Novel rat model of tympanostomy tube otorrhea

详细信息    查看全文

• 作者：Rodrigo C. Silva^a ; ^{Rodrigo.Silva@ent.ufl.edu} ; Joseph E. Dohar^b ; ^c ; ^e ; ^f ; Patricia A. Hebda^b ; ^c ; ^d ; ^e ; ^f
• 关键词：Tympanostomy tube otorrhea ; Rat model ; Cytokines
• 刊名：International Journal of Pediatric Otorhinolaryngology
• 出版年：2012
• 出版时间：February 2012
• 年：2012
• 卷：76
• 期：2
• 页码：179-182
• 全文大小：308 K

文摘

Objective

Tympanostomy tube otorrhea (TTO), caused by the presence of pathogenic bacteria in the middle ear, is the most common complication of TT insertion. No studies have described a reproducible animal model of TTO. We aimed to develop a rat model of TTO which, in turn, could be used to assay the levels of TNF-¦Á and IL-1¦Â through the course of the infection.

Methods

The left Eustachian tubes of 55 male Sprague-Dawley albino rats were occluded with gutta-percha (ETO = Eustachian Tube Occlusion). Middle ear (ME) effusion was ascertained by weekly otomicroscopy. At 3 weeks tympanostomy tubes were placed bilaterally and the MEs were inoculated bilaterally with Streptococcus pneumoniae through the tubes. The rats were randomly assigned to one of two daily ototopical treatments: ciprofloxacin/dexamethasone (CDX) or placebo. The animals in each of the two treatment groups were further divided to receive 1, 2, 5 or 7 days of treatment. The rats were sacrificed after treatment was finished. The rates of otorrhea, positive middle ear (ME) cultures, and levels of TNF-¦Á and IL-1¦Â in the ME fluid were measured.

Results

Left ETO followed by ME inoculation with S. pneumoniae and treatment with placebo resulted in persistent infection (100 % culture-positive ME fluid at 10 days) and otorrhea (85.7 % ). Persistent infection of the left ear was accompanied by significantly elevated the levels of IL-1¦Â and TNF-¦Á. Ears treated with CDX had lower rates of otorrhea at all time points and lower levels of IL-1¦Â and TNF-¦Á.

Conclusions

This study is the first to describe a reproducible animal model of acute TTO. Surgical obstruction of the ET, followed by TT placement and ME inoculation with S. pneumoniae induced persistent otorrhea and infection. Both IL-1¦Â and TNF-¦Á appear to be potential markers of persistent middle ear infection. This novel model may be used in future studies of the pathogenesis and therapy of TTO.