1985 年 105 巻 8 号 p. 751-759
To evaluate the bactericidal activity of antiseptics against many different strains, we devised a modified phenol coefficient method by using microtitration plates based on that of the Association of Analytical chemists, and counted survivors to find the shortest contact time for various concentrations at which almost all bacteria were killed. Benzalkonium chloride (BAC) was bactericidal against all 242 strains tested at 500 μg/ml in 10 min of contact at 25°C. Under the same conditions, chlorhexidine gluconate (CHG) was bactericidal against 90% even at 1000 μg/ml. Among these strains resistant to 1000 μg/ml, Pseudomonas, Serratia, and Proteus species comprised 45% of the strains. The killing rate of BAC was fast, but the bactericidal activity of CHG with short contact time was weaker than its bacteriostatic activity for 24 h. The bactericidal concentration of BAC and CHG for 30 s of contact at 25°C was 500-5000 μg/ml and 5000-30000 μg/ml in a 10% solution of human serum, and 2500->10000 μg/ml and 10000->40000 μg/ml in a suspension of 2.5% dried yeast, respectively. The 10% human serum stimulated the bactericidal activities of BAC and CHG slightly against some test bacteria.