Clinical and laboratory features of the Nocardia spp. based on current molecular taxonomy

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.

The medically important aerobic actinomycetes: epidemiology and microbiology

The aerobic actinomycetes are soil-inhabiting microorganisms that occur worldwide. In 1888, Nocard first recognized the pathogenic potential of this group of microorganisms. Since then, several aerobic actinomycetes have been a major source of interest for the commercial drug industry and have proved to be extremely useful microorganisms for producing novel antimicrobial agents. They have also been well known as potential veterinary pathogens affecting many different animal species. The medically important aerobic actinomycetes may cause significant morbidity and mortality, in particular in highly susceptible severely immunocompromised patients, including transplant recipients and patients infected with human immunodeficiency virus. However, the diagnosis of these infections may be difficult, and effective antimicrobial therapy may be complicated by antimicrobial resistance. The taxonomy of these microorganisms has been problematic. In recent revisions of their classification, new pathogenic species have been recognized. The development of additional and more reliable diagnostic tests and of a standardized method for antimicrobial susceptibility testing and the application of molecular techniques for the diagnosis and subtyping of these microorganisms are needed to better diagnose and treat infected patients and to identify effective control measures for these unusual pathogens. We review the epidemiology and microbiology of the major medically important aerobic actinomycetes.

Powdered chitin agar as a selective medium for enumeration of actinomycetes in water and soil

Agar media made with 0.4% colloidal chitin plus mineral salts and adjusted to pH 8.0 was superior to four other commonly used media for the isolation and enumeration of actinomycetes from water samples. More actinomycetes developed on chitin agar, and the development of bacteria and fungi was suppressed. Frozen and vacuum-dried chitin from aqueous colloidal suspensions was finely divided and gave results comparable to those obtained with media prepared from colloidal suspensions.

Diversity of bacterial strains degrading hexadecane in relation to the mode of substrate uptake

The relative distribution of the modes of hydrocarbon uptake, used by bacteria of the environment for the degradation of long-chain alkanes, has been evaluated. The first mode of uptake, direct interfacial accession, involves contact of cells with hydrocarbon droplets. In the second mode, biosurfactant-mediated transfer, cell contact takes place with hydrocarbons emulsified or solubilized by biosurfactants. Sixty-one strains growing on hexadecane were isolated from polluted and non-polluted soils and identified. The majority (61%) belonged to the Corynebacterium-Mycobacterium-Nocardia group. Criteria selected for characterizing hexadecane uptake were cell hydrophobicity, interfacial and surface tensions and production of glycolipidic extracellular biosurfactants. These properties were determined in flask cultures on an insoluble (hexadecane) and on a soluble (glycerol or succinate) carbon source for a subset of 23 representative strains. Exclusive direct interfacial uptake was utilized by 47% of studied strains. A large proportion of strains (53%) produced biosurfactants. The data on cellular hydrophobicity suggested the existence of two distinct alkane transfer mechanisms in this group. Accordingly, tentative assignments of biosurfactant-mediated micellar transfer were made for 11% of the isolated strains, and of biosurfactant-enhanced interfacial uptake for 42%.

Cefotaxime-resistant Nocardia asteroides strains are isolates of the controversial species Nocardia farcinica

A recent study of Nocardia asteroides revealed that 95% of clinical strains had one of five antibiotic resistance patterns. We found the pattern of resistance to cefotaxime and cefamandole in 19% of 200 clinical N. asteroides isolates. Isolates with this drug resistance pattern were from numerous geographic sources and were associated with significant clinical disease (56% of patients had disseminated infections). Phenotypic studies revealed that these isolates were relatively homogeneous and matched previous descriptions and reference strains of the controversial species N. farcinica. Growth at 45 degrees C, acid production from rhamnose, ability to utilize acetamide as a nitrogen and carbon source, and resistance to tobramycin and cefamandole were features of N. farcinica that could be tested in the clinical laboratory and allowed their distinction from N. asteroides. The serious nature of disease due to N. farcinica and its resistance to the newer cephalosporins suggest a clinical need for laboratory identification of this species. (Current tests used in clinical laboratories do not distinguish N. farcinica from N. asteroides.) This is the first recognition that N. farcinica has a specific drug resistance pattern and confirms the previously described concept that drug resistance patterns of N. asteroides may be associated with specific taxonomic groups.

