Complications of Ear Tubes Can Be Avoided

Release: Embargoed until September 24, 2000Contact: Jennifer FelsheR202-371-4517 (9/23-27)703-519-1549[email protected]

Common Complications of Ear Tubes Can Be Avoided

Study identifies tympanostomy tube that offers resistance to two common bacteria often associated with the necessity of tube removal

Washington, D.C.-- Otitis media, better known as an ear infection, is the most common reason that a child visits a physician. An effective treatment option for chronic occurrence of this disease is the insertion of tubes into the tympanic membrane, which drains infected fluid build-up and ventilates the middle ear.

Although the insertion of tympanostomy tube(s) is effective; in approximately 50 percent of cases, the tubes become covered in a bacterial biofilm which causes a secondary infection and may lead to removal of the tubes. Now, in an effort to avoid this problem, researchers have compared the composition of several ear tubes to find one that is most resistant to specific bacteria. They concluded that the use of PC-coated fluoroplastic tubes may decrease chronic infection and the need for tube removal.

This research study, "In Vitro Resistance to Bacterial Biofilm Formation on Coated Fluoroplastic Tympanostomy Tubes," is authored by Julie A. Berry, MD, of the University of Maryland Medical System, John F. Biedlingmaier, MD, FACS, and Philip J. Whelan, MD, both of Maryland General Hospital in Baltimore, MD. Dr. Berry will present the findings Tuesday, September 26, at the Annual Meeting of the American Academy of Otolaryngology -- Head and Neck Surgery Foundation, being held September 24-27, at the Washington, DC Convention Center.

Bacterial biofilm is a polysaccharide formation believed to be a causative agent in infection at the site of implanted materials. The organisms within this biofilm are relatively resistant to antibiotics, and can become a source of persistent and relapsing infection which, in turn, can lead to removal of the implanted material (in this case, tubes).

The authors hypothesized that the use of tympanostomy tubes that are resistant to biofilm formations may decrease the incidence of secondary infection (chronic otorrhea) and the possible need for tube removal. Three variations of tubes were tested for resistance to biofilm formation after in vitro incubation with the two most commonly offensive organisms. It was found that treating the surface of the fluoroplastic typanostomy tube with phosphorylcholine inhibits the growth of common organisms known to cause chronic otorrhea. (The most commonly used materials for tympanostomy tubes are silicone and fluoroplastic.)

Methodology: Three styles of tympanostomy tubes were tested in this study: fluoroplastic, phophorylcholine (PC) - coated fluoroplastic, and silver oxide-impregnated fluoroplastic. All tubes were submerged in flasks containing suspensions of staphyloccus aureus and pseudomonas aeruginosa prepared in the lab. An identical control group was established by submerging the same types of tubes in flasks containing a sterile suspension. The flasks were incubated for five days; then the tympanostomy tubes were removed and analyzed.

Results: Staphyloccus aureus samples: After incubation, the surfaces of the plain fluoroplastic and PC-coated fluoroplastic tubes could not be distinguished from the controls and had no bacterial biofilm formation. In contrast, the silver oxide-impregnated fluoroplastic tube demonstrated large crusts of thick biofilm. The silver oxide particles appeared to have dissolved into the solution, leaving behind the basic tube material.

Pseudomonas aeruginosa samples: After incubation, the plain fluoroplastic tube had dense biofilm that obscured the natural texture of the tube. The silver oxide-impregnated fluoroplastic tube contained crusts and thick biofilm, rendering the basic tube surface unidentifiable. In contrast, the PC-coated fluoroplastic tube appeared identical to the control tubes with no identifiable biofilm formations characteristic of pseudomonas.

Conclusions: Avoiding biofilm formation is highly important for tympanostomy tubes given that tube insertion for middle ear ventilation remains the most common otological procedure, and the incidence of of subsequent chronic otorrhea may be as high as 50 percent. Adherent biofilms may persist in spite of active host defenses and extensive antimicrobial therapy.

Therefore, use of a tympanostomy tube which offers a reduction in biofilm contamination could substantially reduce the incidence of chronic otorrhea and the subsequent need for tube removal. This study indicates that, of the three types of tubes tested, the PC-coated fluoroplastic tube was the only one to resist both P. aeruginosa and S.aureus. As such, it is concluded that the use of PC-coated fluoroplastic tubes may decrease chronic infection and the need for tube removal.

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