Clinical and Laboratory Features of theNocardiaspp. Based on Current Molecular Taxonomy

Abstract

SUMMARY The recent explosion of newly described species of Nocardia results from the impact in the last decade of newer molecular technology, including PCR restriction enzyme analysis and 16S rRNA sequencing. These molecular techniques have revolutionized the identification of the nocardiae by providing rapid and accurate identification of recognized nocardiae and, at the same time, revealing new species and a number of yet-to-be-described species. There are currently more than 30 species of nocardiae of human clinical significance, with the majority of isolates being N. nova complex, N. abscessus, N. transvalensis complex, N. farcinica, N. asteroides type VI (N. cyriacigeorgica), and N. brasiliensis. These species cause a wide variety of diseases and have variable drug susceptibilities. Accurate identification often requires referral to a reference laboratory with molecular capabilities, as many newer species are genetically distinct from established species yet have few or no distinguishing phenotypic characteristics. Correct identification is important in deciding the clinical relevance of a species and in the clinical management and treatment of patients with nocardial disease. This review characterizes the currently known pathogenic species of Nocardia, including clinical disease, drug susceptibility, and methods of identification.

Pulmonary nocardiosis in a patient with idiopathic CD4 T‐lymphocytopenia

“…Immunodeficient states that predispose to nocardial infections include solid organ or haematopoietic stem cell transplantation, glucocorticoid and other immunosuppressant therapy, HIV infection, malignancy, and diabetes mellitus 4, 5. The occurrence of nocardiosis in patients who are immunodeficient on account of ICL has only been reported previously in a few case reports 2, 3.…”

Diversity and frequency of Nocardia spp. in the soil of Isfahan province, Iran

“…If delicate and branched filaments which are the characteristics of Actinomycetes were seen, they were isolated by Sabouraud dextrose agar medium in tubes. Then by using Kinyoun staining, conventional biochemical tests and physiological criteria such as the capability to degrade the organic compounds such as tyrosine, casein, hypoxanthine, xanthine and starch as substrates, as well as growth in 4% gelatin medium, were studied in order to reach a possible classification to the species level [1] .…”

“…Nocardia species are aerobic Actinomycetes, grampositive, non-spore, filamentous, branching, obligatory aerobic and relatively slow-growing bacteria [1] . So far, more than 50 species in the genus Nocardia are described among which Nocardia asteroids (N. asteroids) complex, Nocardia brasiliensis (N. brasiliensis), Nocardia transvalensis (N. transvalensis), Nocardia otitidiscaviarum (N. otitidiscaviarum), Nocardia farcinica and Nocardia pseudobrasiliensis are more pathogenic in humans [2] .…”

“…Various studies have shown that identification and isolation of these agents in soil of different areas help to diagnose nocardiosis [1] .…”

“…Nocardiosis is sporadic in Iran, but in other countries it is more prevalent. In USA, 500-1 000 new case of nocardiosis was annually reported [1,3,4,25] . Due Contents lists available at ScienceDirect province, which is one of the major tourist cities in the world, the present study was carried out with the goals of isolation and identification of different species of Nocardia in different regions and investigating the effect of environmental factors such as soil pH and type of climate on the frequency of these microorganisms in soil.…”