Infection caused by Nocardia farcinica: case report and review

Nocardia farcinica is a rare Nocardia species causing localised and disseminated infections. A case of Nocardia farcinica infection is presented, and 52 cases previously reported in the literature are reviewed. The hosts usually had predisposing conditions (85%), and acquired the infection through the respiratory tract or skin; the infection then often spread to the brain, kidney, joints, bones and eyes. Pulmonary or pleural infections (43%), brain abscesses (30%) and wound infections (15%) which failed to respond to conventional antimicrobial therapy were the more frequent forms of infection. Nocardia farcinica was frequently isolated from pus (100% of samples), bronchial secretions (41%) and biopsy specimens (63%), but isolation from blood and urine, as in the case presented here, is rare. Antibiotic therapy was adequate in 61% of the patients in whom it was specified, the agents most frequently given being trimethoprim-sulfamethoxazole (54%), amikacin combined with imipenem (7%) and amoxicillin-clavulanate (7%). The high mortality (31%) can be attributed to the severe underlying diseases present, difficulties encountered in identifying the pathogen, inappropriate therapy and late initiation of therapy. Although an infrequent pathogen, Nocardia farcinica should be kept in mind as a cause of infection especially in immunosuppressed patients with indolent infections not responding to third-generation cephalosporins.

Rapid identification of Mycobacterium avium complex in culture using DNA probes

A commercial DNA probe procedure for identification of Mycobacterium avium complex isolates was evaluated for accuracy and applicability for use in the clinical laboratory. The test (Gen-Probe Rapid Diagnostic System for Mycobacterium Avium Complex; Gen-Probe Corp., San Diego, Calif.) uses hybridization in solution of two 125I-labeled cDNA probes. One probe is complementary to rRNA from M. avium, and the other is complementary to rRNA from M. intracellulare. Results are expressed as absolute percent hybridization, with values greater than or equal to 10% considered positive. The procedure accurately identified all 134 M. avium complex isolates and concomitantly identified them to species level. There were no false-positives with 66 other mycobacteria, including 22 M. tuberculosis and 18 M. kansasii isolates, or with 8 Nocardia isolates. The mean percent hybridization (+/- the standard deviation) of M. avium probe-positive isolates (94 isolates) was 48.0 +/- 9.9 (range, 11.5 to 72.7); for M. intracellulare (40 isolates), it was 45.7 +/- 8.8 (range, 22.7 to 60.7). Among the 74 non-M. avium complex isolates, the percent hybridization range was 1.0 to 4.2, except for a single value of 9.7 which was less than 5 when the test was repeated. Four M. avium complex isolates reacted positively with both probes on initial testing, and three were confirmed. On repeat testing of subcultures, each reacted with only one probe, suggesting the presence of a mixed culture. The procedure can be completed in as little as 2 h and could easily be performed in most clinical laboratories.

Actinomycoses and Nocardia pulmonary infections

PURPOSE OF REVIEW

Actinomycosis and nocardiosis are uncommon pulmonary infections with distinct morphologic features. Both infections most commonly present as chronic, debilitating illnesses with radiographic manifestations simulating lung cancer or tuberculosis. Immunocompromised hosts, however, may develop fulminant disease resembling acute bacterial pneumonia. The purpose of this review is primarily to review the clinical features, diagnosis, and management of actinomycosis and nocardiosis.

RECENT FINDINGS

Treatment of actinomycosis is usually simple, requiring long-term, high-dose intravenous penicillin. Short-course chemotherapy, however, has recently been reported to be successful. Pulmonary nocardiosis is an important cause of opportunistic infection in immunosuppressed patients, and the incidence of this infection is increasing. The sulfonamides are still first-line agents in the management of nocardiosis, but resistance is most common among N. farcinica and N. otitidiscaviarum isolates. Carbapenems should be used as an alternative treatment for severely ill patients. Broth microdilution, E-test (AB Biodisk, Solna, Sweden) and BACTEC (Becton Dickinson, Sparks, Maryland, USA) radiometric method may be more useful in the routine clinical laboratory for antimicrobial testing of aerobic actinomycetes.

SUMMARY

The practical distinction between the two diseases is in the matter of therapy. Diagnosis depends on a high degree of suspicion so as to alert the microbiology and pathology laboratories to employ special methods to identify the organisms. Early recognition and prompt treatment usually results in complete cure.

