Tsukamurella asaccharolytica sp. nov., Tsukamurella conjunctivitidis sp. nov. and Tsukamurella sputi sp. nov., isolated from patients with bacteraemia, conjunctivitis and respiratory infection in Hong Kong

Abstract

Three bacterial strains, HKU70^T, HKU71^T and HKU72^T, were isolated from the conjunctival swab, blood and sputum samples of three patients with conjunctivitis, bacteraemia and respiratory infection, respectively, 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 currently recognized <i>Tsukamurella</i> species. 16S rRNA, <i>secA</i>, <i>rpoB</i> and <i>groEL</i> gene sequence analyses revealed that the three strains shared 99.6-99.9, 94.5-96.8, 95.7-97.8 and 97.7-98.9 % nucleotide identities with their corresponding closest <i>Tsukamurella</i> species respectively. DNA-DNA hybridization confirmed that they were distinct from other known species of the genus <i>Tsukamurella</i> (26.2±2.4 to 36.8±1.2 % DNA-DNA relatedness), in line with results of <i>in silico</i> genome-to-genome comparison (32.2-40.9 % Genome-to-Genome Distance Calculator and 86.3-88.9 % average nucleotide identity values]. Fatty acids, mycolic acids, cell-wall sugars and peptidoglycan analyses showed that they were typical of members of <i>Tsukamurella</i>. The G+C content determined based on the genome sequence of strains HKU70^T, HKU71^T and HKU72^T were 69.9, 70.2 and 70.5 mol%, respectively. Taken together, our results supported the proposition and description of three new species, i.e. <i>Tsukamurella sputi</i> HKU70^T (=JCM 33387^T=DSM 109106^T) sp. nov., <i>Tsukamurella asaccharolytica</i> HKU71^T (=JCM 33388^T=DSM 109107^T) sp. nov. and <i>Tsukamurella conjunctivitidis</i> HKU72^T (=JCM 33389^T=DSM 109108^T) sp. nov.