Sensitivity of Campylobacter jejuni to Drying

Several factors were shown to influence the rate of inactivation of Campylobacter sp. when dried on a glass surface. These included strain, temperature and humidity, and medium used to suspend the organism. Of the strains evaluated, all of three isolates of Campylobacter jejuni exhibited greater tolerance to drying than did a strain of nalidixic acid resistant, thermophilic Campylobacter . Inconsistent results were obtained when organisms were dried and maintained at 25 C. Viable cells from two of four strains having an initial population of >107 were not recovered after 24 h in an anhydrous environment at 25 C. Under comparable conditions, drying C. jejuni FRI-CF8 in the presence of skim milk at 25 C resulted in a >10⁷ log₁₀ reduction of cells within 1 day in one instance; a 5 log₁₀ decline after 7 days in another; and inactivation at an intermediate rate on a third occasion. Rates of death were greatly reduced when cells were dried and held at 4 C. At this temperature and in the presence of skim milk and an anhydrous environment, a 5 log₁₀ reduction of CF8 occurred after 6 weeks. In all instances, greater survival occurred when organisms were dried in the presence of Brucella broth than in skim milk. When held in environments of different relative humidities (RH), survival was greatest in the presence of 14% or less RH. Results suggest that C. jejuni is generally quite sensitive to drying and storage at room temperature, but, at refrigeration temperature and the appropriate humidity, large numbers may survive drying and remain viable for several weeks.