[Formation characteristics and significance of bacteria biofilm in middle ear mucosa of rats with chronic suppurative otitis].

OBJECTIVE

To establish the rat model of chronic suppurative otitis media and observe the formation of bacterial biofilm in middle ear mucosa of animal models and discuss the role of bacterial biofilm in the pathogenesis of chronic suppurative otitis media.

METHOD

Twenty-eight rats were divided into six experimental groups and a control group evenly. All rats in experimental groups were infected with pseudomonas aeruginosa solution in 1 X 10(6) cfu/ml concentration through the tympanic membrane puncture approach to bilateral middle ear cavity. On the first, sixth, tenth, fifteenth and twenty-first st day after inoculation respectively, four rats in one experimental group were narcotized, then two-sided tympanic membrane of each rat were observed by using electric otoscope. We rated on the severity of the inflammation from the general pathology level (0 for normal, four for the most serious). After the execution, the two-sided otocysts were obtained. The left was made to SEM specimen and the shape of bacterial biofilm in middle ear mucous was observed. The right was observed by CLSM. Control group were executed at the beginning of the experiment.

RESULT

(1) Bacterial biofilm in line with their respective criteria were found at the six days after the inoculation, and were more typical in shape after ten days. Then the states maintained stably within three weeks. (2) By observing tympanic membrane under electric otoscope, it can be seen that the inflammation severity of otitis media aggravated gradually in the first ten days and achieved the peak, then the state continued to the third week. The differences of tympanic membrane rating between one day group and six day group, six day group and ten day group were statistically significant (P < 0.05, P < 0.01).

CONCLUSION

(1) In this experiment, the process of bacterial biofilm development in rats model is: from beginning to the five days, the bacteria adhere and accumulates. After six days, the 3D structure of bacterial biofilm preliminary formatted. After ten days, the bacterial biofilm achieves the mature and steady state. (2) With the growth and maturity of bacterial biofilm in middle ear mucosa, the inflammation of otitis media is gradually increasing, which suggests that the inflammation severity of otitis media and the maturation of bacterial biofilm in middle ear mucosa are closely related.