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PubMed1982

Numerical classification of some Rhodococci, Corynebacteria and related organisms.

Nineteen strains of Corynebacterium sensu stricto, 23 received as Corynebacterium equi or Rhodococcus equi, marker cultures of Arthrobacter, Brevibacterium, Bacterionema matruchotii, Cellulomonas flavigena, Kurthia zopfii, Listeria denitrificans, Microbacterium lacticum, Rhodococcus rubropertinctus and 88 representatives of Mycobacterium, Nocardia, Rhodococcus and the 'aurantiaca' taxon were the subject of numerical phenetic analyses using 92 characters. The data were examined using the simple matching (SSM) and Jaccard (SJ) coefficients and clustering was achieved using the average linkage algorithm. With a single exception, strains containing meso-diaminopimelic acid, arabinose, galactose and mycolic acids were recovered in five aggregate clusters corresponding to Corynebacterium sensu stricto, Mycobacterium, Nocardia, Rhodococcus and the 'aurantiaca' taxon. Most of the Corynebacterium (Rhodococcus) equi strains formed a good taxospecies which included the type strain of Corynebacterium hoagii. The numerical data, and the results of earlier chemical and genetical studies, also provide sufficient evidence for the transfer of Bacterionema matruchotii to Corynebacterium sensu stricto as Corynebacterium matruchotii comb.nov. and for the recognition of Rhodococcus globerulus sp.nov. for some strains previously classified as Rhodococcus rubropertinctus (Hefferan) Goodfellow & Alderson. The classification of the remaining marker strains correlates well with other major developments in coryneform taxonomy.

Actinomycetales↗
PubMed1997

Development of a Rhodococcus equi-Escherichia coli plasmid shuttle vector.

Isolates of Rhodococcus equi from pneumonic foals possess an 85- or 90-kb virulence-associated plasmid. A prominent, thermoregulated surface antigen, VapA, encoded by these plasmids is thought to be important in virulence. A 135-kb fragment containing the origin of replication of R. equi strain 103 virulence-associated plasmid (pOTS) was identified, sequenced, and its location identified. A simple R. equi-Escherichia coli shuttle plasmid (pRE-1) derived from the E. coli plasmid pACYC177 and the pOTS ori was developed. The plasmid transformed readily and was stable in either host and expressed kanamycin resistance but not beta-lactamase in R. equi. An improved 5.9-kb vector, pRE-7, was developed from pRE-1 and pBluescript. Subcloning of vapA into the multiple cloning site of the beta-galactosidase gene of pRE-7 resulted in weak expression of the gene both in E. coli and R. equi. The shuttle vector may be useful in examining regulation of virulence gene expression in R. equi.

Bacterial Proteins↗
PubMed1993

Rhodococcus equi-associated osteomyelitis in foals.

Two cases of Rhodococcus equi infection in foals are described, in which osteomyelitis was a feature. Because rhodococcal infection is usually low grade and chronic, and because the signs of early metaphysitis can be subtle, any articular or periarticular swelling in a foal from a farm with a history of rhodococcosis should be strongly suspected to be associated with R equi until proven otherwise.

Actinomycetales Infections↗
PubMed2004

Necrotic death of Rhodococcus equi-infected macrophages is regulated by virulence-associated plasmids.

Rhodococcus equi is a gram-positive intracellular pathogen that can cause severe bronchopneumonia in foals and AIDS patients. It has been reported that advanced infection of foals is characterized by tissue necrosis, coinciding with the presence of degenerate bacteria-laden macrophages. Here, we report that the possession of the VapA-expressing plasmid, which has been previously correlated with a high level of virulence for foals and mice, strongly increases cytotoxicity of R. equi for murine macrophage-like (J774E) cells. Isolates containing different, VapB-expressing plasmids are less virulent and also have a lower cytotoxic potential. Isogenic strains lacking either plasmid are avirulent and have a very low cytotoxic potential. We show, using fluorescence-activated cell sorter analysis (annexin V/7-amino-actinomycin D and sub-G1-analysis), Western blotting [poly(ADP-ribose) polymerase processing analysis], and electron microscopy (macrophage and nucleus morphologies) that the deaths of murine macrophages are the result of necrotic rather than apoptotic events. We demonstrate that the bacteria must be alive in order to act cytotoxic. Therefore, one effect of the virulence-associated plasmids during infection with R. equi is the promotion of necrotic damage to the host.

