Nfa34810 Facilitates Nocardia farcinica Invasion of Host Cells and Stimulates Tumor Necrosis Factor Alpha Secretion through Activation of the NF-κB and Mitogen-Activated Protein Kinase Pathways via Toll-Like Receptor 4.

The mechanism underlying the pathogenesis of Nocardia is not fully known. The Nfa34810 protein of Nocardia farcinica has been predicted to be a virulence factor. However, relatively little is known regarding the interaction of Nfa34810 with host cells, specifically invasion and innate immune activation. In this study, we aimed to determine the role of recombinant Nfa34810 during infection. We demonstrated that Nfa34810 is an immunodominant protein located in the cell wall. Nfa34810 protein was able to facilitate the uptake and internalization of latex beads coated with Nfa34810 protein into HeLa cells. Furthermore, the deletion of the nfa34810 gene in N. farcinica attenuated the ability of the bacteria to infect both HeLa and A549 cells. Moreover, stimulation with Nfa34810 triggered macrophages to produce tumor necrosis factor alpha (TNF-α), and it also activated mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways by inducing the phosphorylation of ERK1/2, p38, JNK, p65, and AKT in macrophages. Specific inhibitors of ERK1/2, JNK, and NF-κB significantly reduced the expression of TNF-α, which demonstrated that Nfa34810-mediated TNF-α production was dependent upon the activation of these kinases. We further found that neutralizing antibodies against Toll-like receptor 4 (TLR4) significantly inhibited TNF-α secretion. Taken together, our results indicated that Nfa34810 is a virulence factor of N. farcinica and plays an important role during infection. Nfa34810-induced production of TNF-α in macrophages also involves ERK, JNK, and NF-κB via the TLR4 pathway.

A rare case of isolated cauda equina Nocardia farcinica infection.

Nocardia is a Gram-positive, partially acid-fast, catalase-positive, and urease-positive bacterium that grows aerobically. We present an extremely rare case of cauda equina syndrome due to isolated intramedullary Nocardia farcinica infection. A 44-year-old male presented with low backache and gradually progressive weakness in bilateral lower limbs followed by paraplegia. He was found to have a well-defined, sharply demarcated ring-enhancing lesion located from T11-T12 to L3 vertebral body. He underwent laminectomy and decompression. The histopathological examination revealed a Gram-positive filamentous organism that looks like Nocardia. The culture report was suggestive of Nocardia farcinica. He was then treated with antibiotics and had a remarkable clinical and radiological improvement.

Production of a Novel Tetrahydroxynaphthalene (THN) Derivative from Nocardia sp. CS682 by Metabolic Engineering and Its Bioactivities.

Nargenicin A1 is major secondary metabolite produced by Nocardia sp. CS682, with an effective antibacterial activity against various Gram-positive bacteria. Most Nocardia spp. have metabolic ability to produce compounds of diverse nature, so one-strain-many-compounds (OSMAC) approach can be applied for obtaining versatile compounds from these strains. In this study, we characterized a novel 1, 3, 6, 8-tetrahydroxynaphthalene (THN) derivative by metabolic engineering approach leading to the inactivation of nargenicin A1 biosynthesis. By using genome mining, metabolite profiling, and bioinformatics, the biosynthetic gene cluster and biosynthetic mechanism were elucidated. Further, the antibacterial, anticancer, melanin formation, and UV protective properties for isolated THN compound were performed. The compound did not exhibit significant antibacterial and cytotoxic activities, but it exhibited promising UV protection effects. Thus, metabolic engineering is an effective strategy for discovering novel bioactive molecules.

In Vitro Susceptibility Testing of Tedizolid against Isolates of Nocardia.

