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PubMed1991

Use of a siderophore detection medium, ethylene glycol degradation, and beta-galactosidase activity in the early presumptive differentiation of Nocardia, Rhodococcus, Streptomyces, and rapidly growing Mycobacterium species.

A simplified scheme for the presumptive early identification of Nocardia, Rhodococcus, rapidly growing Mycobacterium, and Streptomyces species is presented. The Nocardia and Streptomyces spp. and the Mycobacterium spp. were positive. The spp. were positive for siderophore activity, but only 25% of the Rhodococcus spp. were positive. The Rhodococcus and Mycobacterium spp. were negative for beta-galactosidase, while the Nocardia and Streptomyces spp. were positive. The Nocardia and Streptomyces spp. and the Mycobacterium spp. were negative for ethylene glycol degradation, while 75% of the Rhodococcus spp. were positive. In combination, these tests were useful for differentiating Mycobacterium, Rhodococcus, and Nocardia species but did not differentiate Nocardia from Streptomyces species.

Actinomycetales↗

PubMed1999

Otomastoiditis caused by Rhodococcus equi in a patient with AIDS.

Rhodococcus equi is a well-recognized pathogen in veterinary medicine and a rare but well-documented cause of cavitary pneumonia in immunocompromised patients. Most cases of Rhodococcus equi infections in these patients involve the lungs. Otomastoiditis due to Rhodococcus equi is rare, and disseminated Rhodococcus equi with otomastoiditis has never been reported. We report a case of otomastoiditis with systemic dissemination due to Rhodococcus equi in a patient with AIDS.

AIDS-Related Opportunistic Infections↗

PubMed1999

[Equine Rhodococcus equi pneumonia: first report in Israel and its significance for man].

Rhodococcus equi is an important pathogen in young horses. In recent years it has been increasingly recognized as an opportunistic infectious agent in patients with immune deficiency. The increase in recognized cases may be related to the increased prevalence of AIDS. However, more cases may have been recognized lately due to increased awareness of the pathogenicity of this bacterium. Based on medical reports, there appears to be an association between Rhodococcus equi infections and exposure to animals, horses in particular. During the past year, 2 cases of rhodococcus pneumonia were diagnosed in foals in Israel. This information deserves the attention of the local medical community because of the zoonotic potential of Rhodococcus equi and the danger of its becoming more common. The climate in Israel is conducive to its growth and viability and since it flourishes in an environment with horses, the significant growth in our equine industry in recent years may contribute to an increase in Rhodococcus infections.

Actinomycetales Infections↗

PubMed1993

Rhodococcus species fatal infection in an immunocompetent host.

A 24-year-old woman had fatal pneumonia-associated adult respiratory distress syndrome caused by Rhodococcus species. Histological examination of lung biopsy tissue showed intracellular coccobacillary microorganisms. Antimicrobial susceptibility tests on the patient's blood isolate showed that it was resistant to clindamycin and norfloxacin but susceptible to several other antimicrobial agents. Also, the isolate's biochemical reactions and pattern of RNA gene-containing restriction fragments were significantly different from those of the 20 recognized Rhodococcus species, suggesting that this patient's infection was caused by an as yet uncharacterized Rhodococcus species. Of the 17 human cases of nonequi Rhodococcus species infection reported to date (including the current case), nine patients were immunocompetent, five had disseminated infection, and four died. Further studies will be required to unequivocally establish the species status of this patient's Rhodococcus isolate biochemically and genetically.

Actinomycetales Infections↗

PubMed1994

Cloning, sequencing, and expression of Rhodococcus L-phenylalanine dehydrogenase. Sequence comparisons to amino-acid dehydrogenases.