Evaluation of partial 16S ribosomal DNA sequencing for identification of nocardia species by using the MicroSeq 500 system with an expanded database

Identification of clinically significant nocardiae to the species level is important in patient diagnosis and treatment. A study was performed to evaluate Nocardia species identification obtained by partial 16S ribosomal DNA (rDNA) sequencing by the MicroSeq 500 system with an expanded database. The expanded portion of the database was developed from partial 5' 16S rDNA sequences derived from 28 reference strains (from the American Type Culture Collection and the Japanese Collection of Microorganisms). The expanded MicroSeq 500 system was compared to (i). conventional identification obtained from a combination of growth characteristics with biochemical and drug susceptibility tests; (ii). molecular techniques involving restriction enzyme analysis (REA) of portions of the 16S rRNA and 65-kDa heat shock protein genes; and (iii). when necessary, sequencing of a 999-bp fragment of the 16S rRNA gene. An unknown isolate was identified as a particular species if the sequence obtained by partial 16S rDNA sequencing by the expanded MicroSeq 500 system was 99.0% similar to that of the reference strain. Ninety-four nocardiae representing 10 separate species were isolated from patient specimens and examined by using the three different methods. Sequencing of partial 16S rDNA by the expanded MicroSeq 500 system resulted in only 72% agreement with conventional methods for species identification and 90% agreement with the alternative molecular methods. Molecular methods for identification of Nocardia species provide more accurate and rapid results than the conventional methods using biochemical and susceptibility testing. With an expanded database, the MicroSeq 500 system for partial 16S rDNA was able to correctly identify the human pathogens N. brasiliensis, N. cyriacigeorgica, N. farcinica, N. nova, N. otitidiscaviarum, and N. veterana.

Group-specific small-subunit rRNA hybridization probes to characterize filamentous foaming in activated sludge systems

Foaming in activated sludge systems is characterized by the formation of a thick, chocolate brown-colored scum that floats on the surface of aeration basins and secondary clarifiers. These viscous foams have been associated with the presence of filamentous mycolic acid-containing actinomycetes. To aid in evaluating the microbial representation in foam, we developed and characterized group-, genus-, and species-specific oligonucleotide probes targeting the small subunit rRNA of the Mycobacterium complex, Gordona spp., and Gordona (Nocardia) amarae, respectively. The use of a universal base analog, 5-nitroindole, in oligonucleotide probe design was evaluated by comparing the characteristics of two different versions of the Mycobacterium complex probe. The temperature of dissociation of each probe was determined. Probe specificity studies with a diverse collection of 67 target and nontarget rRNAs demonstrated the specificity of the probes to the target groups. Whole-cell hybridizations with fluorescein- and rhodamine-labeled probes were performed with pure cultures of various members of the Mycobacterium complex as well as with environmental samples from a full-scale activated sludge plant which experienced foaming. Quantitative membrane hybridizations with activated sludge and anaerobic digester foam showed that 15.0 to 18.3% of the total small-subunit rRNAs could be attributed to members of the Mycobacterium complex, of which a vast majority consisted of Gordona rRNA. Several G. amarae strains made up only a very small percentage of the Gordona strains present. We demonstrated that group-specific rRNA probes are useful tools for the in situ monitoring and identification of filamentous bacteria in activated sludge systems.

Nocardiosis after bone marrow transplantation: a retrospective study

To evaluate the spectrum of nocardiosis after marrow transplantation, we reviewed the medical records of 27 patients with nocardiosis who were treated at three centers, and we reviewed the findings of three cases reported in the literature. Nocardial involvement was defined as invasive nocardiosis (n = 25), colonization (n = 4), or contamination (n = 1). The median time to the diagnosis of nocardiosis after marrow transplantation was 210 days. Nocardia asteroides complex accounted for 96% of isolates. All 25 invasive infections occurred in allogeneic marrow recipients. Ten (40%) of 25 patients with invasive nocardiosis were receiving double-strength oral trimethoprimsulfamethoxazole twice weekly as prophylaxis for Pneumocystis carinii pneumonia. Treatment regimens for nocardiosis included sulfonamides; synergistic agents were also often added. The overall survival rate at 6 years was 34%; survival from the infection itself was 84%. Two of four nocardiosis-related deaths also involved other pathogens. The incidence of nocardiosis among allogeneic marrow recipients averaged 0.3% over 25 years. We conclude that nocardiosis is a rare infection that occurs later after marrow transplantation than other infections and that is marginally associated with increased mortality among long-term survivors of allogeneic marrow transplantation.

