-
Veterinary Research 2004Rhodococcus equi is an important cause of subacute or chronic abscessating bronchopneumonia of foals up to 3-5 months of age. It shares the lipid-rich cell wall envelope... (Review)
Review
Rhodococcus equi is an important cause of subacute or chronic abscessating bronchopneumonia of foals up to 3-5 months of age. It shares the lipid-rich cell wall envelope characteristic of the mycolata, including Mycobacterium tuberculosis, as well as the ability of pathogenic members of this group to survive within macrophages. The possession of a large virulence plasmid in isolates recovered from pneumonic foals is crucial for virulence. The plasmid contains an 27 kb pathogenicity island (PI) that encodes seven related virulence-associated proteins (Vaps), including the immunodominant surface-expressed protein, VapA. Only PI genes are differentially expressed when the organism is grown in macrophages in vitro. Ten of the PI genes, including six Vap genes, have signal sequences, suggesting that they are exported from the cell to interact with the macrophage. Different PI genes are regulated by temperature, pH, iron, oxidative stress and probably also by magnesium, all environmental changes encountered after environmental R. equi are inhaled in dust and are ingested into macrophages in the lung. The basis of pathogenicity of R. equi is its ability to multiply in and eventually to destroy alveolar macrophages. Infectivity is largely or exclusively limited to cells of the monocyte-macrophage lineage. Current evidence suggests that infection of foals with virulent R. equi results in some foals in subversion of cell-mediated immunity and development of an ineffective and sometimes lethal Th2-based immune response. Significant progress has been made recently in the development of R. equi-E. coli shuttle vectors, transformation and random and site specific mutagenesis procedures, all of which will be important in molecular dissection of the mechanisms by which R. equi subverts normal macrophage killing mechanisms and cell-mediated immunity.
Topics: Actinomycetales Infections; Animals; Animals, Newborn; Bronchopneumonia; Horse Diseases; Horses; Rhodococcus equi
PubMed: 15236672
DOI: 10.1051/vetres:2004024 -
Molecular Microbiology Jul 2019Rhodococcus equi is the only recognized animal pathogenic species within an extended genus of metabolically versatile Actinobacteria of considerable biotechnological... (Review)
Review
Rhodococcus equi is the only recognized animal pathogenic species within an extended genus of metabolically versatile Actinobacteria of considerable biotechnological interest. Best known as a horse pathogen, R. equi is commonly isolated from other animal species, particularly pigs and ruminants, and causes severe opportunistic infections in people. As typical in the rhodococci, R. equi niche specialization is extrachromosomally determined, via a conjugative virulence plasmid that promotes intramacrophage survival. Progress in the molecular understanding of R. equi and its recent rise as a novel paradigm of multihost adaptation has been accompanied by an unusual nomenclatural instability, with a confusing succession of names: "Prescottia equi", "Prescotella equi", Corynebacterium hoagii and Rhodococcus hoagii. This article reviews current advances in the genomics, biology and virulence of this pathogenic actinobacterium with a unique mechanism of plasmid-transferable animal host tropism. It also discusses the taxonomic and nomenclatural issues around R. equi in the light of recent phylogenomic evidence that confirms its membership as a bona fide Rhodococcus.
Topics: Actinomycetales Infections; Animals; Genomics; Horses; Phylogeny; Plasmids; Rhodococcus; Rhodococcus equi; Swine; Virulence
PubMed: 31099908
DOI: 10.1111/mmi.14267 -
The Veterinary Clinics of North... Dec 2014Pneumonia caused by Rhodococcus equi is an important cause of disease and death in foals. This article reviews current knowledge of the epidemiology, clinical signs,... (Review)
Review
Pneumonia caused by Rhodococcus equi is an important cause of disease and death in foals. This article reviews current knowledge of the epidemiology, clinical signs, diagnosis, treatment, prevention, and control of R equi pneumonia in foals.
Topics: Actinomycetales Infections; Animals; Animals, Newborn; Horse Diseases; Horses; Pneumonia, Bacterial; Rhodococcus equi
PubMed: 25282322
DOI: 10.1016/j.cveq.2014.08.010 -
Microbiology Spectrum Oct 2017Pneumonia caused by remains an important cause of disease and death in foals. The combination of a macrolide (erythromycin, azithromycin, or clarithromycin) with... (Review)
Review
Pneumonia caused by remains an important cause of disease and death in foals. The combination of a macrolide (erythromycin, azithromycin, or clarithromycin) with rifampin has been the recommended treatment for foals with clinical signs of infection caused by since the early 1980s with, until recently, only rare reports of resistance. Resistance to macrolides and rifampin in isolates of cultured from horses is increasing, with isolates resistant to all macrolides and rifampin now being cultured from up to 40% of infected foals at some farms. This text reviews the available data regarding antimicrobial resistance in , with emphasis on the molecular mechanisms of the recent emergence of resistance to macrolides and rifampin in equine isolates of .