L-Phenylalanine dehydrogenase catalyzes the NAD(+)-dependent, reversible, oxidative deamination of L-phenylalanine to form ammonia, phenyl pyruvate, and NADH. The enzyme has been purified to homogeneity from Rhodococcus sp. M4, and a partial amino acid sequence was obtained. A cosmid library of Rhodococcus sp. M4 genomic DNA was prepared and used to isolate a 2.5-kilobase PstI fragment that contained the pdh gene. The open reading frame of 1068 nucleotides encodes a polypeptide of 356 amino acids, portions of which match the amino acid sequence determined for the purified enzyme. Expression of the Rhodococcus pdh gene in Escherichia coli, which does not contain a phenylalanine dehydrogenase activity, yields a soluble enzyme exhibiting phenylalanine dehydrogenase activity. Both the enzyme purified from Rhodococcus and the enzyme expressed in E. coli are post-translationally modified by removal of the amino-terminal methionine. The overall amino acid sequence is homologous to previously reported sequences of leucine and phenylalanine dehydrogenases as well as several glutamate dehydrogenases. The amino-terminal portion of the enzyme contains residues involved in L-amino acid binding and catalysis, while the carboxyl-terminal portion contains the presumptive dinucleotide-binding domain. A detailed sequence comparison of Rhodococcus phenylalanine dehydrogenase with leucine, phenylalanine, and glutamate dehydrogenases suggests residues involved in general amino acid binding and others that provide for amino acid discrimination.

Amino Acid Oxidoreductases↗

PubMed1995

Empyema with malakoplakic-like lesions by Rhodococcus equi as a presentation of HIV infection.

Rhodococcus equi (Corynebacterium equi) is an aerobic actinomycetes, well described as a cause of pulmonary infection in different animals as horses, pigs and cows. This pathogen has a coccobacillar aspect and a variable acid-fast stain in tissues. Rare cases of human infection by Rhodococcus species were described, the majority by Rhodococcus equi, especially in patients with immunodeficiency syndrome (AIDS) in advanced stages of the disease. Usually the diagnosis of infections by Rhodococcus species is performed by positive blood or bronchoalveolar lavage cultures. Here we described a case of a pleuro-pulmonary infection by Rhodococcus equi, with malakoplakic-like lesions, that was the first manifestation of AIDS, whose diagnosis was performed by pleural biopsy (acid-fast bacteria with a variable coccobacillar aspect inside macrophages) and pleural fluid culture.

AIDS-Related Opportunistic Infections↗

PubMed1980

Ribosomal ribonucleic acid similarities in the classification of Rhodococcus and related taxa.

Duplexes were prepared between 14C-labelled rRNA from both Rhodococcus equi C7 and Rhodococcus rhodochrous N54 and DNA from 16 actinomycetes representing the genera Rhodococcus, Mycobacterium, Nocardia, Saccharopolyspora and Streptomyces. The relationships between the organisms were determined by plotting the temperature at which 50% of the duplex was denatured (Tm(e)) against the percentage of rRNA binding (microgram 14C-labelled rRNA duplexed per 100 micrograms filter-bound DNA). All of the strains formed stable duplexes but each organism occupied a definite area on the rRNA similarity map. All of the organisms share a close phylogenetic relationship but representatives of the genera Rhodococcus, Mycobacterium, Nocardia and Streptomyces fell into four recognizable clusters on the similarity map. These data support and extend current trends in the classification of Rhodococcus and allied taxa. The guanine plus cytosine content of the DNA from the test strains was within the range 69.3 to 76.9 mol %.

Actinomycetales↗

PubMed1996

Differentiation of Rhodococcus species by ribotyping.

The ribosomal RNA gene restriction patterns (ribotyping) was investigated with respect to the characterization of Rhodococcus species and R. rhodochrous strains. Chromosomal DNA was prepared, digested with BamH I, blotted, and hybridized with acetylaminofluorene-labelled 16 + 23S rRNA from E. coli. The type strains of seven Rhodococcus species studied gave different hybridization patterns in each case. All strains tested were clearly distinguishable by ribotyping. Patterns contained two to eight bands between 1.4 kb and 11.8 kb and demonstrated the high genetic divergence of genus Rhodococcus. Investigation of nine R. rhodochrous strains resulted in patterns with seven or eight bands. One fragment, 4.4 kb in size, was common to all R. rhodochrous strains and appears to be characteristic of R. rhodochrous. Ribotyping was evaluated as a tool for distinguishing between Rhodococcus species.