Animals↗
PubMed2005

Maturation of Rhodococcus equi-containing vacuoles is arrested after completion of the early endosome stage.

Rhodococcus equi is a facultative intracellular bacterium that can cause bronchopneumonia in foals and AIDS patients. Here, we have analyzed R. equi-containing vacuoles (RCVs) in murine macrophages by confocal laser scanning microscopy, by transmission electron microscopy and by immunochemistry upon purification. We show that RCVs progress normally through the early stages of phagosome maturation acquiring PI3P, early endosome antigen-1, and Rab5, and loosing all or much of them within minutes. Although mature RCVs possess the normally late endocytic markers, lysosome-associated membrane proteins, lysobisphosphatidic acid and Rab7, they lack other hallmark features of late endocytic organelles such as possession of cathepsin D, acid beta-glucuronidase, proton-pumping ATPase and the ability to fuse with prelabeled lysosomes. Bacterial strains possessing a virulence-associated plasmid maintain a nonacidified compartment for 48 h, whereas isogenic strains lacking such plasmids acidify progressively. In summary, RCVs represent a novel phagosome maturation stage positioned after completion of the early endosome stage and before reaching a fully mature late endosome compartment. In addition, vacuole biogenesis can be influenced by bacterial plasmids.

Animals↗
PubMed1992

[Lung abscess caused by Rhodococcus (Corynebacterium) equi in HIV infection. Two cases].

Rhodococcus (Corynebacterium) equi is a well-known Gram positive bacillus which is usually pathogenic in farm animals but rarely causes diseases in humans. Only 30 cases of human infection have been reported in the literature. R. equi has recently been added to the list of opportunistic agents in severe HIV infection. Its most common manifestation in immunocompromised is a slowly progressive pneumonia which may cavitate. R. equi pulmonary infections are difficult to treat: they usually require prolonged parenteral antibiotic therapy and often need surgical treatment. Two cases of cavitary pneumonia in patients with severe HIV infection are reported here. In one case the disease was associated with pulmonary Kaposi sarcoma and pneumocystis pneumonia; the other case was the first opportunistic infection in the course of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Rhodococcus equi-specific cytotoxic T lymphocytes in immune horses and development in asymptomatic foals.

Rhodococcus equi is an important cause of pneumonia in young horses; however, adult horses are immune due to their ability to mount protective recall responses. In this study, the hypothesis that R. equi-specific cytotoxic T lymphocytes (CTL) are present in the lung of immune horses was tested. Bronchoalveolar lavage (BAL)-derived pulmonary T lymphocytes stimulated with R. equi lysed infected alveolar macrophages and peripheral blood adherent cells (PBAC). As with CTL obtained from the blood, killing of R. equi-infected targets by pulmonary effectors was not restricted by equine lymphocyte alloantigen-A (ELA-A; classical major histocompatibility complex class I), suggesting a novel or nonclassical method of antigen presentation. To determine whether or not CTL activity coincided with the age-associated susceptibility to rhodococcal pneumonia, CTL were evaluated in foals. R. equi-stimulated peripheral blood mononuclear cells (PBMC) from 3-week-old foals were unable to lyse either autologous perinatal or mismatched adult PBAC targets. The defect was not with the perinatal targets, as adult CTL effectors efficiently killed infected targets from 3-week-old foals. In contrast, significant CTL activity was present in three of five foals at 6 weeks of age, and significant specific lysis was induced by PBMC from all foals at 8 weeks of age. As with adults, lysis was ELA-A unrestricted. Two previously described monoclonal antibodies, BCD1b3 and CD1F2/1B12.1, were used to examine the expression of CD1, a nonclassical antigen-presenting molecule, on CTL targets. These antibodies cross-reacted with both foal and adult PBAC. However, neither antibody bound alveolar macrophages, suggesting that the R. equi-specific, major histocompatibility complex-unrestricted lysis is not restricted by a surface molecule identified by these antibodies.

Actinomycetales Infections↗
PubMed1993

Lack of residual lung damage in horses in which Rhodococcus equi-induced pneumonia had been diagnosed.