Topics: Animal Diseases; Animals; Anti-Bacterial Agents; Azithromycin; Clarithromycin; Drug Combinations; Drug Resistance, Bacterial; Erythromycin; Fluoroquinolones; Horses; Lincosamides; Macrolides; Microbial Sensitivity Tests; Rhodococcus equi; Rifampin; Streptogramin B
PubMed: 29052538
DOI: 10.1128/microbiolspec.ARBA-0004-2016 -
The Veterinary Clinics of North... Aug 1993This article summarizes recent advances in understanding of the epidemiology, pathogenesis, clinical and laboratory diagnosis, immunology, treatment, and control of... (Review)
Review
This article summarizes recent advances in understanding of the epidemiology, pathogenesis, clinical and laboratory diagnosis, immunology, treatment, and control of Rhodococcus equi infections in foals. Our understanding of these aspects currently is sufficient to ensure control of this problem on affected farms and in infected foals. More information, however, is needed on factors predisposing foals to R. equi pneumonia, in particular, the nature of the naturally occurring cellular immunodeficiency in foals of 2 to 4 months of age, which also predisposes them to severe respiratory infection with certain other intracellular pathogens. In addition, the relative importance of R. equi pneumonia in the context of other causes of lower respiratory tract infection of foals needs to be defined.
Topics: Actinomycetales Infections; Animals; Horse Diseases; Horses; Rhodococcus equi
PubMed: 8358650
DOI: 10.1016/s0749-0739(17)30404-2 -
Veterinary Microbiology Nov 2013Rhodococcus equi is a soil-dwelling pathogenic actinomycete that causes pulmonary and extrapulmonary pyogranulomatous infections in a variety of animal species and... (Review)
Review
Rhodococcus equi is a soil-dwelling pathogenic actinomycete that causes pulmonary and extrapulmonary pyogranulomatous infections in a variety of animal species and people. Young foals are particularly susceptible and develop a life-threatening pneumonic disease that is endemic at many horse-breeding farms worldwide. R. equi is a facultative intracellular parasite of macrophages that replicates within a modified phagocytic vacuole. Its pathogenicity depends on a virulence plasmid that promotes intracellular survival by preventing phagosome-lysosome fusion. Species-specific tropism of R. equi for horses, pigs and cattle appears to be determined by host-adapted virulence plasmid types. Molecular epidemiological studies of these plasmids suggest that human R. equi infection is zoonotic. Analysis of the recently determined R. equi genome sequence has identified additional virulence determinants on the bacterial chromosome. This review summarizes our current understanding of the clinical aspects, biology, pathogenesis and immunity of this fascinating microbe with plasmid-governed infectivity.
Topics: Actinomycetales Infections; Animals; Horse Diseases; Horses; Host Specificity; Humans; Phagocytosis; Plasmids; Rhodococcus equi
PubMed: 23993705
DOI: 10.1016/j.vetmic.2013.06.016 -
Journal of Veterinary Internal Medicine 2011Pneumonia is a major cause of disease and death in foals. Rhodococcus equi, a gram-positive facultative intracellular pathogen, is a common cause of pneumonia in foals.... (Review)
Review
Pneumonia is a major cause of disease and death in foals. Rhodococcus equi, a gram-positive facultative intracellular pathogen, is a common cause of pneumonia in foals. This article reviews the clinical manifestations of infection caused by R. equi in foals and summarizes current knowledge regarding mechanisms of virulence of, and immunity to, R. equi. A complementary consensus statement providing recommendations for the diagnosis, treatment, control, and prevention of infections caused by R. equi in foals can be found in the same issue of the Journal.
