Nocardia veterana as a pathogen in North American patients.
The molecular methodologies used in our laboratories have allowed us to define a group of Nocardia isolates from clinical samples which resemble the type strain of Nocardia veterana. Three patient isolates and the type strain of N. veterana gave identical and distinctive restriction fragment length polymorphisms (RFLPs) for an amplified portion of the 16S rRNA gene. These three isolates and the N. veterana type strain also gave identical RFLPs for an amplified portion of the 65-kDa heat shock protein gene, but this pattern was identical to that obtained for the Nocardia nova type strain. Sequence analysis of both a 1,359-bp region of the 16S rRNA gene and a 441-bp region of the heat shock protein gene of the patient isolates showed 100% identities with the same regions of the N. veterana type strain. DNA-DNA hybridization of the DNA of one of the patient isolates with the DNA of the N. veterana type strain showed a relative binding ratio of 82%, with 0% divergence, confirming that the isolate was N. veterana. Biochemical and susceptibility testing showed no significant differences among the patient isolates and the N. veterana type strain. Significantly, the results of antimicrobial susceptibility testing obtained for our isolates were similar to those obtained for N. nova, indicating that susceptibility testing alone cannot discriminate between these species. We present two case studies which show that N. veterana is a causative agent of pulmonary disease in immunocompromised patients residing in North America. We also describe difficulties encountered in using 16S rRNA gene sequences alone for discrimination of N. veterana from the related species Nocardia africana and N. nova because of the very high degree of 16S rRNA gene similarity among them.
Conville
Patricia S
PS
Microbiology Service, Department of Laboratory Medicine, Warren G. Magnuson Clinical Center, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland 20892, USA. pconville@nih.gov
Brown
June M
JM
Steigerwalt
Arnold G
AG
Lee
Judy W
JW
Byrer
Dorothy E
DE
Anderson
Victoria L
VL
Dorman
Susan E
SE
Holland
Steven M
SM
Cahill
Barbara
B
Carroll
Karen C
KC
Witebsky
Frank G
FG
D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004275:DNA, Ribosomal / Q000032:analysis; D006360:Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D016867:Immunocompromised Host; D008168:Lung / Q000382:microbiology; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008969:Molecular Sequence Data; D009615:Nocardia / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D009617:Nocardia Infections / Q000382:microbiology*; D009656:North America; D010641:Phenotype; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D000900:Anti-Bacterial Agents; D004275:DNA, Ribosomal; D006360:Heat-Shock Proteins; D012336:RNA, Ribosomal, 16S