Blotting, Southern↗

PubMed1998

Detection of a nitric oxide synthase possibly involved in the regulation of the Rhodococcus sp R312 nitrile hydratase.

Crude homogenates from Rhodococcus sp 312 catalyze the conversion of L-arginine into L-citrulline and NO2-, the usual oxidation product of NO under aerobic conditions. They also catalyze the conversion of N omega-hydroxy-L-arginine (NOHA) into L-citrulline and NO2- with similar rates (10-15 and 100-150 nmol of product.min-1.(mg of protein)-1 respectively for the crude homogenate and for a fraction obtained from ammonium sulfate precipitation). L-citrulline formation is strongly inhibited by classical inhibitors of mammalian nitric oxide synthases (NOSs) such as N omega-methyl-L-arginine (NMA) and thio-L-citrulline (TC). Finally, the lack of inhibitory effects of EGTA, a classical inhibitor of constitutive mammalian NOSs, and the specific immunodetection of a 100 kD protein from Rhodococcus cytosol by an antibody raised against human inducible NOS, is in favor of the presence of a NOS similar to inducible mammalian NOSs in Rhodococcus sp 312. This NOS should be responsible for the NO-dependent inactivation of Rhodococcus Nitrile Hydratase (NHase) in the absence of light; it could regulate the activity of the latter enzyme.

Bacterial Proteins↗

PubMed1998

Thyroid abscess due to Rhodococcus equi in a patient infected with the human immunodeficiency virus.

A case of thyroid abscess due to Rhodococcus equi in an HIV-positive patient with previous pulmonary abscess is reported. Rhodococcus equi is a gram-positive rod that can cause infections in both immunocompetent and immunocompromised patients, though it occurs more frequently in patients with dysfunctional cellular immune systems. Several cases of Rhodococcus equi infection in persons infected with HIV have been reported. In these patients Rhodococcus equi usually invades the lungs, producing pneumonia. These infections often relapse, accompanied by intermittent bacteremia, despite conventional treatment. Extrapulmonary abscesses can occur.

AIDS-Related Opportunistic Infections↗

PubMed1991

Cloning, nucleotide sequence and expression in Escherichia coli of two cobalt-containing nitrile hydratase genes from Rhodococcus rhodochrous J1.

Rhodococcus rhodochrous J1 produces two kinds of cobalt-containing nitrile hydratases (NHases); one is a high molecular mass-NHase (H-NHase) and the other is a low molecular mass-NHase (L-NHase). Both NHases are composed of two subunits of different sizes (alpha and beta subunits). The H- and L-NHase genes were cloned into Escherichia coli by a DNA-probing method using the NHase gene of Rhodococcus sp. N-774, a ferric ion-containing NHase producing strain, as the hybridization probe and their nucleotide sequences were determined. In each of the H- and L-NHase genes, the open reading frame for the beta subunit was located just upstream of that for the alpha subunit, which probably belongs to the same operon. The amino acid sequences of each subunit of the H- and L-NHases from R. rhodochrous J1 showed generally significant similarities to those from Rhodococcus sp. N-774, but the arrangement of the coding sequences for two subunits is reverse of the order found in the NHase gene of Rhodococcus sp. N-774. Each of the NHase genes was expressed in E. coli cells under the control of lac promoter, only when they were cultured in the medium supplemented with CoCl2.

Amino Acid Sequence↗

PubMed1988

Isolation of Rhodococcus rhodochrous from a chronic corneal ulcer.

Organisms belonging to Rhodococcus species have been isolated as the causative agent of infections in many animals and humans. The majority of the human infections so far reported have been limited to immunocompromised patients including AIDS patients. We report an elderly woman with a chronic corneal ulcer infected with Rhodococcus. To our knowledge there is no previous report on a Rhodococcus infection of the eye. Rarity of this type of infection by Rhodococcus in a locally immunocompromised site in an otherwise healthy individual prompted this case history.

Aged↗

PubMed2000

Mycolic acids from Rhodococcus, Gordonia, and Dietzia.

