Sensitivity of Campylobacter jejuni to Drying

Area of Science:

• Microbiology
• Food Safety
• Environmental Microbiology

Background:

• Campylobacter species are significant foodborne pathogens.
• Understanding their survival under environmental stress is crucial for public health.
• Drying is a common environmental condition that can affect bacterial viability.

Purpose of the Study:

• To investigate factors influencing the inactivation rate of Campylobacter species when dried.
• To compare the desiccation tolerance of different Campylobacter strains.
• To determine the impact of temperature, humidity, and suspending medium on Campylobacter survival.

Main Methods:

• Drying Campylobacter sp. on glass surfaces under various conditions.
• Evaluating survival rates at different temperatures (25°C and 4°C).
• Assessing the influence of relative humidity (RH) and suspending media (skim milk, Brucella broth).

Main Results:

• Campylobacter jejuni strains showed greater tolerance to drying than nalidixic acid-resistant thermophilic Campylobacter.
• Inconsistent survival at 25°C, with some strains not recovered after 24 hours in anhydrous conditions.
• Survival significantly increased at 4°C, with a 5 log10 reduction in C. jejuni FRI-CF8 after 6 weeks in skim milk and anhydrous conditions.
• Greater survival was observed when organisms were dried in Brucella broth compared to skim milk.
• Optimal survival occurred at 14% or less relative humidity.

Conclusions:

• Campylobacter jejuni is generally sensitive to drying and room temperature storage.
• Refrigeration temperatures (4°C) and low relative humidity (≤14% RH) significantly enhance the survival of dried Campylobacter.
• These findings have implications for understanding pathogen persistence and developing control strategies in food safety and environmental settings.