There is a paucity of efficacious antimicrobials (especially oral) against clinically relevant species of Nocardia To date, all species of Nocardia have been susceptible to linezolid, the first commercially available oxazolidinone. Tedizolid is a new oxazolidinone with previously reported improved in vitro and in vivo (intracellular) potency against multidrug-resistant strains of Mycobacterium sp. and Nocardia brasiliensis Using the current Clinical and Laboratory Standards Institute-recommended broth microdilution method, 101 isolates of Nocardia spp., including 29 Nocardia cyriacigeorgica, 17 Nocardia farcinica, 13 Nocardia nova complex, 21 Nocardia brasiliensis, 5 Nocardia pseudobrasiliensis, and 5 Nocardia wallacei isolates and 11 isolates of less common species, were tested for susceptibility to tedizolid and linezolid. For the most common clinically significant species of Nocardia, tedizolid MIC50 values were 0.25 µg/ml for N. nova complex, N. brasiliensis, N. pseudobrasiliensis, and N. wallacei, compared to linezolid MIC50 values of 1, 2, 0.5, and 1 µg/ml, respectively. Tedizolid and linezolid MIC90 values were 2 µg/ml for N. nova complex and N. brasiliensis Tedizolid MIC50 and MIC90 values for both N. cyriacigeorgica and N. farcinica were 0.5 µg/ml and 1 µg/ml, respectively, compared to linezolid MIC50 and MIC90 values of 2 and 4 µg/ml, respectively. Based on MIC90 values, this study showed that tedizolid was 2- to 3-fold more active than linezolid in vitro against most common species of Nocardia, with the exception of the N. nova complex and N. brasiliensis, for which values were the same. These results may warrant evaluation of tedizolid as a potential treatment option for Nocardia infections.

Isolation and Structure Identification of Novel Brominated Diketopiperazines from Nocardia ignorata-A Lichen-Associated Actinobacterium.

Actinobacteria are well known for their potential in biotechnology and their production of metabolites of interest. Lichens are a promising source of new bacterial strains, especially Actinobacteria, which afford a broad chemical diversity. In this context, the culture medium of the actinobacterium Nocardia ignorata, isolated from the terrestrial lichen Collema auriforme, was studied. The strain was cultivated in a BioFlo 115 bioreactor, and the culture medium was extracted using an XAD7HP resin. Five known diketopiperazines: cyclo (l-Pro-l-OMet) (1), cyclo (l-Pro-l-Tyr) (2), cyclo (d-Pro-l-Tyr) (3), cyclo (l-Pro-l-Val) (4), cyclo (l-Pro-l-Leu) (5), and one auxin derivative: indole-carboxaldehyde (8) were isolated, along with two new brominated diketopiperazines: cyclo (d-Pro-l-Br-Tyr) (6) and cyclo (l-Pro-l-Br-Tyr) (7). Structure elucidation was performed using HRMS and 1D and 2D NMR analysis, and the synthesis of compounds 6 and 7 was carried out in order to confirm their structure.

Enhanced production of nargenicin A1 and creation of a novel derivative using a synthetic biology platform.

Nargenicin A1, an antibacterial produced by Nocardia sp. CS682 (KCTC 11297BP), demonstrates effective activity against various Gram-positive bacteria. Hence, we attempted to enhance nargenicin A1 production by utilizing the cumulative effect of synthetic biology, metabolic engineering and statistical media optimization strategies. To facilitate the modular assembly of multiple genes for genetic engineering in Nocardia sp. CS682, we constructed a set of multi-monocistronic vectors, pNV18L1 and pNV18L2 containing hybrid promoter (derived from ermE* and promoter region of neo r ), ribosome binding sites (RBS), and restriction sites for cloning, so that each cloned gene was under its own promoter and RBS. The multi-monocistronic vector, pNV18L2 containing transcriptional terminator showed better efficiency in reporter gene assay. Thus, multiple genes involved in the biogenesis of pyrrole moiety (ngnN2, ngnN3, ngnN4, and ngnN5 from Nocardia sp. CS682), glucose utilization (glf and glk from Zymomonas mobilis), and malonyl-CoA synthesis (accA2 and accBE from Streptomyces coelicolor A3 (2)), were cloned in pNV18L2. Further statistical optimization of specific precursors (proline and glucose) and their feeding time led to ~84.9 mg/L nargenicin from Nocardia sp. GAP, which is ~24-fold higher than Nocardia sp. CS682 (without feeding). Furthermore, pikC from Streptomyces venezuelae was expressed to generate Nocardia sp. PikC. Nargenicin A1 acid was characterized as novel derivative of nargenicin A1 produced from Nocardia sp. PikC by mass spectrometry (MS) and nuclear magnetic resonance (NMR) analyses. We also performed comparative analysis of the anticancer and antibacterial activities of nargenicin A1 and nargenicin A1 acid, which showed a reduction in antibacterial potential for nargenicin A1 acid. Thus, the development of an efficient synthetic biological platform provided new avenues for enhancing or structurally diversifying nargenicin A1 by means of pathway designing and engineering.