The effect of prior Rhodococcus equi-induced pneumonia on pulmonary health was investigated in 5 horses (< 24 months old) using endoscopy, radiography, hematologic and bronchoalveolar lavage analyses, and pulmonary function testing. Rhodococcus equi-induced pneumonia had been diagnosed in principal horses when they were foals. Diagnosis was based on positive results of transtracheal aspiration and thoracic radiography at the time of initial clinical examination. Results of reevaluation of the respiratory system of these horses (R+) were compared with those of 5 age-matched healthy horses (R-) that lacked clinical or historical evidence of foalhood pneumonia. Significant differences in variables between the 2 groups of horses were not evident. In both groups, most horses had radiographic evidence of an accentuated bronchointerstitial pattern, although results of analysis of bronchoalveolar lavage specimens were normal and mononuclear cells predominated. Variability in results of the pulmonary function tests was observed within the between the 2 groups of horses. Only normalized dynamic lung compliance was slightly lower in the previously infected horses, but this difference was not significant. We concluded that horses previously infected with and successfully treated for R equi-induced pneumonia do not have detectable evidence of residual lung damage.

Actinomycetales Infections↗
PubMed2004

Rhodococcus equi-infected macrophages are recognized and killed by CD8+ T lymphocytes in a major histocompatibility complex class I-unrestricted fashion.

The goal of this research was to examine the role of cytotoxic T lymphocytes (CTL) in the control of Rhodococcus equi and specifically to determine if R. equi-specific CD8+ CTL occurred in the blood of immune horses. Equine peripheral blood mononuclear cells stimulated with antigen-presenting cells either infected with R. equi or exposed to soluble R. equi antigen lysed R. equi-infected target cells. Lysis was decreased to background by depletion of either CD2+ or CD3+ cells, indicating that the effector cell had a T-lymphocyte, but not NK cell, phenotype. Stimulation induced an increased percentage of CD8+ T cells in the effector population, and depletion of CD8+ T cells resulted in significantly decreased lysis of infected targets. Killing of R. equi-infected macrophages by effector cells was equally effective against autologous and equine leukocyte antigen A (classical major histocompatibility complex [MHC] class I) mismatched targets. To evaluate potential target antigens, target cells were infected with either virulent (80.6-kb plasmid-containing) or avirulent (plasmid-cured) R. equi. The degree of lysis was not altered by the presence of the plasmid, providing evidence that the virulence plasmid, which is required for survival within macrophages, was not necessary for recognition and killing of R. equi-infected cells. These data indicate that immunocompetent adult horses develop R. equi-specific CD8+ CTL, which may play a role in immunity to R. equi. The apparent lack of restriction via classical MHC class I molecules suggests a novel or nonclassical method of antigen processing and presentation, such as presentation by CD1 or other nonclassical MHC molecules.

Animals↗
PubMed1995

Rhodococcus equi-associated necrotizing lymphadenitis in a llama.

A case of Rhodococcus equi-associated necrotizing lymphadenitis in a 2-year-old male llama is described. Caseous necrosis, resembling macroscopically that seen in ovine caseous lymphadenitis, was observed diffusely in the tracheobronchial and mediastinal lymph nodes, and in an extensive lesion in the lungs. Necrosis was present to a lesser extent in the spleen and hepatic and gastric lymph nodes. Numerous bacteria-laden macrophages were present around the necrotic areas. The findings suggest that, as in cattle and pigs, the primary targets of R. equi infection in the llama are the lymphoid organs.

Animals↗
PubMed1986

Quantitative aspects of fecal Rhodococcus (Corynebacterium) equi in foals.

Quantitative aspects of fecal Rhodococcus (Corynebacterium) equi in newborn foals for 12 weeks after birth were investigated on two horse breeding farms. R. equi was found in the feces of foals during week 1 of life. The greatest numbers of R. equi were present in the feces of foals during the first 8 weeks of their lives, which coincides with the age when foals are most liable to be exposed to R. equi.

Age Factors↗
PubMed1988

Rhodococcus (Corynebacterium) equi: bactericidal capacity of neutrophils from neonatal and adult horses.