The mycolic acids from 11 species of Rhodococcus, seven species of Gordonia, and one species of Dietzia were analyzed using capillary gas chromatography and mass spectrometry (GLC/MS). All strains tested in this study were divided into three groups according to the degree of double bonds and the average carbon number (Av.Nc.) of their mycolic acids. The genus Gordonia belongs to the first group possessing an Av.Nc. in the upper 50s and 60s with 0 to 5 double bonds. Some Rhodococcus species possessed Av.Nc. in the 40s with a variety of distributions of polyunsaturated fatty acids from 0 to 4. The rest of the Rhodococcus species and the genus Dietzia possessed Av.Nc. in the 30s with saturated fatty acids. We previously reported on Nocardia strains whose Av.Nc. were in the 50s. Considering the identification of mycolic acid-containing Actinomycetales at the generic level, the Av.Nc. proved to be useful as a means of differentiating the genera Rhodococcus, Gordonia and Nocardia. The genus Dietzia was found to have its own characteristic constitution of mycolic acid molecular species. The mycolic acids from D. maris 58001T were characterized by an almost equal amount of constituents of even- and odd-numbered carbon chains, whereas the major components of mycolic acids in all other strains had even-numbered carbon chains. Another characteristic of Dietzia was some even-numbered mycolic acids which contained odd-numbered straight chains with odd-numbered alpha-branches. These characteristics indicated that Dietzia might possess a novel fatty acid biosynthesis system.

Actinomycetales↗

PubMed2003

Comparative benzene-induced fatty acid changes in a Rhodococcus species and its benzene-sensitive mutant: possible role of myristic and oleic acids in tolerance.

A Gram positive bacterium of the genus Rhodococcus was isolated from a contaminated site in Sydney, Australia, for its ability to tolerate and degrade high concentrations of benzene. To identify fatty acids that may impart this Rhodococcus sp. with tolerance to toxic solvents, a benzene-sensitive strain, labeled M2b, was isolated using EMS mutagenesis. A comparative analysis of fatty acid profiles showed that strain M2b was unable to increase its saturated:unsaturated ratio of fatty acids to the level achieved by the w-t strain when both strains were challenged with benzene. This was due to M2b's increased abundance of myristic acid, and decreased abundance of oleic acid. In addition, by measuring the generalized polarization of the fluorescent membrane probe laurdan using fluorescence spectroscopy, we have shown for the first time the effects of an aromatic hydrocarbon on the membrane fluidity of a Rhodococcus sp. The fluidity of the membranes increased after only 0.5 hr of exposure to benzene, thus suggesting the partitioning of benzene within the lipid bilayer. The response of this Rhodococcus sp. to benzene may suggest a mechanism for how other microorganisms survive when toxic solvents are released within the vicinity of their environment.

Benzene↗

PubMed2000

Rhodococcus equi and HIV-1 infection in Uganda.

OBJECTIVES: To describe three cases of Rhodococcus equi infection in a cohort of HIV-1 infected adults in Entebbe, Uganda and to compare this to the rates and presentation of tuberculosis in this cohort. METHODS: Consecutive HIV-1 infected adults registering with a community HIV/AIDS clinic in Entebbe were enrolled in a cohort between October 1995 and June 1998 as part of an intervention trial of pneumococcal polysaccharide vaccine. Participants were routinely reviewed every 6 months and had open access to the clinic when unwell. Standard protocols were followed for investigation and management of illness. Microbiological investigations followed standard procedures. RESULTS: 1372 (71% female) study participants were followed for 2141 person years of observation (pyo). Rhodococcus equi was isolated from three study participants from blood, a lymph node aspirate and stool. The individuals were undergoing investigation of acute pneumonia, acute cough with cervical lymphadenopathy and chronic fever with wasting, respectively. The clinical features of these cases are described. All had a CD4 T-cell count of <300/ml. The rate of R. equi infection in the cohort was 1.4/1000 pyo. There were 132 cases of pulmonary and extrapulmonary tuberculosis in the cohort which were diagnosed either microbiologically or clinically. The rate of laboratory confirmed mycobacterial disease was 50.1/1000 pyo. The ratio of mycobacterial disease to R. equi disease was 36:1 (95% CI 11-113:1). CONCLUSIONS: Rhodococcus equi infection occurs in HIV-1 infected adults in Africa. The infection is clinically indistinguishable from pulmonary and extra-pulmonary tuberculosis in the cohort described here. Although the rate of R. equi disease is much less than that of tuberculosis, it is important to consider it in the differential diagnosis of tuberculous infection in cases which are smear negative. Rhodococcus equi infection is probably underdiagnosed in Africa due to a lack of microbiological facilities and its resemblance to common commensal organisms.

