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PubMed1996

Attempts to find phenotypic markers of the virulence plasmid of Rhodococcus equi.

Four isolates of Rhodococcus equi, from pneumonic foals, and containing the 85 kb virulence plasmid, a porcine isolate containing an 80 kb plasmid, and their plasmid cured derivatives, were examined for 239 phenotypic properties in an attempt to find characters other than the virulence-associated protein (VapA) which might be encoded by the virulence plasmid in organisms grown at 37 degrees C. Tests chosen included those which have previously given variable results for R. equi isolates, since such variability might be attributed to plasmid curing, and characteristics which have been described as properties of plasmids of Rhodococcus species other than R. equi. Tests included cadmium resistance, Congo red binding, resistance to 26 antibiotics, conventional clinical microbiological tests, utilization of 95 different carbon sources, enzymatic activities in API ZYM, fluorogenic assays for exo- and endopeptidase, glycosidase activities, and testosterone degradation. Apart from production of VapA by foal isolates, no phenotypic property was identified in the plasmid-positive isolates. Phenotypic characteristics of R. equi that have not been described before, and might be useful in identification were: metabolism of N-acetyl-beta D-glucopyranoside, alpha- and beta-hydroxybutyric, alpha-ketobutyric and N-acetyl-glutamic acids, of methylpyruvate, heptanoate, nonanoate and stearate esters; exopeptidase activity against alanine-alanine-tyrosine, alanine-phenylalanine-lysine, glycine-arginine, lysine-alanine, and valine-glycine-alanine; endopeptidase activity against arginine and methionine; and hydrolysis of bis-phosphate ester.

Amino Acids↗

PubMed1997

Rhodococcus equi pneumonia in a patient with occult HIV infection: successful therapy.

We report a case of Rhodococcus equi cavitary pneumonia in a 37-year-old patient with occult HIV infection. Because of his good immune status, the patient was given oral erythromycin and rifampin which rapidly resolved the infection. This modality of treatment may be sufficient in HIV-positive selected patients fur the resolution of Rhodococcus equi pneumonia.

Actinomycetales Infections↗

PubMed1998

Physical and serologic examinations of foals at 30 and 45 days of age for early diagnosis of Rhodococcus equi infection on endemically infected farms.

OBJECTIVE: To evaluate results of physical and serologic examinations of foals at 30 and 45 days of age on 3 types of farms with various prevalences of clinical disease (endemic, sporadic, none) caused by Rhodococcus equi and to determine whether evaluations were helpful in early diagnosis and control of the disease. DESIGN: Prospective cohort study. ANIMALS: 144 foals at 30 and 45 days of age. PROCEDURE: During a 2-year period, 36 foals on farms at which R equi infection was endemic, 71 foals on farms at which the disease was sporadically detected, and 37 foals on farms without the disease were examined by means of auscultation of lungs, serum biochemical and hematologic analyses, and determination of antibody titers against R equi, using ELISA. Transtracheal aspirates were obtained from 14 of 32 foals that had clinical signs of disease and 7 of 41 seropositive foals that did not have clinical signs of disease. RESULTS: Prevalences of respiratory tract disease and seropositive conversion rates for 45-day-old foals on endemically and sporadically infected farms were significantly higher than on farms without the disease. Rhodococcus equi was isolated from tracheal aspirates of seropositive foals, even when clinical signs were not evident. CLINICAL IMPLICATIONS: Physical and serologic examinations of foals at 30 and 45 days of age were useful for early diagnosis of R equi infection, especially for foals on farms at which the disease was endemic.

Actinomycetales Infections↗

PubMed2004

Aldoxime dehydratase co-existing with nitrile hydratase and amidase in the iron-type nitrile hydratase-producer Rhodococcus sp. N-771.

