Nasal Saline Irrigations
Sinonasal saline irrigation has been documented as a vehicle for infection with Naegleria fowleri, a thermophilic, microscopic amoeba, isolated from warm freshwater, that can cause primary amebic meningoencephalitis (PAM). The presence of Naegleria fowleri and other microorganisms in the water system has led the Food and Drug Administration to recommend three methods to use for safe preparation of nasal saline irrigants: boiling, distilling, and filtration.
Explore this issue:July 2016
Allison G. Ordemann, MD, a resident in the otolaryngology and communicative sciences program at the University of Mississippi Medical Center in Jackson, presented the results of her study comparing sterile water to three methods of water sterilization (carbon filtration, boiling, and ultraviolet light). The study, which had a benchtop translational research design as well as a cost comparison, included seven potential disease-causing microorganisms: Staphylococcus aureus, Pseudomonas aeruginosa, Moraxella catarrhalis, Acinetobacter baumannii, Klebsiella pneumoniae, Legionella pneumophila, and Naegleria fowleri. The isolates were prepared as overnight cultures that were used to spike sterile saline. The investigators subjected the test samples to boiling, carbon filtration, or ultraviolet light (SteriPEN Ultra, MFR INFO TK) and assessed purification by plating 0.1 ml of each sample onto appropriate media. Controls included samples of sterile water as well as untreated test samples. The researchers performed two trials, using six technical replicas of each water purification system.
Carbon filtration reduced, but did not eliminate, the number of organisms present in test samples. In contrast, boiling for five minutes and ultraviolet light treatment each resulted in the eradication of viable organisms. Negative samples produced no growth, while positive samples grew numerous organisms. A cost comparison between bottled water and ultraviolet water sterilization found that the two methods became equal in less than two years of consistent use of the ultraviolet light.
Because carbon filtration reduced contamination but did not sterilize water, the investigators concluded that carbon filtration is unsafe for the preparation of nasal saline irrigant. In contrast, both boiling and ultraviolet treatment resulted in sterilization and were equivalent to purchased sterile water. The investigators proposed that UV light treatment might represent a time savings over boiled water and a cost savings over distilled water. Dr. Ordemann did note that there were nonviable Naegleria fowleri present after treatment with ultraviolet light, warranting caution. Brent A. Senior, MD, Nathaniel and Sheila Harris Distinguished Professor and chief of the division of rhinology, allergy, and endoscopic skull base surgery at the University of North Carolina in Chapel Hill, called the study practical and helpful. An audience member raised the suggestion that patients could also microwave water as a strategy to decrease boiling time and inconvenience.