Comparison of restriction enzyme pattern analysis and full gene sequencing of 16S rRNA gene for Nocardia species identification, the first report of Nocardia transvalensis isolated of sputum from Iran, and review of the literature.

Nocardial infections occur in different organs of the body and are common in immune disorder diseases of individuals. The aim of this study was to assess Nocardia species identification by phenotypic tests and molecular techniques applied to nocardiosis in Iranian patients. In the current study, various clinical samples were collected and cultured on conventional media and using the paraffin baiting method. Various phenotypic tests were performed. For accurate identification at the species level, restriction fragment length polymorphisms (RFLP) in the hsp65 and partial 16S rRNA genes and full gene sequencing of the 16S rRNA gene were used. Twenty-seven Nocardia spp. were isolated and analysis of phenotypic tests results showed Nocardia asteroides complex, Nocardia otitidiscaviarum, Nocardia nova, and Nocardia spp. New RFLP patterns of Nocardia strains with hsp65 and partial 16S rRNA genes were obtained. Full gene sequencing of the 16S rRNA gene identified Nocardia cyriacigeorgica, N. otitidiscaviarum, Nocardia farcinica, Nocardia transvalensis, and N. nova. Nocardia infections are rarely reported and this genus is the cause of various illnesses. Accurate identification of Nocardia spp. is important for epidemiology studies and treatment. It should also be noted that some species may have similar RFLP patterns; therefore, full gene sequencing of the 16S rRNA gene is necessary for confirmation.

Nocardia Colonization: A Risk Factor for Lung Deterioration in Cystic Fibrosis Patients?

BACKGROUND: Cystic fibrosis (CF) patients are predisposed to infection and colonization with different microbes. Some cause deterioration of lung functions, while others are colonizers without clear pathogenic effects. Our aim was to understand the effects of Nocardia species in sputum cultures on the course of lung disease in CF patients. MATERIAL AND METHODS: A retrospective study analyzing the impact of positive Nocardia spp. in sputum of 19 CF patients over a period of 10 years, comparing them with similar status patients without Nocardia growth. Pulmonary function tests (PFTs) are used as indicators of lung disease severity and decline rate in functions per year is calculated. RESULTS: No significant difference in PFTs of CF patients with positive Nocardia in sputum was found in different sub-groups according to number of episodes of growth, background variables, or treatment plans. The yearly decline in PFTs was similar to that recognized in CF patients. The control group patients showed similar background data. However, a small difference was found in the rate of decline of their PFTs, which implies a possibly slower rate of progression of lung disease. CONCLUSIONS: The prognosis of lung disease in CF patients colonized with Nocardia does not seem to differ based on the persistence of growth on cultures, different treatment plans or risk factors. Apparently, Nocardia does not cause a deterioration of lung functions with time. However, it may show a trend to faster decline in PFTs compared to similar status CF patients without isolation of this microorganism in their sputum.

[GLUCOSE METABOLISM IN SURFACTANTS PRODUCER NOCARDIA VACCINII IMV B-7405].

Key enzymes of glucose metabolism were detected in the cells of surfactants producer Nocardia vaccinii IMV B-7405 grown on this substrate. It has been established that glucose catabolism is performed through gluconate (FAD(+)-dependent glucose dehydrogenase activity 698 ± 35 nmol x min(-1) x mg(-1) of protein). Oxidation of gluconate to 6-phosphogluconate is catalised by gluconokinase (178 ± 9 nmol x min(-1) x mg(-1) of protein). 6-Phosphogluconate was involved into pentose phosphate cycle by constitutive NADP(+)-dependent 6-phosphogluconate dehydrogenase (activity 357 ± 17 nmol x min(-1) x mg(-1) of protein). The data obtained serve as the basis for theoretical calculations of optimal molar ratio of concentrations of energetically nonequivalent substrates for intensifying the surfactants synthesis on their mixture.

[Influence of heavy metals on surfactants synthesis by Nocardia vaccinii IMV B-7405].

