Spectrum and clinicomicro- biological profile of Nocardia keratitis caused by rare species of Nocardia identified by 16S rRNA gene sequencing

Purpose To report the predisposing factors, clinical profile, and treatment outcome of patients with keratitis that was caused by a rare species of Nocardia. Methods Between April 2006 and October 2008, medical and microbiology records of patients with keratitis that was caused by Nocardia were reviewed. Isolates were identified to species level by 16S rRNA gene sequencing, and antibiotic susceptibility testing was performed by E-test to amikacin, azithromycin, clarithromycin, ciprofloxacin, gatifloxacin, and tobramycin. Results Of 19 cases with Nocardia keratitis, 8 were caused by unusual isolates. Species distribution among the eight isolates was as follows: the Nocardia levis (2 of 8), Nocardia amamiensis (2 of 8), Nocardia abscessus (1 of 8), Nocardia puris (1 of 8), Nocardia beijingensis (1 of 8), and Nocardia thailandica (1 of 8). All eight (100%) isolates were sensitive to amikacin and tobramycin. Trauma to the cornea was the major predisposing factor in seven of the eight patients. Five patients presented with the characteristic wreath-pattern infiltrate. The infection resolved to topical therapy with amikacin sulphate (2.5%) in six patients, whereas two patients treated with the same antibiotic were lost to follow-up at a point when the lesion was showing signs of resolution. Conclusion The healing response in Nocardia keratitis cases was the same, irrespective of species. Eye (2010) 24, 1259-1262; doi:10.1038/eye.2009.299; published online 4 December 2009