We identified an aldoxime dehydratase (Oxd) gene in the 5'-flanking region of the nitrile hydratase-amidase gene cluster in the photoreactive iron-type nitrile hydratase-producer, Rhodococcus sp. N-771. The enzyme showed 96.3%, 77.6%, and 30.4% identities with the Oxds of Rhodococcus globerulus A-4, Pseudomonas chlororaphis B23, and Bacillus sp. OxB-1, respectively. The enzyme was expressed in Escherichia coli under the control of the lac- or T7 promoters in its intact and His6-tagged forms, purified, and characterized. The enzyme had heme b as a prosthetic group, catalyzed a stoichiometric dehydration of aldoxime into nitrile, and exhibited the highest activity at neutral pH and at around 30 degrees C similar to the known Oxd from Bacillus sp. OxB-1. The activity was enhanced by reducing agents, such as Na2S, Na2S2(O4), 2-mercaptoethanol, and L-cysteine and supplementary additions of electron acceptors such as flavins, sulfite ion, and vitamin K3. The effect of various chemicals on the enzyme activity was different in the presence and absence of the reducing reagent, Na2S. The enzyme preferentially acts on aliphatic-type substrates and the substrate specificity of the enzyme coincides with that reported for nitrile hydratase produced by the strain.

Journal Article↗

PubMed1977

The actinomycete-genus Rhodococcus: a home for the "rhodochrous" complex.

A numerical taxonomic classification study was carried out on 177 strains representing the "rhodochrous" complex and the genera Gordona, Mycobacterium and Nocardia. The strains were examined for 92 unit characters and the data were analysed by computer. Three clusters were defined at the 75 to 80% similarity level. The first was a heterogeneous cluster corresponding to the "rhodochrous" taxon whereas the other two contained Mycobacterium and Nocardia strains respectively. The good correlation between the numerical analysis and chemo-taxonomic, serological and genetical data collected from previous studies provides sufficient evidence for raising the "rhodochrous" taxon to generic status. We consider the generic name Rhodococcus Aopf to have priority over Proactinomyces (Jensen) Bradley & Bond, Jensenia Bisset & Moore and Gordona Tsukamura. In addition to the type species, Rhodococcus rhodochrous, nine species are recognized: R. bronchialis, R. coprophilus, R. corallinus, R. erythropolis, R. equi, R. rhodnii, R. rubrus, R. rubropertinctus and R. terrae.

Genetics, Microbial↗

PubMed1986

Distribution and application of mycobactins for the characterization of species within the genus Rhodococcus.

Representatives of 11 species of Rhodococcus were examined for their ability to synthesize mycobactin, a lipid-soluble siderophore, following iron-limited growth on solidified glycerol/asparagine medium. Rhodococcus bronchialis, R. terrae and R. rubropertinctus formed mycobactins, whereas the remaining species (R. coprophilus, R. equi, R. erythropolis, R. rhodnii, R. rhodochrous, R. ruber, R. maris and R. luteus) failed to synthesize these compounds even under conditions of strictly iron-limited growth. The mycobactins from R. terrae and R. rubropertinctus showed close similarity by thin-layer chromatography and high-performance liquid chromatography and could be easily distinguished from that of R. bronchialis.

Actinomycetales↗

PubMed1981

Occurrence of Rhodococcus coprophilus and associated actinomycetes in feces, sewage, and freshwater.

Freshwater, sewage, and fecal samples from various sources were examined for Rhodococcus coprophilus, associated actinomycetes, Escherichia coli, and fecal streptococci. Rhodococcus coprophilus was isolated consistently from feces of farm animals, poultry reared in proximity to farm animals, freshwater, and wastewater polluted with animal fecal wastes. It was not isolated from samples of human feces. The ratio of R. coprophilus total actinomycetes was higher in feces from cattle, sheep, ducks, and geese than in specimens from pigs, horses, and fowl. In samples from two freshwater streams polluted by fecal material from farm animals, the ratios of R. copropilus to total actinomycetes were similar to those found in fecal specimens from cattle and sheep. Ratios of fecal coliform to fecal streptococci could not distinguish between fresh human and animal fecal samples and, furthermore, were not reflected in the stream waters polluted by animal fecal material. R. coprophilus has potential in water and dairy bacteriology as a specific indicator organism of fecal pollution due to farm animal wastes.