The production of surfactants by Nocardia vaccinii IMV B-7405 in glycerol -and hydrocarbon-containing medium after addition Cd(3+) Pb(2+) and Cu(2+) was investigated. It was established that the introduction of 0.1 mM Cu(2+) in the exponential growth phase of IMV B-7405 strain or simultaneous addition of Cu(2+) (0.1 mM) and Cd(2+) (0.3 mM), Cu(2+) (0.1 mM) and Pb(2+) (0.3 mM) in stationary phase was accompanied by the increase of conditional concentration of the surfactant (by 53 and 20-26%, respectively) compared with indexes in the medium without metals cations. It was established that the surfactants of N. vaccinii IMV B-7405 possessed protective functions from heavy metals influence. After surfactants elimination the survival of cells of strain IMV B-7405 in the presence of Cu(2+) (1.5-2.5 mM), Cd(2+) or Pb(2+) (0.1-0.3 mM) decreased a few times (to 5-45%). The inhibition action of Cu(2+) on alkane hydroxylase activity (the first enzyme of hydrocarbon catabolism) and stimulation--on phosphoenolpyruvate synthetase (enzyme of surface-active glycolipids biosynthesis) in MB B-7405 have been established.

[Synthesis of surfactants by Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 on industrial waste].

The synthesis of surfactants by Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 on industrial waste (food and oil-processing industry, production of biodiesel) was investigated. The possibility of replacing the expensive substrates (n-hexadecane and ethanol) by industrial waste (oil and fat industry, fried sunflower oil, glycerol, liquid paraffin) for the surfactant biosynthesis was established. The conditional concentration of surfactants was maximal on oil containing substrates and exceeded those on n-hexadecane and ethanol 2-3 times. The highest rates of surfactants synthesis were observed on fried sunflower oil with the use of inoculum grown on carbohydrate substrates (glucose, molasses). It was established that the addition of glucose (0.1%) was accompanied by 2-4-fold intensification of surfactants synthesis by R. erythropolis IMV Ac-5017 and N. vaccinii IMV B-7405 on fried sunflower oil (2%).

Microbial gutta-percha degradation shares common steps with rubber degradation by Nocardia nova SH22a.

Nocardia nova SH22a, a bacterium capable of degrading gutta-percha (GP) and natural rubber (NR), was used to investigate the GP degradation mechanism and the relations between the GP and NR degradation pathways. For this strain, a protocol of electroporation was systematically optimized, and an efficiency of up to 4.3 × 10(7) CFU per µg of plasmid DNA was achieved. By applying this optimized protocol to N. nova SH22a, a Tn5096-based transposon mutagenesis library of this bacterium was constructed. Among about 12,000 apramycin-resistant transformants, we identified 76 stable mutants defective in GP or NR utilization. Whereas 10 mutants were specifically defective in GP utilization, the growth of the other 66 mutants was affected on both GP and NR. This indicated that the two degradation pathways are quite similar and share many common steps. The larger number of GP-degrading defective mutants could be explained in one of two ways: either (i) the GP pathway is more complex and harbors more specific steps or (ii) the steps for both pathways are almost identical, but in the case of GP degradation there are fewer enzymes involved in each step. The analysis of transposition loci and genetic studies on interesting genes confirmed the crucial role of an α-methylacyl-coenzyme A racemase in the degradation of both GP and NR. We also demonstrated the probable involvement of enzymes participating in oxidoreduction reactions, ß-oxidation, and the synthesis of complex cell envelope lipids in the degradation of GP.

Two different primary oxidation mechanisms during biotransformation of thymol by gram-positive bacteria of the genera Nocardia and Mycobacterium.

