Tsukamurella ocularis sp. nov. and Tsukamurella hominis sp. nov., isolated from patients with conjunctivitis in Hong Kong.

Three bacterial strains, HKU63, HKU64 and HKU65, were isolated from the conjunctival swabs of three patients with conjunctivitis in Hong Kong. The three strains were aerobic, Gram-stain-positive, catalase-positive, non-sporulating and non-motile bacilli and exhibited unique biochemical profiles distinguishable from closely related Tsukamurella species. 16S rRNA gene sequence analysis revealed that the three strains shared identical sequences with each other, being most closely related to Tsukamurella tyrosinosolvens and Tsukamurella pulmonis, sharing 99.9 % sequence identity. Sequence analysis of three additional housekeeping genes, groEL, secA and rpoB, revealed 100 % nucleotide sequence identity between HKU63 and HKU64, 94.2-97.0 % nucleotide sequence identities between HKU63/HKU64 and HKU65 and the three strains shared 82.9-98.9 % sequence identities with other currently recognized Tsukamurella species. DNA-DNA hybridization confirmed that they were distinct from other known species of the genus Tsukamurella(23.0±4.2 to 50.7±3.7 % DNA-DNA relatedness), of which HKU63 and HKU64 represented the same species (≥95.2±4.8 % DNA-DNA relatedness) while HKU65 represented another species. Fatty acid, mycolic acid, cell-wall sugar and peptidoglycan analyses showed that they were typical of members of Tsukamurella. The G+C content of strains HKU63, HKU64 and HKU65 were 71.3±1.9, 71.3±2.0 and 71.2±2.3 mol% (mean±sd; n=3), respectively. A novel species, Tsukamurella ocularis sp. nov. is proposed to accommodate strains HKU63 and HKU64, with HKU63 (=JCM 31969=DSM 105034) designated as the type strain whilst another novel species, Tsukamurella hominis sp. nov., is proposed to accommodate the third strain, HKU65, which is designated as the type strain (=JCM 31971=DSM 105036).