Nocardia arizonensis sp. nov., obtained from human respiratory specimens

Abstract

In 2008, three clinical isolates (W9405(T), W9409 and W9575) were obtained from bronchial wash or sputum specimens from patients from the state of Arizona and characterised by polyphasic analysis. All three clinical isolates 16S rRNA gene sequences were found to be 100% identical to each other and showed the strains belong in the genus Nocardia. BLASTn searches in the GenBank database of near full-length 16S rRNA gene sequences showed the highest sequence similarities to the type strains of Nocardia takedensis (98.3%, sequence similarity), Nocardia lijiangensis (97.4%), Nocardia harenae (97.4%), and Nocardia xishanensis (97.1%). The DNA-DNA relatedness between isolate W9405(T) and the type strain of N. takedensis is 26.0 ± 2.4% when measured in silico using genomic DNA sequences. The G+C content of isolate W9405(T) is 68.6 mol%. Chemotaxonomic analyses of the clinical isolates were consistent with their assignment to the genus Nocardia: whole cell hydrolysates contain meso-diaminopimelic acid as the diagnostic diamino acid of peptidoglycan; the whole-cell sugars are arabinose and galactose; the predominant phospholipids include diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol; MK-8-(H4)(ω-cyc) as the major menaquinone; mycolic acids ranging from 38 to 62 carbon atoms; and palmitic acid, tuberculostearic acid, palmitelaidic acid and oleic acid are the major fatty acids. Genus and species specific profiles were obtained following analysis by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectra of the clinical isolates. All isolates were found to be intermediately resistant or resistant to minocycline and resistant to ciprofloxacin but were susceptible to amikacin, imipenem and linezolid. Our polyphasic analysis suggest the three clinical isolates obtained from patients in Arizona represent a novel species of Nocardia for which we propose the name Nocardia arizonensis, with strain W9405(T) (=DSM 45748(T) = CCUG 62754(T) = NBRC 108935(T)) as the type strain.