Rapid identification of clinically relevant Nocardia species to genus level by 16S rRNA gene PCR

Two regions of the gene coding for 16S rRNA in Nocardia species were selected as genus-specific primer sequences for a PCR assay. The PCR protocol was tested with 60 strains of clinically relevant Nocardia isolates and type strains. It gave positive results for all strains tested. Conversely, the PCR assay was negative for all tested species belonging to the most closely related genera, including Dietzia, Gordona, Mycobacterium, Rhodococcus, Streptomyces, and Tsukamurella. Besides, unlike the latter group of isolates, all Nocardia strains exhibited one MlnI recognition site but no SacI restriction site. This assay offers a specific and rapid alternative to chemotaxonomic methods for the identification of Nocardia spp. isolated from pathogenic samples.

Nocardia cyriacigeorgici sp. nov

Chemotaxonomic and 16S rRNA gene sequence analyses of an isolate from the bronchial secretions of a patient with chronic bronchitis demonstrated clearly that it belongs to the genus Nocardia. The 16S rRNA gene sequence data, as well as the biochemical characteristics of the isolate, indicated that it belongs to a new species that differs from previously described members of the genus Nocardia. The name Nocardia cyriacigeorgici sp. nov. is proposed for this isolate, and is represented by strain IMMIB D-1627T (= DSM 44484T).

Identification of nocardia species by restriction endonuclease analysis of an amplified portion of the 16S rRNA gene

Identification of clinical isolates of Nocardia to the species level is important for defining the spectrum of disease produced by each species and for predicting antimicrobial susceptibility. We evaluated the usefulness of PCR amplification of a portion of the Nocardia 16S rRNA gene and subsequent restriction endonuclease analysis (REA) for species identification. Unique restriction fragment length polymorphism (RFLP) patterns were found for Nocardia sp. type strains (except for the N. asteroides type strain) and representative isolates of the drug pattern types of Nocardia asteroides (except for N. asteroides drug pattern type IV, which gave inconsistent amplification). A variant RFLP pattern for Nocardia nova was also observed. Twenty-eight clinical isolates were evaluated both by traditional biochemical identification and by amplification and REA of portions of the 16S rRNA gene and the 65-kDa heat shock protein (HSP) gene. There was complete agreement among the three methods on identification of 24 of these isolates. One isolate gave a 16S rRNA RFLP pattern consistent with the biochemical identification but was not identifiable by its HSP gene RFLP patterns. Three isolates gave 16S rRNA RFLP patterns which were inconsistent with the identification obtained by both biochemical tests and HSP gene RFLP; sequence analysis suggested that two of these isolates may belong to undefined species. The PCR and REA technique described appears useful both for the identification of clinical isolates of Nocardia and for the detection of new or unusual species.

Sulfonamide resistance in isolates of Nocardia spp. from a US multicenter survey

Recent reports of increasing in vitro sulfonamide resistance in Nocardia prompted us to investigate the findings. Despite the reports, there is a paucity of clinical reports of sulfonamide failure in treatment of nocardia disease. We reviewed 552 recent susceptibilities of clinical isolates of Nocardia from six major laboratories in the United States, and only 2% of the isolates were found to have resistant MICs of trimethoprim-sulfamethoxazole and/or sulfamethoxazole. We hypothesize that the discrepancies in the apparent sulfonamide resistance between our study and the previous findings may be associated with difficulty in the laboratory interpretation of in vitro MICs for trimethoprim-sulfamethoxazole and sulfamethoxazole and the lack of quality controls for Nocardia for these agents.

Infection with Nocardia species in Queensland. A review of 102 clinical isolates

OBJECTIVE

To review the species distribution, pathologic significance and disease associations of clinical isolates of Nocardia and related bacteria in Queensland, and to examine the characteristics, treatment and outcome of patients infected with these organisms.

DESIGN AND SETTING

A retrospective review of Queensland State Health Laboratory records provided microbiological data for Nocardia isolates referred from other laboratories during the period January 1983 to December 1988. Clinical information was extracted from hospital case notes, or obtained from detailed questionnaires completed by attending physicians. Nocardia isolates were classified as "significant" if specific treatment for nocardiosis was given, or on the basis of autopsy findings.

PATIENTS

One hundred and two patients had a Nocardia species or a related organism isolated from clinical specimens during the study period.

