Ocular nocardiosis: HSP65 gene sequencing for species identification of Nocardia spp.

PURPOSE: To assess hsp65 gene sequencing for detection and species identification of genus Nocardia from ocular isolates.

DESIGN

A prospective study based on laboratory investigation.

METHODS

Genus-specific hsp65 gene sequencing was used to identify the genus Nocardia isolated from 11 consecutive cases of ocular nocardiosis to the species level.

RESULTS

Eleven eye clinical isolates belong to six species: N. arthritidis (3/11), N. neocaledoniensis (3/11), N. asiatica (2/11), N. asteroids type 4 (1/11), N. brasiliensis (1/11), and N. pseudobrasiliensis (1/11). N. arthritidis is the most important etiologic species that causes Nocardia keratitis. N. neocaledoniens is isolated in the conjunctiva, and might cause conjunctivitis.

CONCLUSIONS

Genus-specific hsp65 gene sequencing can be a rapid and reliable adjunct in the diagnosis of ocular Nocardia to the genus and species level. N. arthritidis other than N. asteroids (often appeared in surveys) is the most important etiologic species in ocular nocardiasis. N. neocaledoniensis can be isolated in conjunctiva, and might be able to cause conjunctivitis. The diversity of species has important implications for the etiology, pathogenesis, and treatment (drug susceptibility).