title: New Nocardia taxon among isolates of Nocardia brasiliensis associated with invasive disease.
abstract: Nocardia brasiliensis, the second most frequently isolated aerobic actinomycete in the clinical laboratory, is usually associated with localized cutaneous infections. However, 22% of 238 N. brasiliensis isolates from the United States and 12% of 66 isolates from Queensland, Australia, which had been collected over a 17-year period, were associated with extracutaneous and/or disseminated diseases. Of the 62 invasive isolates, 37 (60%) were susceptible to ciprofloxacin and/or were susceptible to clarithromycin and resistant to minocycline, compared with only 6 (3%) of 242 localized cutaneous isolates. The 43 isolates with this susceptibility pattern appeared to define a new taxon. They were similar to Nocardia asteroides complex isolates clinically in proportions from persons with pulmonary (70%), central nervous system (23%), and/or disseminated diseases (37%) in the setting of corticosteroids (74%) or AIDS (14%). This putative new taxon differed from N. brasiliensis in the hydrolysis of adenine (92 versus 4%), beta-lactamase patterns on isoelectric focusing, and the presence of two early mycolic acid-ester peaks by high-performance liquid chromatography. Restriction analysis of a 439-bp fragment of the 65-kDa heat shock protein gene revealed that N. brasiliensis and the new taxon had different restriction patterns with 8 of the 11 enzymes tested. Screening of invasive isolates of N. brasiliensis for susceptibility to ciprofloxacin will identify most isolates of the new taxon, which likely represents a new Nocardia species.
authors.affiliation: Department of Microbiology, University of Texas Health Center, Tyler 75710, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Wallace
authors.forename: B A
authors.initials: BA
authors.lastname: Brown
authors.forename: Z
authors.initials: Z
authors.lastname: Blacklock
authors.forename: R
authors.initials: R
authors.lastname: Ulrich
authors.forename: K
authors.initials: K
authors.lastname: Jost
authors.forename: J M
authors.initials: JM
authors.lastname: Brown
authors.forename: M M
authors.initials: MM
authors.lastname: McNeil
authors.forename: G
authors.initials: G
authors.lastname: Onyi
authors.forename: V A
authors.initials: VA
authors.lastname: Steingrube
authors.forename: J
authors.initials: J
authors.lastname: Gibson
mesh_terms: D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004352:Drug Resistance, Microbial; D006801:Humans; D008969:Molecular Sequence Data; D009171:Mycolic Acids / Q000302:isolation & purification; D009615:Nocardia / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D009617:Nocardia Infections / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017192:Skin Diseases, Bacterial / Q000382:microbiology; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D009171:Mycolic Acids