-
BMC Infectious Diseases Dec 2011Rhodococcus equi (R.equi) is an acid fast, GRAM + coccobacillus, which is widespread in the soil and causes pulmonary and extrapulmonary infections in immunocompromised...
BACKGROUND
Rhodococcus equi (R.equi) is an acid fast, GRAM + coccobacillus, which is widespread in the soil and causes pulmonary and extrapulmonary infections in immunocompromised people. In the context of HIV infection, R.equi infection (rhodococcosis) is regarded as an opportunistic disease, and its outcome is influenced by highly active antiretroviral therapy (HAART).
CASE PRESENTATION
We report two cases of HIV-related rhodococcosis that disseminated despite suppressive HAART and anti-rhodococcal treatment; in both cases there was no immunological recovery, with CD4+ cells count below 200/μL. In the first case, pulmonary rhodococcosis presented 6 months after initiation of HAART, and was followed by an extracerebral intracranial and a cerebral rhodococcal abscess 1 and 8 months, respectively, after onset of pulmonary infection. The second case was characterized by a protracted course with spread of infection to various organs, including subcutaneous tissue, skin, colon and other intra-abdominal tissues, and central nervous system; the spread started 4 years after clinical resolution of a first pulmonary manifestation and progressed over a period of 2 years.
CONCLUSIONS
Our report highlights the importance of an effective immune recovery, despite fully suppressive HAART, along with anti-rhodococcal therapy, in order to clear rhodococcal infection.
Topics: AIDS-Related Opportunistic Infections; Actinomycetales Infections; Anti-Bacterial Agents; Antiretroviral Therapy, Highly Active; Female; HIV Infections; Humans; Middle Aged; Rhodococcus equi
PubMed: 22168333
DOI: 10.1186/1471-2334-11-343 -
Respiratory Care Oct 2011Rhodococcus equi is an emerging opportunistic pathogen in immunocompromised patients. A lung-transplant recipient developed weight loss, nonproductive cough, dyspnea,...
Rhodococcus equi is an emerging opportunistic pathogen in immunocompromised patients. A lung-transplant recipient developed weight loss, nonproductive cough, dyspnea, and somnolence. Computed tomogram showed a pulmonary nodule and pleural changes in the right allograft that was due to R. equi infection. Alteration of cell-mediated immunity is a predisposing risk factor for R. equi infection in humans. Our patient developed R. equi infection soon after a course of high-dose corticosteroids for acute allograft infection and animal exposure. A course of intravenous vancomycin followed by single-agent long-term therapy with oral ciprofloxacin was successful.
Topics: Actinomycetales Infections; Anti-Bacterial Agents; Ciprofloxacin; Humans; Immunity, Cellular; Immunocompromised Host; Lung Transplantation; Male; Middle Aged; Postoperative Complications; Pulmonary Disease, Chronic Obstructive; Rhodococcus equi; Solitary Pulmonary Nodule; Tomography, X-Ray Computed; Transplantation, Homologous; Vancomycin
PubMed: 21513607
DOI: 10.4187/respcare.01132 -
Journal of Veterinary Internal Medicine 2001
Topics: Actinomycetales Infections; Animals; Animals, Newborn; Female; Horse Diseases; Horses; Infectious Disease Transmission, Vertical; Pneumonia, Bacterial; Pregnancy; Rhodococcus equi
PubMed: 11380022
DOI: 10.1892/0891-6640(2001)015<0169:eifepo>2.3.co;2 -
PloS One 2013Two closely related bacterial species, Segniliparus rotundus and Segniliparus rugosus, have emerged as important human pathogens, but little is known about the immune... (Comparative Study)
Comparative Study
Two closely related bacterial species, Segniliparus rotundus and Segniliparus rugosus, have emerged as important human pathogens, but little is known about the immune responses they elicit or their comparative pathophysiologies. To determine the virulence and immune responses of the two species, we compared their abilities to grow in phagocytic and non-phagocytic cells. Both species maintained non-replicating states within A549 epithelial cells. S. rugosus persisted longer and multiplied more rapidly inside murine bone marrow-derived macrophages (BMDMs), induced more pro-inflammatory cytokines, and induced higher levels of macrophage necrosis. Activation of BMDMs by both species was mediated by toll-like receptor 2 (TLR2), followed by mitogen-activated protein kinases (MAPK) and nuclear factor κB (NF-κB) signaling pathways, indicating a critical role for TLR2 in Segniliparus-induced macrophage activation. S. rugosus triggered faster and stronger activation of MAPK signaling and IκB degradation, indicating that S. rugosus induces more pro-inflammatory cytokines than S. rotundus. Multifocal granulomatous inflammations in the liver and lung were observed in mice infected with S. rugosus, but S. rotundus was rapidly cleared from all organs tested within 15 days post-infection. Furthermore, S. rugosus induced faster infiltration of innate immune cells such as neutrophils and macrophages to the lung than S. rotundus. Our results suggest that S. rugosus is more virulent and induces a stronger immune response than S. rotundus.
