Bacterial output from three respiratory therapy humidifying devices

Area of Science:

• Medical Microbiology
• Infectious Disease Control
• Respiratory Therapy

Background:

• Hospital-acquired infections are a major concern.
• Air humidification devices are essential for patient care but can harbor microorganisms.
• Evaluating the microbial output of these devices is critical for patient safety.

Purpose of the Study:

• To assess the relative hazard of different air humidification devices used in hospitals.
• To quantify bacterial output from evaporative humidifiers versus nebulizers.
• To determine the risk of bacterial aerosolization from these devices.

Main Methods:

• Three common air humidification devices were evaluated: two evaporative types and one nebulizer.
• Device reservoirs were inoculated with Pseudomonas cepacia.
• Bacterial output in the gas stream was sampled using an Andersen six-stage bacterial sampler.
• Sampling occurred after a warm-up period for the nebulizer.

Main Results:

• Nebulizers produced heavily contaminated bacterial aerosols (>1000 P. cepacia colonies) even after warming.
• Evaporative humidifiers yielded virtually no viable organisms.
• Bacterial output was significantly higher from the nebulizer compared to evaporative devices.

Conclusions:

• Nebulizers pose a significant risk of delivering contaminated bacterial aerosols to hospitalized patients.
• Evaporative humidifiers are a safer alternative regarding bacterial output.
• Infection control protocols should consider the type of humidification device used.