The capacity of hematogenous polymorphonuclear neutrophilic leukocytes (PMNL) to kill Rhodococcus equi was compared in horses of various ages. A radioisotope bactericidal assay was used to determine the capacity of PMNL to kill R equi. Assays were conducted on PMNL from horses in 3 groups: group I, 13 foals with a mean age of 3.3 days; group II, 10 group-I foals at a mean age of 35.7 days; and group III, adult dams of group-I foals. Bacteria were obtained from the lungs of a foal with R equi pneumonia and opsonized with fresh adult equine serum that contained R equi specific antibody. The mean peak percentage of R equi killed by PMNL was 78.9 for group I, 90.1 for group II, and 87.9 for group III. There was no significant difference (P greater than 0.05) among groups; however, 15% of foals in group I (2 foals) had a mean peak percentage of 30.5 killed, which was significantly (P less than 0.05) lower than the percentage for other foals in group I. The results of our investigation indicated that the capacity of PMNL to kill opsonized R equi is similar in neonatal, young, and adult horses. However, some neonatal foals have a substantially lower capacity to kill R equi, which may be an important factor in the pathogenesis of R equi infections.

Actinomycetales Infections↗
PubMed1985

Correlation of in vitro properties of Rhodococcus (Corynebacterium) equi with virulence for mice.

To study the virulence of Rhodococcus (Corynebacterium) equi, seven ATCC strains of different serotypes were tested for their LD50 in mice, clearance of the organism from the lungs and spleen following intravenous or intratracheal inoculation, and in vitro interaction with murine peritoneal macrophages. Strains ATCC 33704 and 33705 were virulent for mice and multiplied in the lungs and spleen, resulting in death of the animal in 5 days. The other five strains were avirulent for mice. The number of bacteria in the lungs and spleen of mice given these five strains decreased immediately. Pulmonary clearance of strains ATCC 33703, 33706, and 33707 was significantly more rapid than that of the virulent strains ATCC 33704 and 33705 12 hr after inoculation. Complete clearance of the avirulent strain ATCC 33707 occurred by day 14, while that of virulent ATCC 33704 and 33705 strains occurred by day 30. The virulent strains ATCC 33704 and 33705 were resistant not only to phagocytosis but also to intracellular killing by macrophages. Strains ATCC 33702 and 33706 were rapidly killed by macrophages although they were rather resistant to phagocytosis. Strain ATCC 33703 was easily phagocytized though resistant to killing by macrophages. The most avirulent strains, ATCC 33707 and 6939, were easily phagocytized and rapidly killed by macrophages. These results indicate that virulence appeared to be related to the ability of the organisms to resist clearance from the lungs and spleen and to resist phagocytosis and intracellular killing by macrophages.

Animals↗
PubMed1995

Rhodococcus meningitis in an immunocompetent host.

Rhodococcus species are increasingly being recognized as pathogens, especially in patients infected with the human immunodeficiency virus. Most cases of rhodococcus infection in these patients are due to Rhodococcus equi and involve the lungs. CNS infections due to Rhodococcus species are rare, and meningitis due to non-equi Rhodococcus has never been reported in a healthy host. We report a case of meningitis due to non-equi Rhodococcus in a previously healthy 24-year-old woman. We also review and summarize the reported cases of CNS infections caused by Rhodococcus species.

Actinomycetales Infections↗
PubMed2004

Can whole genome analysis refine the taxonomy of the genus Rhodococcus?

The current systematics of the genus Rhodococcus is unclear, partly because many members were originally included before the application of a polyphasic taxonomic approach, central to which is the acquisition of 16S rRNA sequence data. This has resulted in the reclassification and description of many new species. Hence, the literature is replete with new species names that have not been brought together in an organized and easily interpreted form. This taxonomic confusion has been compounded by assigning many xenobiotic degrading isolates with phylogenetic positions but without formal taxonomic descriptions. In order to provide a framework for a taxonomic approach based on multiple genetic loci, a survey was undertaken of the known genome characteristics of members of the genus Rhodococcus including: (i) genetics of cell envelope biosynthesis; (ii) virulence genes; (iii) gene clusters involved in metabolic degradation and industrially relevant pathways; (iv) genetic analysis tools; (v) rapid identification of bacteria including rhodococci with specific gene RFLPs; (vi) genomic organization of rrn operons. Genes encoding virulence factors have been characterized for Rhodococcus equi and Rhodococcus fascians. Based on peptide signature comparisons deduced from gene sequences for cytochrome P-450, mono- and dioxygenases, alkane degradation, nitrile metabolism, proteasomes and desulfurization, phylogenetic relationships can be deduced for Rhodococcus erythropolis, Rhodococcus globerulus, Rhodococcus ruber and a number of undesignated Rhodococcus spp. that may distinguish the genus Rhodococcus into two further genera. The linear genome topologies that exist in some Rhodococcus species may alter a previously proposed model for the analysis of genomic fingerprinting techniques used in bacterial systematics.

