Explore This IssueJuly 2016
Antibiotic Exposure and CRS
Alice Z. Maxfield, MD, a rhinology fellow in the department of otolaryngology at Massachusetts General Hospital in Boston, suggested in the first presentation that general antibiotic exposure is a significant risk factor for the development of chronic rhinosinusitis (CRS). She began by explaining that antibiotic use is associated with multiple adverse effects, including allergy, widespread antibiotic resistance, and infection with Clostridium difficile and Candida albicans, as well as loss of microbial diversity. Additionally, CRS is independently associated with the depletion of microbiome diversity and the introduction of opportunistic infections. She and her team hypothesized that the use of antibiotics leads to loss of biodiversity of the sinonasal microbiome, resulting in the development of CRS. Confirmation of their hypothesis would mean that antibiotic use is an unrecognized risk factor for the development of CRS.
The case control study used the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) guidelines. The investigators studied patients referred to the tertiary Massachusetts Eye and Ear Sinus Center for a range of sinonasal disorders. Of the 1,162 patients studied, 410 were diagnosed with CRS according to established consensus criteria. The remainder (752) were considered controls. The case group was further differentiated into those without nasal polyps (CRSsNP) and those with nasal polyps (CRSwNP). All patients were given a validated quality of life (QOL) questionnaire. Additionally, the class, diagnosis, and timing of previous non-sinusitis-related antibiotic exposures were recorded. The results from the antibiotic exposure questionnaire were also validated using a randomized administrative data review of 452 patient charts. From this data, the investigators calculated the odds ratio of developing CRS following antibiotic exposure as well as the impact of antibiotic use on the subsequent QOL.
The investigators found a higher median age in the case group. They also found that antibiotic use significantly increased the odds of developing CRSsNP. Additionally, antibiotic exposure, as confirmed by antibiotic review, was associated with worse CRS QOL scores over at least the subsequent two years.
Dr. Maxfield said that while microbial diversity in CRS is still controversial, antibiotics may result in long-term consequences. Specifically, the study indicated that the use of antibiotics more than doubles the risk of developing CRSsNP, leading Dr. Maxfield to estimate that antibiotics might be implicated in 25% of the disease burden in their study population and to suggest that CRS may be an unrecognized side effect of antibiotic use.
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.
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.
Pathophysiology of Chronic Rhinosinusitis
Approximately 25% of patients with olfactory disturbances have CRS. Camilo Reyes, MD, a current fellow in the rhinology-skull base surgery program at the Medical College of Georgia-Augusta University in Augusta, Ga., measured improvement in olfactory disturbances in patients with CRS using the Sinonasal Outcome Test (SNOT-22) scores at first and last postoperative visit. The study included 134 patients with CRS: 87 with eosinophilic CRS (eCRS) and 47 with non-eosinophilic CRS (neCRS). The researchers found that patients with eCRS had higher preoperative olfactory experience than patients with neCRS. Additionally, approximately two-thirds of patients in both groups demonstrated subjective improvement in olfaction after surgery. Thus, both the study group and control group had a significant post-surgery improvement in olfactory experience.
Lara Pullen is a freelance medical writer based in Illinois.