Topics: Actinomycetales; Actinomycetales Infections; Animals; Bone Marrow Cells; Cell Death; Cytokines; Extracellular Signal-Regulated MAP Kinases; Female; Immunity, Cellular; Immunity, Humoral; Intracellular Space; Kinetics; Lung; Macrophages; Mice; Mice, Inbred C57BL; NF-kappa B; Phenotype; Phosphorylation; Signal Transduction; Species Specificity; Toll-Like Receptor 2; p38 Mitogen-Activated Protein Kinases
PubMed: 23555735
DOI: 10.1371/journal.pone.0059646 -
The Journal of Veterinary Medical... Dec 2023Forty-five foals with Rhodococcus equi infection and pneumonia symptoms were classified into a surviving group and a dead group. Using serum samples, the oxidative...
Forty-five foals with Rhodococcus equi infection and pneumonia symptoms were classified into a surviving group and a dead group. Using serum samples, the oxidative stress index (OSI) was determined at the first visit and the follow-up visit. The OSI of the surviving group was significantly lower at the follow-up than that at the first visit. No significant difference was observed between the OSI of the dead group at the first and follow-up visits. In the surviving group, treatment at the first visit mitigated inflammation and reduced OSI. However, in the dead group, poor response to the treatment provided at the first visit led to continued inflammation, and no change was observed the OSI.
Topics: Animals; Horses; Rhodococcus equi; Pneumonia, Bacterial; Judgment; Actinomycetales Infections; Horse Diseases; Inflammation; Oxidative Stress
PubMed: 37853622
DOI: 10.1292/jvms.23-0260 -
Emerging Infectious Diseases May 2010Tropheryma whipplei, which causes Whipple disease, is found in human feces and may cause gastroenteritis. To show that T. whipplei causes gastroenteritis, PCRs for T....
Tropheryma whipplei, which causes Whipple disease, is found in human feces and may cause gastroenteritis. To show that T. whipplei causes gastroenteritis, PCRs for T. whipplei were conducted with feces from children 2-4 years of age. Western blotting was performed for samples from children with diarrhea who had positive or negative results for T. whipplei. T. whipplei was found in samples from 36 (15%) of 241 children with gastroenteritis and associated with other diarrheal pathogens in 13 (33%) of 36. No positive specimen was detected for controls of the same age (0/47; p = 0.008). Bacterial loads in case-patients were as high as those in patients with Whipple disease and significantly higher than those in adult asymptomatic carriers (p = 0.002). High incidence in patients and evidence of clonal circulation suggests that some cases of gastroenteritis are caused or exacerbated by T. whipplei, which may be co-transmitted with other intestinal pathogens.
Topics: Actinomycetales Infections; Blotting, Western; Child, Preschool; DNA, Bacterial; Diarrhea; Feces; Female; France; Gastroenteritis; Humans; Incidence; Male; Phylogeny; Polymerase Chain Reaction; Prospective Studies; Tropheryma
PubMed: 20409366
DOI: 10.3201/eid1605.091801 -
Infection and Immunity Oct 2019The soil-dwelling, saprophytic actinomycete is a facultative intracellular pathogen of macrophages and causes severe bronchopneumonia when inhaled by susceptible foals....
The soil-dwelling, saprophytic actinomycete is a facultative intracellular pathogen of macrophages and causes severe bronchopneumonia when inhaled by susceptible foals. Standard treatment for disease is dual-antimicrobial therapy with a macrolide and rifampin. Thoracic ultrasonography and early treatment with antimicrobials prior to the development of clinical signs are used as means of controlling endemic infection on many farms. Concurrently with the increased use of macrolides and rifampin for chemoprophylaxis and the treatment of subclinically affected foals, a significant increase in the incidence of macrolide- and rifampin-resistant isolates has been documented. Previously, our laboratory demonstrated decreased fitness of strains that were resistant to macrolides, rifampin, or both, resulting in impaired growth in iron-restricted media and in soil. The objective of this study was to examine the effect of macrolide and/or rifampin resistance on intracellular replication of in equine pulmonary macrophages and in an mouse infection model in the presence and absence of antibiotics. In equine macrophages, the macrolide-resistant strain did not increase in bacterial numbers over time and the dual macrolide- and rifampin-resistant strain exhibited decreased proliferation compared to the susceptible isolate. In the mouse model, in the absence of antibiotics, the susceptible isolate outcompeted the macrolide- or rifampin-resistant strains.
Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Clarithromycin; Colony Count, Microbial; Drug Resistance, Bacterial; Genetic Fitness; Horses; Liver; Lung; Macrophages, Alveolar; Male; Mice; Mice, Nude; Microbial Sensitivity Tests; Primary Cell Culture; Rhodococcus equi; Rifampin; Spleen
PubMed: 31331959
DOI: 10.1128/IAI.00281-19 -
PLoS Pathogens Sep 2021Rhodococcus equi is a major cause of foal pneumonia and an opportunistic pathogen in immunocompromised humans. While alveolar macrophages constitute the primary...
Rhodococcus equi is a major cause of foal pneumonia and an opportunistic pathogen in immunocompromised humans. While alveolar macrophages constitute the primary replicative niche for R. equi, little is known about how intracellular R. equi is sensed by macrophages. Here, we discovered that in addition to previously characterized pro-inflammatory cytokines (e.g., Tnfa, Il6, Il1b), macrophages infected with R. equi induce a robust type I IFN response, including Ifnb and interferon-stimulated genes (ISGs), similar to the evolutionarily related pathogen, Mycobacterium tuberculosis. Follow up studies using a combination of mammalian and bacterial genetics demonstrated that induction of this type I IFN expression program is largely dependent on the cGAS/STING/TBK1 axis of the cytosolic DNA sensing pathway, suggesting that R. equi perturbs the phagosomal membrane and causes DNA release into the cytosol following phagocytosis. Consistent with this, we found that a population of ~12% of R. equi phagosomes recruits the galectin-3,-8 and -9 danger receptors. Interestingly, neither phagosomal damage nor induction of type I IFN require the R. equi's virulence-associated plasmid. Importantly, R. equi infection of both mice and foals stimulates ISG expression, in organs (mice) and circulating monocytes (foals). By demonstrating that R. equi activates cytosolic DNA sensing in macrophages and elicits type I IFN responses in animal models, our work provides novel insights into how R. equi engages the innate immune system and furthers our understanding how this zoonotic pathogen causes inflammation and disease.
Topics: Actinomycetales Infections; Animals; Cytosol; DNA; Female; Horse Diseases; Horses; Immunity, Innate; Interferon Type I; Macrophages; Male; Mice; Rhodococcus equi
PubMed: 34473814
DOI: 10.1371/journal.ppat.1009888 -
Head and Neck Pathology Dec 2011Infectious pseudotumors are unusual proliferations of histiocytes in response to certain microbial organisms. Occasionally this process may involve large airways,... (Review)
Review
Infectious pseudotumors are unusual proliferations of histiocytes in response to certain microbial organisms. Occasionally this process may involve large airways, producing a mass lesion that may cause respiratory obstruction. Infectious pseudotumors can be confused with malignancy in their radiologic appearance and clinical presentation. We present a case of an aggressive endotracheal pseudotumor associated with Rhodococcus equi infection in a patient with advanced HIV disease. Microscopically, the lesion was composed of sheets of epithelioid histiocytes with large, strongly eosinophilic intra-cytoplasmic granules and features of malakoplakia. In this report, we review the literature of these unusual lesions and compare them to cases of conventional malakoplakia involving the large airways. We also explore the pathogenetic mechanisms that may contribute to the distinctive histologic appearance of Rhodococcus-associated pseudotumors.
Topics: AIDS-Related Opportunistic Infections; Actinomycetales Infections; Diagnosis, Differential; HIV Infections; Histiocytes; Humans; Larynx; Malacoplakia; Male; Middle Aged; Rhodococcus equi; Trachea
PubMed: 21519873
DOI: 10.1007/s12105-011-0259-x -
Revista Argentina de Microbiologia 2020We report the case of a twenty-year-old immunocompetent male patient presenting to the emergency room with pharyngitis and fever. Blood cultures were drawn and...
We report the case of a twenty-year-old immunocompetent male patient presenting to the emergency room with pharyngitis and fever. Blood cultures were drawn and Arcanobacterium haemolyticum (rough biotype) was recovered. The presence of the arcanolysin gene was investigated at the molecular level and the upstream region was amplified and sequenced in order to correlate it with the smooth or rough biotype. Although the isolate was susceptible to penicillin, vancomycin and gentamicin, empirical treatments first with amoxicillin/clavulanic acid (1g/12h) and then with ceftriaxone (1g/12h) failed and the infection evolved to sepsis. Finally, treatment with vancomycin (1g/12h) plus piperacillin/tazobactam (4.5g/8h) was effective. Lemierre's syndrome was ruled out. To the best of our knowledge, this is the first case of bacteremia by A. haemolyticum reported in Argentina.
Topics: Actinomycetales Infections; Adult; Arcanobacterium; Bacteremia; Humans; Male; Sepsis; Young Adult
PubMed: 32201068
DOI: 10.1016/j.ram.2020.01.001