2001 年 47 巻 4 号 p. 414-418
Both calcined shell calcium, which was recently reported to have bactericidal effects on Escherichia coli O157 : H7, Pseudomonas aeruginosa, and Staphylococcus aureus, and calcium oxide, which is the main component in calcined shell calcium, were examined as a bactericide against Legionella species. A calcined shell calcium solution of 0.025% or above reduced L. pneumophila counts from the original 7.0 × 106 CFU/ml to less than 300 CFU/ml after an incubation period of 1 hr. In water samples taken from the cooling tower of a prefabricated house, a calcined shell calcium solution of 0.05% or above reduced L. pneumophila counts to less than 10 CFU/ml after an incubation period of 1 hr. There was no difference between the bactericidal effects of the calcined shell calcium manufactured from the shells of surf clams and that manufactured from oysters; surf clams and oysters are equally effective. Calcium oxide also showed similar bactericidal effects against L. pneumophila, and thus we believe that the effect is not specific to calcined shell calcium, but rather to effects caused by the alkalinity of calcium oxide. The use of calcium oxide or calcined shell calcium as a bactericidal agent against Legionella species in the cooling tower water of hotels or other buildings is therefore expected.