Thymol has antibacterial, antifungal, insecticidal, and antioxidative properties which are the basis for the wide use of this compound in the cosmetic, food, and pharmaceutical industries. Although thymol is a ubiquitously occurring substance in the environment, data about its degradation and detoxification by bacteria are sparse. Here, we show the existence of two different pathways for the biotransformation of thymol by Nocardia cyriacigeorgica and Mycobacterium neoaurum which were described for the first time for gram-positive bacteria. The first pathway starts with hydroxylation of thymol to thymohydroquinone (2-isopropyl-5-methylbenzene-1,4-diol) with subsequent oxidation to thymobenzoquinone (2-isopropyl-5-methyl-1,4-benzoquinone). The second pathway involves hydroxylation of the methyl group followed by oxidation to 3-hydroxy-4-isopropylbenzoic acid, possibly via the aldehyde 3-hydroxy-4-isopropylbenzaldehyde. It is noteworthy that the branched side chain of thymol was not oxidized. Similarities and differences of these oxidation processes with those of the gram-negative bacterium Pseudomonas putida, fungi, and plants are discussed and, in addition, the toxicity of thymol towards N. cyriacigeorgica and M. neoaurum was tested. The experiments showed a temporary growth inhibition with 0.025 % thymol. This was explained by degradation of thymol and the formation of products which are less toxic than thymol itself.

[Effect of surface-active substances of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Ac-5017, and Nocardia vaccinii K-8 on phytopathogenic bacteria].

The effect of surface-active substances (SAS's) of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Ac-5017, and Nocardia vaccinii K-8 on phytopathogenic bacteria has been studied. It was shown that the survival of cells (10(5)-10(7) in a milliliter) of the Pseudomonas and Xanthomonas phytopathogenic bacteria was found to be 0-33% after treatment with SAS preparations of the IMV Ac-5017 and IMV B-7241 strains for 2 h (0.15-0.4 mg/mL). In the presence of N. vaccinii K-8 SAS preparations (0.085-0.85 mg/mL), the number of cells of the majority of the studied phytopathogenic bacteria decreased by 95-100%. These data show prospects for using microbial SAS's for the construction of ecologically friendly drugs for regulating the number of phytopathogenic bacteria.

In vitro actinomycete biofilm development and inhibition by the polyene antibiotic, nystatin, on IUD copper surfaces.

The presence of intrauterine contraceptive devices (IUDs) gives a solid surface for attachment and an ideal niche for biofilm to form and flourish. Pelvic actinomycosis is often associated with the use of IUDs. Treatment of IUD-associated pelvic actinomycosis requires the immediate removal of the IUD. Therefore, this article presents in vitro evidence to support the use of novel antibiotics in the treatment of actinomycete biofilms. Twenty one clinical actinomycetes isolates from endocervical swabs of IUD wearers were assessed for their biofilm forming ability. An in vitro biofilm model with three isolates, Streptomyces strain A4, Nocardia strain C15 and Nocardia strain C17 was subjected to treatment with nystatin. Inhibition of biofilm formation by nystatin was found to be concentration dependent, with MBIC50 values in the range 0.08-0.16 mg ml(-1). Furthermore, at a concentration of 0.16 mg ml(-1), nystatin inhibited the twitching motility of the isolates, providing evidence for a possible mechanism of biofilm inhibition.

Construction of a Nocardia brasiliensis fluorescent plasmid to study Actinomycetoma pathogenicity.

Nocardia brasiliensis, is a bacteria that lives as saprophyte in soil and causes a disease called actinomycetoma in both human and animals. Nocardia brasiliensis is an intracellular, facultative bacterium that replicates and survives within host macrophages. The mechanisms involved in the evasion of the microbicidal actions of macrophages remain unclear. The filamentous growth of N. brasiliensis is resistant to unicellular preparations, leading to inaccurate quantification of bacterial numbers by means of colony forming units (CFU). As successful survival studies with green fluorescent protein (GFP)-expressing bacterial strains have been reported, we constructed a recombinant GFP-expressing strain of N. brasiliensis. The virulence of the modified strain is maintained because it induces mycetoma in BALB/c mice. This new strain can be used for bacterial survival assays using cytometry and to elucidate the pathogenicity mechanisms in Actinomycetoma infection.

Decrease of virulence for BALB/c mice produced by continuous subculturing of Nocardia brasiliensis.