Actinomycetaceae↗

PubMed1995

Multiple Polychlorinated Biphenyl Transformation Systems in the Gram-Positive Bacterium Rhodococcus sp. Strain RHA1.

The cloned bphA gene of the polychlorinated biphenyl (PCB) degrader Rhodococcus sp. strain RHA1 was expressed in Rhodococcus erythropolis IAM1399 cells, resulting in the transformation of di-, tri-, and tetrachlorobiphenyls. Disruption of the bphA1 gene in RHA1 resulted in a lack of growth on biphenyl and a loss of PCB transformation activity. However, the bphA1 insertion mutant of RHA1, designated RDA1, retained the ability to transform PCB congeners when grown on ethylbenzene as its carbon source. It also transformed 4-chlorobiphenyl to 4-chlorobenzoate, although it was suspected to be deficient in bphB and bphC gene activities as well as bphA. This suggested that an alternative PCB degradation system distinct from the one encoded by the cloned bph genes was present.

Journal Article↗

PubMed1981

Porcine abortions associated with Fungi, Actinomycetes, and Rhodococcus sp.

History, lesions, and results of microbiologic examinations are given for four porcine abortions associated with fungi and one each associated with Actinomadura madurae, an aerobic actinomycete, and Rhodococcus sp. The fungi were Gliomastix sp., Petriellidium boydii, Aspergillus fumigatus, and Exophiala jeanselmei. Parvovirus, isolated from one fetus, was the only other infectious agent identified. The presence of fungi, Actinomadura madurae, and Rhodococcus sp. in fetal and placental lesions indicates that they are a primary cause of sporadic abortion in pigs.

Abortion, Veterinary↗

PubMed2001

Metabolism of dibenzo-p-dioxin and chlorinated dibenzo-p-dioxin by a gram-positive bacterium, Rhodococcus opacus SAO101.

A dibenzo-p-dioxin-degrading bacterial strain, Rhodococcus opacus SAO101, was isolated from forest soil samples collected from the subtropical islands of Japan by enrichment of a mineral salt medium containing dibenzofuran as the sole carbon and energy source. The isolated bacterium could utilize dibenzo-p-dioxin as the sole carbon and energy source, and also many monocyclic aromatic compounds, such as toluene, phenol, and chlorobenzene, as well as bicyclic aromatic compounds, such as biphenyl, naphthalene, and dibenzothiophene. Furthermore, strain SAO101 has a high co-oxidative potential for chlorinated dibenzo-p-dioxin. Metabolite analysis of dibenzo-p-dioxin degradation by strain SAO101 revealed the formation of dihydrodiol, 2,2',3'-trihydroxybiphenyl ether, and a meta-cleavage compound of 2,2',3'-trihydroxybiphenyl ether, and the accumulation of dihydroxy compounds. On the basis of these results, the metabolic pathway of dibenzo-p-dioxin was proposed. This is the first report of the degradation of dibenzofurans/dibenzo-p-dioxins by a Rhodococcus species.

Journal Article↗

PubMed1999

Search for Virulence-Associated Antigens of Rhodococcus equi in Strains Isolated from Patients with Acquired Immunodeficiency Syndrome.

Rhodococcus equi (formerly Corynebacterium equi) are known to be highly virulent, intermediate in virulence, or avirulent correlated with specific virulence-associated antigens identified immunochemically by different molecular weights. The association of virulence antigens with infection of AIDS patients by this organism has not been sufficiently evaluated in Brazil or Italy. The objective of the present study was to search for virulence-associated antigens of 15-to 17-kD and 20-kD in Rhodococcus equi strains isolated from patients with rhodococcal infection and AIDS. Four Brazilian and 9 Italian strains were studied. All isolates were analyzed by gel electrophoresis followed by immunoblotting using specific monoclonal antibodies to identify virulence-associated antigens. The results obtained on gel electrophoresis analyses showed complexing of R. equi components with proteins of molecular weights ranging from 10-to 150-kD. By immunoblotting, a wide diversity in R. equi virulence-associated antigens was detected: 1 of the 4 Brazilian isolates and 2 Italian isolates had the 15-to 17-kD virulence-associated antigen, 3 Brazilian isolates and 1 Italian isolate had the 20-kD virulence-associated antigen, and the other Italian isolates had no virulence-associated antigens. These results indicate that the pathogenicity of R. equi strains for humans does not depend only on the presence of these well established virulence-associated antigens.