Topics: Actinomycetales Infections; Animals; Horse Diseases; Horses; Rhodococcus equi; Virulence
PubMed: 22092609
DOI: 10.1111/j.1939-1676.2011.00804.x -
Microbiology and Molecular Biology... May 2021The development and spread of antimicrobial resistance are major concerns for human and animal health. The effects of the overuse of antimicrobials in domestic animals... (Review)
Review
The development and spread of antimicrobial resistance are major concerns for human and animal health. The effects of the overuse of antimicrobials in domestic animals on the dissemination of resistant microbes to humans and the environment are of concern worldwide. is an ideal model to illustrate the spread of antimicrobial resistance at the animal-human-environment interface because it is a natural soil saprophyte that is an intracellular zoonotic pathogen that produces severe bronchopneumonia in many animal species and humans. Globally, is most often recognized as causing severe pneumonia in foals that results in animal suffering and increased production costs for the many horse-breeding farms where the disease occurs. Because highly effective preventive measures for are lacking, thoracic ultrasonographic screening and antimicrobial chemotherapy of subclinically affected foals have been used for controlling this disease during the last 20 years. The resultant increase in antimicrobial use attributable to this "screen-and-treat" approach at farms where the disease is endemic has likely driven the emergence of multidrug-resistant (MDR) in foals and their environment. This review summarizes the factors that contributed to the development and spread of MDR , the molecular epidemiology of the emergence of MDR , the repercussions of MDR for veterinary and human medicine, and measures that might mitigate antimicrobial resistance at horse-breeding farms, such as alternative treatments to traditional antibiotics. Knowledge of the emergence and spread of MDR is of broad importance for understanding how antimicrobial use in domestic animals can impact the health of animals, their environment, and human beings.
Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Drug Resistance, Multiple; Humans; Rhodococcus equi; Soil
PubMed: 33853933
DOI: 10.1128/MMBR.00011-21 -
Clinical Microbiology and Infection :... Mar 2019Rhodococcus equi is a recognized cause of disease in humans, especially in individuals who are immunocompromised. Because diphtheroids are regarded as part of normal... (Review)
Review
BACKGROUND
Rhodococcus equi is a recognized cause of disease in humans, especially in individuals who are immunocompromised. Because diphtheroids are regarded as part of normal respiratory flora, the importance of R. equi as a pulmonary pathogen may not be fully appreciated and its prevalence may be underestimated. Most treatment recommendations for R. equi infection were established before antiretroviral drugs became available for human immunodeficiency virus/AIDS therapy, and therapeutic strategies may need to be updated.
OBJECTIVES
To review the role of R. equi as a cause of pulmonary infection; to highlight its importance for clinicians and microbiologists; and to challenge current approaches to treatment, whether in immunodeficient or immunocompetent individuals.
SOURCES
A PubMed search using combinations of the following terms: 'Rhodococcus (automatically including Corynebacterium) equi' AND 'pneumonia' OR 'pulmonary' infection, then cross-checking references in the resulting cases, case series and reviews.
CONTENT
We provide a review that details the challenges in the diagnosis, microbiology and pathogenesis of pulmonary infection caused by R. equi and the options for treatment.
IMPLICATIONS
Ten to 14 days of treatment may be effective for pneumonia due to R. equi. Our review suggests that longer courses of therapy are needed for cavitary lesions and lung masses. However, recommendations for excessively prolonged treatment of all pulmonary infections arose during a time when many cases occurred in individuals with AIDS and before effective antiretroviral therapy was available. We suggest that the rationale for prolonged therapy with multiple antibiotics needs to be re-evaluated.
Topics: AIDS-Related Opportunistic Infections; Actinomycetales Infections; Anti-Bacterial Agents; Disease Management; Humans; Immunocompromised Host; Lung; Pneumonia, Bacterial; Rhodococcus equi
PubMed: 29777923
DOI: 10.1016/j.cmi.2018.04.033 -
Veterinary Journal (London, England :... Apr 2012Rhodococcus equi pneumonia is a worldwide infectious disease of major concern to the equine breeding industry. The disease typically manifests in foals as... (Review)
Review
Rhodococcus equi pneumonia is a worldwide infectious disease of major concern to the equine breeding industry. The disease typically manifests in foals as pyogranulomatous bronchopneumonia, resulting in significant morbidity and mortality. Inhalation of aerosolised virulent R. equi from the environment and intracellular replication within alveolar macrophages are essential components of the pathogenesis of R. equi pneumonia in the foal. Recently documented evidence of airborne transmission between foals indicates the potential for an alternative contagious route of disease transmission. In the first of this two-part review, the complexity of the host, pathogen and environmental interactions that underpin R. equi pneumonia will be discussed through an exploration of current understanding of the epidemiology and pathogenesis of R. equi pneumonia in the foal.
Topics: Actinomycetales Infections; Age Factors; Animals; Animals, Newborn; Bronchopneumonia; Horse Diseases; Horses; Host-Pathogen Interactions; Pneumonia, Bacterial; Prevalence; Rhodococcus equi; Virulence
PubMed: 22015138
DOI: 10.1016/j.tvjl.2011.08.014