AIDS-Related Opportunistic Infections↗

PubMed1997

Active site-directed inhibitors of Rhodococcus 20 S proteasome. Kinetics and mechanism.

We have studied the mechanism of inhibition of the recombinant Rhodococcus proteasome by four different chemical classes of active site-directed small molecule inhibitors. Clasto-lactacystin beta-lactone is a time-dependent inhibitor of the Rhodococcus proteasome's ability to hydrolyze Suc-Leu-Leu-Val-Tyr-AMC, a substrate for this proteasome's single type of active site, and proceeds with a kinact/[I] of 1,700 M-1 s-1. Using peptide mapping of tryptic digests, LC/MS, and amino acid sequence analysis, we have established that the Ogamma of the hydroxyl group on the N-terminal threonine of the beta-subunit is the sole modification made by the beta-lactone. Active site titrations of the Rhodococcus proteasome with reversible peptide aldehydes show the expected stoichiometry of one inhibitor molecule per beta-subunit. Prior modification with beta-lactone completely abrogates the binding of peptidyl boronic acid inhibitors, suggesting that these inhibitors also inactivate the enzyme by reacting with the Ogamma moiety on Thr1. High performance liquid chromatography analysis of peptidyl vinyl sulfone-modified intact Rhodococcus proteasome beta-subunit and its tryptic peptides suggests that the peptidyl vinyl sulfone modifies a residue in the N-terminal 20 amino acids. This modification is also blocked by prior treatment with beta-lactone.

Binding Sites↗

PubMed2000

Rhodococcus koreensis sp. nov., a 2,4-dinitrophenol-degrading bacterium.

A 2,4-dinitrophenol-degrading bacterial strain, DNP505T, which was isolated from an industrial wastewater, was taxonomically studied by a polyphasic approach using phenotypic, chemotaxonomic and genetic methods. Strain DNP505T has a cell wall of chemotype IV containing meso-diaminopimelic acid, arabinose and galactose. The predominant menaquinone is MK-8(H2). Mycolic acids contain 43-53 carbon atoms. Strain DNP505T has a cellular fatty acid profile containing straight-chain saturated, unsaturated and 10-methyl-branched fatty acids and has C16:0 as the major fatty acid. The DNA G+C content is 66 mol%. Strain DNP505T formed a coherent cluster with Rhodococcus species in a phylogenetic inference based on 16S rDNA sequences. Interestingly, strain DNP505T was found to have two types of 16S rDNA sequence, which showed 10 bp sequence differences (99.3% nucleotide similarity). Its differences in some phenotypic characteristics and its genetic distinctiveness indicate that strain DNP505T is separate from Rhodococcus species described previously. It is therefore proposed that strain DNP505T should be placed in the genus Rhodococcus as a new species, Rhodococcus koreensis. The type strain of the new species is strain DNP505T (= KCTC 0569BPT = JCM 10743T).

2,4-Dinitrophenol↗

PubMed2001

A taxonomic note on the authorship and date of valid publication of Rhodococcus sputi.

Authorship of the name Rhodococcus sputi is variously attributed to Tsukamura 1978 or Tsukamura and Yano 1985. DNA-DNA binding data indicate that this species and Rhodococcus obuensis Tsukamura 1983 and Rhodococcus chubuensis Tsukamura 1983 are subjective (heterotypic) synonyms. Although these organisms have been placed in the genus Gordonia as Gordonia sputi, the correct name of the taxon created by unification of these three species is directly affected by the date of valid publication of these species as members of the genus Rhodococcus. Thus, the name R. sputi only has priority if the authorship is attributed to Tsukamura 1978. The question of authorship and priority is clarified in the present work.

Authorship↗