Actinobacteria↗
PubMed2000

Isolation and characterization of Corynebacterium ulcerans from cephalic implants in macaques.

To determine the prevalence of colonization by Corynebacterium ulcerans, we cultured samples from the cephalic implant-skin margin and pharynx of 26 rhesus macaques and one pig-tailed macaque. All but one of the samples from the cephalic implants yielded a mixed population of bacteria. C. ulcerans grew from the cephalic implants in 56% and from the pharynx in 3% of the implanted animals. We screened nine of these isolates for diphtheria toxin (DT) and phospholipase D (PLD). Polymerase chain reactions (PCR) failed to identify DT in any of the tested isolates, which also lacked DT activity in Elek tests. However, all nine isolates tested had PLD toxin activity as determined by conjoint hemolysis on sheep blood agar plates in the presence of equi factor (Rhodococcus equi). In addition, PCR assays and Southern blot hybridization confirmed the presence of pld in the isolates. The role of the PLD toxin in promoting colonization of cephalic implants by C. ulcerans is unknown. We found C. ulcerans to be a frequent contaminant of the cephalic implant-skin margin. Further studies are necessary to investigate the relative clinical importance of this organism and the efficacy of various implant maintenance protocols in preventing infection.

Animals↗
PubMed1994

[Serodiagnosis of caseous lymphadenitis (pseudotuberculosis) in sheep].

Random postmortal isolation of Corynebacterium pseudotuberculosis from the sheep used in a research project and the consequently determined serological positivity of these animals indicated the serological examination of the flock from which the sheep came. No symptoms of caseous lymphadenitis were ever observed in the flock in question and no data on the occurrence of this disease were available in the flock history. The sera of 228 head of sheep were used for examinations, while this number of sheep represented half the flock head. Agar-gel immunodiffusion (AID) and neutralization of the toxin C. pseudotuberculosis (NTX) were applied as serological assays. The antigen in both tests was an isolated form of toxin i.e. phospholipase D (PLD). To determine the effect of PLD, the intensity of its synergic hemolytic effect with the equi factor Rhodococcus equi was found out and it was expressed in activity units (AU). Undiluted serum with PLD containing 5,000 AU/ml was examined in AID. Positive precipitation was observed in 79 examined sera, out of which 71 were also positive in NTX. NTX demonstrated the inhibition of synergic hemolytic activity of PLD with the equi factor, which was used to sensibilize sheep erythrocytes in agar medium. PLD with the terminal content of 10 AU/ml was used, as well as twofold dilution series of sera. The first evaluated dilution series was 1:10. In this dilution series, the highest number of sera, 22, had the positive reaction. The highest positivity at a dilution series 1:5,120 was found out in one serum. A total of 71 sera had positive reactions in NTX and those sera were also positive in AID. The determined 34.7% positivity substantiated the importance of serodiagnosis for the intravital diagnosis of caseous lymphadenitis of sheep, particularly of its chronic form. AID and NTX are usable tests for serodiagnosis of this disease.

Animals↗
PubMed1986

Ecology of Rhodococcus (Corynebacterium) equi in soil on a horse-breeding farm.

The ecology of Rhodococcus (Corynebacterium) equi in soil was studied on a horse-breeding farm. R. equi was cultured from soil at a depth of 0, 10, and 20 cm on the six sites of the farm at monthly intervals for 10 months from March to December of 1983. The highest numbers of R. equi were found in the surface soil. The mean number of bacteria in soil samples at every depth increased remarkably from 0 or 10(2) to 10(4) colony-forming units (CFU) g-1 of soil in the middle of April, and later decreased gradually. R. equi inoculated into six soil exudate broths prepared from surface soils at separate sites yielded suspensions with different optical densities, indicating differences in growth. The distribution of serotypes in the soil was similar to that in the horses on the farm. These findings indicated that R. equi could multiply in the soil and flourish in the cycle existing between horses and their soil environment.

Actinomycetales↗