The Effect of Cold Diluent on the Viable Count of Pseudomonas pyocyanea

Abstract

SUMMARY: Young actively dividing cultures of Pseudomonas pyocyanea (aeruginosa) at 37° were killed when diluted into cold liquids which were without effect when used above 18°. In general the simpler the composition of the diluent the more lethal it was; distilled water was the most active. The cooling had to be rapid to be effective. Old cultures were only slightly sensitive to this effect. The killed organisms appeared normal when examined under the microscope. Under similar conditions Staphylococcus aureus was resistant to cold shock.