Journal Article↗

PubMed2003

Cloning and characterization of a 4-nitrophenol hydroxylase gene cluster from Rhodococcus sp. PN1.

A 4-nitrophenol (4-NP)-degrading bacterium was isolated from activated sludge and identified as a Rhodococcus sp. This bacterium, designated as strain PN1, could utilize 4-NP as a sole carbon, nitrogen and energy source. Degradation tests of 4-NP using cell suspensions of strain PN1 revealed that the degradation was induced by 4-NP and that 4-nitrocatechol (4-NC) was one of the metabolites. A gene library was constructed from the total DNA of strain PN1 and introduced into Rhodococcus rhodochrous ATCC 12674. Two recombinant strains showed 4-NP hydroxylase activity, and a 9.1-kb DNA fragment encoding the activity was isolated from one of the strains. In addition, a 2.4-kb smaller fragment expressing the activity was subcloned from the 9.1-kb fragment and sequenced. The sequence analysis showed that the fragment encodes a two-component 4-NP hydroxylase, the predicted amino acid sequence of which exhibits significant similarity to those of phenol hydroxylases and 4-hydroxyphenylacetate 3-hydroxylases belonging to the two-component flavin diffusible monooxygenase (TC-FDM) family proposed by Galán et al. (J. Bacteriol., 182, 627-636, 2000).

Journal Article↗

PubMedDate not supplied

[Periodic macromolecule syntheses in synchronized cultures of species belonging to the "Rhodococcus" genus ("Rhodochrous" group) (author's transl)].

The synthesis of total proteins, total RNA and DNA in exponential synchronous cultures of species belonging to the Rhodococcus genus (Nocardia restricta and N. canicruria) has been studied by chemical methods and pulsed incorporations of labelled precursors in the acid-insoluble fraction. The replication of DNA is discontinuous. Syntheses of RNA and proteins are periodic: they happen during two main periods during the time necessary for a doubling of the cell mass. A slowdown of these syntheses occurs during the DNA replication. This periodicity allows to explain the regular discontinuities previously observed on the absorbance curves of synchronous cultures. The discontinuous pattern in the macromolecules synthesis of Rhodococcus allows a comparison with the cell cycle of some lower eukaryotes but is different from the cycle of fast-growing bacteria.

Bacterial Proteins↗

PubMed1983

Sensitivity to capreomycin and prothionamide in strains of Mycobacterium, Nocardia, Rhodococcus, and related taxa for taxonomical purposes.

Sensitivity to capreomycin and to prothionamide was analysed for 150 strains belonging to the genera Mycobacterium, Nocardia, Rhodococcus, and related taxa. The analyses showed, e.g., that strains of Mycobacterium chelonei and Nocardia brasiliensis were more resistant to capreomycin than the other strains tested and that M. farcinogenes differed from M. senegalense concerning sensitivity to this drug. The analysis showed, furthermore, that strains of Mycobacterium differ from those of Nocardia, Rhodococcus, "Mycobacterium album", and "Gordona aurantiaca" in being more sensitive to prothionamide than these organisms. Strains designated N. amarae were more sensitive to both drugs than were the other tested strains of Nocardia, which indicates that N. amarae diverges from the other species of this genus.

Capreomycin↗

PubMed1978

DNA homology studies on Nocardia and Rhodococcus strains.