RESULTS

The 102 isolates included Nocardia asteroides (45), N, brasiliensis (35), N. caviae (5) and N. transvalensis (5). Clinical results were available for 93 patients, of whom 74 (80%) had a significant isolate recovered. Primary pulmonary or disseminated disease occurred in 35 patients, and was caused mainly by N. asteroides. Significant infections of skin and soft tissues, primarily due to N. brasiliensis, were found in 39 patients. Preexisting lung disease and treatment with steroids and immunosuppression were risk factors for pulmonary and disseminated nocardiosis. A history of inoculation in an outdoor setting was frequent in patients with cutaneous disease. Antibiotic regimens that included trimethoprim-sulfamethoxazole or another sulfonamide agent were used to treat the majority of patients with significant infection. Deaths were confined to those with pulmonary and disseminated disease, with a case fatality rate of 40% in that group.

CONCLUSION

Infection with Nocardia species appears to be more common than is generally appreciated. The local species distribution and disease spectrum are similar to those described elsewhere. A high index of suspicion for nocardiosis should be maintained in susceptible hosts with pulmonary infiltrates, particularly when there is evidence for metastatic infection, and in patients with superficial infections and a history of outdoor injury.

Identification of nocardiae and streptomycetes of medical importance

During a taxonomic investigation of Nocardia spp. and Streptomyces spp., we received 658 isolates from laboratories of both human and veterinary medicine. Our procedure leading to the identification of 92% of these isolates, the species that they represented, and a characteristic pattern of properties of the strains of these species are presented. A key devised for the tentative identification of species of nocardiae and streptomycetes that are believed to be of medical importance is included to assist clinical microbiologists in identifying their strains.

Sequence-based identification of aerobic actinomycetes

We investigated the utility of 500-bp 16S rRNA gene sequencing for identifying clinically significant species of aerobic actinomycetes. A total of 28 reference strains and 71 clinical isolates that included members of the genera Streptomyces, Gordonia, and Tsukamurella and 10 taxa of Nocardia were studied. Methods of nonsequencing analyses included growth and biochemical analysis, PCR-restriction enzyme analysis of the 439-bp Telenti fragment of the 65 hsp gene, susceptibility testing, and, for selected isolates, high-performance liquid chromatography. Many of the isolates were included in prior taxonomic studies. Sequencing of Nocardia species revealed that members of the group were generally most closely related to the American Type Culture Collection (ATCC) type strains. However, the sequences of Nocardia transvalensis, N. otitidiscaviarum, and N. nova isolates were highly variable; and it is likely that each of these species contains multiple species. We propose that these three species be designated complexes until they are more taxonomically defined. The sequences of several taxa did not match any recognized species. Among other aerobic actinomycetes, each group most closely resembled the associated reference strain, but with some divergence. The study demonstrates the ability of partial 16S rRNA gene sequencing to identify members of the aerobic actinomycetes, but the study also shows that a high degree of sequence divergence exists within many species and that many taxa within the Nocardia spp. are unnamed at present. A major unresolved issue is the type strain of N. asteroides, as the present one (ATCC 19247), chosen before the availability of molecular analysis, does not represent any of the common taxa associated with clinical nocardiosis.

DNA amplification and restriction endonuclease analysis for differentiation of 12 species and taxa of Nocardia, including recognition of four new taxa within the Nocardia asteroides complex

Nineteen reference and 156 clinical strains of the genus Nocardia belonging to 12 taxonomic groups were studied for restriction fragment length polymorphism (RFLP) by using an amplified 439-bp segment of the 65-kDa heat shock protein gene. Of 30 restriction endonucleases, digestion with MspI and then digestion with BsaHI produced RFLP band patterns which separated all 12 groups except N. asteroides type IV from 6 of 12 N. transvalensis isolates and N. carnea from the N. asteroides type VI isolates. Commonly encountered species such as N. nova, N. farcinica, N. brasiliensis sensu stricto, and N. otitidiscaviarum were easily separated. Each taxon resulted in a single RFLP band pattern that included > or = 96% of all biochemically grouped isolates for 9 of 12 taxa with MspI and for 8 of 12 taxa with BsaHI. With the use of both patterns, only 6 of 175 (3.4%) isolates failed to fit the biochemically defined group patterns. These studies provide the first evidence for the separate identities of four antibiogram-defined (but currently unnamed) groups within the N. asteroides complex (types I, II, IV, and VI) and the presence of two subgroups within N. transvalensis. They also provide genotypic evidence for the separate identities of N. nova and N. farcinica. The lack of BstEII recognition sites in amplicons obtained from nocardiae provides a simple and rapid method for the differentiation of nocardiae from mycobacteria. DNA amplification with RFLP analysis is the first rapid method that distinguishes all clinically significant taxa and recognized species within the genus Nocardia.

