[Experimental study on the treatment of non-tuberculous mycobacterial keratitis]

To explore the optimal treatment for non-tuberculous mycobacterial keratitis (NTMK).

Experimental study.Fifty-one New Zealand white rabbits were inoculated with non-tuberculous mycobacteria (NTM) to establish the animal model of NTMK. Eyes with NTMK were randomly divided into 7 groups and topically treated with amikacin (2.5%) (B), gatifloxacin (3%) (C), azithromycin (1%) (D), amikacin (2.5%) plus gatifloxacin(3%) (E) , amikacin (2.5%) plus gatifloxacin (3%) combined with debridement (F), early lamellar keratoplasty (G) and balanced salt water (as a control) (A). All the drugs were administered 8 times per day within initial 7 days followed by 4 times per day after 1 week. The clinical manifestations of each rabbit were observed and recorded every week. The score of clinical manifestations before and after treatment does not meet the normal distribution, so it was presented by the median ± quantile interval and compared with rank sum test and SNK test. Fisher exact test was used to compare differences in the distribution of presenting the healing rate of keratitis.

After 1 week treatment, six eyes were cured in group G, and none were cured in other groups, the scores of clinical manifestations of group B, C, D, E, F and G were 6 ± 4, 8 ± 2, 6 ± 4, 8 ± 3, 7 ± 4, 3 ± 1, they were higher than that of group A (q = 20.36, 11.43, 19.21, 16.93, 18.64, 37.50, P < 0.05). After 2 weeks, the scores of group B, C, E, F and G were higher than that of group A (q = 23.50, 16.71, 15.21, 12.43, 30.87, P < 0.05), and the healing rate of group G was higher than that of group A. After 3 weeks, the score of clinical manifestations of group B, D, F and G was higher than that of group A, and the healing rate of group F and G was higher than that of group A. After 4 weeks, the inflammation of group F and G were healed, and a little inflammation remained in the eye of group A. The score of clinical manifestations of group D, E, F and G was higher than that of group A. None was detected in the bacterial culture after 4 weeks. In histopathological examination, there were integrated and proliferated corneal epithelium, fibroblast cells proliferation in the eyes of experimental groups was found, while corneal cells edema, stroma degeneration and necrosis with lymphocytes and plasma cells in the ulcerated lesion in the corneal stromal of group A.

Amikacin, gatifloxacin or azithromycin is effective in arresting NTM, while antibiotic combined with debridement is more effective and early lamellar keratoplasty is the most rapid and thorough treatment of NTMK.