; D004926:Escherichia coli / Q000254:growth & development; D006863:Hydrogen-Ion Concentration; D016952:Legionella pneumophila / Q000254:growth & development; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000648:ultrastructure; D013211:Staphylococcus aureus / Q000254:growth & development; D013696:Temperature; D014867:Water / Q000737:chemistry; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D004269:DNA, Bacterial; D004202:Disinfectants; D014867:Water; D002713:Chlorine; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D004259:DNA-Directed DNA Polymerase