Numerical Classification of Some Named Strains of Nocardia asteroides and Related Isolates from Soil

Abstract

One hundred and forty-nine strains of nocardiae, freshly isolated from soil samples obtained from a number of countries with either tropical or temperate climates, and from rubber pipe seals, were compared with appropriate marker cultures in a numerical phenetic study using 156 unit characters. Marker strains were chosen to represent the Nocardia asteroides complex, other Nocardia species and related taxa in an effort both to classify the new soil isolates and, possibly, clarify the structure of the heterogeneous N. asteroides complex. The data were examined using the simple matching (SSM) and pattern (DP) coefficients, and clustering was achieved using both single and average linkage algorithms. Cluster composition was not markedly affected by either of the coefficients or clustering methods. The estimated test error of 7.1% was rather high and could account for a few apparently anomalous results. The 16 defined clusters, containing 185 of the 197 strains studied, were divided into seven major and nine minor clusters, four of which were further subdivided into two subclusters. Marker strains allowed four clusters to be designated as N. asteroides, seven as Nocardia species and one each as Nocardia carnea, Nocardia farcinica, Nocardia autotrophica, Mycobacterium farcinogenes and Rhodococcus species. Twelve strains formed single member clusters including the type strains of Nocardia aerocolonigenes, Nocardia amarae, Nocardia fukuyae, Nocardia orientalis and Nocardia otitidis-caviarum. The majority of the soil and rubber isolates were recovered in the major clusters labelled N. asteroides, N. carnea and Nocardia species and clusters of soil isolates without marker strains seem to represent new centres of variation. The study highlights the need for additional reproducible tests to help both define and determine the status of defined clusters within the N. asteroides complex which would considerably benefit both the ecological and epidemiological study of these organisms.

The medically important aerobic actinomycetes: epidemiology and microbiology

“…infections. The heterogeneity within the species N. asteroides has been well documented by numerical phenetic (196,204,431,512,596,598), genetic (174,402), and immunologic (365,449,472) (518). Also, as suggested for N. farcinica infections, infections with N. nova may be more common than is presently suspected; however, the successful detection of these newly recognized species of microorganisms is dependent upon the performance of appropriate isolation and characterization techniques (621 (510).…”

“…4 140 characters, found that some of the taxa recognized by Gordon, in particular, the N. asteroides complex, were heterogeneous (196). In 1980, Orchard and Goodfellow were able to distinguish five different clusters by using numerical taxonomic characters (431). Table 2 summarizes characteristics useful in differentiating the medically important Nocardia spp.…”

“…Currently, the chemotaxonomic criteria used to assign bacteria to the genus Nocardia include the presence of the meso isomer of 2,6-diaminopimelic acid (DAP) and whole-cell sugars, arabinose and galactose (cell wall type IV) (331); intermediate-chain mycolic acids (46 to 60 carbons) (11,88,89,201,203,335); a fatty acid profile showing major amounts of straight-chain, unsaturated, and tuberculostearic acids (336); and the presence of a menaquinone fraction containing a tetrahydrogenated menaquinone with eight isoprene units as the predominant isoprenoic quinone (119,649,650). Tests that have established the heterogeneity of N. asteroides include numerical taxonomy (48,394,431,600), mycolic acid analysis by gas chromatography (651), DNA relatedness (651), and antimicrobial resistance patterns (625). These studies have indicated that many isolates recovered from clinical specimens and previously identified as N. asteroides are actually different species.…”

“…Nocardia spp. and related bacteria are considered saprophytic soil microorganisms, primarily responsible for the decomposition of organic plant material (197,431,449). In one Australian environmental survey, pathogenic species of the genus Nocardia were detected in house dust, beach sand, garden soil, and swimming pools (481).…”

Transfer of Rhodococcus aichiensis Tsukamura 1982 and Nocardia amarae Lechevalier and Lechevalier 1974 to the Genus Gordona as Gordona aichiensis comb. nov. and Gordona amarae comb. nov.

“…Several analyses of the type strain of N. arnarae have revealed notable differences between this organism and authentic nocardiae with respect to sensitivity to nocardiophages (28) and lysozyme (5,16), serological cross-reactions (22), and the presence of MK-9(H2) as the major menaquinone (5). Furthermore, the results of rRNA-DNA pairing experiments (18) and numerical phenetic analyses (5,19) have revealed that there is only a loose relationship between N. amarae and the genus Nocardia sensu stricto. Classification of R. aichiensis in the genus Rhodococcus is also open to question.…”