Nasal Saline Devices
Abstract & Commentary
Can Salt Water Really Be Harmful?
By David Kiefer, MD, Editor
Synopsis: There is mounting evidence for a risk for bacterial contamination of nasal saline irrigation devices (such as neti pots) that may have clinical relevance.
Source: Psaltis AJ, et al. Contamination of sinus irrigation devices: A review of the evidence and clinical relevance. Am J Rhinol Allergy 2012;26:201-203.
This article is a review of published literature on bacterial contamination of nasal saline irrigation devices (NSID), including neti pots, squeeze bottles, and bulb syringes. The authors do not describe their literature search strategy, but detail seven studies published between 2001-2010. Six of the seven studies obtained the NSID from patients; these trials showed contamination rates ranging from 25-100%. One of the trials was an in vitro study, presumably because the bulb syringe was tested without having been used by patients to treat their condition(s). Interestingly, even in the in vitro study bacteria were isolated from the NSID.
The most common bacterial species isolated in the trials reviewed were Staphylococcus aureus and Pseudomonas aeruginosa. A variety of other bacteria were mentioned, including coliforms, gram-positive cocci, Klebsiella pneumonia, and other Staphylococcus and Pseudomonas species. One study found bacteria but didn’t identify the species. Some but not all of the bacterial species isolated in these trials are found to a varying degree in human sinonasal cavities; a “sharing” of bacteria between the NSID and nasal passages was discussed in this article, but the clinical relevance of this remains to be determined.
The authors of this review also commented on other results from the individual trials. For example, from one of the trials (Williams et al., 2008), it appears that the highest bacterial growth occurs when unbuffered, isotonic saline solutions are used for irrigation. In addition, despite manufacturers’ claims, there does not seem to be a difference in rates of bacterial contamination between different NSIDs. Furthermore, four studies examined contamination rates relative to duration of NSID use; three of these studies found increased contamination rates with time. In some cases, colonization of the NSID began after only 1 or 2 weeks of use. The literature did not provide guidance about how often to exchange a NSID for a new one; many manufacturer recommendations are to use for only 3 months and then discard. The authors did not detail contamination results relevant to plastic vs ceramic neti pots.
There are several problems with this review, some of which are inherent in any compilation or review article. For example, individual studies may not have commented on whether patients were in the habit of cleaning their NSID, clearly an important variable in the measurement of bacterial contamination rates. Also, some patients were postoperative from sinus surgery, which is known to be a period of intense bacterial shedding, compromising the generalizability of the pooled results. Finally, the authors make no mention of the type of water used by the patients in these individual studies, an important omission relevant to recent fatal infections.
Commentary
In some respects, this study should evoke a response such as “Duh!” or “We already knew that it is important to clean out our neti pots.” Equally as relevant would be this reclaim: “So what?” The authors themselves, in a section entitled “Clinical Relevance,” comment on the fact that at least in two of the reviewed studies there was no correlation between the presence of bacteria in a NSID and a patient’s symptoms. Besides, we could argue that the bacteria mentioned, especially Staphylococcus, are omnipresent in the environment and on our bodies, and are not necessarily a clinical problem; pathogenicity has been proven to be more a factor of quantity and location of bacteria and how they interact with our normal flora.
This article and the topic it attempts to tackle illustrate some larger issues. In medicine, it is a good habit to always consider the risks of any treatment, even seemingly innocuous interventions such as nasal saline irrigation. I have to admit that I have been lax about such counseling for my patients with acute/chronic sinusitis, allergic rhinitis, or upper respiratory infections. I felt as if I had won the battle if I alleviated their concerns about the possible discomfort or uncouth appearance of nasal irrigation and quickly would end the discussion with “It’s safe. Don’t worry about it.” This study and others remind us to round out patient education with all relevant important details about a health condition and treatment options. The authors mention the importance of practicing good NSID hygiene, which they argue is best achieved by rinsing with boiling (not cold) water, rinsing with Milton’s antibacterial solution, or microwaving for 90 seconds on high. Whether it is important to regularly exchange a NSID for a new one, another suggestion from the authors of this article remains to be definitively determined. Nonetheless, some hybrid of these recommendations should be a part of a clinician’s nasal saline counseling.
The second important caveat to this study is how it ties in to media reports. Last fall, there were headlines and articles detailing two deaths in Louisiana presumed secondary to nasal saline irrigation.1 Indeed, it appears that an amoeba, Naegleria fowleri, most often found in warm, outdoor freshwater had colonized the water heaters of these two households and, when that water was used for nasal saline irrigation, led to fatal brain infections.2 The safety of the water source used for nasal saline irrigation is separate from though ultimately related to the NSID contamination as investigated in this review. Over time, nasal saline irrigation using sterile water will still lead to NSID contamination due to the dynamic nose-NSID relationship, but the nature of this interaction is mostly unknown. We need safe water and probably a mostly clean NSID. But many questions remain, such as the actual risk of adverse effects by using water that is less than sterile, or how contaminated a NSID has to be (not a nice image, I know) before it leads to disease, or the role of the patient’s normal flora and immune system health in preventing infections.
Until these issues are resolved, officials have taken a prudent approach. The FDA became involved, and now recommends that people buy sterile or distilled water, or boil water for 3-5 minutes and cool it to “lukewarm” for use.3 Another option is to use a water filter with an absolute pore size of 1 micron or smaller, and they defer to the Centers for Disease Control for guidance on choosing a water filter. The FDA also offers advice, similar to the above-mentioned care instructions, for practicing good NSID hygiene. Other information, in English and Spanish, and with a video (www.fammed.wisc.edu/research/past-projects/nasal-irrigation), exists to help people use this important and proven technique in a safe and effective way.4
Perhaps all of this is overkill — nasal saline irrigation has been around, and arguably safely used, for centuries. However, despite the flaws in this current NSID contamination review, these are plausible risks that we should factor in when counseling patients until new and better research surfaces. Yes, there are extra steps involved (boiling water, cleaning neti pots, etc.) that may decrease patient adherence for some, but it seems worth it to be on the safe side.
References
1. Parker-Pope T. Rare Infection Prompts Neti Pot Warning. New York Times September 3, 2012. Available at: http://well.blogs.nytimes.com/2012/09/03/rare-infection-prompts-neti-pot-warning/. Accessed Feb. 7, 2013.
2. Yoder JS, et al. Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water. Clin Infect Dis 2012;55:e79-85.
3. Food and Drug Administration. Is Rinsing Your Sinuses Safe? August 23, 2012. Available at: www.fda.gov/ForConsumers/ConsumerUpdates/ucm316375.htm. Accessed Feb. 7, 2013.
4. Department of Family Medicine, University of Wisconsin. Nasal Irrigation (Nasal Wash) for Common Upper Respiratory Conditions. Available at: https://www.fammed.wisc.edu/research/past-projects/nasal-irrigation. Accessed Feb. 7, 2013.
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