Distribution of nocardia species in clinical samples and their routine rapid identification in the laboratory

Eighty-six Nocardia strains isolated from clinical samples in Belgium were identified by 16S rRNA gene sequencing. Eighty-three (96%) strains belonged to only six Nocardia species: N. farcinica (38 [44%]), N. nova (19 [22%]), N. cyriacigeorgica (13 [15%]), N. brasiliensis (6 [6.9%]), N. abscessus (5 [5.8%]), and N. paucivorans (2 [2.3%]). A gallery of nine conventional and enzymatic tests was developed for the rapid identification of the most common species isolated during this survey. Pyrrolidonyl aminopeptidase, gamma-glutamyl aminopeptidase, alpha-mannosidase, and alpha-glucosidase were found to be highly discriminating and could be used to develop an identification scheme.

Nocardial infections in bone marrow transplant recipients

Infections caused by Nocardia species have been infrequently described in bone marrow transplant (BMT) recipients. We reviewed six cases of nocardiosis occurring in our population of BMT recipients and the four cases previously reported in the literature. The rate of nocardial infection at our institution was 0.2% (1 of 554) among autologous BMT recipients and 1.7% (5 of 302) among allogeneic BMT recipients (odds ratio, 9.3 [95% confidence interval, 1.1-80.1]; P = .046). All 10 patients had received immunosuppressive medications, and all but one allogeneic BMT recipient had acute or chronic graft-vs.-host disease (GVHD). Four patients had extensive exposure to soil or dust before nocardiosis developed. Seventy percent of the patients died, but death was less often due to progressive nocardial infection than to complications of GVHD and associated invasive infection with Aspergillus species. Three patients had nocardiosis despite receiving prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMZ) on an intermittent basis two or three times a week. These data show that nocardial infection is an important if infrequent complication of bone marrow transplantation and is associated with a high rate of invasive fungal infection. TMP-SMZ prophylaxis given intermittently does not reliably protect against infection.

Cutaneous nocardiosis. Case reports and review

Two cases of cutaneous nocardial infection are reported. The Nocardia species are gram-positive, partially acid-fast bacteria. Cutaneous involvement may develop as one of four types: (1) mycetoma, (2) lymphocutaneous (sporotrichoid) infection, (3) superficial skin infection, or (4) systemic disease with cutaneous involvement. A review of each of these types of infection is included, as well as potential clues that may suggest the diagnosis of nocardiosis.

Nocardia veterana sp. nov., isolated from human bronchial lavage

A nocardioform bacterium was isolated from the bronchoscopic lavage of a 78-year-old man with a past history of tuberculous pleurisy, who presented with bilateral upper lobe lesions at Austin and Repatriation Medical Centre, Heidelberg, Australia. The strain was aerobic, Gram-positive, produced beige substrate mycelium and scant white aerial mycelium. It showed chemotaxonomic markers which were consistent with the classification of Nocardia: i.e. meso-diaminopimelic acid, N-glycolylmuramic acid, arabinose and galactose as diagnostic sugars; phospholipids phosphatidylinositol mannosides, phosphatidylinositol, phosphatidylethanolamine and diphosphatidylglycerol; a menaquinone with a cyclic isoprene side chain, MK-8(H4cycl.); a fatty acid pattern composed of unbranched saturated and monounsaturated fatty acids with a considerable amount of tuberculostearic acid; and mycolic acids composed of 54-62 carbon atoms with three principal mycolic acids which were mono- and polyunsaturated, showing a chain length C56, C58 and C60 and accounting for over 70% of the entire pattern. The 16S rDNA sequence showed the highest similarity to the type strain of Nocardia vaccinii; the DNA-DNA similarity of the two strains was 31%. These data, together with distinct physiological traits and molecular biological analyses, as well as chemotaxonomic results, led to the conclusion that the novel isolate represents a new species within the genus Nocardia for which the name Nocardia veterana sp. nov. is proposed. The type strain is M157222T (DSM 44445T = NRRL B-24136T).