The genetic homogeneity of Nocardia amarae, Nocardia autotrophica and Rhodococcus strains and the relationship among these groups of microorganisms have been studied using the DNA reassociation method. Strains belonging to N. amarae and N. autotrophica form genetically homogeneous groups. Distinct differences have been found out among Rhodococcus strains.

DNA, Bacterial↗

PubMed2026

Polyethylene transformation by a psychrotolerant Rhodococcus strain assessed by transcriptomics and 13C-isotope tracing.

Polyethylene is increasingly accumulating in nature, including remote places like the Arctic. While abiotic processes fragment polyethylene in situ, biotic transformation by microorganisms is assumed to occur. However, the enzymes and pathways involved remain poorly characterized. In this study, we used an in-house biobank from cold environments to screen for potential bacteria capable of degrading polyethylene by screening the strains in silico using the database PlasticDB and in vivo using a fluorescence-based assay. Using transcriptomic and proteomic analyses to identify genes in promising candidate strains that encode extracellular enzymes potentially capable of degrading PE, we selected a Rhodococcus erythropolis strain and two of its enzymes: a hypothetical protein (Hypr1) and a lipase family protein (Lip2). Expressing the candidate genes heterologously in Escherichia coli resulted in positive results in the fluorescence-based assay for polyethylene transformation. Applying 13C-labelled polyethylene for assessing and estimating polyethylene transformation and carbon assimilation, we found that R. erythropolis and both untransformed and recombinant E. coli extracellularly transformed the initially added polyethylene after 70 days. In addition, untransformed E. coli and R. erythropolis converted small, but significant amounts of polyethylene-derived carbon to carbon dioxide. The 13C-label was also traced into the bacterial biomass of R. erythropolis. Overall, our results provide evidence for biotic transformation of untreated polyethylene and suggests a hypothetical protein and a lipase family protein as two novel enzyme candidates associated with PE transformation.

Rhodococcus↗

PubMed1996

Cytologic features of pulmonary malakoplakia related to Rhodococcus equi in an immunocompromised host.

Cytologic features are described in bronchial brushings of a large cavitary lung mass from an immunosuppressed patient who had undergone liver transplantation. Scattered histiocytes with abundant eosinophilic, vacuolated cytoplasm were noted in a background of bronchial cells. Within approximately one fourth of the histiocytes, targetoid intracytoplasmic inclusions were present, consistent with Michaelis-Gutmann bodies. They were diffusely positive by histo-chemical staining with von Kossa, Gomori methenamine silver, and periodic acid-Schiff stains, and focally positive with Prussian blue stain. Cultures of the abscess yielded Rhodococcus equi. The characteristic microscopic features of pulmonary malakoplakia can be discerned in bronchial brushings, and should be sought, particularly in immunocompromised patients.

Cytodiagnosis↗

PubMed2001

Rhodococcus equi and cytomegalovirus pneumonia in a renal transplant patient: diagnosis by fine-needle aspiration biopsy.

Rhodococcus equi is a common cause of pneumonia in animals. Human infection is rare. Increasing number of cases are being reported in immunosuppressed individuals mostly associated with HIV infection, but also in solid organ transplant recipients and leukemia/lymphoma patients. We report on an adult male who developed pneumonia and gastroenteritis 4 mo after receiving a renal transplant. CT scan of the lungs showed a dominant 2.5-cm upper lobe lung mass and smaller bilateral nodules. He underwent a diagnostic bronchoscopy with fine-needle aspiration biopsy of the largest lung nodule. Smears showed histiocytic granulomatous inflammation, foamy macrophages, and acute inflammatory exudate. Scattered foamy macrophages displayed intracellular coccobacilli identifiable on Diff-Quik stain. A few cells with changes suggestive of viral inclusions were identified. Cytomegalovirus (CMV) immunostain was positive in the cell block sections. Lung cultures grew R. equi. To the best of our knowledge, this is the first report of coinfection with R. equi and CMV.

Actinomycetales Infections↗