BACKGROUND: Subculturing has been extensively used to attenuate human pathogens. In this work we studied the effect of continuous subculturing of Nocardia brasiliensis HUJEG-1 on virulence in a murine model. METHODS: Nocardia brasiliensis HUJEG-1 was subcultured up to 130 times on brain heart infusion over four years. BALB/c mice were inoculated in the right foot pad with the bacteria subcultured 0, 40, 80, 100 and 130 times (T0, T40, T80 T100 and T130). The induction of resistance was tested by using T130 to inoculate a group of mice followed by challenge with T0 12 weeks later. Biopsies were taken from the newly infected foot-pad and immunostained with antibodies against CD4, CD8 and CD14 in order to analyze the in situ immunological changes. RESULTS: When using T40, T80 T100 and T130 as inoculums we observed lesions in 10, 5, 0 and 0 percent of the animals, respectively, at the end of 12 weeks. In contrast, their controls produced mycetoma in 80, 80, 70 and 60% of the inoculated animals. When studying the protection of T130, we observed a partial resistance to the infection. Immunostaining revealed an intense CD4+ lymphocytic and macrophage infiltrate in healing lesions. CONCLUSIONS: After 130 in vitro passages of N. brasiliensis HUJEG-1 a severe decrease in its virulence was observed. Immunization of BALB/c mice, with these attenuated cells, produced a state of partial resistance to infection with the non-subcultured isolate.

Horizontal gene transfer (HGT) as a mechanism of disseminating RDX-degrading activity among Actinomycete bacteria.

AIMS: Hexahydro-1,3,5-trinitro-1,3,5,-triazine (RDX) is a cyclic nitramine explosive that is a major component in many high-explosive formulations and has been found as a contaminant of soil and groundwater. The RDX-degrading gene locus xplAB, located on pGKT2 in Gordonia sp. KTR9, is highly conserved among isolates from disparate geographical locations suggesting a horizontal gene transfer (HGT) event. It was our goal to determine whether Gordonia sp. KTR9 is capable of transferring pGKT2 and the associated RDX degradation ability to other bacteria. METHODS AND RESULTS: We demonstrate the successful conjugal transfer of pGKT2 from Gordonia sp. KTR9 to Gordonia polyisoprenivorans, Rhodococcus jostii RHA1 and Nocardia sp. TW2. Through growth and RDX degradation studies, it was demonstrated that pGKT2 conferred to transconjugants the ability to degrade and utilize RDX as a nitrogen source. The inhibitory effect of exogenous inorganic nitrogen sources on RDX degradation in transconjugant strains was found to be strain specific. CONCLUSIONS: Plasmid pGKT2 can be transferred by conjugation, along with the ability to degrade RDX, to related bacteria, providing evidence of at least one mechanism for the dissemination and persistence of xplAB in the environment. SIGNIFICANCE AND IMPACT OF STUDY: These results provide evidence of one mechanism for the environmental dissemination of xplAB and provide a framework for future field relevant bioremediation practices.

Isolation of nocobactin NAs as Notch signal inhibitors from Nocardia farcinica, a possibility of invasive evolution.

Notch signaling inhibitors with the potential of immune suppressor production by pathogenic bacteria for easy host infection were searched from extracts of Nocardia sp. Nocobactin NA-a (compound 1) and nocobactin NA-b (compound 2), which have been suggested as pathogenesis factors, were isolated from N. farcinica IFM 11523 isolated from the sputum of a Japanese patient with chronic bronchitis. Compounds 1 and 2 showed Notch inhibitory activities with IC50 values of 12.4 and 17.6 µM, respectively. Compound 1 and 2 decreased of Notch1 protein, Notch intracellular domain, and hairy and enhancer of split 1, which is a Notch signaling target protein. In addition, compounds 1 and 2 showed cytotoxicity against mouse macrophage-like cell line RAW264.7 with IC50 values of 18.9 and 21.1 µM, respectively. These results suggested that the Notch inhibitors production by pathogenic bacteria may increase pathogen infectivity.

An Unusual Presentation From a Sporadic Partially Acid-Fast Aerobic Actinomycete Resistant to Common Antibiotics.

Nocardia causes rare opportunistic infections, that can be challenging to diagnose because of atypical features on conventional microbiological identification techniques. Immunosuppressed patients are more susceptible to infections from Nocardia and are associated with multi-organ involvement. We report a case of a 63-year-old male who developed peritonitis from Nocardia farcinica that rarely causes infections in humans. The nonspecific symptoms, negative blood cultures, and slow growth can make diagnosis difficult. Despite aggressive therapy, the virulence and inherent resistance to the antibiotics can result in high mortality from Nocardia farcinica infections.